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Amarila Malik - One of the best experts on this subject based on the ideXlab platform.

  • construction and functional analysis of the recombinant bacteriocins weissellicin mbf from Weissella confusa mbf8 1
    Current Pharmaceutical Biotechnology, 2020
    Co-Authors: Amarila Malik, Elita Yuliantie, Nisa Yulianti Suprahman, Theresa Linardi, Angelina Wening Widiyanti, Jeanita Haldy, Catherine Tjia, Hiroshi Takagi
    Abstract:

    BACKGROUND Bacteriocins (Bac1, Bac2, and Bac3) from Weissella confusa MBF8-1, weissellicin- MBF, have been reported as potential alternative substances as well as complements to the existing antibiotics against many antimicrobial-resistant pathogens. Previously, the genes encoded in the large plasmid, pWcMBF8-1, and the spermicidal activity of their synthetic peptides, originally discovered Indonesia, have been studied. Three synthetic bacteriocins peptides of this weissellicin-MBF have been reported for their potential activities, i.e. antibacterial and spermicidal. OBJECTIVE The aim of this study was to construct the recombinant Bacteriocin (r-Bac) genes, as well as to investigate the gene expressions and their functional analysis. METHODS Here, the recombinant Bacteriocin (r-Bac) genes were constructed and the recombinant peptides (r-Bac1, r-Bac2, and r-Bac3) in B. subtilis DB403 cells were produced on a large scale. After purification, using the His-tag affinity column, their potential bioactivities were measured as well as their antibacterial minimum inhibitory concentrations against Leuconostoc mesenteroides and Micrococcus luteus, were determined. RESULTS Pure His-tag-recombinant Bac1, Bac2, and Bac3 were obtained and they could inhibit the growth of L. mesenteroides and M. luteus. CONCLUSION The recombinant bacteriocin could be obtained although with weak activity in inhibiting gram-positive bacterial growth.

  • three bacteriocin peptides from a lactic acid bacterium Weissella confusa mbf8 1 with spermicidal activity
    Current Pharmaceutical Biotechnology, 2019
    Co-Authors: Gusti Sartono, Nicholas C K Heng, Izzatu Rizqiyah, Amarila Malik
    Abstract:

    Background The development of antibiotic resistance amongst bacterial pathogens and a population explosion, e.g. in countries such as Indonesia, are two issues the world is facing today. These issues have stimulated interest in the development of new antimicrobial therapeutic agents and contraceptive strategies, such as novel spermicides. Bacteriocins, which are bacterially-derived antimicrobial peptides, may fulfill some of the criteria for these new agents. Methods Weissella confusa MBF8-1, originally isolated from a homemade soy product, exhibits antibacterial activity that was subsequently found to be plasmid-encoded, presumably by three peptides Bac1, Bac2 and Bac3. In the present study, we tested cell-free MBF8-1 bacteriocin preparations and chemically-synthesized versions of Bac1, Bac2 and Bac3 peptides for (i) its antibacterial activity against the indicator bacterium Leuconostoc mesenteroides and (ii) its ability to affect the motility of spermatozoa. Nisin, a known lantibiotic bacteriocin, was used as the control. Results Here, we demonstrate that synthetic Bac1, in combination with synthetic Bac2, was sufficient to inhibit the growth of L. mesenteroides and affect sperm motility. However, the presence of all three synthetic peptides, s-Bac1, s-Bac2 and s-Bac3, was required for full potency. Conclusion In summary, the bacteriocin-like peptides of W. confusa MBF8-1 have the potential to be developed as a narrow-spectrum antimicrobial agent and a novel spermicidal agent.

  • draft genome sequence of Weissella confusa mbf8 1 a glucansucrase and bacteriocin producing strain isolated from a homemade soy product
    Genome Announcements, 2017
    Co-Authors: Nicholas C K Heng, Chia Wen Yeh, Amarila Malik
    Abstract:

    ABSTRACT We report here the draft genome sequence of Weissella confusa MBF8-1, an isolate from a homemade fermented soybean product that produces sucrases and exhibits antibacterial (bacteriocin) activity. The draft genome of W. confusa MBF8-1 comprises a 2.2-Mbp chromosome and a 17.8-kbp bacteriocin-encoding plasmid. Two putative glucansucrase genes were also identified.

  • identification and sequence analysis of pwcmbf8 1 a bacteriocin encoding plasmid from the lactic acid bacterium Weissella confusa
    Fems Microbiology Letters, 2016
    Co-Authors: Amarila Malik, Chia Wen Yeh, Sumayyah Sumayyah, Nicholas C K Heng
    Abstract:

    Members of the Gram-positive lactic acid bacteria (LAB) are well-known for their beneficial properties as starter cultures and probiotics. Many LAB species produce ribosomally synthesized proteinaceous antibiotics (bacteriocins). Weissella confusa MBF8-1 is a strain isolated from a fermented soybean product that not only produces useful exopolysaccharides but also exhibits bacteriocin activity, which we call weissellicin MBF. Here, we show that bacteriocin production by W. confusa MBF8-1 is specified by a large plasmid, pWcMBF8-1. Plasmid pWcMBF8-1 (GenBank accession number [KR350502][1]), which was identified from the W. confusa MBF8-1 draft genome sequence, is 17 643 bp in length with a G + C content of 34.8% and contains 25 open reading frames (ORFs). Six ORFs constitute the weissellicin MBF locus, encoding three putative double-glycine-motif peptides (Bac1, Bac2, Bac3), an ABC transporter complex (BacTE) and a putative immunity protein (BacI). Two ORFs encode plasmid partitioning and mobilization proteins, suggesting that pWcMBF8-1 is transferable to other hosts. To the best of our knowledge, plasmid pWcMBF8-1 not only represents the first large Weissella plasmid to be sequenced but also the first to be associated with bacteriocin production in W. confusa . [1]: /lookup/external-ref?link_type=GEN&access_num=KR350502&atom=%2Ffemsle%2F363%2F8%2Ffnw059.atom

  • sucrase activity and exopolysaccharide partial characterization from three Weissella confusa strains
    Hayati Journal of Biosciences, 2015
    Co-Authors: Amarila Malik, Sheilla Sheilla, Wangi Firdausi, Tri Lestari Handayani, Endang Saepudin
    Abstract:

    Exopolysaccharides (EPSs) produced by lactic acid bacteria have been well known for their important economic value in food, pharmaceutical and health industries. Large extracellular enzyme sucrases are used by lactic acid bacteria to polymerize EPS, i.e. fructansucrase and glucansucrase. This study aimed to characterize sucrase activity of three Weissella confusa strains MBF8-1, MBF8-2 and MBFCNC-2(1), which were isolated previously from local beverages and their EPS products as well. All strains showed ability to form mucoid and slimy colonies by visual inspection on agar plate using raffinose as substrate suggesting that they possessed fructansucrase activity besides glucansucrase. Obtained EPS products were characterized by HPLC analysis after hydrolysis using 3% TCA at 100C for 1 hour, and by viscosity as well. All strains exhibited similar peak patterns, assuming that all of them possessed fructan EPS product. Supernatant and cell pellet were also analyzed by in situ activity assay performing periodic acid Schiff staining after polyacrylamide gel electrophoresis; only cell pellet showed sucrase activity. Viscosity observation showed that EPS products from all strains were able to increase the viscosity slightly.

Prathapkumar Halady Shetty - One of the best experts on this subject based on the ideXlab platform.

  • preferential growth stimulation of probiotic bacteria by galactan exopolysaccharide from Weissella confusa kr780676
    Food Research International, 2021
    Co-Authors: Palanisamy Bruntha Devi, Digambar Kavitake, Jabastin Jayamanohar, Prathapkumar Halady Shetty
    Abstract:

    Abstract Many microbial exopolysaccharides (EPS) are reported to have prebiotic properties. This study reports the prebiotic properties of a galactan exopolysaccharide produced by Weissella confusa KR780676 of fermented food origin. We have reported potential techno-functional properties of this EPS earlier. We have studied the parameters such as enzymatic hydrolysis, growth proliferation effect on probiotic bacteria and in vitro fecal fermentation to demonstrate the prebiotic property of the galactan. The galactan showed strong resistance to simulated human digestive juices such as α-amylase (99.1%), gastric (98.4%) and intestinal fluid hydrolysis (98.8%). It also encouraged the growth of probiotic bacteria viz, Lactobacillus plantarum MTCC9510 (recently reclassified as Lactiplantibacillus plantarum) and L. fermentum MTCC903 (recently reclassified as Limosilactobacillus fermentum) from 6.69 to 9.45 log CFU/mL and 7.13 to 9.05 log CFU/mL respectively in 72 h of fermentation. Carbohydrate utilization also exhibited the same pattern. Fecal fermentation of galactan for 48 h through in vitro studies exhibited significant changes in microbial population and short chain fatty acids (SCFAs) production. Bifidobacterium sp. and Lactobacillus sp. showed significantly (p ≤ 0.05) higher growth when compared to Enterococcus sp. (9.62 log CFU/mL, 8.45 log CFU/mL and 8.31 log CFU/mL respectively from 6.54 log CFU/mL) at the end of fermentation. SCFAs (acetic acid, butyric acid and propionic acid production) increased significantly (p ≤ 0.05) from 4.53 to 69.12 mM/L, 1.27 to 5.47 mM/L and 0.68 to 42.11 mM/L respectively. These results clearly prove the potential prebiotic property of the galactan EPS and could be used as an effective prebiotic to positively modulate the gut microbiome homeostasis.

  • Report on aflatoxin-binding activity of galactan exopolysaccharide produced by Weissella confusa KR780676
    3 Biotech, 2020
    Co-Authors: Digambar Kavitake, Palanisamy Bruntha Devi, Sujatha Kandasamy, Sanjay Pratap Singh, Prathapkumar Halady Shetty
    Abstract:

    Galactan exopolysaccharide (EPS) produced by Weissella confusa KR780676 isolated from an Indian traditional fermented food has been reported earlier. In this manuscript, we have studied aflatoxin-binding ability of this galactan EPS. Aflatoxin B1 (AFB1) binding ability of galactan EPS was observed in an increasing trend with increasing EPS concentration (20-100 mg/mL). At lower concentrations (< 20 mg/mL) of EPS, the binding activity was undetectable, while notable binding was seen from 30 mg/mL. Enhanced AFB1 binding (32.40%) was recorded at 50 mg/mL of EPS and it increased gradually up to 34.79% at 100 mg/mL concentrations of EPS. The intensity of bands in high-performance thin-layer chromatography (HPTLC) analysis confirms the AFB1 binding efficiency of galactan EPS, which shows its potential application for removal of toxins in food and feed industry. Galactan EPS binding activity to AFB1 is further studied with particle size analysis (PSA). This is the first study reporting the aflatoxin-binding activity of any kind of EPS from lactic acid bacteria.

  • Evaluation of oil-in-water (O/W) emulsifying properties of galactan exopolysaccharide from Weissella confusa KR780676
    Journal of Food Science and Technology, 2020
    Co-Authors: Digambar Kavitake, Palanisamy Bruntha Devi, Sangeeta Balyan, Prathapkumar Halady Shetty
    Abstract:

    Galactan exopolysaccharide (EPS) was extracted from Weissella confusa KR780676 isolated from idli batter. The present study reports the effect of galactan EPS concentration, pH, ionic strength, temperature, salinity, monovalent salts on the emulsion formed with vegetable oils (virgin coconut oil, groundnut oil, olive oil and mustard oil). Emulsion determination test revealed the oil-in-water type of emulsion. Microscopic observation showed the phase of oil droplet distribution of emulsions. Groundnut and olive oil showed significant emulsifying activity (50–60%) and stability (90%) irrespective of the EPS concentration. One percent of EPS also showed good emulsifying activity (50–70%) and stability (100%) with groundnut and olive oil in wide range of temperature (− 20, 4, 30, 40, 50 and 60 °C), pH (3–8), salinity (1, 5, 10, 20 and 30% of NaCl) and monovalent salt (1, 5, 10, 20 and 30% of KCl). Galactan could be used as a prominent emulsifier for applications in the food industry as it possesses significant activity with most of the influential factors in wide range and also obtained from lactic acid bacteria that are regarded as Generally Regarded as Safe (GRAS).

  • effect of γ irradiation on physico chemical and antioxidant properties of galactan exopolysaccharide from Weissella confusa kr780676
    Journal of Food Science and Technology-mysore, 2019
    Co-Authors: Digambar Kavitake, Palanisamy Bruntha Devi, Sujatha Kandasamy, Mana Techi, U K Abid, Prathapkumar Halady Shetty
    Abstract:

    Exopolysaccharide (EPS) produced by Weissella confusa KR780676 from an Indian fermented food (Idli) has been characterized as galactan in earlier report. In this study, the galactan EPS was irradiated at different doses (0, 4, 8, and 16 kGy) using 60Co as γ-source and effect of γ-irradiation on physico-chemical and antioxidant potential of galactan EPS was studied. Color and flow properties showed moderate change after the γ-irradiation treatment. Particle size analysis and scanning electron microscopy exhibited significant breakdown of the EPS particles into smaller average hydrodynamic diameter size from 495.54 to 198.44 nm with increasing irradiation doses. Overall, pH showed decrease, while the water activity showed an increasing trend with the increasing irradiation dose. No significant effect was observed in the functional groups of EPS as revealed in the FT-IR spectroscopic analysis. After the treatment, semi-crystalline nature of the EPS changed to amorphous as shown in XRD analysis due to the breakdown. Antioxidant activities of galactan EPS increased marginally after the treatment. However, hydroxyl radical scavenging activity increased significantly from 48 to 67%. Changes in physico-chemical and antioxidant properties of galactan EPS with γ-irradiation treatment altered the functional properties of EPS positively, making it more suitable for wider application in the food industry.

  • probiotic characterization and antioxidant properties of Weissella confusa kr780676 isolated from an indian fermented food
    Lwt - Food Science and Technology, 2018
    Co-Authors: Shivangi Sharma, Digambar Kavitake, Sujatha Kandasamy, Prathapkumar Halady Shetty
    Abstract:

    Abstract Weissella confusa (KR780676), isolated from an Indian traditional fermented food (Idli batter) exhibited good growth and survival under simulated gastro-intestinal conditions. Cells also showed strong cell surface hydrophobicity, auto-aggregation and moderate biofilm formation ability indicating the potential for adhesion on to the host cell as multiple aggregates. Thermostability, cholesterol removal, β-galactosidase production and proteolytic activity of the strain indicated potential functional ability. Cell-free extract showed prominent hydroxyl radical scavenging activity, while intact cells exhibited significant DPPH, superoxide anion radical scavenging potential and lipid peroxidation inhibition. CLSM imaging confirmed inhibition of biofilm formation by P. aeruginosa KT266804. Besides, probiotic and functional properties, safety evaluation results revealed no haemolytic, DNase and gelatinase activity. Further, sensitivity towards antibiotics confirmed the potential of W. confusa as a functional starter culture candidate in fermented foods.

Maija Tenkanen - One of the best experts on this subject based on the ideXlab platform.

  • optimization of isomaltooligosaccharide size distribution by acceptor reaction of Weissella confusa dextransucrase and characterization of novel α 1 2 branched isomaltooligosaccharides
    Journal of Agricultural and Food Chemistry, 2016
    Co-Authors: Minna Juvonen, Ilkka Kajala, Shraddha Shukla, Hannu Maaheimo, Arun Goyal, Kati Katina, Päivi Tuomainen, Maija Tenkanen
    Abstract:

    Long-chain isomaltooligosaccharides (IMOs) are promising prebiotics. IMOs were produced by a Weissella confusa dextransucrase via maltose acceptor reaction. The inputs of substrates (i.e., sucrose and maltose, 0.15–1 M) and dextransucrase (1–10 U/g sucrose) were used to control IMO yield and profile. According to response surface modeling, 1 M sucrose and 0.5 M maltose were optimal for the synthesis of longer IMOs, whereas the dextransucrase dosage showed no significant effect. In addition to the principal linear IMOs, a homologous series of minor IMOs were also produced from maltose. As identified by MSn and NMR spectroscopy, the minor trisaccharide contained an α-(1→2)-linked glucosyl residue on the reducing residue of maltose and thus was α-d-glucopyranosyl-(1→2)-[α-d-glucopyranosyl-(1→4)]-d-glucopyranose (centose). The higher members of the series were probably formed by the attachment of a single unit branch to linear IMOs. This is the first report of such α-(1→2)-branched IMOs produced from maltose ...

  • optimization of isomaltooligosaccharide size distribution by acceptor reaction of Weissella confusa dextransucrase and characterization of novel α 1 2 branched isomaltooligosaccharides
    Journal of Agricultural and Food Chemistry, 2016
    Co-Authors: Qiao Shi, Minna Juvonen, Ilkka Kajala, Shraddha Shukla, Hannu Maaheimo, Arun Goyal, Kati Katina, Päivi Tuomainen, Yaxi Hou, Maija Tenkanen
    Abstract:

    Long-chain isomaltooligosaccharides (IMOs) are promising prebiotics. IMOs were produced by a Weissella confusa dextransucrase via maltose acceptor reaction. The inputs of substrates (i.e., sucrose and maltose, 0.15-1 M) and dextransucrase (1-10 U/g sucrose) were used to control IMO yield and profile. According to response surface modeling, 1 M sucrose and 0.5 M maltose were optimal for the synthesis of longer IMOs, whereas the dextransucrase dosage showed no significant effect. In addition to the principal linear IMOs, a homologous series of minor IMOs were also produced from maltose. As identified by MS(n) and NMR spectroscopy, the minor trisaccharide contained an α-(1→2)-linked glucosyl residue on the reducing residue of maltose and thus was α-d-glucopyranosyl-(1→2)-[α-d-glucopyranosyl-(1→4)]-d-glucopyranose (centose). The higher members of the series were probably formed by the attachment of a single unit branch to linear IMOs. This is the first report of such α-(1→2)-branched IMOs produced from maltose by a dextransucrase.

  • Rye bran as fermentation matrix boosts in situ dextran production by Weissella confusa compared to wheat bran
    Applied Microbiology and Biotechnology, 2016
    Co-Authors: Ilkka Kajala, Rossana Coda, Shraddha Shukla, Arun Goyal, Maija Tenkanen, Jari Mäkelä, Ndegwa Henry Maina, Riikka Juvonen, Päivi Ekholm, Kati Katina
    Abstract:

    The consumption of fiber-rich foods such as cereal bran is highly recommended due to its beneficial health effects. Pre-fermentation of bran with lactic acid bacteria can be used to improve the otherwise impaired flavor and textural qualities of bran-rich products. These positive effects are attributed to enzymatic modification of bran components and the production of functional metabolites like organic acids and exopolysaccharides such as dextrans. The aim of this study was to investigate dextran production in wheat and rye bran by fermentation with two Weissella confusa strains. Bran raw materials were analyzed for their chemical compositions and mineral content. Microbial growth and acidification kinetics were determined from the fermentations. Both strains produced more dextran in rye bran in which the fermentation-induced acidification was slower and the acidification lag phase longer than in wheat bran. Higher dextran production in rye bran is expected to be due to the longer period of optimal pH for dextran synthesis during fermentation. The starch content of wheat bran was higher, which may promote isomaltooligosaccharide formation at the expense of dextran production. W. confusa Cab3 produced slightly higher amounts of dextran than W. confusa VTT E-90392 in all raw materials. Fermentation with W. confusa Cab3 also resulted in lower residual fructose content which has technological relevance. The results indicate that wheat and particularly rye bran are promising matrices for producing technologically significant amounts of dextran, which facilitates the use of nutritionally valuable raw bran in food applications.

  • structure modeling and functional analysis of recombinant dextransucrase from Weissella confusa cab3 expressed in lactococcus lactis
    Preparative Biochemistry & Biotechnology, 2016
    Co-Authors: Shraddha Shukla, Ilkka Kajala, Kati Katina, Maija Tenkanen, Riikka Juvonen, Antti Nyyssölä, Anil Kumar Verma, Rwivoo Baruah, Arun Goyal
    Abstract:

    ABSTRACTThe dextransucrase gene from Weissella confusa Cab3, having an open reading frame of 4.2 kb coding for 1,402 amino acids, was amplified, cloned, and expressed in Lactococcus lactis. The recombinant dextransucrase, WcCab3-rDSR was expressed as extracellular enzyme in M17 medium with a specific activity of 1.5 U/mg which after purification by PEG-400 fractionation gave 6.1 U/mg resulting in 4-fold purification. WcCab3-rDSR was expressed as soluble and homogeneous protein of molecular mass, approximately, 180 kDa as analyzed by SDS-PAGE. It displayed maximum enzyme activity at 35°C at pH 5.0 in 50 mM sodium acetate buffer. WcCab3-rDSR gave Km of 6.2 mM and Vm of 6.3 µmol/min/mg. The characterization of dextran synthesized by WcCab3-rDSR by Fourier transform infrared and nuclear magnetic resonance spectroscopic analyses revealed the structural similarities with the dextran produced by the native dextransucrase. The modeled structure of WcCab3-rDSR using the crystal structures of dextransucrase from La...

  • Lactose- and cellobiose-derived branched trisaccharides and a sucrose-containing trisaccharide produced by acceptor reactions of Weissella confusa dextransucrase
    Food chemistry, 2015
    Co-Authors: Qiao Shi, Minna Juvonen, Ilkka Kajala, Hannu Maaheimo, Ndegwa Henry Maina, Yaxi Hou, Antti Nyyssölä, Liisa Virkki, Maija Tenkanen
    Abstract:

    Dextran-producing Weissella have received significant attention. However, except for maltose, the acceptor reactions of Weissella dextransucrases with different sugars have not been investigated. The action of recombinant Weissella confusa VTT E-90392 dextransucrase was tested with several potential acceptors, particularly, analogs lactose and cellobiose. The major acceptor products of both disaccharides were identified as branched trisaccharides, with a glucosyl residue α-(1→2)-linked to the acceptor’s reducing end. An additional product, isomelezitose (6Fru-α-Glcp-sucrose), was also produced when using lactose as an acceptor. This is the first report of the synthesis of isomelezitose by a dextransucrase. The NMR spectra of the three trisaccharides were fully assigned, and their structures were confirmed by selective enzymatic hydrolysis. The trisaccharides prepared from 13C6glc sucrose and lactose were analyzed by ESI-MSn, and the fragmentation patterns of these compounds were characterized.

Wenxiang Ping - One of the best experts on this subject based on the ideXlab platform.

  • characterization of exopolysaccharides produced by Weissella confusa xg 3 and their potential biotechnological applications
    International Journal of Biological Macromolecules, 2021
    Co-Authors: Dan Zhao, Lina Liu, Jing Jiang, Wenxiang Ping, Shuo Wang
    Abstract:

    Abstract In this study, exopolysaccharides (EPSs) produced by Weissella confusa XG-3 were characterized. The monosaccharide composition of XG-3 EPS was determined to include glucose according to GC data, and its molecular weight was 3.19 × 106 Da, as determined by HPLC. Scanning electron microscopy (SEM) revealed a smooth, porous, and branched structure, and atomic force microscopy (AFM) confirmed the presence of round lumps and chains on irregular surfaces of XG-3 EPS. The results of the Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR) analyses suggested that XG-3 EPS is a linear α-(1,6)-linked dextran. X-ray diffraction (XRD) data confirmed the noncrystalline amorphous structure, and the results of the Congo red assay corresponded to the random coiled chain conformation of XG-3 dextran. XG-3 dextran exhibited good radical scavenging activity and reducing power and possessed high thermal stability, with a degradation temperature (Td) of 306.8 °C. The absolute value of the zeta potential and particle size of XG-3 dextran continually increased with increasing dextran concentration. The water contact angle showed that XG-3 dextran had relatively high hydrophobicity in the presence of sucrose. XG-3 dextran stimulated the growth of Lactobacillus spp. and Bifidobacterium spp. These findings indicate that XG-3 dextran has unique characteristics and can be potentially applied as a food additive and an antioxidant.

  • the response surface optimization of exopolysaccharide produced by Weissella confusa xg 3 and its rheological property
    Preparative Biochemistry & Biotechnology, 2020
    Co-Authors: Dan Zhao, Lina Liu, Jing Jiang, Shangxu Guo, Wenxiang Ping
    Abstract:

    The response surface methodology (RSM) was used to optimize the exopolysaccharide (EPS) production by a lactic acid bacteria (LAB) Weissella confusa XG-3. Two-level factorial design screened three ...

Ndegwa Henry Maina - One of the best experts on this subject based on the ideXlab platform.

  • brewers spent grain as substrate for dextran biosynthesis by leuconostoc pseudomesenteroides dsm20193 and Weissella confusa a16
    Microbial Cell Factories, 2021
    Co-Authors: Prabin Koirala, Ndegwa Henry Maina, Kati Katina, Hanna Nihtila, Rossana Coda
    Abstract:

    Lactic acid bacteria can synthesize dextran and oligosaccharides with different functionality, depending on the strain and fermentation conditions. As natural structure-forming agent, dextran has proven useful as food additive, improving the properties of several raw materials with poor technological quality, such as cereal by-products, fiber-and protein-rich matrices, enabling their use in food applications. In this study, we assessed dextran biosynthesis in situ during fermentation of brewers´ spent grain (BSG), the main by-product of beer brewing industry, with Leuconostoc pseudomesenteroides DSM20193 and Weissella confusa A16. The starters performance and the primary metabolites formed during 24 h of fermentation with and without 4% sucrose (w/w) were followed. The starters showed similar growth and acidification kinetics, but different sugar utilization, especially in presence of sucrose. Viscosity increase in fermented BSG containing sucrose occurred first after 10 h, and it kept increasing until 24 h concomitantly with dextran formation. Dextran content after 24 h was approximately 1% on the total weight of the BSG. Oligosaccharides with different degree of polymerization were formed together with dextran from 10 to 24 h. Three dextransucrase genes were identified in L. pseudomesenteroides DSM20193, one of which was significantly upregulated and remained active throughout the fermentation time. One dextransucrase gene was identified in W. confusa A16 also showing a typical induction profile, with highest upregulation at 10 h. Selected lactic acid bacteria starters produced significant amount of dextran in brewers’ spent grain while forming oligosaccharides with different degree of polymerization. Putative dextransucrase genes identified in the starters showed a typical induction profile. Formation of dextran and oligosaccharides in BSG during lactic acid bacteria fermentation can be tailored to achieve specific technological properties of this raw material, contributing to its reintegration into the food chain.

  • isolation and characterization of indigenous Weissella confusa for in situ bacterial exopolysaccharides eps production in chickpea sourdough
    Food Research International, 2020
    Co-Authors: Viola Galli, Rossana Coda, Ndegwa Henry Maina, Manuel Venturi, Lisa Granchi
    Abstract:

    Legume-based sourdough represents a potential ingredient for the manufacture of novel baked products. However, the lack of gluten of legume flours can restrict their use due to their poor technological properties. To overcome such issue, the in situ production of bacterial exopolysaccharides (EPS) during fermentation has been proposed. In this study, an EPS-producing lactic acid bacteria for in situ production in chickpea sourdough was isolated. After several backsloppings of the spontaneously fermented chickpea flour dough, a dominant strain of Weissella confusa was isolated and identified. W. confusa Ck15 was able to produce linear dextran with 2.6% α-(1 → 3) linked branches, from sucrose. Temperature of 30 °C, dough yield of 333, and 2% of sucrose addition were used to produce fermented chickpea sourdoughs. The acidification and rheology of the sourdoughs inoculated with W. confusa Ck15, Leuconostoc pseudomesenteroides DSM 20193, as positive control, and Lactobacillus plantarum F8, as negative control, were compared. The in situ dextran production by W. confusa Ck15 fermentation led to the highest viscosity increase (5.90 Pa·s) and the highest EPS percentage in the doughs (1.49%), compared to the other doughs. The in situ dextran production represents a potential approach for improving the use of legume flour in bakery products; overall, this experiment represents a first step for the exploitation of microbial EPS for setting up a baking process for chickpea based product.

  • Rye bran as fermentation matrix boosts in situ dextran production by Weissella confusa compared to wheat bran
    Applied Microbiology and Biotechnology, 2016
    Co-Authors: Ilkka Kajala, Rossana Coda, Shraddha Shukla, Arun Goyal, Maija Tenkanen, Jari Mäkelä, Ndegwa Henry Maina, Riikka Juvonen, Päivi Ekholm, Kati Katina
    Abstract:

    The consumption of fiber-rich foods such as cereal bran is highly recommended due to its beneficial health effects. Pre-fermentation of bran with lactic acid bacteria can be used to improve the otherwise impaired flavor and textural qualities of bran-rich products. These positive effects are attributed to enzymatic modification of bran components and the production of functional metabolites like organic acids and exopolysaccharides such as dextrans. The aim of this study was to investigate dextran production in wheat and rye bran by fermentation with two Weissella confusa strains. Bran raw materials were analyzed for their chemical compositions and mineral content. Microbial growth and acidification kinetics were determined from the fermentations. Both strains produced more dextran in rye bran in which the fermentation-induced acidification was slower and the acidification lag phase longer than in wheat bran. Higher dextran production in rye bran is expected to be due to the longer period of optimal pH for dextran synthesis during fermentation. The starch content of wheat bran was higher, which may promote isomaltooligosaccharide formation at the expense of dextran production. W. confusa Cab3 produced slightly higher amounts of dextran than W. confusa VTT E-90392 in all raw materials. Fermentation with W. confusa Cab3 also resulted in lower residual fructose content which has technological relevance. The results indicate that wheat and particularly rye bran are promising matrices for producing technologically significant amounts of dextran, which facilitates the use of nutritionally valuable raw bran in food applications.

  • Lactose- and cellobiose-derived branched trisaccharides and a sucrose-containing trisaccharide produced by acceptor reactions of Weissella confusa dextransucrase
    Food chemistry, 2015
    Co-Authors: Qiao Shi, Minna Juvonen, Ilkka Kajala, Hannu Maaheimo, Ndegwa Henry Maina, Yaxi Hou, Antti Nyyssölä, Liisa Virkki, Maija Tenkanen
    Abstract:

    Dextran-producing Weissella have received significant attention. However, except for maltose, the acceptor reactions of Weissella dextransucrases with different sugars have not been investigated. The action of recombinant Weissella confusa VTT E-90392 dextransucrase was tested with several potential acceptors, particularly, analogs lactose and cellobiose. The major acceptor products of both disaccharides were identified as branched trisaccharides, with a glucosyl residue α-(1→2)-linked to the acceptor’s reducing end. An additional product, isomelezitose (6Fru-α-Glcp-sucrose), was also produced when using lactose as an acceptor. This is the first report of the synthesis of isomelezitose by a dextransucrase. The NMR spectra of the three trisaccharides were fully assigned, and their structures were confirmed by selective enzymatic hydrolysis. The trisaccharides prepared from 13C6glc sucrose and lactose were analyzed by ESI-MSn, and the fragmentation patterns of these compounds were characterized.

  • cloning and characterization of a Weissella confusa dextransucrase and its application in high fibre baking
    PLOS ONE, 2015
    Co-Authors: Ilkka Kajala, Kati Katina, Maija Tenkanen, Ndegwa Henry Maina, Qiao Shi, Yaxi Hou, Antti Nyyssölä, Riikka Juvonen
    Abstract:

    Wheat bran offers health benefits as a baking ingredient, but is detrimental to bread textural quality. Dextran production by microbial fermentation improves sourdough bread volume and freshness, but extensive acid production during fermentation may negate this effect. Enzymatic production of dextran in wheat bran was tested to determine if dextran-containing bran could be used in baking without disrupting bread texture. The Weissella confusa VTT E-90392 dextransucrase gene was sequenced and His-tagged dextransucrase Wc392-rDSR was produced in Lactococcus lactis. Purified enzyme was characterized using 14C-sucrose radioisotope and reducing value-based assays, the former yielding Km and Vmax values of 14.7 mM and 8.2 μmol/(mg∙min), respectively, at the pH optimum of 5.4. The structure and size of in vitro dextran product was similar to dextran produced in vivo. Dextran (8.1% dry weight) was produced in wheat bran in 6 h using Wc392-rDSR. Bran with and without dextran was used in wheat baking at 20% supplementation level. Dextran presence improved bread softness and neutralized bran-induced volume loss, clearly demonstrating the potential of using dextransucrases in bran bioprocessing for use in baking.