The Experts below are selected from a list of 21894 Experts worldwide ranked by ideXlab platform

Lin Zeng - One of the best experts on this subject based on the ideXlab platform.

  • Amino Sugars Reshape Interactions between Streptococcus mutans and Streptococcus gordonii.
    Applied and environmental microbiology, 2020
    Co-Authors: Lulu Chen, Robert A. Burne, Alejandro R. Walker, Lin Zeng
    Abstract:

    ABSTRACT Amino Sugars, particularly glucosamine (GlcN) and N-acetylglucosamine (GlcNAc), are abundant carbon and nitrogen sources supplied in host secretions and in the diet to the biofilms colonizing the human oral cavity. Evidence is emerging that these Amino Sugars provide ecological advantages to beneficial commensals over oral pathogens and pathobionts. Here, we performed transcriptome analysis on Streptococcus mutans and Streptococcus gordonii growing in single-species or dual-species cultures with glucose, GlcN, or GlcNAc as the primary carbohydrate source. Compared to glucose, GlcN caused drastic transcriptomic shifts in each species of bacteria when it was cultured alone. Likewise, cocultivation in the presence of GlcN yielded transcriptomic profiles that were dramatically different from the single-species results from GlcN-grown cells. In contrast, GlcNAc elicited only minor changes in the transcriptome of either organism in single- and dual-species cultures. Interestingly, genes involved in pyruvate metabolism were among the most significantly affected by GlcN in both species, and these changes were consistent with measurements of pyruvate in culture supernatants. Differing from what was found in a previous report, growth of S. mutans alone with GlcN inhibited the expression of multiple operons required for mutacin production. Cocultivation with S. gordonii consistently increased the expression of two manganese transporter operons (slo and mntH) and decreased expression of mutacin genes in S. mutans. Conversely, S. gordonii appeared to be less affected by the presence of S. mutans but did show increases in genes for biosynthetic processes in the cocultures. In conclusion, Amino Sugars profoundly alter the interactions between pathogenic and commensal streptococci by reprogramming central metabolism. IMPORTANCE Carbohydrate metabolism is central to the development of dental caries. A variety of Sugars available to dental microorganisms influence the development of caries by affecting the physiology, ecology, and pathogenic potential of tooth biofilms. Using two well-characterized oral bacteria, one pathogen (Streptococcus mutans) and one commensal (Streptococcus gordonii), in an RNA deep-sequencing analysis, we studied the impact of two abundant Amino Sugars on bacterial gene expression and interspecies interactions. The results indicated large-scale remodeling of gene expression induced by GlcN in particular, affecting bacterial energy generation, acid production, protein synthesis, and release of antimicrobial molecules. Our study provides novel insights into how Amino Sugars modify bacterial behavior, information that will be valuable in the design of new technologies to detect and prevent oral infectious diseases.

  • Amino Sugars reshape interactions between streptococcus mutans and streptococcus gordonii
    bioRxiv, 2020
    Co-Authors: Lulu Chen, Robert A. Burne, Alejandro R. Walker, Lin Zeng
    Abstract:

    Amino Sugars, particularly glucosamine (GlcN) and N-acetylglucosamine (GlcNAc), are abundant carbon and nitrogen sources that are continually supplied in host secretions and in the diet to the biofilms colonizing the human oral cavity. Evidence is emerging that these Amino Sugars provide ecological advantages to beneficial commensals over oral pathogens and pathobionts. Here, we performed transcriptome analysis on Streptococcus mutans and Streptococcus gordonii growing in single-species or dual-species cultures with glucose, GlcN or GlcNAc as the primary carbohydrate source. Compared to glucose, GlcN caused drastic transcriptomic shifts in each bacterium when they were cultured alone. Likewise, co-cultivation in the presence of GlcN yielded transcriptomic profiles that were dramatically different than the single-species results from GlcN-grown cells. In contrast, GlcNAc elicited only minor changes in the transcriptome of either organism in single- and dual-species cultures. Interestingly, genes involved in pyruvate metabolism were among the most significantly affected by GlcN in both species, and these changes were consistent with measurements of pyruvate in culture supernates. Differing from a previous report, growth of S. mutans alone with GlcN inhibited expression of multiple operons required for mutacin production. Co-cultivation with S. gordonii consistently increased the expression by S. mutans of two manganese transporter operons (slo and mntH) and decreased expression of mutacin genes. Conversely, S. gordonii appeared to be less affected by the presence of S. mutans, but did show increases in genes for biosynthetic processes in the co-cultures. In conclusion, Amino Sugars profoundly alter the interactions between a pathogenic and commensal streptococcus by reprogramming central metabolism.

  • Amino Sugars Modify Antagonistic Interactions between Commensal Oral Streptococci and Streptococcus mutans.
    Applied and environmental microbiology, 2019
    Co-Authors: Lulu Chen, Brinta Chakraborty, Jing Zou, Robert A. Burne, Lin Zeng
    Abstract:

    ABSTRACT N-Acetylglucosamine (GlcNAc) and glucosamine (GlcN) enhance the competitiveness of the laboratory strain DL1 of Streptococcus gordonii against the caries pathogen Streptococcus mutans. Here, we examine how Amino Sugars affect the interaction of five low-passage-number clinical isolates of abundant commensal streptococci with S. mutans by utilizing a dual-species biofilm model. Compared to that for glucose, growth on GlcN or GlcNAc significantly reduced the viability of S. mutans in cocultures with most commensals, shifting the proportions of species. Consistent with these results, production of H2O2 was increased in most commensals when growing on Amino Sugars, and inhibition of S. mutans by Streptococcus cristatus, Streptococcus oralis, or S. gordonii was enhanced by Amino Sugars on agar plates. All commensals except S. oralis had higher arginine deiminase activities when grown on GlcN and, in some cases, GlcNAc. In ex vivo biofilms formed using pooled cell-containing saliva (CCS), the proportions of S. mutans were drastically diminished when GlcNAc was the primary carbohydrate. Increased production of H2O2 could account in large part for the inhibitory effects of CCS biofilms. Surprisingly, Amino Sugars appeared to improve mutacin production by S. mutans on agar plates, suggesting that the commensals have mechanisms to actively subvert antagonism by S. mutans in cocultures. Collectively, these findings demonstrate that Amino Sugars can enhance the beneficial properties of low-passage-number commensal oral streptococci and highlight their potential for moderating the cariogenicity of oral biofilms. IMPORTANCE Dental caries is driven by dysbiosis of oral biofilms in which dominance by acid-producing and acid-tolerant bacteria results in loss of tooth mineral. Our previous work demonstrated the beneficial effects of Amino Sugars GlcNAc and GlcN in promoting the antagonistic properties of a health-associated oral bacterium, Streptococcus gordonii, in competition with the major caries pathogen Streptococcus mutans. Here, we investigated 5 low-passage-number clinical isolates of the most common streptococcal species to establish how Amino Sugars may influence the ecology and virulence of oral biofilms. Using multiple in vitro models, including a human saliva-derived microcosm biofilm, experiments showed significant enhancement by at least one Amino sugar in the ability of most of these bacteria to suppress the caries pathogen. Therefore, our findings demonstrated the mechanism of action by which Amino Sugars may affect human oral biofilms to promote health.

  • Amino Sugars Modify Antagonistic Interactions between Commensal Oral Streptococci and Streptococcus mutans
    2019
    Co-Authors: Lulu Chen, Brinta Chakraborty, Jing Zou, Robert A. Burne, Lin Zeng
    Abstract:

    ABSTRACT N-acetylglucosamine (GlcNAc) and glucosamine (GlcN) enhance the competitiveness of the laboratory strain DL1 of Streptococcus gordonii against the caries pathogen Streptococcus mutans. Here we examine how Amino Sugars affect the interaction of five low-passage clinical isolates of abundant commensal streptococci with S. mutans utilizing a dual-species biofilm model. Compared to glucose, growth on GlcN or GlcNAc significantly reduced the viability of S. mutans in co-cultures with most commensals, shifting the proportions of species. Consistent with these results, production of H2O2 was increased in most commensals when growing on Amino Sugars, and inhibition of S. mutans by Streptococcus cristatus, Streptococcus oralis, or S. gordonii was enhanced by Amino Sugars on agar plates. All commensals except S. oralis had higher arginine deiminase activities when grown on GlcN, and in some cases GlcNAc. In ex vivo biofilms formed using pooled cell-containing saliva (CCS), the proportions of S. mutans were drastically diminished when GlcNAc was the primary carbohydrate. Increased production of H2O2 could account in large part for the inhibitory effects of CCS biofilms. Surprisingly, Amino Sugars appeared to improve mutacin production by S. mutans on agar plates, suggesting that the commensals have mechanisms to actively subvert antagonism by S. mutans in co-cultures. Collectively, these findings demonstrate that Amino Sugars can enhance the beneficial properties of low-passage commensal oral streptococci and highlight their potential for moderating the cariogenicity of oral biofilms. SIGNIFICANCE Dental caries is driven by dysbiosis of oral biofilms in which dominance by acid-producing and acid-tolerant bacteria results in loss of tooth mineral. Our previous work demonstrated the beneficial effects of Amino Sugars, GlcNAc and GlcN, in promoting the antagonistic properties of a health-associated oral bacterium, Streptococcus gordonii, in competition with the major caries pathogen Streptococcus mutans. Here we investigated 5 low-passage clinical isolates of the most common streptococcal species to establish how Amino Sugars may influence the ecology and virulence of oral biofilms. Using multiple in vitro models, including a human saliva-derived microcosm biofilm, experiments showed significant enhancement by at least one Amino sugar in the ability of most of these bacteria to suppress the caries pathogen. Therefore, our findings demonstrated the mechanism of action by which Amino Sugars may affect human oral biofilms to promote health.

  • Amino Sugars Enhance the Competitiveness of Beneficial Commensals with Streptococcus mutans through Multiple Mechanisms
    Applied and environmental microbiology, 2016
    Co-Authors: Lin Zeng, Tanaz Farivar, Robert A. Burne
    Abstract:

    ABSTRACT Biochemical and genetic aspects of the metabolism of the Amino Sugars N-acetylglucosamine (GlcNAc) and glucosamine (GlcN) by commensal oral streptococci and the effects of these Sugars on interspecies competition with the dental caries pathogen Streptococcus mutans were explored. Multiple S. mutans wild-type isolates displayed long lag phases when transferred from glucose-containing medium to medium with GlcNAc as the primary carbohydrate source, but commensal streptococci did not. Competition in liquid coculture or dual-species biofilms between S. mutans and Streptococcus gordonii showed that S. gordonii was particularly dominant when the primary carbohydrate was GlcN or GlcNAc. Transcriptional and enzymatic assays showed that the catabolic pathway for GlcNAc was less highly induced in S. mutans than in S. gordonii. Exposure to H2O2, which is produced by S. gordonii and antagonizes the growth of S. mutans, led to reduced mRNA levels of nagA and nagB in S. mutans. When the gene for the transcriptional regulatory NagR was deleted in S. gordonii, the strain produced constitutively high levels of nagA (GlcNAc-6-P deacetylase), nagB (GlcN-6-P deaminase), and glmS (GlcN-6-P synthase) mRNA. Similar to NagR of S. mutans (NagRSm), the S. gordonii NagR protein (NagRSg) could bind to consensus binding sites (dre) in the nagA, nagB, and glmS promoter regions of S. gordonii. Notably, NagRSg binding was inhibited by GlcN-6-P, but G-6-P had no effect, unlike for NagRSm. This study expands the understanding of Amino sugar metabolism and NagR-dependent gene regulation in streptococci and highlights the potential for therapeutic applications of Amino Sugars to prevent dental caries. IMPORTANCE Amino Sugars are abundant in the biosphere, so the relative efficiency of particular bacteria in a given microbiota to metabolize these sources of carbon and nitrogen might have a profound impact on the ecology of the community. Our investigation reveals that several oral commensal bacteria have a much greater capacity to utilize Amino Sugars than the dental pathogen Streptococcus mutans and that the ability of the model commensal Streptococcus gordonii to compete against S. mutans is substantively enhanced by the presence of Amino Sugars commonly found in the oral cavity. The mechanisms underlying the greater capacity and competitive enhancements of the commensal are shown to depend on how the genes for the catabolic enzymes are regulated, the role of the allosteric modulators affecting such regulation, and the ability of Amino Sugars to enhance certain activities of the commensal that are antagonistic to S. mutans.

Xu Dong Zhang - One of the best experts on this subject based on the ideXlab platform.

  • effects of long term and recently imposed tillage on the concentration and composition of Amino Sugars in a clay loam soil in ontario canada
    Soil & Tillage Research, 2014
    Co-Authors: C F Drury, Bin Zhang, Xueming Yang, Daniel W Reynolds, Xu Dong Zhang
    Abstract:

    Abstract Tillage disturbance influences soil microorganisms and consequently the production and decomposition of microbial residues such as Amino Sugars. However, our understanding is still limited with respect to the changes in Amino Sugars which occur in soil after tillage operations. In this study, changes in Amino Sugars in a clay loam soil (mesic Typic Argiaquoll) in Ontario, Canada were tracked in long-term (29 years) no-tillage (NT), long-term conventional moldboard plow tillage (MP), and long-term bluegrass ( Poa pratensis L.) sod (BG) as well as when long-term (13 years) NT was converted to MP, long-term MP was converted to NT, and long-term BG was converted to MP. Our objective was to determine if the quantity of Amino Sugars in the soil as well as their composition (i.e. whether they originate from bacterial or fungal residues) would respond to changes in tillage practices. We also wanted to evaluate the effects of converting from grassland to arable cropping (corn and soybean) on the Amino sugar composition of soils. Soil samples were collected at depths of 0–5, 5–10, and 10–20 cm after 1 (1997), 6 (2002), 11 (2007), and 16 (2012) years following tillage conversion. Concentrations of Amino Sugars were much greater under long-term BG than under both long-term NT and MP treatments. In the 0–5 cm depth, long-term NT significantly increased total Amino Sugars and fungal-derived glucosamine (GluN) by 18 and 25%, respectively, compared with long-term MP whereas long-term NT had 26% lower MurA concentrations than long-term CT. Concentrations of total Amino Sugars in the 0–5 cm depth were reduced significantly within the first year after conversion of long-term NT and BG to MP, due primarily to decreases in the GluN concentrations. On the other hand, concentrations of Amino Sugars in soil accumulated gradually after conversion of long-term MP to NT. The results confirmed our hypothesis that loss of soil Amino Sugars is rapid and substantial when MP is initiated after NT and BG, while their recovery is gradual when NT is initiated after MP.

  • long term impacts of manure straw and fertilizer on Amino Sugars in a silty clay loam soil under temperate conditions
    Biology and Fertility of Soils, 2013
    Co-Authors: Xueli Ding, Xiaozeng Han, Xu Dong Zhang
    Abstract:

    There is increasing evidence that microorganisms participate in soil C sequestration and stabilization in the form of resistant microbial residues. The type of fertilizers influences microbial activity and community composition; however, little is known about its effect on the microbial residues and their relative contribution to soil C storage. The aim of this study was to investigate the long-term impact (21 years) of different fertilizer treatments (chemical fertilizer, crop straw, and organic manure) on microbial residues in a silty clay loam soil (Udolls, USDA Soil Taxonomy). Amino Sugars were used to indicate the presence and origin of microbial residues. The five treatments were: CK, unfertilized control; NPK, chemical fertilizer NPK; NPKS1, NPK plus crop straw; NPKS2, NPK plus double amounts of straw; and NPKM, NPK plus pig manure. Long-term application of inorganic fertilizers and organic amendments increased the total Amino sugar concentrations (4.4–8.4 %) as compared with the control; and this effect was more evident in the plots that continuously received pig manure (P < 0.05). The increase in total Amino sugar stock was less pronounced in the straw-treated plots than the NPKM. These results indicate that the accumulation of soil Amino Sugars is largely influenced by the type of organic fertilizers entering the soil. Individual Amino sugar enrichment in soil organic carbon was differentially influenced by the various fertilizer treatments, with a preferential accumulation of bacterial-derived Amino Sugars compared with fungal-derived glucosamine in manured soil.

  • Effects of extraneous inorganic nitrogen forms on the dynamics of soil Amino Sugars
    Ying yong sheng tai xue bao = The journal of applied ecology, 2012
    Co-Authors: Wei Zhang, Xu Dong Zhang, Li-chen Zheng, Fu-lin Tian
    Abstract:

    Substrate availability affects microbial growth, whereas extraneous nitrogen forms can significantly affect microbial metabolic processes. As for soil Amino Sugars, the stable residues in microbial cell wall, their synthesis, decomposition and turnover are closely related to the availability of extraneous carbon and nitrogen. Using isotope tracing technique to study soil Amino Sugars can further understand the substrate utilization profiles by soil microorganisms. In this study, two incubation tests were conducted, with glucose plus 15N-labelled NH4+ or NO3- as the substrates, respectively. The 15N enrichment in each kind of soil Amino Sugars was identified by gas chromatography/ mass spectrometry (GC/MS) to trace the dynamics of soil 15N-labelled and native Amino Sugars. During the incubation, the content of soil 15N-labelled Amino Sugars increased significantly, and the transformation rate from NH4+ to Amino Sugars was significantly higher than that from NO3-, suggesting the preferred utilization of NH4+ than NO3- by soil microorganisms. Significant changes in the amounts of soil unlabelled Amino Sugars were observed. The amount of unlabelled glucosamine increased with NH4+ addition, but decreased gradually with NO3- addition. The content of unlabelled muramic acid decreased gradually, especially with NO3- addition. Either the increase or the decrease of galactosamine did not exceed 20% to the original value. These compound-specific changes showed that the heterogeneous microbial residues played different roles on the turnover and stabilization of nitrogen in soil matrix. Fungal cell wall residues were easily accumulated in soil matrix, which benefited the stabilization of soil organic matter, while bacterial cell wall residues were easily degraded, playing an important role in the turnover of soil organic matter.

  • plant n incorporation into microbial Amino Sugars as affected by inorganic n addition a microcosm study of 15n labeled maize residue decomposition
    Soil Biology & Biochemistry, 2011
    Co-Authors: Xueli Ding, Bin Zhang, Xu Dong Zhang
    Abstract:

    Abstract Carbon (C) and/or nitrogen (N) in plant residues can be assimilated into microbial biomass during the plant residue decomposition before incorporation into SOM in the form of microbial residues. Yet, microbial transformation of plant residue-N into microbial residues and the effects of inorganic N inputs on this process have not been well documented. Here, we undertook a 38-week incubation with a silt loam soil amended with a 15N-labeled maize (Zea mays L.) residue to determine how the transformation of maize residue-N into soil Amino Sugars was affected by rates of inorganic N addition. The newly metabolized Amino Sugars derived from maize residue-N were differentiated and quantified by using an isotope-based gas chromatography–mass spectrometry technique. We found that greater amounts of maize residue-N were transformed into Amino Sugars with lower inorganic N addition at the early stages of the plant residue degradation. However, the trend was reversed during later stages of decay as greater percentage of maize residue-N (8.6–9.4%) were enriched in Amino Sugars in the Nmed and Nhigh soils, as compared with N0 and Nlow (7.5–8.2%). This indicated that higher availability of inorganic N could delay the transformation process of plant-N into microbial residues during the mineralization of plant residues. The dynamic transformations of the plant residue-N into individual Amino Sugars were compound-specific, with very fast incorporation into bacterial MurAM-new found during the initial weeks, while the dynamics of maize residue-derived GluN exhibited a delayed response to assimilate plant-N into fungal products. The findings indicated differential contributions of maize residue decomposing microorganisms over time. Moreover, we found no preferential utilization of inorganic N over plant residue-N into Amino Sugars during the incubation course, but inorganic N inputs altered the rate of plant-N accumulation in microbial-derived organic matters. Our results indicated that higher N availability had a positive impact on the accumulation or stabilization of newly-produced microbial residues in the long term.

  • differentiating the dynamics of native and newly immobilized Amino Sugars in soil frequently amended with inorganic nitrogen and glucose
    European Journal of Soil Science, 2011
    Co-Authors: Wei Zhang, Xu Dong Zhang
    Abstract:

    Summary The application of available substrates regulates the soil-microbial environment and thus directly affects microbial metabolic processes. As stable microbial residues, the turnover of soil Amino Sugars is dependent on the availability of fresh inputs of carbon and nitrogen (N), which can be investigated by differentiating between the newly synthesized and the natively resistant fractions by isotope tracing techniques. Therefore, a series of incubations were conducted with soils amended with glucose plus 15 N-labelled inorganic N. The treatments included (i) glucose + 15 NH4 + added once a week, (ii) glucose + 15 NO3 − added once a week and (iii) glucose added once a week, but 15 NH4 + added every 3 weeks. The 15 N enrichment in the target compound was identified by gas chromatography/mass spectrometry (GC/MS) and the dynamics of Amino Sugars were found to be compound-specific in response to different substrate applications. The content of 15 N-containing glucosamine increased significantly across all treatments but the unlabelled portion was decreased only after glucose + 15 NO3 − amendment. The synthesis of 15 N-labelled muramic acid was concomitant with the decomposition of the original unlabelled soil portion and the net accumulation occurred in the glucose + 15 NH4 + treatment. Both the increase and decline of galactosamine content was smaller and showed no significant difference among treatments. Using the dynamics of glucosamine and muramic acid as a basis, the response of different microbial communities to glucose and nitrogen additions was observed. Fungal cell wall residues mainly contributed to the stabilization of soil organic matter, while bacterial cell wall components were easily degraded to provide either carbon or N.

Kai-uwe Hinrichs - One of the best experts on this subject based on the ideXlab platform.

  • Optimizing sample pretreatment for compound-specific stable carbon isotopic analysis of Amino Sugars in marine sediment
    Biogeosciences, 2014
    Co-Authors: Rong Zhu, Yu-shih Lin, Julius S. Lipp, Travis B. Meador, Kai-uwe Hinrichs
    Abstract:

    Amino Sugars are quantitatively significant constituents of soil and marine sediment, but their sources and turnover in environmental samples remain poorly understood. The stable carbon isotopic composition of Amino Sugars can provide information on the lifestyles of their source organisms and can be monitored during incubations with labeled substrates to estimate the turnover rates of microbial populations. However, until now, such investigation has been carried out only with soil samples, partly because of the much lower abundance of Amino Sugars in marine environments. We therefore optimized a procedure for compound-specific isotopic analysis of Amino Sugars in marine sediment, employing gas chromatography–isotope ratio mass spectrometry. The whole procedure consisted of hydrolysis, neutralization, enrichment, and derivatization of Amino Sugars. Except for the derivatization step, the protocol introduced negligible isotopic fractionation, and the minimum requirement of Amino sugar for isotopic analysis was 20 ng, i.e., equivalent to ~8 ng of Amino sugar carbon. Compound-specific stable carbon isotopic analysis of Amino Sugars obtained from marine sediment extracts indicated that glucosamine and galactosamine were mainly derived from organic detritus, whereas muramic acid showed isotopic imprints from indigenous bacterial activities. The δ 13 C analysis of Amino Sugars provides a valuable addition to the biomarker-based characterization of microbial metabolism in the deep marine biosphere, which so far has been lipid oriented and biased towards the detection of archaeal signals.

  • Optimizing sample pretreatment for compound-specific stable carbon isotopic analysis of Amino Sugars in marine sediment
    2014
    Co-Authors: Rong Zhu, Yu-shih Lin, Julius S. Lipp, Travis B. Meador, Kai-uwe Hinrichs
    Abstract:

    Abstract. Amino Sugars are quantitatively significant constituents of soil and marine sediment, but their sources and turnover in environmental samples remain poorly understood. The stable carbon isotopic composition of Amino Sugars can provide information on the lifestyles of their source organisms and can be monitored during incubations with labeled substrates to estimate the turnover rates of microbial populations. However, until now, such investigation has been carried out only with soil samples, partly because of the much lower abundance of Amino Sugars in marine environments. We therefore optimized a procedure for compound-specific isotopic analysis of Amino Sugars in marine sediment employing gas chromatography-isotope ratio mass spectrometry. The whole procedure consisted of hydrolysis, neutralization, enrichment, and derivatization of Amino Sugars. Except for the derivatization step, the protocol introduced negligible isotopic fractionation, and the minimum requirement of Amino sugar for isotopic analysis was 20 ng, i.e. equivalent to ~ 8 ng of Amino sugar carbon. Our results obtained from δ13C analysis of Amino Sugars in selected marine sediment samples showed that muramic acid had isotopic imprints from indigenous bacterial activities, whereas glucosamine and galactosamine were mainly derived from organic detritus. The analysis of stable carbon isotopic compositions of Amino Sugars opens a promising window for the investigation of microbial metabolisms in marine sediments and the deep marine biosphere.

Robert A. Burne - One of the best experts on this subject based on the ideXlab platform.

  • Amino Sugars Reshape Interactions between Streptococcus mutans and Streptococcus gordonii.
    Applied and environmental microbiology, 2020
    Co-Authors: Lulu Chen, Robert A. Burne, Alejandro R. Walker, Lin Zeng
    Abstract:

    ABSTRACT Amino Sugars, particularly glucosamine (GlcN) and N-acetylglucosamine (GlcNAc), are abundant carbon and nitrogen sources supplied in host secretions and in the diet to the biofilms colonizing the human oral cavity. Evidence is emerging that these Amino Sugars provide ecological advantages to beneficial commensals over oral pathogens and pathobionts. Here, we performed transcriptome analysis on Streptococcus mutans and Streptococcus gordonii growing in single-species or dual-species cultures with glucose, GlcN, or GlcNAc as the primary carbohydrate source. Compared to glucose, GlcN caused drastic transcriptomic shifts in each species of bacteria when it was cultured alone. Likewise, cocultivation in the presence of GlcN yielded transcriptomic profiles that were dramatically different from the single-species results from GlcN-grown cells. In contrast, GlcNAc elicited only minor changes in the transcriptome of either organism in single- and dual-species cultures. Interestingly, genes involved in pyruvate metabolism were among the most significantly affected by GlcN in both species, and these changes were consistent with measurements of pyruvate in culture supernatants. Differing from what was found in a previous report, growth of S. mutans alone with GlcN inhibited the expression of multiple operons required for mutacin production. Cocultivation with S. gordonii consistently increased the expression of two manganese transporter operons (slo and mntH) and decreased expression of mutacin genes in S. mutans. Conversely, S. gordonii appeared to be less affected by the presence of S. mutans but did show increases in genes for biosynthetic processes in the cocultures. In conclusion, Amino Sugars profoundly alter the interactions between pathogenic and commensal streptococci by reprogramming central metabolism. IMPORTANCE Carbohydrate metabolism is central to the development of dental caries. A variety of Sugars available to dental microorganisms influence the development of caries by affecting the physiology, ecology, and pathogenic potential of tooth biofilms. Using two well-characterized oral bacteria, one pathogen (Streptococcus mutans) and one commensal (Streptococcus gordonii), in an RNA deep-sequencing analysis, we studied the impact of two abundant Amino Sugars on bacterial gene expression and interspecies interactions. The results indicated large-scale remodeling of gene expression induced by GlcN in particular, affecting bacterial energy generation, acid production, protein synthesis, and release of antimicrobial molecules. Our study provides novel insights into how Amino Sugars modify bacterial behavior, information that will be valuable in the design of new technologies to detect and prevent oral infectious diseases.

  • Amino Sugars reshape interactions between streptococcus mutans and streptococcus gordonii
    bioRxiv, 2020
    Co-Authors: Lulu Chen, Robert A. Burne, Alejandro R. Walker, Lin Zeng
    Abstract:

    Amino Sugars, particularly glucosamine (GlcN) and N-acetylglucosamine (GlcNAc), are abundant carbon and nitrogen sources that are continually supplied in host secretions and in the diet to the biofilms colonizing the human oral cavity. Evidence is emerging that these Amino Sugars provide ecological advantages to beneficial commensals over oral pathogens and pathobionts. Here, we performed transcriptome analysis on Streptococcus mutans and Streptococcus gordonii growing in single-species or dual-species cultures with glucose, GlcN or GlcNAc as the primary carbohydrate source. Compared to glucose, GlcN caused drastic transcriptomic shifts in each bacterium when they were cultured alone. Likewise, co-cultivation in the presence of GlcN yielded transcriptomic profiles that were dramatically different than the single-species results from GlcN-grown cells. In contrast, GlcNAc elicited only minor changes in the transcriptome of either organism in single- and dual-species cultures. Interestingly, genes involved in pyruvate metabolism were among the most significantly affected by GlcN in both species, and these changes were consistent with measurements of pyruvate in culture supernates. Differing from a previous report, growth of S. mutans alone with GlcN inhibited expression of multiple operons required for mutacin production. Co-cultivation with S. gordonii consistently increased the expression by S. mutans of two manganese transporter operons (slo and mntH) and decreased expression of mutacin genes. Conversely, S. gordonii appeared to be less affected by the presence of S. mutans, but did show increases in genes for biosynthetic processes in the co-cultures. In conclusion, Amino Sugars profoundly alter the interactions between a pathogenic and commensal streptococcus by reprogramming central metabolism.

  • Amino Sugars Modify Antagonistic Interactions between Commensal Oral Streptococci and Streptococcus mutans.
    Applied and environmental microbiology, 2019
    Co-Authors: Lulu Chen, Brinta Chakraborty, Jing Zou, Robert A. Burne, Lin Zeng
    Abstract:

    ABSTRACT N-Acetylglucosamine (GlcNAc) and glucosamine (GlcN) enhance the competitiveness of the laboratory strain DL1 of Streptococcus gordonii against the caries pathogen Streptococcus mutans. Here, we examine how Amino Sugars affect the interaction of five low-passage-number clinical isolates of abundant commensal streptococci with S. mutans by utilizing a dual-species biofilm model. Compared to that for glucose, growth on GlcN or GlcNAc significantly reduced the viability of S. mutans in cocultures with most commensals, shifting the proportions of species. Consistent with these results, production of H2O2 was increased in most commensals when growing on Amino Sugars, and inhibition of S. mutans by Streptococcus cristatus, Streptococcus oralis, or S. gordonii was enhanced by Amino Sugars on agar plates. All commensals except S. oralis had higher arginine deiminase activities when grown on GlcN and, in some cases, GlcNAc. In ex vivo biofilms formed using pooled cell-containing saliva (CCS), the proportions of S. mutans were drastically diminished when GlcNAc was the primary carbohydrate. Increased production of H2O2 could account in large part for the inhibitory effects of CCS biofilms. Surprisingly, Amino Sugars appeared to improve mutacin production by S. mutans on agar plates, suggesting that the commensals have mechanisms to actively subvert antagonism by S. mutans in cocultures. Collectively, these findings demonstrate that Amino Sugars can enhance the beneficial properties of low-passage-number commensal oral streptococci and highlight their potential for moderating the cariogenicity of oral biofilms. IMPORTANCE Dental caries is driven by dysbiosis of oral biofilms in which dominance by acid-producing and acid-tolerant bacteria results in loss of tooth mineral. Our previous work demonstrated the beneficial effects of Amino Sugars GlcNAc and GlcN in promoting the antagonistic properties of a health-associated oral bacterium, Streptococcus gordonii, in competition with the major caries pathogen Streptococcus mutans. Here, we investigated 5 low-passage-number clinical isolates of the most common streptococcal species to establish how Amino Sugars may influence the ecology and virulence of oral biofilms. Using multiple in vitro models, including a human saliva-derived microcosm biofilm, experiments showed significant enhancement by at least one Amino sugar in the ability of most of these bacteria to suppress the caries pathogen. Therefore, our findings demonstrated the mechanism of action by which Amino Sugars may affect human oral biofilms to promote health.

  • Amino Sugars Modify Antagonistic Interactions between Commensal Oral Streptococci and Streptococcus mutans
    2019
    Co-Authors: Lulu Chen, Brinta Chakraborty, Jing Zou, Robert A. Burne, Lin Zeng
    Abstract:

    ABSTRACT N-acetylglucosamine (GlcNAc) and glucosamine (GlcN) enhance the competitiveness of the laboratory strain DL1 of Streptococcus gordonii against the caries pathogen Streptococcus mutans. Here we examine how Amino Sugars affect the interaction of five low-passage clinical isolates of abundant commensal streptococci with S. mutans utilizing a dual-species biofilm model. Compared to glucose, growth on GlcN or GlcNAc significantly reduced the viability of S. mutans in co-cultures with most commensals, shifting the proportions of species. Consistent with these results, production of H2O2 was increased in most commensals when growing on Amino Sugars, and inhibition of S. mutans by Streptococcus cristatus, Streptococcus oralis, or S. gordonii was enhanced by Amino Sugars on agar plates. All commensals except S. oralis had higher arginine deiminase activities when grown on GlcN, and in some cases GlcNAc. In ex vivo biofilms formed using pooled cell-containing saliva (CCS), the proportions of S. mutans were drastically diminished when GlcNAc was the primary carbohydrate. Increased production of H2O2 could account in large part for the inhibitory effects of CCS biofilms. Surprisingly, Amino Sugars appeared to improve mutacin production by S. mutans on agar plates, suggesting that the commensals have mechanisms to actively subvert antagonism by S. mutans in co-cultures. Collectively, these findings demonstrate that Amino Sugars can enhance the beneficial properties of low-passage commensal oral streptococci and highlight their potential for moderating the cariogenicity of oral biofilms. SIGNIFICANCE Dental caries is driven by dysbiosis of oral biofilms in which dominance by acid-producing and acid-tolerant bacteria results in loss of tooth mineral. Our previous work demonstrated the beneficial effects of Amino Sugars, GlcNAc and GlcN, in promoting the antagonistic properties of a health-associated oral bacterium, Streptococcus gordonii, in competition with the major caries pathogen Streptococcus mutans. Here we investigated 5 low-passage clinical isolates of the most common streptococcal species to establish how Amino Sugars may influence the ecology and virulence of oral biofilms. Using multiple in vitro models, including a human saliva-derived microcosm biofilm, experiments showed significant enhancement by at least one Amino sugar in the ability of most of these bacteria to suppress the caries pathogen. Therefore, our findings demonstrated the mechanism of action by which Amino Sugars may affect human oral biofilms to promote health.

  • Amino Sugars Enhance the Competitiveness of Beneficial Commensals with Streptococcus mutans through Multiple Mechanisms
    Applied and environmental microbiology, 2016
    Co-Authors: Lin Zeng, Tanaz Farivar, Robert A. Burne
    Abstract:

    ABSTRACT Biochemical and genetic aspects of the metabolism of the Amino Sugars N-acetylglucosamine (GlcNAc) and glucosamine (GlcN) by commensal oral streptococci and the effects of these Sugars on interspecies competition with the dental caries pathogen Streptococcus mutans were explored. Multiple S. mutans wild-type isolates displayed long lag phases when transferred from glucose-containing medium to medium with GlcNAc as the primary carbohydrate source, but commensal streptococci did not. Competition in liquid coculture or dual-species biofilms between S. mutans and Streptococcus gordonii showed that S. gordonii was particularly dominant when the primary carbohydrate was GlcN or GlcNAc. Transcriptional and enzymatic assays showed that the catabolic pathway for GlcNAc was less highly induced in S. mutans than in S. gordonii. Exposure to H2O2, which is produced by S. gordonii and antagonizes the growth of S. mutans, led to reduced mRNA levels of nagA and nagB in S. mutans. When the gene for the transcriptional regulatory NagR was deleted in S. gordonii, the strain produced constitutively high levels of nagA (GlcNAc-6-P deacetylase), nagB (GlcN-6-P deaminase), and glmS (GlcN-6-P synthase) mRNA. Similar to NagR of S. mutans (NagRSm), the S. gordonii NagR protein (NagRSg) could bind to consensus binding sites (dre) in the nagA, nagB, and glmS promoter regions of S. gordonii. Notably, NagRSg binding was inhibited by GlcN-6-P, but G-6-P had no effect, unlike for NagRSm. This study expands the understanding of Amino sugar metabolism and NagR-dependent gene regulation in streptococci and highlights the potential for therapeutic applications of Amino Sugars to prevent dental caries. IMPORTANCE Amino Sugars are abundant in the biosphere, so the relative efficiency of particular bacteria in a given microbiota to metabolize these sources of carbon and nitrogen might have a profound impact on the ecology of the community. Our investigation reveals that several oral commensal bacteria have a much greater capacity to utilize Amino Sugars than the dental pathogen Streptococcus mutans and that the ability of the model commensal Streptococcus gordonii to compete against S. mutans is substantively enhanced by the presence of Amino Sugars commonly found in the oral cavity. The mechanisms underlying the greater capacity and competitive enhancements of the commensal are shown to depend on how the genes for the catabolic enzymes are regulated, the role of the allosteric modulators affecting such regulation, and the ability of Amino Sugars to enhance certain activities of the commensal that are antagonistic to S. mutans.

Bruno Glaser - One of the best experts on this subject based on the ideXlab platform.

  • Improved δ13C analysis of Amino Sugars in soil by ion chromatography–oxidation–isotope ratio mass spectrometry
    Rapid communications in mass spectrometry : RCM, 2014
    Co-Authors: Michaela A. Dippold, Stefanie Boesel, Anna Gunina, Yakov Kuzyakov, Bruno Glaser
    Abstract:

    RATIONALE Amino Sugars build up microbial cell walls and are important components of soil organic matter. To evaluate their sources and turnover, δ(13)C analysis of soil-derived Amino Sugars by liquid chromatography was recently suggested. However, Amino sugar δ(13)C determination remains challenging due to (1) a strong matrix effect, (2) CO2 -binding by alkaline eluents, and (3) strongly different chromatographic behavior and concentrations of basic and acidic Amino Sugars. To overcome these difficulties we established an ion chromatography-oxidation-isotope ratio mass spectrometry method to improve and facilitate soil Amino sugar analysis. METHODS After acid hydrolysis of soil samples, the extract was purified from salts and other components impeding chromatographic resolution. The Amino sugar concentrations and δ(13)C values were determined by coupling an ion chromatograph to an isotope ratio mass spectrometer. The accuracy and precision of quantification and δ(13)C determination were assessed. RESULTS Internal standards enabled correction for losses during analysis, with a relative standard deviation

  • Compound-specific δ13C analysis of individual Amino Sugars : a tool to quantify timing and amount of soil microbial residue stabilization
    Rapid communications in mass spectrometry : RCM, 2005
    Co-Authors: Bruno Glaser, Simone Gross
    Abstract:

    There is strong scientific evidence that microbial residues such as Amino Sugars may be stabilized in soil. However, up to now, no investigation has been carried out to quantify both the amount and timing of such stabilization. This is primarily due to methodological constraints, because it is not possible to differentiate between stabilized (old) and recently produced (new) Amino Sugars when these biomarkers are conventionally analyzed, e.g. by means of gas chromatography and flame ionization detection. Therefore, the aim of the present study was to test whether compound-specific isotope analysis (delta13C) of Amino Sugars extracted from soil could be used to differentiate between old and new microbial residues. For this aim a method for the delta13C analysis of individual Amino Sugars was developed and optimized. First results of delta13C values of glucosamine, galactosamine, mannosamine, and muramic acid in soil samples from two different ecological studies are presented, clearly indicating that discrimination between soil inherent and newly formed Amino Sugars is possible in stable isotope labeling experiments. Our results further showed that, in the short term (within 1 month), only few Amino Sugars were built, thus making highly 13C-enriched substrates necessary for the quantification of new Amino sugar production and for the determination of Amino sugar turnover rates.

  • Amino Sugars and muramic acid biomarkers for soil microbial community structure analysis
    Soil Biology & Biochemistry, 2004
    Co-Authors: Bruno Glaser, Mariabelen Turrion, Kassem Alef
    Abstract:

    Abstract Characterizing functional and phylogenetic microbial community structure in soil is important for understanding the fate of microbially-derived compounds during the decomposition and turn-over of soil organic matter. This study was conducted to test whether Amino Sugars and muramic acid are suitable biomarkers to trace bacterial, fungal, and actinomycetal residues in soil. For this aim, we investigated the pattern, amounts, and dynamics of three Amino Sugars (glucosamine, mannosamine and galactosamine) and muramic acid in the total microbial biomass and selectively cultivated bacteria, fungi, and actinomycetes of five different soils amended with and without glucose. Our results revealed that total Amino sugar and muramic acid concentrations in microbial biomass, extracted from soil after chloroform fumigation varied between 1 and 27 mg kg−1 soil. In all soils investigated, glucose addition resulted in a 50–360% increase of these values. In reference to soil microbial biomass-C, the total Amino sugar- and muramic acid-C concentrations ranged from 1–71 g C kg−1 biomass-C. After an initial lag phase, the cultivated microbes revealed similar Amino sugar concentrations of about 35, 27 and 17 g glucosamine-C kg−1 TOC in bacteria, fungi, and actinomycetes, respectively. Mannosamine and galactosamine concentrations were lower than those for glucosamine. Mannosamine was not found in actinomycete cultures. The highest muramic acid concentrations were found in bacteria, but small amounts were also found in actinomycete cultures. The concentrations of the three Amino Sugars studied and muramic acid differed significantly between bacteria and the other phylogenetic microbial groups under investigation (fungi and actinomycetes). Comparison between the Amino sugar and muramic acid concentrations in soil microbial biomass, extracted after chloroform fumigation, and total concentrations in the soil showed that living microbial biomass contributed negligible amounts to total Amino sugar contents in the soil, being at least two orders of magnitude greater in the soils than in the soil inherent microbial biomass. Thus, Amino Sugars are significantly stabilized in soil.

  • Amino Sugars and muramic acid—biomarkers for soil microbial community structure analysis
    Soil Biology and Biochemistry, 2004
    Co-Authors: Bruno Glaser, Mariabelen Turrion, Kassem Alef
    Abstract:

    Abstract Characterizing functional and phylogenetic microbial community structure in soil is important for understanding the fate of microbially-derived compounds during the decomposition and turn-over of soil organic matter. This study was conducted to test whether Amino Sugars and muramic acid are suitable biomarkers to trace bacterial, fungal, and actinomycetal residues in soil. For this aim, we investigated the pattern, amounts, and dynamics of three Amino Sugars (glucosamine, mannosamine and galactosamine) and muramic acid in the total microbial biomass and selectively cultivated bacteria, fungi, and actinomycetes of five different soils amended with and without glucose. Our results revealed that total Amino sugar and muramic acid concentrations in microbial biomass, extracted from soil after chloroform fumigation varied between 1 and 27 mg kg−1 soil. In all soils investigated, glucose addition resulted in a 50–360% increase of these values. In reference to soil microbial biomass-C, the total Amino sugar- and muramic acid-C concentrations ranged from 1–71 g C kg−1 biomass-C. After an initial lag phase, the cultivated microbes revealed similar Amino sugar concentrations of about 35, 27 and 17 g glucosamine-C kg−1 TOC in bacteria, fungi, and actinomycetes, respectively. Mannosamine and galactosamine concentrations were lower than those for glucosamine. Mannosamine was not found in actinomycete cultures. The highest muramic acid concentrations were found in bacteria, but small amounts were also found in actinomycete cultures. The concentrations of the three Amino Sugars studied and muramic acid differed significantly between bacteria and the other phylogenetic microbial groups under investigation (fungi and actinomycetes). Comparison between the Amino sugar and muramic acid concentrations in soil microbial biomass, extracted after chloroform fumigation, and total concentrations in the soil showed that living microbial biomass contributed negligible amounts to total Amino sugar contents in the soil, being at least two orders of magnitude greater in the soils than in the soil inherent microbial biomass. Thus, Amino Sugars are significantly stabilized in soil.

  • Effects of deforestation on contents and distribution of Amino Sugars within particle-size fractions of mountain soils
    Biology and Fertility of Soils, 2002
    Co-Authors: Mariabelen Turrion, Bruno Glaser, Wolfgang Zech
    Abstract:

    Identifying Amino sugar pools in soil may advance our knowledge about microbially derived substances. Our objective was to study the effects of deforestation followed by pasture establishment on Amino sugar contents and patterns in mountain soils of the Sui Checti Valley in the Alay Range, Kyrgyzia. Soil A horizons (0–10 cm) under pasture and forest were fractionated into clay, silt, fine and coarse sand fractions. Soil organic C, N, glucosamine (GlcN), galactosamine, mannosamine and muramic acid (MurAc) were analysed in the fine earth, particle-size fractions and humus layers. Deforestation of Juniperus turkestanica and pasture establishment led to a significant increase in the Amino sugar content in the fine earth and soil organic matter (SOM) reflecting different accumulation of Amino Sugars in different ecosystems. Deforestation affected principally the Amino Sugars in the coarse and fine sand fractions that generally are related to particulate organic matter. High concentrations of Amino Sugars were found in the clay fraction, corroborating the general assumption that it contains a high microbial biomass and microbially altered organic matter. The pasture soil samples have a significantly higher GlcN to MurAc ratio indicating a higher fungal contribution to SOM than in forest soils. Although other studies revealed that pasture is associated with high amounts of bacterial Amino Sugars, our study gave evidence that deforestation tends to lead to the accumulation of mainly fungi-derived Amino Sugars. It is proposed that this might be due to a lowering of soil pH.