Weissella Genus Research Articles

Antifungal activity of metabolites of Weissella cibaria KM14 isolated from traditional Korean food kimchi against three spoilage fungi

The Weissella genus has recently gained popularity due to its antifungal and probiotic properties. In this study, the antifungal activity of isolate KM14 of Weissella cibaria on Aspergillus fumigatus, Penicillium expansum, and P. oxalicum were evaluated by the overlay method and microplate inhibition analysis; results showed that the bacterium had a high inhibition rate against these three fungi, ranging from 99.4 to 94.3%. The evaluation of the antifungal activity of compounds (organic acid/proteins/H2O2) produced by the bacterium revealed that organic acids were responsible for this activity. As observed by scanning electron microscopy (SEM), shrunken hyphae and pores on the cell surface were observed in cell free supernatant (CFS)-treated fungi. The predominant organic acids identified in the CFS were lactic acid and acetic acid, respectively. Furthermore, the genome of W. cibaria KM14 contained a significant number of genes (130) that were responsible for organic acid biosynthesis. Based on these data, it has been speculated that W. cibaria KM14-CFS inhibits fungal growth via two potential mechanisms: decreasing hyphal surface decoration and damaging the mycelia.

The Weissella and Periweissella genera: up-to-date taxonomy, ecology, safety, biotechnological, and probiotic potential.

Bacteria belonging to the genera Weissella and Periweissella are lactic acid bacteria, which emerged in the last decades for their probiotic and biotechnological potential. In 2015, an article reviewing the scientific literature till that date on the taxonomy, ecology, and biotechnological potential of the Weissella genus was published. Since then, the number of studies on this genus has increased enormously, several novel species have been discovered, the taxonomy of the genus underwent changes and new insights into the safety, and biotechnological and probiotic potential of weissellas and periweissellas could be gained. Here, we provide an updated overview (from 2015 until today) of the taxonomy, ecology, safety, biotechnological, and probiotic potential of these lactic acid bacteria.

Effects of Vachellia mearnsii Tannin Extract as an Additive on Fermentation Quality, Aerobic Stability, and Microbial Modulation of Maize Silage.

Maize silage is produced to alleviate the effects of forage shortages on ruminant animals, particularly during the dry season. Microorganisms play a significant role in silage fermentation and thus, to a large extent, determine the silage quality. The modulation of silage microorganisms may help to inhibit undesirable bacteria and improve the silage quality. Therefore, condensed tannin extract from Vachellia mearnsii bark was used as an additive in maize silage during ensiling. Hence, this study evaluated the effects of a tannin extract (condensed tannin) additive on the fermentative quality, aerobic stability, and bacterial composition of maize silage. A mini-silo experiment on maize with five treatments was conducted for 75 days. The silage treatments were as follows: (T1) maize forage with no inoculation (negative control); (T2) maize forage inoculated with LAB and 1% tannin extract; (T3) maize forage inoculated with LAB only (positive control); (T4) and maize forage inoculated with LAB and 2% tannin extract; (T5) maize forage inoculated with LAB and 3% tannin extract. The results showed that the additives modulated the silage microorganism composition. However, this was without affecting the silage's fermentative quality and aerobic stability. All the silages recorded a pH below 4.2, which indicated well-fermented silage. The tannin extract suppressed the growth of undesirable bacteria, such as Dysgonomonas, Gluconacetobacter and Clostridium genera, while promoting desirable bacteria, such as Lactobacillus and Weissella genera, which were attributed to the silage quality. It is thus concluded that tannins can be strategically used as silage additives to modulate the microbial composition of silage and improve the silage quality by promoting the dominance of the desirable bacteria in the silage.

Weissella and the two Janus faces of the genus

The genus Weissella belongs to the lactic acid bacteria group. It occurs naturally in foods and is a component of the human microbiome. A few Weissella species are candidate probiotics due to their potential for survival under the harsh conditions present in the gastrointestinal tract of humans and animals. Various species have also shown potential for treating and preventing periodontal disease, skin pathologies, and atopic dermatitis; some are used as starters for the fermentation of foods due to their production of exopolysaccharides; and others are used as protective cultures due to their production of weissellicin, a bacteriocin. However, a few Weissella species are opportunistic pathogens, such as W. ceti, which is the etiological agent of weissellosis, a disease in rainbow trout. Additionally, most Weissella species are intrinsically vancomycin-resistant. Thus, the Weissella genus is important from both medical and industrial points of view, and the Janus faces of this genus should be considered in any expected biotechnological applications. In this review, we present an overview of the probiotic potential and pathogenic cases of the Weissella genus reported in the literature.

The Weissella Genus: Clinically Treatable Bacteria with Antimicrobial/Probiotic Effects on Inflammation and Cancer.

Weissella is a genus earlier considered a member of the family Leuconostocaceae, which was reclassified into the family Lactobacillaceae in 1993. Recently, there have been studies emphasizing the probiotic and anti-inflammatory potential of various species of Weissella, of which W. confusa and W. cibaria are the most representative. Other species within this genus include: W. paramesenteroides, W. viridescens, W. halotolerans, W. minor, W. kandleri, W. soli, W. ghanensis, W. hellenica, W. thailandensis, W. fabalis, W. cryptocerci, W. koreensis, W. beninensis, W. fabaria, W. oryzae, W. ceti, W. uvarum, W. bombi, W. sagaensis, W. kimchi, W. muntiaci, W. jogaejeotgali, W. coleopterorum, W. hanii, W. salipiscis, and W. diestrammenae. Weissella confusa, W. paramesenteroides, W. koreensis, and W. cibaria are among the few species that have been isolated from human samples, although the identification of these and other species is possible using metagenomics, as we have shown for inflammatory bowel disease (IBD) and healthy controls. We were able to isolate Weissella in gut-associated bacteria (post 24 h food deprivation and laxatives). Other sources of isolation include fermented food, soil, and skin/gut/saliva of insects/animals. With the potential for hospital and industrial applications, there is a concern about possible infections. Herein, we present the current applications of Weissella on its antimicrobial and anti-inflammatory mechanistic effects, the predisposing factors (e.g., vancomycin) for pathogenicity in humans, and the antimicrobials used in patients. To address the medical concerns, we examined 28 case reports focused on W. confusa and found that 78.5% of infections were bacteremia (of which 7 were fatal; 1 for lack of treatment), 8 were associated with underlying malignancies, and 8 with gastrointestinal procedures/diseases of which 2 were Crohn's disease patients. In cases of a successful resolution, commonly administered antibiotics included: cephalosporin, ampicillin, piperacillin-tazobactam, and daptomycin. Despite reports of Weissella-related infections, the evolving mechanistic findings suggest that Weissella are clinically treatable bacteria with emerging antimicrobial and probiotic benefits ranging from oral health, skin care, obesity, and inflammatory diseases to cancer.

Functional and Safety Characterization of Weissella paramesenteroides Strains Isolated from Dairy Products through Whole-Genome Sequencing and Comparative Genomics

Strains belonging to the Weissella genus are frequently recovered from spontaneously fermented foods. Their functional, microbial-modulating, and probiotic traits enhance not only the sensorial properties but also the nutritional value, beneficial effects, and safety of fermented products. Sporadic cases of opportunistic pathogenicity and antibiotic resistance have deprived safety status from all Weissella species, which thus remain understudied. Our study increased the number of available high-quality and taxonomically accurate W. paramesenteroides genomes by 25% (9 genomes reported, leading to a total of 36 genomes). We conducted a phylogenetic and comparative genomic analysis of the most dominant Weissella species (W. cibaria, W. paramesenteroides, W. viridescens, W. soli, W. koreensis, W. hellenica and W. thailadensis). The phylogenetic tree corroborated species assignment but also revealed phylogenetic diversity within the Weissella species, which is likely related to the adaptation of Weissella in different niches. Using robust alignment criteria, we showed the overall absence of resistance and virulence genes in Weissella spp., except for one W. cibaria isolate carrying blaTEM-181. Enrichment analysis showed the association of Weissella species several CAZymes, which are essential for biotechnological applications. Additionally, the combination of CAZyme metabolites with probiotics can potentially lead to beneficial effects for hosts, such as the inhibition of inflammatory processes and the reduction of cholesterol levels. Bacteriocins and mobile genetic elements MGEs (Inc11 plasmid and ISS1N insertion sequence) were less abundant, however W. thailadensis and W. viridescens showed significant association with specific bacteriocin-encoding genes. Lastly, an analysis of phenotypic traits underlined the need to carefully evaluate W. cibaria strains before use as food additives and suggested the possibility of employing W. paramesenteroides and W. hellenica in the fermentation process of vegetable products. More studies providing high-resolution characterization of Weissella strains from various sources are necessary to elucidate the safety of Weissella spp. and exploit their beneficial characteristics.

Microbial Community, Co-Occurrence Network Relationship and Fermentation Lignocellulose Characteristics of Broussonetia papyrifera Ensiled with Wheat Bran.

Broussonetia papyrifera has a high lignocellulose content leading to poor palatability and low digestion rate of ruminants. Thus, dynamic profiles of fermentation lignocellulose characteristics, microbial community structure, potential function, and interspecific relationships of B. papyrifera mixing with wheat bran in different ratios: 100:0 (BP100), 90:10 (BP90), 80:20 (BP80), and 65:35 (BP65) were investigated on ensiling days 5, 15, 30, and 50. The results showed that adding bran increased the degradation rate of hemicellulose, neutral detergent fiber, and the activities of filter paper cellulase, endoglucanase, acid protease, and neutral protease, especially in the ratio of 65:35. Lactobacillus, Pediococcus, and Weissella genus bacteria were the dominant genera in silage fermentation, and Pediococcus and Weissella genus bacteria regulated the process of silage fermentation. Compared with monospecific B. papyrifera silage, adding bran significantly increased the abundance of Weissella sp., and improved bacterial fermentation potential in BP65 (p < 0.05). Distance-based redundancy analysis showed that lactic acid bacteria (LAB) were significantly positive correlated with most lignocellulose content and degrading enzymes activities, while Monascus sp. and Syncephalastrum sp. were opposite (p < 0.05). Co-occurrence network analysis indicated that there were significant differences in microbial networks among different mixing ratios of B. papyrifera silage prepared with bran. There was a more complex, highly diverse and less competitive co-occurrence network in BP65, which was helpful to silage fermentation. In conclusion, B. papyrifera ensiled with bran improved the microbial community structure and the interspecific relationship and reduced the content of lignocellulose.

Novel Insights Into the Phylogeny and Biotechnological Potential of Weissella Species.

In this study, the genomes of the Weissella (W.) beninensis, W. diestrammenae, W. fabalis, W. fabaria, W. ghanensis, and W. uvarum type strains were sequenced and analyzed. Moreover, the ability of these strains to metabolize 95 carbohydrates was investigated, and the genetic determinants of such capability were searched within the sequenced genomes. 16S rRNA gene and genome-based-phylogeny of all the Weissella species described to date allowed a reassessment of the Weissella genus species groups. As a result, six distinct species groups within the genus, namely, W. beninensis, W. kandleri, W. confusa, W. halotolerans, W. oryzae, and W. paramesenteroides species groups, could be described. Phenotypic analyses provided further knowledge about the ability of the W. beninensis, W. ghanensis, W. fabaria, W. fabalis, W. uvarum, and W. diestrammenae type strains to metabolize certain carbohydrates and confirmed the interspecific diversity of the analyzed strains. Moreover, in many cases, the carbohydrate metabolism pathway and phylogenomic species group clustering overlapped. The novel insights provided in our study significantly improved the knowledge about the Weissella genus and allowed us to identify features that define the role of the analyzed type strains in fermentative processes and their biotechnological potential.

Bacterial Community Diversity of a Congolese Traditional Fermented Food, “Pand&amp;#233;”, Revealed by Illumina Miseq&amp;lt;sup&amp;gt;TM&amp;lt;/sup&amp;gt; Sequencing of 16S rRNA Gene

Pandé is a Congolese fermented food produced from fruit pulps of raffia palm. The aim of this study was to explore the diversities in bacterial communities in the unfermented pulps (control) (PNFL) and fermented pulps obtained from fruits using boiling (PMF) and purchased at markets in Brazzaville (PFL) and using Illumina MiSeqTM sequencing of 16S rRNA gene. A total number of 157,054 sequences was obtained and grouped into 737 operational taxonomic units (OTUs). These were classified into 13 phyla, 26 classes, 48 orders, 96 families and 176 genera. At the phylum level, the most frequent bacterial communities were: for PFM, Proteobacteria (38.94%) and Firmicutes (19.37%); for PFL, Firmicutes (69.10%) and Proteobacteria (30.89%); for PNFL, Firmicutes (84.92%) and Proteobacteria (14.22%). were the most frequent in PFL, while Acidobacteria (40.02%), Proteobacteria (38.94%) and Firmicutes (19.37%) were preponderant in PFM. Firmicutes (84.92%) and Proteobacteria (14.22%) were the most common in unfermented pulps (PNFL). Lactobacillus (47.70%) and Gluconobacter genera (15.33%) were the most represented in the PFL sample. Acidipila (35.56%) and Rhizomicrobium (11.41%) were preponderant genera in the PFM sample. Weissella genus was the most frequent in the PNFL sample. Hierarchical cluster indicated that the samples could be grouped into two groups of different origins. PCA showed that main genera were higher in the fermented samples. The diversity was higher in the fermented pulps or Pandé than in the unfermented pulps. Pandé can be a potential source for the isolation of bacteria with biotechnological potential.

Selective Fermentation of Lactobacillus and Streptococcus In Vitro: Effects of Chinese Fermented Glutinous Rice on the Growth Promotion of Potential Probiotics

A functional Chinese fermented glutinous rice has been developed with the supplementation of Fu brick tea (CRW-FBT). In this study, we aimed to evaluate its effect on the growth of potential probiotic strains in the Lactobacillus, Streptococcus, and Weissella genus, compared with traditional Chinese fermented glutinous rice (CRW). The growth profiles of lactic acid bacteria were analyzed based on fermentations in vitro, and the optical densities were recorded at 600 nm during the whole fermentation. Growth curve, maximum OD600 nm, and growth rate were measured and compared among samples with different ratios of CRW-FBT and CRW addition. Through the multiple analysis of growth parameters, we found that all the tested strains obtained better growth results when CRW-FBT was supplemented to the media, compared with the CRW and basic media. The bacterial growth was promoted by exhibiting the shortened lag time, prolonged logarithmic phase and stationary phase, and increased growth rate and cell density, as well as the better performance after 24 h and 48 h fermentation. Besides, short-chain fatty acids and organic acids in CRW-FBT were founded. Our work demonstrated the positive effect of Fu brick tea supplemented in the CRW and illustrated its beneficial role in the food fermentation industry for the purpose of microorganism enrichment and the improvement of microbial metabolism.

Gut Microbiota Dysbiosis Influences Metabolic Homeostasis in Spodoptera frugiperda.

Insect gut microbiota plays important roles in acquiring nutrition, preventing pathogens infection, modulating immune responses, and communicating with environment. Gut microbiota can be affected by external factors such as foods and antibiotics. Spodoptera frugiperda (Lepidoptera: Noctuidae) is an important destructive pest of grain crops worldwide. The function of gut microbiota in S. frugiperda remains to be investigated. In this study, we fed S. frugiperda larvae with artificial diet with antibiotic mixture (penicillin, gentamicin, rifampicin, and streptomycin) to perturb gut microbiota, and then examined the effect of gut microbiota dysbiosis on S. frugiperda gene expression by RNA sequencing. Firmicutes, Proteobacteria, Bacteroidetes, and Actinobacteria were the most dominant phyla in S. frugiperda. We found that the composition and diversity of gut bacterial community were changed in S. frugiperda after antibiotics treatment. Firmicutes was decreased, and abundance of Enterococcus and Weissella genera was dramatically reduced. Transcriptome analysis showed that 1,394 differentially expressed transcripts (DETs) were found between the control and antibiotics-treated group. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) results showed that antibiotics-induced dysbiosis affected many biological processes, such as energy production, metabolism, and the autophagy–lysosome signal pathway. Our results indicated that dysbiosis of gut microbiota by antibiotics exposure affects energy and metabolic homeostasis in S. frugiperda, which help better understand the role of gut microbiota in insects.

Weissella: An Emerging Bacterium with Promising Health Benefits.

Weissella strains have been the subject of much research over the last 5 years because of the genus' technological and probiotic potential. Certain strains have attracted the attention of the pharmaceutical, medical, and food industries because of their ability to produce antimicrobial exopolysaccharides (EPSs). Moreover, Weissella strains are able to keep foodborne pathogens in check because of the bacteriocins, hydrogen peroxide, and organic acids they can produce; all listed have recognized pathogen inhibitory activities. The Weissella genus has also shown potential for treating atopic dermatitis and certain cancers. W. cibaria, W. confusa, and W. paramesenteroides are particularly of note because of their probiotic potential (fermentation of prebiotic fibers) and their ability to survive in the gastrointestinal tract. It is important to note that most of the Weissella strains with these health-promoting properties have been shown to be save safe, due to the absence or the low occurrence of virulence or antibiotic-resistant genes. A large number of scientific studies continue to report on and to support the use of Weissella strains in the food and pharmaceutical industries. This review provides an overview of these studies and draws conclusions for future uses of this rich and previously unexplored genus.

Integrated Phenotypic-Genotypic Analysis of Candidate Probiotic Weissella Cibaria\xa0Strains 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.

Vaginal Microbiota during Estrous Cycle and its Plausible Association with Certain Hematological Parameters in Bubalus bubalis

The study on the dynamics of vaginal microbiota during the estrous cycle and its plausible association with certain hematological parameters in Bubalus bubalis was conducted on nine buffalo heifers at a private dairy farm. Out of nine, eight heifers responded to the synchronization protocol and included in the experiment. Blood collection using vacutainers and vaginal flushing using sterile normal saline with a syringe and AI sheath was carried out on ‘0’ (estrus), 4th (metestrus), 9th (diestrus) and 19th day (proestrus) of the synchronized estrous cycle. The collected vaginal samples were lyophilized, DNA isolated using Qiagen stool kit, and amplified with fusion primer for Bacteria (16S rRNA), Fungi (ITS 6-8), and Archaea (16S rRNA). The amplicon library constructed was sequenced through Ion PGM machine and annotation was carried out through MG-RAST with rRNA database SILVA ssu with 98% identity. The results revealed four major domains - Bacteria (93.8%), Eukaryota (5.7%), Archaea (0.006%), and Unclassified sequences (0.41%). A total of 2196 bacterial species, 17 fungal species, and two archaeal species were detected confirming the richest diversity of vaginal microflora in buffalo heifers. The highly abundant domain-bacteria contained 18 bacterial phyla and were grouped into four high (&gt;5%), six moderate (0.1-5%), and eight less abundant groups (0-0.1%). The results of hematological parameters were within the normal range. There was no impact of four stages of the estrous cycle on hematological parameters studied and no associations of bacterial phyla with them. Out of a total of 588 bacterial genera, only 14 showed a negative association, while four genera showed a positive association with blood monocytes. Similarly, only Moraxella, Microcoleus, Thiomonas showed negative associations with WBC, lymphocyte, and granulocyte, and Weissella genus showed a negative association with lymphocyte. No association was observed between types of white blood cells and fungus or archaea. These results of association of vaginal microflora with hematological parameters may be of unknown reasons and suggest further investigations.

Isolation and Identification of Lactic Acid Bacteria in Wine Production by MALDI-TOF MS Biotyper

Abstract The aim of this study was to identify lactic acid bacteria (LAB) in grapes, must and wines. A total amount of 90 samples including grape (n = 30), must (no = 30) and wine (no = 30) were collected from vineyards in Slovakia. LAB were used cultured on MRS agar with subsequent confirmation with MALDI-TOF mass spectrometry (Bruker Daltonics). Altogether, 904 isolates were identified. Members of the family Lactobacillaeceae were the most abundant in grape (60%), must (46%) and wine (51%). Lactobacillus, Lactococcus, Leuconostoc, Pediococcus and Weissella genera and 27 species of LAB were isolated from the examined samples. Leuconostoc mesenteroides spp. mesenteroides was the most abundant species in grape, must and wine.

Isolation, characterization and selection of potential probiotic lactic acid bacteria from feces of wild boar, native pig and commercial pig

In livestock production, lactic acid bacteria (LAB) play an important role in improving performance, mitigating diseases due to their ability to maintain the balance of gastrointestinal microbes and resistance to pathogenic bacteria. As resident adapted microorganisms, LAB should be isolated and characterized from the homologous host to improve their efficiency as additives in pig feeding. In present study, cultivable LAB numbers from commercial pig (CP), native pig (NP) and wild boar (WB) samples ranged from 4.64 to 7.39 (log10 CFU/g), and the LAB counts in commercial pig and native pig feces were much higher than wild boar. Ninety-six LAB strains were detected in commercial pig, native pig and wild boar feces, being represented by thirteen different species of Enterococcus, Lactobacillus, Pediococcus and Weissella genera. Tests in vitro were conducted including survival in simulated gastrointestinal tract conditions, antimicrobial activity, organic acid production, hydrophobicity, auto-aggregation, Caco-2 surface adhesion, haemolytic activity and antibiotic resistance. According to the results of acid and bile salt resistant and bacteriostatic test, twelve LAB strains were selected as potential probiotics and their cell surface properties were further evaluated. Based on multivariate principal component analysis, nine probiotic LAB strains (Lactobacillus plantarum NCUA001005 and NCUA001014, Pediococcus pentosaceus NCUA006009, Lactobacillus reuteri NCUA064001 and NCUA064006, Lactobacillus johnsonii NCUA063001, NCUA063006 and NCUA063008, Lactobacillus casei NCUA011001) showed better characteristics and might be selected to explore their potential use as probiotics. These strains were good candidates for further investigation in vivo studies to assess their potential health benefits as feed supplements.

Nutritional, Microbial, and Allergenic Changes during the Fermentation of Cashew 'Cheese' Product Using a Quinoa-Based Rejuvelac Starter Culture.

Fermentation has been applied to a multitude of food types for preservation and product enhancing characteristics. Interest in the microbiome and healthy foods makes it important to understand the microbial processes involved in fermentation. This is particularly the case for products such as fermented cashew (Anacardium occidentale). We hereby describe the characterisation of cashew samples throughout an entire fermentation production process, starting at the quinoa starter inoculum (rejuvelac). The viable bacterial count was 108 -109 colony forming units/g. The nutritional composition changed marginally with regards to fats, carbohydrates, vitamins, and minerals. The rejuvelac starter culture was predominated by Pediococcus and Weissella genera. The ‘brie’ and ‘blue’ cashew products became dominated by Lactococcus, Pediococcus, and Weissella genera as the fermentation progressed. Cashew allergenicity was found to significantly decrease with fermentation of all the end-product types. For consumers concerned about allergic reactions to cashew nuts, these results suggested that a safer option is for products to be made by fermentation.

Complete Genome Sequence of Weissella hellenica 0916-4-2 and Its Comparative Genomic Analysis.

Weissella genus from Leuconostocaceae family forms a group of Gram-positive lactic acid bacteria (LAB) that mostly reside in fermented foods and some have been isolated from the environment and vertebrates including humans. Currently there are 23 recognized species, 16 complete and 37 draft genome assemblies for this genus. Weissella hellenica has been found in various sources and is characterized by their probiotic and bacteriocinogenic properties. Despite its widespread importance, little attention has been paid to genomic characterization of this species with the availability of draft assembly of two species in the public database so far. In this manuscript, we identified W. hellenica 0916-4-2 from fermented kimchi and completed its genome sequence. Comparative genomic analysis identified 88 core genes that had interspecies mean amino acid identity of more than 65%. Whole genome phylogenetic analysis showed that three W. hellenica strains clustered together and the strain 0916-4-2 was close to strain WiKim14. In silico analysis for the secondary metabolites biosynthetic gene cluster showed that Weissella are far less producers of secondary metabolites compared to other members of Leuconostocaceae. The availability of the complete genome of W. hellenica 0916-4-2 will facilitate further comparative genomic analysis of Weissella species, including studies of its biotechnological potential and improving the nutritional value of various food products.

Biogenic Amine Production by Lactic Acid Bacteria: A Review.

Lactic acid bacteria (LAB) are considered as the main biogenic amine (BA) producers in fermented foods. These compounds derive from amino acid decarboxylation through microbial activities and can cause toxic effects on humans, with symptoms (headache, heart palpitations, vomiting, diarrhea) depending also on individual sensitivity. Many studies have focused on the aminobiogenic potential of LAB associated with fermented foods, taking into consideration the conditions affecting BA accumulation and enzymes/genes involved in the biosynthetic mechanisms. This review describes in detail the different LAB (used as starter cultures to improve technological and sensorial properties, as well as those naturally occurring during ripening or in spontaneous fermentations) able to produce BAs in model or in real systems. The groups considered were enterococci, lactobacilli, streptococci, lactococci, pediococci, oenococci and, as minor producers, LAB belonging to Leuconostoc and Weissella genus. A deeper knowledge of this issue is important because decarboxylase activities are often related to strains rather than to species or genera. Moreover, this information can help to improve the selection of strains for further applications as starter or bioprotective cultures, in order to obtain high quality foods with reduced BA content.

Identification, characterization and selection of autochthonous lactic acid bacteria as probiotic for feedlot cattle

Livestock microbiota is becoming a focus of interest for veterinaries, animal nutritionists and microbiologists in view to select beneficial bacteria with impact in health and animal productivity. As resident adapted microorganisms, lactic acid bacteria (LAB) were isolated, identified and characterized from the homologous host to promote their permanence/efficiency acting as additives in feedlot cattle feeding. Cultivable LAB numbers from cattle feces (CF), pens soil (PS) and feed rations (FR) ranged from 5 to 6 log CFU/g during feedlot permanence. Isolates (500) were identified by (GTG)5-PCR and sequence analysis of 16S rRNA, being represented by Enterococcus, Lactobacillus, Leuconostoc, Pediococcus and Weissella genera and 20 different species. Genetic mapping showed that predominant LAB species in CF and PS samples were Lactobacillus (Lb) mucosae (34%), Enterococcus (E) hirae (26%) and E. faecium-durans (20%), while in FR E. faecium-durans (46%), Pediococcus (P). pentosaceous, P. acidilactici (17%) and Lb. acidophilus (11%) were mainly isolated. Surface characterization showed most of LAB as high hydrophilic, however several strains from CF and PS revealed strong hydrophobic and auto-aggregative character with a positive correlation between both superficial properties. Adhesion to polystyrene displayed variable biofilm formation patterns for Enterococcus and Lactobacillus strains depending on the presence of Tween in MRS medium. When antagonistic activity of isolated LAB against bovine relevant pathogens was evaluated, organic acids and hydrogen peroxide production were mostly responsible for inhibition; bacteriocin production was shown only by a Lb. mucosae strain. In addition, tolerance to acid and bile salts showed lactobacilli to withstand GIT conditions, while enterococci were more sensitive to low acid environment. On these bases, several Lactobacillus strains may be selected to explore their potential use as direct fed bacteria in feedlot cattle.