Characterization of Weissella Species during a 3-Year Observational Study - An Emerging Threat.

Weissella species are mistaken for Lactobacillus or Leuconostoc because of their Gram-staining property and resistance to vancomycin. In this study, we aimed to evaluate the demographic pattern, presenting symptoms, risk factors, associated pathologies, and clinical outcomes in patients with Weissella infection. We also analyzed the antibiotic susceptibility pattern of the Weissella species isolated. This retrospective observational study was done from January 2021 to August 2023 in a tertiary care referral center in Uttar Pradesh. All Weissella species isolated from blood cultures or cerebrospinal fluid (CSF) samples during this period were included in the study. Twenty-four-hour growth from a positive blood culture or CSF sample was identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Demographic and clinical details of the patients were extracted from the hospital information system. Kirby-Bauer disk diffusion was used for antibiotic susceptibility testing. During the 3-year study, 13 isolates of Weissella species were identified in our laboratory. Among the patients, male predominance was seen. The age range of the patients was 5-53 years. The samples were blood samples (n = 11) and CSF samples (n = 2). Of these isolates, 12 (92.3%) were identified as Weissella confusa and 1 (7.69%) was identified as Weissella viridescens. Common risk factors were anemia, prolonged hospital stay, indwelling catheter, chemotherapy, and chronic kidney disease. All the isolates in this study were sensitive to amikacin, daptomycin, amoxicillin-clavulanate, minocycline, and linezolid. Death was attributed to Weissella infection in three patients. Weissella species are opportunistic organisms that need to be identified quickly and precisely to guarantee the right course of treatment.

Weissella confusa with thermostable ß-hemolytic exopolysaccharide.

Consuming cooked meat contaminated with bacteria that carry thermostable hemolytic exopolysaccharide (ESP), could lead to severe diseases. Culture of a 5- h boiled sample of meat goulash on blood agar showed growth of a gram positive rod-shaped, mucoid and hemolytic bacterium. Biochemical tests and amplification of 1500 bp product of 16S rDNA and sequencing revealed bacterial identity as Weissella confusa. After 1 h boiling of bacterial suspension, they were alive and hemolytic, increased in volume and aggregated. After 8 h boiling of bacterial suspension with coverslip, live bacteria showed hemolysis, clustered and adhered to coverslip. Bacterial bacteriocin and hemolytic activities remained unchanged upon autoclaving. Purified bacterial EPS retained hemolytic activity after autoclaving. Boiling contaminated meat had no negative impact on viability of heat-stable W. confusa and its hemolytic EPS. Thermostable hemolytic EPS protected W. confusa from excessive heat. Hygienic practice in butcheries and kitchens are necessary to eliminate bacterial contaminants.

Extraction, purification and characterisation of exopolysaccharides produced by newly isolated lactic acid bacteria strains and the examination of their influence on resistant starch formation.

Exopolysaccharides (EPS) were produced by four newly isolated lactic acid bacteria strains, then further extracted, separated and characterised under standardised conditions. Using a sucrose carbon source, these LAB strains belonging to Weissella confusa/cibaria produced EPS with a dextran high molecular weight fraction. The obtained yields of EPS ranged from 3.2 g/L to 47.1 g/L and outstandingly high yields were obtained using Weissella confusa/cibaria 3MI3 isolated from spontaneous spelt sourdough. After purification the influence of EPS-dextran of molar mass 3,244,000 g/mol on resistant starch formation in wheat starch pastes and pasted samples after temperature-cycled storage was examined. Size exclusion chromatography with post-column derivatisation revealed that a 1.5% share of EPS dextran limited formation of high molar mass resistant starch in starch pastes during storage. This work provides new insight on hindering resistant starch formation by using EPS, which could be efficiently produced in sourdough, thus improving the properties of sourdough bread.

Exploring the bacterial community for starters in traditional high-salt fermented Chinese fish (Suanyu).

Traditional high-salt fermented Suanyu is an ethnic fermented fish product in southwest China. Lactic acid bacteria (LAB) are the most appropriate strains because of their technological properties during ripening fermentation. The diversity of LAB in high-salt fermented Chinese Suanyu was examined through high-throughput sequencing (HTS), and the most suitable LAB strain was acquired through strain isolation and characterization, surimi simulation fermentation system, and principal component analysis (PCA). The processing adaptability of the strain was examined via Suanyu fermentation. Results showed that Lactobacillus, Tetragenococcus, and Weissella were the dominant bacteria in Suanyu, and their contributions were 53.99%, 35.60%, and 4.10%, respectively. The most suitable strain (Lactobacillus plantarum B7) rapidly produced acid, exhibited a strong antibacterial activity, showed salt tolerance, and had no amino acid decarboxylase activity. pH decreased to about 3.6. Eventually, the ability to tolerate 20% salt was observed, and the activity of amino acid decarboxylase was negative. Fermented Suanyu with B7 rapidly produced acid (11.7% d-1). The non-protein nitrogen (NPN) and total free amino acid (FAA) contents of fermented Suanyu were higher and its total volatile base nitrogen (TVB-N), thiobarbituric acid (TBARS), and biogenic amines (BAs) levels were lower than those of naturally fermented Suanyu. Therefore, B7 is a potential microbial starter for Suanyu industrial production.

Brevilactibacter coleopterorum sp. nov., isolated from the intestine of the dark diving beetle Hydrophilus acuminatus, and Weissella coleopterorum sp. nov., isolated from the intestine of the diving beetle Cybister lewisianus.

A polyphasic taxonomic approach was used to characterize two novel bacterial strains, designated as HDW11T and HDW19T, isolated from intestine samples of the dark diving beetle Hydrophilus acuminatus and the diving beetle Cybister lewisianus, respectively. Both isolates were Gram-stain-positive, facultatively anaerobic and non-motile. Strain HDW11T grew optimally at 30 °C, pH 8 and in the presence of 1% (w/v) NaCl. Strain HDW19T grew optimally at 25 °C, pH 7 and in the presence of 0.3% (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences and genome sequences revealed that strain HDW11T is a member of the genus Brevilactibacter and is closely related to Brevilactibacter flavus VG341T [with 97.9% 16S rRNA sequence identity and 79.1% average nucleotide identity (ANI)], and that strain HDW19T belongs to the genus Weissella and is closely related to W. koreensis KCTC 3621T (with 98.9% 16S rRNA sequence identity and 79.5% ANI). The major cellular fatty acids of strains HDW11T and HDW19T were C18:1 ω9c and anteiso-C15:0, respectively. The sole respiratory quinone of strain HDW11T was MK-9 (H4). The major polar lipid components of strain HDW11T were diphosphatidylglycerol and phosphatidylglycerol, and the major polar lipid component of strain HDW19T was diphosphatidylglycerol. The genomic DNA G+C content of strains HDW11T and HDW19T were 72.1 and 37.2 mol%, respectively. The results of phylogenetic, phenotypic, chemotaxonomic and genotypic analyses suggest that strain HDW11T represents a novel species within the genus Brevilactibacter, and that strain HDW19T represents a novel species within the genus Weissella. We propose the name Brevilactibacter coleopterorum sp. nov. for strain HDW11T (=KACC 21335T=KCTC 49320T=JCM 33680T) and the name Weissella coleopterorum for strain HDW19T (=KACC 21347T=KCTC 43114T=JCM 33684T).

Biochemical changes and microbial community dynamics during spontaneous fermentation of Zhacai, a traditional pickled mustard tuber from China.

Zhacai is a traditional fermented vegetable that has been consumed in China for centuries. It is currently manufactured by spontaneous fermentation and therefore mostly relies on the activities of autochthonous microorganisms. Here, we characterized microbial community dynamics and associated biochemical changes in 12% salted Zhacai during a 90-day spontaneous fermentation process using high-throughput sequencing and chromatography-based approaches to identify associations between microorganisms and fermentation characteristics. Amplicon sequencing targeting bacterial 16S rRNA genes revealed that bacterial communities were dominated by halophilic bacteria (HAB, i.e., Halomonas and Idiomarina) and lactic acid bacteria (LAB, i.e., Lactobacillus-related genera and Weissella) after 30 days of fermentation. In addition, the relative abundances of the fungal genera Debaryomyces, Sterigmatomyces, and Sporidiobolus increased as fermentation progressed. Concomitantly, pH decreased while titratable acidity increased during fermentation, along with associated variation in biochemical profiles. Overall, the levels of organic acids (i.e., lactic and acetic acid), free amino acids (i.e., alanine, lysine, and glutamic acid), and volatiles (i.e., alcohols, esters, aldehydes, and ketones) increased in mature Zhacai. In addition, the abundances of Lactobacillus-related species, Halomonas spp., Idiomarina loihiensis, as well as that of the yeast Debaryomyces hansenii, were strongly correlated with increased concentrations of organic acids, amino acids, biogenic amines, and volatiles. This study provides new detailed insights into the succession of microbial communities and their potential roles in Zhacai fermentation.

Integrated Phenotypic-Genotypic Analysis of Candidate Probiotic Weissella Cibaria Strains Isolated from Dairy Cows in Kuwait.

Probiotics represent a possible strategy for controlling intestinal infections in livestock. Members of the Weissella genus are increasingly being studied for health-related applications in animals and humans. Here we investigated the functional properties of two Weissella cibaria strains isolated from cows reared in Kuwait breeding facilities by combining phenotypic with genomic analyses. W. cibaria SP7 and SP19 exhibited good growth in vitro under acidic conditions and in the presence of bile salts compared to the reference probiotic Lacticaseibacillus (formerly Lactobacillus) rhamnosus GG. Both strains were able to adhere to Caco-2 and HT-29 cell lines, as well as to mucin. The cell-free supernatants of the two isolates exhibited inhibitory activity towards Escherichia coli ATCC 25,922 and Salmonella enterica UC3605, which was ultimately due to the low pH of supernatants. W. cibaria SP19 showed a co-aggregation ability similar to that of L. rhamnosus GG when incubated with S. enterica. Whole genome sequencing and analysis revealed that both strains harbored several genes involved in carbohydrate metabolism and general stress responses, indicating bacterial adaptation to the gastrointestinal environment. We also detected genes involved in the adhesion to host epithelial cells or extracellular matrix. No evidence of acquired antibiotic resistance or hemolytic activity was found in either strain. These findings shed light on the potential of W. cibaria for probiotic use in livestock and on the mechanisms underlying host-microbe interaction in the gut. W. cibaria` strain SP19 exhibited the best combination of in vitro probiotic properties and genetic markers, and is a promising candidate for further investigation.

Probiotic and technological features of Enterococcus and Weissella isolates from camel milk characterised by an Argane feeding regimen.

The objectives of this study were to isolate lactic acid bacteria (LAB) from a raw Moroccan camel milk collected after the incorporation of a specific Argane by-products diet, and to investigate their technological properties as well as their probiotic features. The molecular identification of the isolates indicated that they belong to Weissella confusa, Weissella cibaria or Enterococcus durans species. Our results revealed that the tested isolates have a fast acidifying ability (values ranging between 0.045 ± 0.01 to 0.93 ± 0.01 after only 4 h incubation), important proteolysis, autolysis, lipolytic activities and an important diacetyl and exopolysaccharides production. All these isolates demonstrated a high tolerance to gastrointestinal conditions, namely to gastric simulated juice (survival rate ranged between 75.05 ± 7.88 and 85.55 ± 1.77%) and to bile salts (survival rate between 42.79 ± 1.11 and 82.75 ± 1.01%). The autoaggregation, hydrophobicity and antioxidant activity mean values of the isolates were 13.26-41.16%, 13.23-54.47% and 47.57-63.31%, respectively. Importantly, LAB cultures exhibited antibacterial activity against Gram-negative and Gram-positive pathogenic bacteria and none of the tested isolates presented antibiotic resistance, haemolytic or DNase activities. This study revealed interesting properties for LAB isolated and supported their utilization as autochthone starters for camel milk fermentation that represent a challenge process. These results presented as well the probiotic potential for a possible human consumption.

Molecular analysis of the dominant lactic acid bacteria of chickpea liquid starters and doughs and propagation of chickpea sourdoughs with selected Weissella confusa.

Fermented chickpea liquid is used as a leavening agent in chickpea bread production. In the present study, traditional chickpea liquid starter and dough samples were collected from bakeries in Turkey and microbiologically investigated. Culture-independent analysis for microbiota diversity, performed by MiSeq Illumina, identified Clostridium perfringens as major group in all samples, while Weissella spp. Dominated LAB community. A culture-dependent methodology was applied and 141 isolates were confirmed to be members of the LAB group based on 16s rRNA gene sequence analysis. In particular, 11 different LAB species were identified confirming the high frequency of isolation of weissellas, since Weissella confusa and Weissella cibaria constituted 47.8 and 12.4%, respectively, of total LAB isolated. The other species were Enterococcus faecium, Enterococcus lactis, Lactobacillus brevis, Lactobacillus plantarum, Leuconostoc mesenteroides, Leuconostoc mesenteroides subsp. Dextranium, Pediococcus acidilactici, Pediococcus pentosaceus and Streptococcus lutetiensis. Due to high frequency of isolation, W. confusa strains were investigated at technological level and W. confusa RL1139 was used as mono-culture starter in the experimental chickpea sourdough production. Chemical and microbiological properties, as well as volatile organic compounds (VOCs) of the chickpea liquid starters and doughs were subjected to a multivariate analysis. Control and W. confusa inoculated chickpea liquid starter and dough samples were close to each other in terms of some characteristics related to chemical, microbiological and VOCs profile, but the inoculated sourdough showed a higher generation of certain VOCs, like butanoic acid (81.52%) and ethyl acetate (8.15%) than control sourdough. This is important in order to maintain typical characteristics of the traditional chickpea dough, but at the same time improving the aroma profile. This work demonstrated that W. confusa RL1139 can be applied at large scale production level without compromising the typical characteristics of the final product.

Dynamics and species diversity of lactic acid bacteria involved in the spontaneous fermentation of various palm tree saps during palm wine tapping in Côte d'Ivoire.

To document and speed up research on the usefulness and selection of potential health-promoting bacterial starter cultures from unexplored fermented saps of various palm species in Côte d'Ivoire, benchmark tapping processes were successfully developed and implemented at field level. Therefore, spontaneously fermented saps of three palm species (Elaeis guineensis, Raphia hookeri, Borassus aethiopum) were collected throughout tapping process and lactic acid bacteria (LAB) diversity and dynamics were studied through a multiphasic approach. Overall microbiological analysis revealed a LAB species diversity throughout tapping process. LAB isolates belonged to two main (GTG)5-PCR clusters, namely Fructobacillus durionis (40.33%) and Leuconostoc mesenteroides (45.66%), with Leuconostoc pseudomesenteroides, Lactobacillus paracasei, Lactobacillus fermentum Weissella cibaria, Enterococcus casseliflavus and Lactococcus lactis occurring occasionally. LAB diversity was higher in fermented saps from E. guineensis (8 species) than those of R. hookeri (5 species) and B. aethiopum (3 species). Dynamic study revealed that F. durionis and L. mesenteroides dominated the fermentations from the beginning until the end of tapping process in all palm wine types. But the earlier stages of the process were also populated by some species like W. cibaria, L. pseudomesenteroides and L. fermentum, which population decreased or disappeared after some days. Also, species of Enterococcus and Lactococcus genera were sporadically detected uniquely in sap from E. guineensis. This study is the first to investigate extensively the LAB diversity and dynamics throughout palm trees tapping process in Côte d'Ivoire and is relevant for future selection of health promoting bacteria.

In vitro assessment of potential probiotic characteristics of indigenous Lactococcus lactis and Weissella oryzae isolates from rainbow trout (Oncorhynchus mykiss Walbaum).

AIM: The objective of this study was to evaluate the probiotic potential of lactic acid bacteria (LAB) isolated from the intestinal ecosystem of rainbow trout. METHODS AND RESULTS: Among LAB isolates, 10 of them were selected and screened for resistance to acid and bile salts, pancreatin, sodium chloride and temperature, hydrophobicity, growth profile and antimicrobial activity against fish pathogens. Then, biosafety assessments were investigated. Selected LAB tolerated to gastrointestinal physiological conditions, pancreatin and a range of sodium chloride and temperature. They also exhibited hydrophobicity and showed antagonistic activity against Streptococcus iniae and Yersinia ruckeri. Results of 16S rRNA gene sequencing showed that selected LAB belonged to the Lactococcus lactis (n = 5) and Weissella oryzae (n = 5) species. They exhibited no ß-haemolytic activity, while six selected LAB were resistant to some antibiotics. None of them harboured virulence factors. CONCLUSIONS: This study revealed probiotic characteristics of indigenous LAB isolated from the intestinal ecosystem of rainbow trout. However, further studies are required to confirm the effectiveness of these isolates as probiotics in aquaculture. SIGNIFICANCE AND IMPACT OF THE STUDY: To the best of our knowledge, for the first time, the presence of probiotic candidates belonging to W. Oryzae was confirmed in fish intestinal microbiota.

Weissella muntiaci sp. nov., isolated from faeces of Formosan barking deer (Muntiacus reevesi).

A Gram-stain-positive strain, 8 H-2T, was isolated from faeces of Reeves' muntjac (Muntiacus reevesi) barking deer in Taiwan. Cells of the strain were short rod-shaped, non-motile, non-haemolytic, asporogenous, facultatively anaerobic, heterofermentative and did not exhibit catalase and oxidase activities. Comparative analyses of 16S rRNA, pheS and dnaA gene sequences demonstrated that the novel strain was a member of the genus Weissella. On the basis of 16S rRNA gene sequence similarities, the type strains of Weissella oryzae (99.2 %), Weissella confusa (97.8 %), Weissella cibaria (97.6 %) and Weissella soli (97.3 %) were the closest neighbours to strain 8 H-2T. The concatenated housekeeping gene sequence (pheS and dnaA) similarities of 8 H-2T to closely related type strains were 72.5-84.9 %, respectively. The genomic DNA G+C content was 40.5 mol%. The average nucleotide identity and digital DNA-DNA hybridization values with these type strains were 70.2-75.4% and 25.1-30.1 %, respectively. Phenotypic and genotypic test results demonstrated that strain 8 H-2T represents a novel species belonging to the genus Weissella, for which the name Weissella muntiaci sp. nov. is proposed. The type strain is 8 H-2T (=BCRC 81133T=NBRC 113537T).

Weissella sagaensis sp. nov., isolated from traditional Chinese yogurt.

Three Gram-stain-positive bacterial strains, designated X0750T, X0278 and X0401, isolated from traditional yogurt in Tibet Autonomous Region, PR China, were characterized by a polyphasic approach, including sequence analyses of the 16S rRNA gene and three housekeeping genes (pheS, rpoA and recA), determination of average nucleotide identity (ANI) and average amino acid identity (AAI), in silico DNA-DNA hybridization (isDDH), fatty acid methyl ester (FAME) analysis and phenotypic characterization. Strain X0750T was phylogenetically related to the type strains of Weissella hellenica, Weissella bombi, Weissella paramesenteroides, Weissella jogaejeotgali, Weissella thailandensis, Weissella oryzae, Weissella cibaria and Weissella confusa, having 94.4-100 % 16S rRNA gene sequence similarities, 76.7-90.0 % pheS gene sequence similarities, 88.9-99.4 % rpoA gene sequence similarities and 77.6-92.8 % recA gene sequence similarities, respectively. ANI, isDDH and AAI values between strain X0750T and type strains of phylogenetically related species were less than 90.4, 40.9 and 92.8 % respectively, confirming that strain X0750T represents a novel species within the genus Weissella. Based upon the data obtained in the present study, a novel species, Weissella sagaensis sp. nov., is proposed and the type strain is X0750T(=NCIMB 15192T=CCM 8924T=LMG 31184T=CCTCC AB 2018403T).

Meningitis due to Weissella Confusa.

Bacterial meningitis is a life-threatening condition that should be addressed as an emergency. The typical culprit microorganisms are targeted empirically with ceftriaxone and vancomycin, in the absence of an immunocompromised state. In this case report, however, we are describing a case of meningitis secondary to Weissella confusa, bacteria inherently resistant to the two drugs commonly used to empirically treat meningitis. Weissella spp. are Gram-positive, catalase-negative coccobacilli and an infrequent cause of infection in humans. Bacteremia followed by endocarditis are the typical clinical manifestations of W. confusa in humans. Other reported manifestations include post-operative osteomyelitis, thumb abscess, infected prosthetic joint, infected peritoneal fluid and peritonitis. To our knowledge, this is the first case of meningitis due to Weissella confusa in the literature. Therefore, we conclude that the isolation of Gram-positive coccobacilli resistant to vancomycin, especially in an immunocompromised host, should raise the suspicion of W. confusa.

Evaluation of Probiotic Properties and Prebiotic Utilization Potential of Weissella paramesenteroides Isolated From Fruits.

Weissella paramesenteroides has gained a considerable attention as bacteriocin and exopolysaccharide producers. However, potential of W. paramesenteroides to utilize different prebiotics is unexplored area of research. Fruits being vectors of various probiotics, five W. paramesenteroides strains, namely, FX1, FX2, FX5, FX9, and FX12, were isolated from different fruits. They were screened and selected based on their ability to survive at pH 2.5 and in 1.0% sodium taurocholate, high cell surface hydrophobicity, mucin adhesion, bile-induced biofilm formation, antimicrobial activity (AMA) against selected enteropathogens, and prebiotic utilization ability, implicating the functional properties of these strains. In vitro safety evaluation showed that strains were susceptible to antibiotics except vancomycin and did not harbor any virulent traits such as biogenic amine production, hemolysis, and DNase production. Based on their functionality, two strains FX5 and FX9 were selected for prebiotic utilization studies by thin layer chromatography (TLC) and short-chain fatty acids (SCFAs) production by high performance liquid chromatography. TLC profile evinced the ability of these two strains to utilize low molecular weight galactooligosaccharides (GOS) and fructooligosaccharides (FOS), as only the upper low molecular weight fractions were disappeared from cell-free-supernatants (CFS). Enhanced ß-galactosidase activity correlated with galactose accumulation in residual CFS of GOS displayed GOS utilization ability. Both the strains exhibited AMA against E. coli and Staph. aureus and high SCFAs production in the presence of prebiotic, suggesting their synbiotic potential. Thus, W. paramesenteroides strains FX5 and FX9 exhibit potential probiotic properties with prebiotic utilization and can be taken forward to evaluate synergistic synbiotic potential in detail.

Composition, diversity and function of gastrointestinal microbiota in wild red-billed choughs (Pyrrhocorax pyrrhocorax)

Hitherto, virtually nothing is known about the microbial communities related to the bird species in the family Corvidae. To fill this gap, the present study was conducted to provide a baseline description of the gut microbiota of wild red-billed choughs (Pyrrhocorax pyrrhocorax). In this study, microbiota from four gastrointestinal locations (oropharynx, gizzard, small intestine, and large intestine) of three wild red-billed choughs were analyzed using the Illumina MiSeq sequencing platform by targeting the V4-V5 regions of the 16S rRNA genes. The gut microbiota of the red-billed choughs were dominated by the phylum Firmicutes (59.56%), followed by Proteobacteria (16.56%), Bacteroidetes (13.86%), and Actinobacteria (7.03%), which were commonly detected in avian gut ecosystems. Genus-level compositions were found to be largely dominated by Lactobacillus (18.21%), Weissella (12.37%), Erysipelatoclostridium (6.94%), Bacteroides (6.63%), Escherichia-Shigella (5.15%), Leuconostoc (4.60%), Proteus (3.33%), Carnobacterium (2.71%), Lactococcus (1.69%), and Enterococcus (1.63%). The overall intestinal microbiota was enriched with functions related to ATP-binding cassette (ABC) transporters, DNA repair and recombination proteins, purine metabolism, ribosome, transcription factors, pyrimidine metabolism, peptidases, and two-component system. In terms of four different gastrointestinal locations, hierarchical clustering analysis and principal coordinate analysis showed that microbial communities of the oropharynx, gizzard, small intestine, and large intestine formed four separated clusters. A total of 825 OTUs and 382 genera were detected in all four gastrointestinal locations, which were considered as the major microbes in the intestines of red-billed choughs. Coexistence of lactic acid bacteria and potential pathogens in the gut environments of red-billed choughs required further investigations

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Development of a System of High Ornithine and Citrulline Production by a Plant-Derived Lactic Acid Bacterium, Weissella confusa K-28.

As a bacterium used in industry for production of several amino acids, an endotoxin-free Corynebacterium (C.) glutamicum is well known. However, it is also true that the endotoxin-producing other Corynebacterium species is present. An aim of this study is to obtain a lactic acid bacterium (LAB) that produces ornithine and citrulline at high levels. We successfully isolated a strain, designated K-28, and identified it as Weissella (W.) confusa. The production of ornithine and citrulline by K-28 was 18 ± 1 and 10 ± 2 g/L, respectively, with a 100 ± 9% conversion rate when arginine was continuously fed into a jar fermenter. Although the ornithine high production using C. glutamicum is industrially present, the strains have been genetically modified. In that connection, the wild-type of C. glutamicum produces only 0.5 g/L ornithine, indicating that W. confusa K-28 is superior to C. glutamicum to use a probiotic microorganism. We confirmed that W. confusa K-28 harbors an arginine deiminase (ADI) gene cluster, wkaABDCR. The production of ornithine and the expression of these genes significantly decreased under the aerobic condition rather than anaerobic one. The expression level of the five genes did not differ with or without arginine, suggesting that the production of amino acids in the K-28 strain was not induced by exogenous arginine.

Phylogenetic Analyses of pheS, dnaA and atpA Genes for Identification of Weissella confusa and Weissella cibaria Isolated from a South African Sugarcane Processing Factory.

A previous study reported on the isolation of 430 polysaccharide (gum)-producing bacteria from a South African sugarcane processing factory and the identification of isolates by comparative 16S rRNA gene sequencing. A large number of isolates (202) belonged to the genus Weissella and clustered with reference strains of Weissella cibaria and Weissella confusa. In this study, we identified 147 strains as W. cibaria and 55 as W. confusa based on phylogenetic analyses of pheS and dnaA gene sequences of representative isolates. We also included atpA gene sequence analysis of Weissella isolates as potential future phylogenetic marker to differentiate amongst strains of W. cibaria and W. confusa.

Metagenomic analysis of bacterial community composition in Dhanaan: Ethiopian traditional fermented camel milk.

This study was conducted to evaluate the safety and bacterial profile of Dhanaan (Ethiopian traditional fermented camel milk). The composition of the microbial community in Dhanaan samples was analysed by a metagenomic approach of 16S rRNA gene amplicon sequencing. Metagenomic profiling identified 87 different bacterial microorganisms (OTUs) in six samples analysed. Although the Dhanaan samples contained various lactic acid bacteria (LAB), they also all contained undesirable microorganisms in large proportions. The following LAB genera were identified: Streptococcus, Lactococcus and Weissella. One Streptococcus species represented by OTU-1 (operational taxonomic unit) was found in all Dhanaan samples and the dominating species in four out of six samples. This common isolate was found to be closely related to S. lutetiensis and S. infantarius. Undesirable microorganisms from genera such as Escherichia, Klebsiella, Enterobacter, Acinetobacter and Clostridium were, however, also frequent, or even dominant in Dhanaan samples. Thus, this calls for a change in the Dahnaan manufacturing practice to an improved and safer production system. Starter cultures suitable for Dhanaan production might be developed from the Streptococcus, Weissella and Lactococcus microorganisms identified in this study. However, further safety evaluation and technological characterization need to be conducted on strains defined by OTU-1, OTU-2, OTU-3, OTU-8 and OTU-35 before they can be used as food grade starter cultures.

Isolation and characterization of high exopolysaccharide-producing Weissella confusa VP30 from young children's feces.

BACKGROUND: Lactic acid bacteria (LAB) are known to have a significant ability to colonize the human intestinal tract and adhere to the surface of intestinal epithelial cells. Among the various lactic acid bacteria, exopolysaccharide (EPS) producing strains are known to provide a variety of health benefits for their hosts (e.g. anti-inflammatory, antioxidant, antitumor and stress tolerant effects). Recently, EPSs and EPS-producing lactic acid cultures have gained interest within the food industry and are playing important roles as biothickeners and texturizing agents due to their hydrocolloidal nature. In this study, 156 lactic acid bacterial strains isolated from fecal samples of healthy young children were screened and evaluated for active EPS-production capability. RESULTS: Among the various human origin lactic acid flora isolated, Weissella confusa VP30 showed the highest EPS productivity and its EPS producing properties were characterized under various cultural conditions in this research. To document the safety of W. confusa VP30, antibiotic resistance, hemolytic, and ammonia production properties were evaluated in addition. No significant negative results were observed. The maximum EPS production by W. confusa VP30 was 59.99 ± 0.91 g/l after 48 h of cultivation in media containing 10% sucrose, far exceeding EPS production by other bacterial strains reported elsewhere. Based on gel permeation chromatography (GPC), the molecular weight of EPS produced by W. confusa VP30 was 3.8 × 106 Da. Structural analysis of the released EPS fraction by 13C and 1H nuclear magnetic resonance (NMR) spectroscopy revealed that W. confusa VP30 can produce dextran with glucose units linked with 96.5% α (1 → 6) glycosidic bonds and 3.5% α (1 → 3) branches. CONCLUSION: The high EPS production capability and safety of W. confusa VP30 justify food industry consideration of this cell strain for further evaluation and potential industrial use.