The Experts below are selected from a list of 843 Experts worldwide ranked by ideXlab platform
Che Ok Jeon - One of the best experts on this subject based on the ideXlab platform.
-
Dynamics of microbial communities and metabolites in ganjang, a traditional Korean fermented soy sauce, during fermentation.
Food microbiology, 2020Co-Authors: Dong Min Han, Byung Hee Chun, Tingye Feng, Hyung Min Kim, Che Ok JeonAbstract:Six different ganjang batches were prepared and the microbial communities in the ganjang samples and raw materials (meju and solar salts), as well as the metabolites generated during fermentation were analyzed. The varying amounts of raw materials used differentially affected the microbial communities. Halophilic or halotolerant microbes derived from solar salts were abundant during middle or late fermentation. By contrast, non-halophilic microbes derived from meju were abundant mainly during early fermentation. Debaryomyces, Tetragenococcus, and Staphylococcus were abundant in all ganjang batches, which suggested that these may be the most common microbes involved in ganjang fermentation. The salt concentrations did not affect the abundance of Debaryomyces, which was abundant in all ganjang batches. Tetragenococcus was abundant in low salt ganjang, whereas Staphylococcus was abundant in high salt ganjang. Metabolite analysis revealed that carbohydrate concentrations were high in ganjang prepared using high amounts of meju. The level of lactate, which may be largely produced by Tetragenococcus, in low salt ganjang was high because of high microbial activity. The amino acid concentrations of the ganjang batches were mainly associated with meju quantity, but not salt concentration. These results indicated that the production of amino acids may be associated with indigenous proteases in meju, but not microbial activities during ganjang fermentation.
-
Genomic and metabolic features of Tetragenococcus halophilus as revealed by pan-genome and transcriptome analyses.
Food microbiology, 2019Co-Authors: Byung Hee Chun, Kyung Hyun Kim, Sang Eun Jeong, Dong Min Han, Dongbin Park, Che Ok JeonAbstract:The genomic and metabolic diversity and features of Tetragenococcus halophilus, a moderately halophilic lactic acid bacterium, were investigated by pan-genome, transcriptome, and metabolite analyses. Phylogenetic analyses based on the 16S rRNA gene and genome sequences of 15 T. halophilus strains revealed their phylogenetic distinctness from other Tetragenococcus species. Pan-genome analysis of the T. halophilus strains showed that their carbohydrate metabolic capabilities were diverse and strain dependent. Aside from one histidine decarboxylase gene in one strain, no decarboxylase gene associated with biogenic amine production was identified from the genomes. However, T. halophilus DSM 20339T produced tyramine without a biogenic amine-producing decarboxylase gene, suggesting the presence of an unidentified tyramine-producing gene. Our reconstruction of the metabolic pathways of these strains showed that T. halophilus harbors a facultative lactic acid fermentation pathway to produce l-lactate, ethanol, acetate, and CO2 from various carbohydrates. The transcriptomic analysis of strain DSM 20339T suggested that T. halophilus may produce more acetate via the heterolactic pathway (including d-ribose metabolism) at high salt conditions. Although genes associated with the metabolism of glycine betaine, proline, glutamate, glutamine, choline, and citrulline were identified from the T. halophilus genomes, the transcriptome and metabolite analyses suggested that glycine betaine was the main compatible solute responding to high salt concentration and that citrulline may play an important role in the coping mechanism against high salinity-induced osmotic stresses. Our results will provide a better understanding of the genome and metabolic features of T. halophilus, which has implications for the food fermentation industry.
-
Tetragenococcus halophilus MJ4 as a starter culture for repressing biogenic amine (cadaverine) formation during saeu-jeot (salted shrimp) fermentation
Food microbiology, 2019Co-Authors: Kyung Hyun Kim, Hee Lee, Byung Hee Chun, Sang Eun Jeong, Che Ok JeonAbstract:Biogenic amines (BAs) are frequently present in traditionally fermented salted foods. In this study, a Tetragenococcus halophilus strain (MJ4) with no BA-producing ability was isolated from a fish (anchovy) sauce. Strain MJ4 did not produce BAs from supplied precursors and no BA-producing genes were identified in its genome. Bacterial community analysis showed that in non-inoculated saeu-jeot (shrimp sauce) fermentation, Tetragenococcus predominated after 82 days, while in strain MJ4-inoculated saeu-jeot, Tetragenococcus predominated during the entire fermentation. Strain MJ4 repressed the growth of T. muriaticus, a known BA producer, during fermentation, but metabolite analysis demonstrated that metabolite profiles, including amino acids, were similar regardless of MJ4 inoculation. The metabolite analysis also showed that strain MJ4 clearly repressed the formation of cadaverine during fermentation. This study suggests that the use of strain MJ4 as a starter culture in salted fish fermentation may be a good strategy for the reduction of BA formation.
-
Functional Characterization of Bacterial Communities Responsible for Fermentation of Doenjang: A Traditional Korean Fermented Soybean Paste
Frontiers in microbiology, 2016Co-Authors: Woo Yong Jung, Ji Young Jung, Hyo Jung Lee, Che Ok JeonAbstract:Doenjang samples were prepared in triplicate and their microbial abundance, bacterial communities, and metabolites throughout fermentation were analyzed to investigate the functional properties of microorganisms in doenjang. Viable bacterial cells were approximately three orders of magnitude higher than fungal cells, suggesting that bacteria are more responsible for doenjang fermentation. Pyrosequencing and proton nuclear magnetic resonance spectroscopy were applied for the analysis of bacterial communities and metabolites, respectively. Bacterial community analysis based on 16S rRNA gene sequences revealed that doenjang samples included Bacillus, Enterococcus, Lactobacillus, Clostridium, Staphylococcus, Corynebacterium, Oceanobacillus, and Tetragenococcus. These genera were found either in doenjang-meju or solar salts, but not in both, suggesting two separate sources of bacteria. Bacillus and Enterococcus were dominant genera during the fermentation, but their abundances were not associated with metabolite changes, suggesting that they may not be major players in doenjang fermentation. Tetragenococcus was dominant in 108 day-doenjang samples, when lactate, acetate, putrescine, and tyramine increased quickly as glucose and fructose decreased, indicating that Tetragenococcus might be primarily responsible for organic acid and biogenic amine production. Lactobacillus was identified as a dominant group from the 179-day samples, associated with the increase of γ-aminobutyric acid (GABA) and the decrease of galactose, indicating a potential role for this genus as a major GABA producer during fermentation. The results of this study clarified the functional properties of major bacterial communities in the doenjang fermentation process, contributing to the production of safe and high-quality doenjang.
-
effects of temperature on bacterial communities and metabolites during fermentation of myeolchi aekjeot a traditional korean fermented anchovy sauce
PLOS ONE, 2016Co-Authors: Ji Young Jung, Byung Hee Chun, Hyo Jung Lee, Che Ok JeonAbstract:Myeolchi-aekjeot (MA) in Korea is produced outdoors without temperature controls, which is a major obstacle to produce commercial MA products with uniform quality. To investigate the effects of temperature on MA fermentation, pH, bacterial abundance and community, and metabolites were monitored during fermentation at 15°C, 20°C, 25°C, and 30°C. Initial pH values were approximately 6.0, and pH values increased after approximately 42 days, with faster increases at higher temperatures. Bacterial abundances increased rapidly in all MA samples after quick initial decreases during early fermentation and then they again steadily decreased after reaching their maxima, which were significantly greater at higher temperatures. Bacterial community analysis revealed that Proteobacteria and Tenericutes were predominant in all initial MA samples, but they were rapidly displaced by Firmicutes as fermentation progressed. Photobacterium and Mycoplasma belonging to Proteobacteria and Tenericutes, respectively, which may include potentially pathogenic strains, were dominant in initial MA, but decreased with the growth of Chromohalobacter, which occurred faster at higher temperatures--they were dominant until 273 and 100 days at 15°C and 20°C, respectively, but not detected after 30 days at 25°C and 30°C. Chromohalobacter also decreased with the appearance of subsequent genera belonging to Firmicutes in all MA samples. Tetragenococcus, halophilic lactic acid bacteria, appeared predominantly at 20°C, 25°C, and 30°C; they were most abundant at 30°C, but not detected at 15°C. Alkalibacillus and Lentibacillus appeared as dominant genera with the decrease of Tetragenococcus at 25°C and 30°C, but only Lentibacillus was dominant at 15°C and 20°C. Metabolite analysis showed that amino acids related to tastes were major metabolites and their concentrations were relatively higher at high temperatures. This study suggests that high temperatures (approximately 30°C) may be appropriate in MA fermentation, in the light of faster disappearance of potentially pathogenic genera, higher amino acids, growth of Tetragenococcus, and faster fermentation.
Annelies Justé - One of the best experts on this subject based on the ideXlab platform.
-
Characterization of Tetragenococcus strains from sugar thick juice reveals a novel species, Tetragenococcus osmophilus sp. nov., and divides Tetragenococcus halophilus into two subspecies, T. halophilus subsp. halophilus subsp. nov. and T. halophilus
International Journal of Systematic and Evolutionary Microbiology, 2012Co-Authors: Annelies Justé, Bart Lievens, S. Van Trappen, Christel Verreth, Ilse Cleenwerck, P. De Vos, Kris WillemsAbstract:Most bacteria recovered so far from sugar thick juice during storage represent strains of the species Tetragenococcus halophilus. Recently, several Gram-positive, non-motile, non-spore-forming cocci with other physiological and genetic traits were isolated from sugar thick juice samples from different origins. In this study, representative isolates were investigated using a polyphasic taxonomic approach. The 16S rRNA gene sequence similarity between these isolates and their closest relative, Tetragenococcus muriaticus, was 97.4 %. The level of DNA–DNA relatedness between isolate T1T, representing the newly found Tetragenococcus isolates, and T. muriaticus was 57 %. Isolate T1T had a DNA G+C content of 36.7 mol%. Phylogenetic data and genomic and phenotypic features demonstrated that the isolates represent a novel species, for which the name Tetragenococcus osmophilus sp. nov. is proposed with T1T as the type strain ( = LMG 26041T = DSM 23765T). Additionally, T. halophilus isolates from high-salt and high-sugar environments showed clear differences in several physiological and genetic characteristics like RAPD fingerprints and 16S rRNA gene sequences. DNA–DNA hybridizations, however, showed 79 to 80 % relatedness between osmophilic and halophilic T. halophilus isolates, demonstrating that the different strains belong to the same species. Based on the phenotypic and genotypic differences observed, as well as the different origins of the strains and the industrial relevance of thick juice degradation, two subspecies of T. halophilus are described in this manuscript: T. halophilus subsp. halophilus subsp. nov. for the strains isolated from salt media and T. halophilus subsp. flandriensis subsp. nov. for the strains isolated from sugar-rich environments, which were first isolated in Flanders, Belgium. The type strains for the subspecies are IAM 1676T ( = LMG 11490T = DSM 20339T) and T5T ( = LMG 26042T = DSM 23766T), respectively.
-
Development of a DNA Array for the Simultaneous Detection and Identification of Sugar Thick Juice Bacterial Contaminants
Food Analytical Methods, 2011Co-Authors: Annelies Justé, Bart Lievens, Ingeborg Frans, Michael Klingeberg, Chris W. Michiels, Kris A. WillemsAbstract:Despite the use of generally accepted good storage practices, sugar thick juice degradation caused by microbiological contamination occasionally occurs, causing considerable financial loss. In this study, a DNA array was developed for simultaneous detection and identification of the most prominent microflora present during thick juice storage, which may cause degradation of the thick juice. Specific oligonucleotides were developed for several bacterial taxa, including the genera Bacillus , Kocuria , Staphylococcus and Tetragenococcus and the species Aerococcus viridans , Leuconostoc mesenteroides and Tetragenococcus halophilus . The DNA array was validated using both pure cultures and industrial samples. In addition, comparisons were made between the developed array, PCR assays specifically targeting the thick juice contaminants and classical microbial platings. The array was found to be reliable and sensitive enough to detect and identify the target bacteria. In addition, the array was used to monitor the target microbial populations in thick juice during long-term storage and degradation. Results are discussed in relation to DNA stability in thick juice.
-
sugar- and salt-rich environments
2008Co-Authors: Annelies Justé, Bart Lievens, Ingeborg Frans, Terence L. Marsh, Michael Klingeberg, Chris W. Michiels, Kris A. WillemsAbstract:Tetragenococcus halophilus strains isolated fro
-
Genetic and physiological diversity of Tetragenococcus halophilus strains isolated from sugar- and salt-rich environments.
Microbiology (Reading England), 2008Co-Authors: Annelies Justé, Bart Lievens, Ingeborg Frans, Terence L. Marsh, Michael Klingeberg, Chris W. Michiels, Kris A. WillemsAbstract:Tetragenococcus halophilus is known to flourish in extreme salt environments. Recently, this halophilic bacterium also appeared as the dominant microflora during storage of sugar thick juice, an intermediate product of beet sugar production. Although T. halophilus can cause degradation of thick juice, dominance of this bacterium does not always result in degradation. In this study T. halophilus strains from high-salt and high-sugar environments, and in particular from degraded and non-degraded thick juice, were compared in detail. Both physiological and genetic characterization using Biolog, repetitive PCR fingerprinting (rep-PCR) and random amplified polymorphic DNA (RAPD) technology, revealed clear differences between T. halophilus strains isolated from salt- and sugar-rich environments. However, no strain pattern could be specifically and systematically associated with degraded or non-degraded thick juice. Remarkably, halophilic T. halophilus strains were not able to grow in sugar thick juice. Irrespective of the differences between the strains from high-salt or high-sugar environments, DNA-DNA hybridization grouped all strains within the species T. halophilus, except one isolate from sugar thick juice that showed different physiological and genetic characteristics, and that may represent a new species of Tetragenococcus.
-
Predominance of Tetragenococcus halophilus as the cause of sugar thick juice degradation
Food microbiology, 2007Co-Authors: Annelies Justé, Bart Lievens, Terence L. Marsh, M Klingeberg, Christiaan Michiels, Kris WillemsAbstract:The industrial storage of sugar thick juice was simulated on a laboratory scale. Terminal Restriction Fragment Length Polymorphism (T-RFLP) analysis and the application of Clone Libraries in parallel with classical microbiology were used to study the bacterial diversity and all revealed a dominance (>99%) of Tetragenococcus halophilus during storage. The degradation of thick juice correlated with the appearance of l-lactic acid and high concentrations of T. halophilus. In addition, pure cultures of T. halophilus induced degradation of sterile thick juice. A specific PCR was developed to detect T. halophilus and industrial thick juice samples from Belgium, Germany and France all contained T. halophilus, suggesting a consistent association of this organism with thick juice. T. halophilus has been known only as a halophile thus far, and this report is the first to show an association of this organism with a sugar-rich environment.
Bon Kimura - One of the best experts on this subject based on the ideXlab platform.
-
rapid identification of Tetragenococcus halophilus and Tetragenococcus muriaticus important species in the production of salted and fermented foods by matrix assisted laser desorption ionization time of flight mass spectrometry maldi tof ms
Food Control, 2014Co-Authors: Takashi Kuda, Yukino Izawa, Hajime Takahashi, Saori Yoshida, Takashi Koyanagi, Bon KimuraAbstract:Tetragenococcus halophilus and Tetragenococcus muriaticus are moderately halophilic lactic acid bacteria, characteristically grouped as tetrads arrangement of cocci, are found in fermentation period of various salted and fermented foods, such as soy sauce and fish sauce. T. halophilus may be one of the most important contributor to the salted and fermented products. In this study, a MALDI-TOF MS method was developed for the rapid identification of T. halophilus and T. muriaticus. Before the MS analysis, the cells were washed with ethanol and treated with formic acid, then ionized with a matrix: α-cyano-4-hydroxycinnamic acid. The MS peak similarity in each of eleven stock strains of the same species was higher than 78%, and the similarity of the two different species was about 36%. The similarity between the two Tetragenococcus and other lactic acid cocci (LAC) including Tetragenococcus koreensis and Tetragenococcus solitarius, was only 24% and less. The MALDI-TOF MS results were obtained in 30 min, from colonies grown on agar plates for viable counts. The MALDI-TOF MS method is a very rapid, simple and accurate method for discrimination of T. halophilus from T. muriaticus and other LAC, and therefore will be useful for quality control in production of salted and fermented food.
-
suppressive effect of Tetragenococcus halophilus isolated from fish nukazuke on histamine accumulation in salted and fermented fish
Food Chemistry, 2012Co-Authors: Takashi Kuda, Yukino Izawa, Saeko Ishii, Yuko Torido, Hajime Takahashi, Bon KimuraAbstract:Abstract Occasionally, quantities higher than 1000 mg/kg of histamine (Hm) accumulate in salted and fermented fish products by the histidine decarboxylase of halophilic lactococci Tetragenococcus sp. In a total of 200 isolates from fish nukazuke (salted and fermented fish with rice bran), 13 strains produced Hm more than 200 μg/ml in 0.5% histidine containing broth, whereas 130 isolates produced absolutely no Hm. Among the strains, 22 strains suppressed the Hm production of the Hm-forming (HmF) strains. Both the HmF and Hm-suppressing (HmS) strains were identified as Tetragenococcus halophilus. To observe the Hm-suppressing effect, a specified quantity of live cells was needed. In the case of 10% NaCl salted sardine, inoculation with 3 log cells/g of a strain HmF-131 resulted in a significant Hm accumulation, 2800 μg/g in 30 days at 20 °C. The increase in Hm was clearly suppressed by 9 log live cells/g of strain HmS-129. These results suggest that HmS-129 can be used as a starter for salted and fermented fish products, enhancing food safety.
-
comparison of pcr dgge and pcr sscp analysis for bacterial flora of japanese traditional fermented fish products aji narezushi and iwashi nukazuke
Journal of the Science of Food and Agriculture, 2010Co-Authors: Choa An, Hajime Takahashi, Bon Kimura, Takashi KudaAbstract:BACKGROUND: The bacterial flora of two Japanese traditional fermented fish products, aji-narezushi (salted and long-fermented horse mackerel (Trachurus japonicas) with rice) and iwashi-nukazuke (salted and long-fermented sardine (Sardinops melanostica) with rice bran), was analysed using non-culture-based polymerase chain reaction (PCR) denaturing gradient gel electrophoresis (DGGE) and culture-based PCR single-strand conformation polymorphism (SSCP) methods. RESULTS: Viable plate counts in aji-narezushi and iwashi-nukazuke were about 6.3-6.6 and 5.7-6.9 log colony-forming units g(-1) respectively. In the PCR-DGGE analysis, Lactobacillus acidipiscis was detected as the predominant bacterium in two of three aji-narezushi samples, while Lactobacillus versmoldensis was predominant in the third sample. By the PCR-SSCP method, Lb. acidipiscis and Lactobacillus plantarum were isolated as the predominant bacteria, while Lb. versmoldensis was not detected. The predominant bacterium in two of three iwashi-nukazuke samples was Tetragenococcus muriaticus, while Tetragenococcus halophilus was predominant in the third sample. CONCLUSION: The results suggest that the detection of some predominant lactic acid bacteria species in fermented fish by cultivation methods is difficult.
-
comparison of pcr dgge and pcr sscp analysis for bacterial flora of japanese traditional fermented fish products aji narezushi and iwashi nukazuke
Journal of the Science of Food and Agriculture, 2010Co-Authors: Hajime Takahashi, Bon Kimura, Takashi KudaAbstract:BACKGROUND: The bacterial flora of two Japanese traditional fermented fish products, aji-narezushi (salted and long-fermented horse mackerel (Trachurus japonicas) with rice) and iwashi-nukazuke (salted and long-fermented sardine (Sardinops melanostica) with rice bran), was analysed using non-culture-based polymerase chain reaction (PCR) denaturing gradient gel electrophoresis (DGGE) and culture-based PCR single-strand conformation polymorphism (SSCP) methods. RESULTS:Viable plate counts in aji-narezushi and iwashi-nukazuke were about 6.3–6.6 and 5.7–6.9 log colony-forming units g−1 respectively. In the PCR-DGGE analysis, Lactobacillus acidipiscis was detected as the predominant bacterium in two of three aji-narezushi samples, while Lactobacillus versmoldensis was predominant in the third sample. By the PCR-SSCP method, Lb. acidipiscis and Lactobacillus plantarum were isolated as the predominant bacteria, while Lb. versmoldensis was not detected. The predominant bacterium in two of three iwashi-nukazuke samples was Tetragenococcus muriaticus, while Tetragenococcus halophilus was predominant in the third sample. CONCLUSION: The results suggest that the detection of some predominant lactic acid bacteria species in fermented fish by cultivation methods is difficult. Copyright © 2010 Society of Chemical Industry
-
differentiation of Tetragenococcus populations occurring in products and manufacturing processes of puffer fish ovaries fermented with rice bran
International Journal of Food Microbiology, 2000Co-Authors: Takeshi Kobayashi, Bon Kimura, Tateo FujiiAbstract:Abstract Tetragenococcus strains isolated from the manufacturing process of Japanese puffer fish ovaries fermented with rice-bran were characterized and differentiated phenotypically and genotypically. A total of 413 Tetragenococcus isolates were evaluated. On the basis of five representative substrates, the isolates were grouped into seven groups. An RFLP (restriction fragment length polymorphisms) analysis of the 16S rRNA gene of representative strains of major groups revealed that they could be grouped into two groups: one was identified as the most prominent halophilic lactic acid coccus, Tetragenococcus halophilus, and the other as T. muriaticus, which has recently been added to the genus Tetragenococcus as a new species. Physiologically, the major differences between the two groups were found in the ability to grow in medium not supplemented with NaCl and the fermentation of l -arabinose, sucrose and d -mannitol, and several other carbohydrates.
Kris Willems - One of the best experts on this subject based on the ideXlab platform.
-
Characterization of Tetragenococcus strains from sugar thick juice reveals a novel species, Tetragenococcus osmophilus sp. nov., and divides Tetragenococcus halophilus into two subspecies, T. halophilus subsp. halophilus subsp. nov. and T. halophilus
International Journal of Systematic and Evolutionary Microbiology, 2012Co-Authors: Annelies Justé, Bart Lievens, S. Van Trappen, Christel Verreth, Ilse Cleenwerck, P. De Vos, Kris WillemsAbstract:Most bacteria recovered so far from sugar thick juice during storage represent strains of the species Tetragenococcus halophilus. Recently, several Gram-positive, non-motile, non-spore-forming cocci with other physiological and genetic traits were isolated from sugar thick juice samples from different origins. In this study, representative isolates were investigated using a polyphasic taxonomic approach. The 16S rRNA gene sequence similarity between these isolates and their closest relative, Tetragenococcus muriaticus, was 97.4 %. The level of DNA–DNA relatedness between isolate T1T, representing the newly found Tetragenococcus isolates, and T. muriaticus was 57 %. Isolate T1T had a DNA G+C content of 36.7 mol%. Phylogenetic data and genomic and phenotypic features demonstrated that the isolates represent a novel species, for which the name Tetragenococcus osmophilus sp. nov. is proposed with T1T as the type strain ( = LMG 26041T = DSM 23765T). Additionally, T. halophilus isolates from high-salt and high-sugar environments showed clear differences in several physiological and genetic characteristics like RAPD fingerprints and 16S rRNA gene sequences. DNA–DNA hybridizations, however, showed 79 to 80 % relatedness between osmophilic and halophilic T. halophilus isolates, demonstrating that the different strains belong to the same species. Based on the phenotypic and genotypic differences observed, as well as the different origins of the strains and the industrial relevance of thick juice degradation, two subspecies of T. halophilus are described in this manuscript: T. halophilus subsp. halophilus subsp. nov. for the strains isolated from salt media and T. halophilus subsp. flandriensis subsp. nov. for the strains isolated from sugar-rich environments, which were first isolated in Flanders, Belgium. The type strains for the subspecies are IAM 1676T ( = LMG 11490T = DSM 20339T) and T5T ( = LMG 26042T = DSM 23766T), respectively.
-
Predominance of Tetragenococcus halophilus as the cause of sugar thick juice degradation
Food microbiology, 2007Co-Authors: Annelies Justé, Bart Lievens, Terence L. Marsh, M Klingeberg, Christiaan Michiels, Kris WillemsAbstract:The industrial storage of sugar thick juice was simulated on a laboratory scale. Terminal Restriction Fragment Length Polymorphism (T-RFLP) analysis and the application of Clone Libraries in parallel with classical microbiology were used to study the bacterial diversity and all revealed a dominance (>99%) of Tetragenococcus halophilus during storage. The degradation of thick juice correlated with the appearance of l-lactic acid and high concentrations of T. halophilus. In addition, pure cultures of T. halophilus induced degradation of sterile thick juice. A specific PCR was developed to detect T. halophilus and industrial thick juice samples from Belgium, Germany and France all contained T. halophilus, suggesting a consistent association of this organism with thick juice. T. halophilus has been known only as a halophile thus far, and this report is the first to show an association of this organism with a sugar-rich environment.
Jun Huang - One of the best experts on this subject based on the ideXlab platform.
-
Effect of co-culture with Tetragenococcus halophilus on the physiological characterization and transcription profiling of Zygosaccharomyces rouxii.
Food research international (Ottawa Ont.), 2019Co-Authors: Shangjie Yao, Yao Jin, Rongqing Zhou, Jun HuangAbstract:Zygosaccharomyces rouxii and Tetragenococcus halophilus are widely existed and play vital roles during the manufacture of fermented foods such as soy sauce. The aim of this study was to elucidate the effect of T. halophilus CGMCC 3792 on the physiological characterizations and transcription profiling of Z. rouxii CGMCC 3791. Salt tolerance analysis revealed that co-culture with T. halophilus enhanced the salt tolerance of Z. rouxii during salt stress. Analysis of the volatile compounds revealed that co-culture reduced the level of 1-butanol, improved the level of octanoic acid which all were produced by T. halophilus and reduced the level of phenylethyl alcohol produced by Z. rouxii. The presence of Z. rouxii decreased the contents of 3,4-dimethylbenzaldehyde and acetic acid produced by T. halophilus. In addition, co-culture improved the content of benzyl alcohol significantly. Analysis of membrane fatty acid showed that co-culture improved the content of palmitic (C16:0) and stearic (C18:0) acids in cells of Z. rouxii, and reduced the contents of myristic (C14:0), palmitoleic acid (C16:1) and oleic acid (C18:1). In order to further explore the interactions between the two strains, RNA-seq technology was used to investigate the effect of co-culture with T. halophilus on the transcription profiling of Z. rouxii. By comparing cells incubated in co-culture group with cells incubated in single-culture group, a total of 967 genes were considered as differentially expressed genes (DEGs). Among the DEGs, 72 genes were up-regulated, while 895 genes were down-regulated. These DEGs took party in various activities in cells of Z. rouxii, and the result showed co-culture with T. halophilus had a positive effect on proteolysis, the attachment of a cell to another cell, extracellular protein accumulation, energy metabolism, and a negative effect on oxidative phosphorylation, small molecular substances metabolism, DNA replication and repair, and transcription in cells of Z. rouxii. Results presented in this study may contribute to further understand the interactions between Zygosaccharomyces rouxii and Tetragenococcus halophilus.
-
Aflatoxin B1 degradation by salt tolerant Tetragenococcus halophilus CGMCC 3792.
Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association, 2018Co-Authors: Jun Huang, Yao Jin, Dazhan Shen, Suyi Zhang, Rongqing ZhouAbstract:Abstract This study explores aflatoxin B1 (AFB1) degradation by salt tolerant Tetragenococcus halophilus CGMCC 3792 (T. halophilus CGMCC 3792). Six non-toxic degradation products of AFB1 were identified by liquid chromatography/time-of-flight mass spectrometry (LC/TOF-MS), including m/z 243.06 (C14H10O4), 361.09 (C18H16O8), 229.09 (C14H12O3), 277.14 (C16H20O4), 217.12 (C14H16O2), 221.15 (C14H20O2). Two pathways were proposed based on molecular formulas and MS/MS spectra, and the final degradation product was m/z 221.15 (C14H20O2). The degradation ratio of active cell component (66%) and intracellular component (57%) was significantly higher than extracellular component (14%). AFB1 degradation ratio of intracellular component, initially at around 60%, was decreased to 32% after proteinase K treatment, and to 7% after heating, to 9% after proteinase K plus SDS treatment, and to 16% after TFA treatment. It suggests that the AFB1 removal mainly resulted from enzyme biodegradation. The degradation ratio was 92% in AFB1 polluted soy sauce mash. The high degradation ratio of AFB1 by T. halophilus CGMCC 3792 indicates its great potential for application in oriental fermentation condiment process.
-
Metabolic response of Tetragenococcus halophilus under salt stress
Biotechnology and Bioprocess Engineering, 2017Co-Authors: Jun Huang, Rongqing ZhouAbstract:In this study, the effect of salt stress on metabolic response of Tetragenecoccus halophilus was investigated, and the metabolic alternations were analyzed using liquid chromatography-mass spectrometry according to the metabolomics approach. A total of 81 intracellular metabolites were identified, and significant differences were observed in the levels of metabolites mainly participating in central carbon metabolism, fatty acid metabolism, and amino acid metabolism. Analysis of the membrane fatty acid distribution showed that higher proportions of unsaturated fatty acid were observed in salt-treated cells. Additionally, salt-stressed cells exhibited higher amounts of compatible solutes including proline, glycine, citrulline, and N-acetyltyrptophan, and lower amounts of branched-chain amino acids. Interestingly, higher amounts of indole, salicylic acid, and coronatine, which are regarded as signaling molecule and suggested to combat osmotic stress, were detected in salt-shocked cells compared with the untreated cells. Taken together, these results suggested that increased unsaturated membrane fatty acids, accumulation of compatible solutes, and up-regulation of signaling molecule may be potential mechanisms employed by T. halophilus during salt stress.
-
Comparing the differences of characteristic flavour between natural maturation and starter culture for Mucor-type Douchi
International Journal of Food Science & Technology, 2016Co-Authors: Jun Huang, Ru Liang, Rongqing ZhouAbstract:Summary In this research, effects of maturation times on volatiles of Mucor-type Douchi were investigated. Results showed that 2-year matured sample exhibited higher concentrations of characteristic flavours including alcohols, esters, phenols, ketones and pyrazines. Additionally, effects of starter cultures addition on volatiles were investigated, and results demonstrated that inoculated fermented samples presented higher amounts of aldehydes, ketones, phenols and pyrazines compared with that of naturally fermented sample. Analysis of odour activity value (OAV) suggested that increased OAVs of eight compounds that mainly contributed to the flavour of Douchi ranged from onefold to 6.5-fold in the Tetragenococcus halophilus, Zygosaccharomyces rouxii and Candida versatilis co-cultured sample. Furtherly, by comparing the characteristic flavour of co-cultured and 2-year matured samples, no significant difference was observed in the OAV of flavour except rose-like and soapy flavour, which indicated that co-culture of the three strains during Douchi fermentation may facilitate the formation of flavours and shorten the fermentation process.
-
Acid tolerance response of Tetragenococcus halophilus: A combined physiological and proteomic analysis
Process Biochemistry, 2016Co-Authors: Jun Huang, Rongqing ZhouAbstract:Abstract Tetragenococcus halophilus is known to flourish in extreme salt environments, and frequently existed during the manufacture of fermented foods, where various environmental stresses are encountered. In this study, acid tolerance response of T. halophilus was investigated based on physiological and proteomic analysis. The optimal acid-adaptation condition was optimized to stimulate acid tolerance response effectively. After acid adaptation at pH 4.0 for 1 h, the highest survival rate at lethal pH 2.5 was observed. Analysis of the physiological data showed that higher intracellular pH and NH4+ pool were detected in cells adapted at pH 4.0 compared with cells without acid adaptation. In addition, the activities of hexokinase, pyruvate kinase, and lactate dehydrogenase were determined, and significantly higher activities were monitored in cells after acid adaptation. Comparison of the intracellular amino acid pools indicated that six amino acids (glutamate, aspartate, isoleucine, leucine, citrulline, ornithine) exhibited notable alternations during acid treatments, and acid pre-adaption led to higher pools of amino acid compared to that without acid pre-treatment. Proteomic analysis demonstrated that eight proteins (Glk, Pfk, Fba, Gap, Gpm, Eno, Pyk, and Ldh) involved in carbohydrate metabolism and three classic stress response proteins (Ssb, UspA, and GroL) were up-regulated after acid adaptation. Results presented in this study may help to further understand the acid tolerance response in T. halophilus and improve the industrial performance of this species.
