Latilactobacillus curvatus: A Candidate Probiotic with Excellent Fermentation Properties and Health Benefits

Simulating the activity of the natural antimicrobial system of milk on the growth of selected cultures involved in cheesemaking and ripening

The impact of three antimicrobial proteins (lactoferrin, lactoperoxidase, lysozyme) on the growth of cultures involved in cheesemaking and ripening was studied. Strains were grown in the optimal media growth of each strain or in cheese simulated environment. The media were supplemented with the antimicrobial proteins together (MIX; 1:1:1) or individually at concentrations found in milk (1x) and cheese (2.5x). Growth properties were evaluated using a novel approach by combining flow cytometry and spectrophotometric assay. Flow cytometry measures cell viability (live/injured/dead cells; total cells). Lactococcus cremoris CUC-C (starter culture) was stimulated by lactoperoxidase and lysozyme reaching higher optical density and total cells than control (without antimicrobial proteins). In cheese simulated environment, the live cells of L. cremoris CUC-C increased of more than 30% in the MIX condition without an increase in total cells. Flow cytometry allowed to show this protective effect. For cultures involved in ripening, the total cells of Lactiplantibacillus plantarum ATCC 14917 and Lacticaseibacillus paracasei subsp. tolerans LMA-1802 decreased of 1 log in the MIX condition. Although the same log reduction, different inhibition behavior was observed. Live cells for Lpb. plantarum ATCC 14917 remained unchanged while for Lcb. paracasei LMA-1802, injured cells increased. These observations were only possible by flow cytometry. The higher concentration (2.5x) tended to decrease the growth properties (lower maximal rate, longer lag phase) of strains as compared to the lower one (1x). The strain-dependent sensitivity to the three antimicrobial proteins underlines the importance of evaluating their effect on cultures prior cheesemaking to ensure proper functionality.

Effect of marination with bioprotective culture-containing marinade on Salmonella spp. and Listeria monocytogenes in chicken breast meat

This study investigated the survival of Pseudomonas spp., Salmonella spp., and Listeria monocytogenes in chicken breast meat marinated with a marinade containing bioprotective lactic acid bacteria (Latilactobacillus curvatus, Latilactobacillus sakei, and Lactiplantibacillus plantarum) during storage at 4°C and 8°C. In the first phase, a natural, chemical-free marinade (pH 3.6) was evaluated over 7 days. In this marinade, Pseudomonas spp. did not survive, Salmonella spp. were inactivated within 7 days, L. monocytogenes counts showed negligible reduction, and bioprotective cultures remained stable. In the second phase, chicken breast meat contaminated with Salmonella spp. and L. monocytogenes was divided into control (non-marinated), marinated control (M-C), and marinated with a marinade containing mixture of bioprotective cultures (M-PC). Initial pH values were 5.99 (control), 5.24 (M-C), and 5.32 (M-PC). At 4°C, L. monocytogenes counts in the M-PC group were 4.4 log10 cfu/g lower than the control and 1.4 log10 cfu/g lower than the M-C group on Day 14 (p < 0.05). By Day 14, Pseudomonas spp. counts were 9.4, 7.3, and 5.7 log10 cfu/g in the control, M-C, and M - PC groups, respectively (p < 0.05). At 8°C, Salmonella spp. in the M-PC group fell below 1.0 log10 cfu/g by Day 12, and L. monocytogenes counts were significantly lower than in the M-C group (p < 0.05). Marinating with bioprotective cultures enhanced microbial safety and extended shelf life compared to marinating without them. This approach could offer significant potential for improving the preservation and safety of poultry products. PRACTICAL APPLICATION: Marinated poultry meat, whether prepared domestically by consumers or commercially produced by the poultry meat industry, is widely enjoyed for its flavor and convenience. In this study, bioprotective cultures were incorporated into the marinade as an alternative to chemical preservatives. The findings demonstrate that marinating chicken breast meat with a marinade composed entirely of natural ingredients and enriched with bioprotective cultures not only extends the product's shelf life but also significantly limits the survival of Pseudomonas spp., Salmonella spp. and Listeria monocytogenes. These results suggest that meat products marinated with bioprotective cultures, or ready-to-use marinades containing such cultures, can be effectively developed and marketed by the meat industry to meet consumer demand for safer, long-lasting, and naturally preserved food products.

Evaluation of the nutritional value of fermented pangasius fish waste and its potential as a poultry feed supplement

Background and Aim

The increasing global demand for sustainable and nutrient-dense poultry feed necessitates innovative approaches to utilize byproducts such as pangasius fish waste. This study explores the potential of bioconverted fermented pangasius fish waste (FPW) produced through microbial fermentation as a poultry feed supplement.

Materials and Methods

The study was conducted in two stages. In the first stage, bioconversion of pangasius fish waste utilized a microbial consortium (PaRmYl: Pseudomonas aeruginosa, Rhizopus microsporus, and Yarrowia lipolytica) at varying inoculum doses (5%, 10%, and 20%) and fermentation durations (2, 4, and 8 days). Nutritional content, enzyme activity, and antioxidant properties were analyzed. The second stage involved biological testing on 90 broiler chickens (randomized into three treatment groups with 30 replications each) to assess digestibility and nitrogen retention of FPW-based feed.

Results

Fermentation with a 10% inoculum dose over 4 days yielded the optimal nutritional composition, with crude protein content increasing to 37.27%, enhanced amino acid (EAA/NEAA ratio: 0.88), and fatty acid profiles (notably ω-3 and ω-6). Protease and lipase activity peaked at 1.49 U/mL and 1.21 U/mL, respectively, with antioxidant activity showing an IC50 value of 39.84 ppm. Biological tests demonstrated significantly higher dry matter digestibility (75.53%) and nitrogen retention (75.53%) in broilers fed FPW compared to non-fermented feed.

Conclusion

FPW, produced through microbial bioconversion, offers a sustainable and cost-effective poultry feed supplement, enhancing digestibility and nutrient retention while addressing environmental concerns related to fish processing waste.

Chemical structure of lipoteichoic acid in the probiotic strain Latilactobacillus curvatus CP2998

Latilactobacillus curvatus, found in various fermented foods, is a promising probiotic with unique health benefits. Lipoteichoic acid (LTA) is a characteristic amphiphilic surface polymer of Gram-positive bacteria and exhibits immunomodulatory activities. Despite the structural diversity of LTA among different bacterial species and strains, no information is available on the chemical structure of LTA in L. curvatus. In this study, we aimed to determine the structure of LTA isolated from L. curvatus CP2998. One- and two-dimensional nuclear magnetic resonance spectra of intact LTA revealed that LTA had a glycerolphosphate polymer as a hydrophilic main chain with partial substitutions of α-linked glucose and d-alanine at the hydroxy group at position 2 of the glycerol residue. The anchor glycolipid fraction was obtained by hydrofluoric acid treatment. Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry spectrum of the anchor glycolipid revealed that it contained diglucosyldiacylglycerol and diglucosylmonoacylglycerol. Our results suggest that L. curvatus CP2998 possesses a typical type I LTA structure; however, the lactic acid bacteria-specific anchor glycolipid structures, such as tri- or tetra-saccharides and three fatty acid residues, were not identified.

Screening approaches and potential of isolated lactic acid bacteria for improving fermentation of Saccharina latissima

BACKGROUND

With the growing interest in applying fermentation to seaweed biomasses, there is a need for fast and efficient selection of microbial strains that have the ability to 1) acidify quickly, 2) utilize seaweed constituents and c) exhibit some proteolytic activity. The present study aims to provide a fast methodology to screen large bacterial collections for potential applications in optimized seaweed fermentations, as well as investigate and assess the performance of a selected bacterial collection of the National Food Institute Culture Collection (NFICC) in seaweed fermentation. This approach is directed toward high-throughput (HT) methodologies, employing microwell assays for different phenotypical characteristics of lactic acid bacteria isolated from different sources. The overarching aim is the deeper understanding of the selection criteria when designing starter cultures for seaweed fermentation.

RESULTS

By employing high-throughput analytical workflows, the screening processing time is minimized, and among the different strains from a well-characterized strain collection, it was possible to distinguish between strong acidifiers and to replicate similar results when the volumes were scaled from 96-well plates to lab-scale fermentations (40 mL) of whole seaweed. Lactiplantibacillus plantarum, Lacticaseibacillus paracasei and, to a lesser extent, Lacticaseibacillus rhamnosus were among the fastest strains to reach the lowest endpoint pH values (< 4.5) in less than 48 h. Although the results regarding proteolytic capacity were not sufficient to prove that the candidates can also provide some flavor generation by the cleavage of proteins, NFICC1746 and NFICC2041 exhibited potential in releasing free alanine, glutamate and asparate as free amino acids.

CONCLUSIONS

With the described methodology, a large number of terrestrial lactic acid bacteria (LAB) isolates were screened for their performance and possible application for fermentation of brown sewaeeds. With a a fast conversion of sugars to organic acids, three potential new plant-isolated strains from NFICC, specifically Lactiplantibacillus plantarum ssp. argentoratensis (NFICC983), Lacticaseibacillus paracasei (NFICC1746) and Lacticaseibacillus rhamnosus (NFICC2041), were identified as promising candidates for future synthetic consortia aimed at application in bioprocessed seaweed. The combination of such strains will be the future focus to further optimize robust seaweed fermentations.

Influence of supplementation with probiotic bacteria Lactiplantibacillus plantarum and Latilactobacillus curvatus on selected parameters of duodenum iron metabolism in rats on a high-fat, iron-deficient diet

OBJECTIVES

A high-fat, iron (Fe)-deficient Western diet induces obesity and dysregulates Fe metabolism. We compared the influence of Lactiplantibacillus plantarum and Latilactobacillus curvatus with and without Fe supplementation on duodenal Fe uptake under high-fat diet conditions.

METHODS

Rats were fed a high-fat diet (HF group) or high-fat, Fe-deficient diet (HFDEF group) or control diet (C group) for 8 wk. For the next 8 wk, the rats in the C and HF groups continued on the same diet, whereas the rats in the HFDEF group were divided into six groups and fed high-fat, Fe-deficient diet combinations with L. plantarum (Lp), L. curvatus (Lc), and Fe supplementation (HFDEF, HFDEFFe, HFDEFLp, HFDEFLc, HFDEFFeLp, HFDEFFeLc). Duodenum and serum samples were collected for analysis.

RESULTS

In the duodenum, the Fe content was higher in the HFDEFFeLp and HFDEFFeLc groups; the ferroportin level was higher in the HFDEFFeLp and HFDEFFeLc groups versus the HF group; the divalent metal transporter 1 level was higher in the HFDEFFeLc group versus the C and HF groups; and duodenal cytochrome B was higher in the HFDEFLc versus all the other groups. In addition, duodenal expression of the solute carrier family 11 member 2 gene was higher in the HFDEF group versus the C, HF, HFDEFFe, HFDEFFeLp, and HFDEFFeLc groups; that of the TFRC gene was higher in the HFDEFFeLc group versus the C, HF, HFDEF, and HFDEFFe groups; and that of the HJV gene was higher in the HFDEFFeLp group versus the C, HF, HFDEF, HFDEFFe, and HFDEFLc groups.

CONCLUSIONS

L. plantarum and L. curvatus supplementation shows some potential to enhance duodenal cellular Fe uptake in rats on a high-fat, Fe-deficient diet.

Microbiota in the ptarmigan intestine-An Inuit delicacy and its potential in popular cuisine

The consumption of prey intestines and their content, known as gastrophagy, is well-documented among Arctic Indigenous peoples, particularly Inuit. In Greenland, Inuit consume intestines from various animals, including the ptarmigan, a small herbivorous grouse bird. While gastrophagy provides the potential to transfer a large number of intestinal microorganisms from prey to predator, including to the human gut, its microbial implications remain to be investigated. This study addresses this gap by investigating the microbial composition of the Greenlandic rock ptarmigan's gastrointestinal tract by analyzing the crop, stomach, and intestines while also comparing it with the microbiota found in garum, a fermented sauce made from ptarmigan meat and intestines. Through 16S rRNA gene sequencing, we assessed whether garum made from ptarmigan intestines provides access to microbial diversity otherwise only accessible through gastrophagy. Our findings reveal that garum made from ptarmigan intestines displayed distinct flavors and microbial composition similar to that found in the ptarmigan gut and intestines, highlighting the potential role of fermented products in mediating food microbial diversity associated with Indigenous food practices. Furthermore, our study underscores the broader importance of understanding microbial diversity in different food systems, particularly in the context of shifting dietary patterns and concerns about diminishing food microbial diversity. By elucidating the microbial richness gained through gastrophagy this research contributes to a deeper understanding of traditional and Indigenous foodways and their implications for human gut health.

Unexplored microbial diversity from 2,500 food metagenomes and links with the human microbiome

Complex microbiomes are part of the food we eat and influence our own microbiome, but their diversity remains largely unexplored. Here, we generated the open access curatedFoodMetagenomicData (cFMD) resource by integrating 1,950 newly sequenced and 583 public food metagenomes. We produced 10,899 metagenome-assembled genomes spanning 1,036 prokaryotic and 108 eukaryotic species-level genome bins (SGBs), including 320 previously undescribed taxa. Food SGBs displayed significant microbial diversity within and between food categories. Extension to >20,000 human metagenomes revealed that food SGBs accounted on average for 3% of the adult gut microbiome. Strain-level analysis highlighted potential instances of food-to-gut transmission and intestinal colonization (e.g., Lacticaseibacillus paracasei) as well as SGBs with divergent genomic structures in food and humans (e.g., Streptococcus gallolyticus and Limosilactobabillus mucosae). The cFMD expands our knowledge on food microbiomes, their role in shaping the human microbiome, and supports future uses of metagenomics for food quality, safety, and authentication.

Microbial Community Dynamics and Metabolite Changes during Wheat Starch Slurry Fermentation

Wheat starch fermentation slurry is the main substrate for producing Ganmianpi, a traditional Chinese fermented wheat starch-based noodle. In the present work, the microbial population dynamics and metabolite changes in wheat starch fermentation slurry at different fermentation times (0, 1, 2, 3, and 4 days) were measured by using high-throughput sequencing analysis and headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME/GC-MS) methods. The texture and sensory properties of Ganmianpi made from fermented starch slurry are also evaluated. The results showed that Latilactobacillus curvatus and Leuconostoc citreum were the dominant bacteria in wheat starch fermentation slurry, while Saccharomyces cerevisiae and Kazachstania wufongensis were identified as the main species of fungi. With the extension of fermentation time, the reducing sugar content first increased and then decreased, when the titratable acidity content showed an increasing trend, and the nonvolatile acid was significantly higher than the volatile acid. A total of 62 volatile flavor compounds were identified, and the highest content is alcohols, followed by acids. Fermentation significantly reduced the hardness and chewiness of Ganmianpi, and increased its resilience and cohesiveness. Ganmianpi made from fermented starch slurry for two and three days showed a higher sensory score than other samples. The present study is expected to provide a theoretical basis for exploiting the strains with potential for commercial application as starter cultures and quality improvement of Ganmianpi.

Metagenomics reveals differences in the composition of bacterial antimicrobial resistance and antibiotic resistance genes in pasteurized yogurt and probiotic bacteria yogurt from China

Antimicrobial resistance has become a global public health concern, and antibiotic resistance genes (ARG) in food are a research focus. In China, probiotics and pasteurized yogurts are the 2 main types of commercially available yogurt, but the distribution and differences of antibiotic-resistant bacteria and gene types in these products are not well known. This study used a shotgun metagenomic approach to analyze 22 different types of yogurt collected from 9 main yogurt-producing areas in China; each type of yogurt included 8 different batches of samples. The abundance and diversity of bacteria identified in probiotic yogurt were significantly higher than those in pasteurized yogurt, with Acetobacter, Raoultella, and Burkholderia identified as unique and highly abundant genera in probiotic yogurt. Similarly, the abundance of Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp. was higher than that in pasteurized yogurt. A total of 1,149 ARG subtypes belonging to 16 ARG types were identified, with the highest abundance of rifampicin, multidrug efflux pumps, and quinolone resistance genes detected. Network analysis revealed significant nonrandom co-occurrence relationships between different types and subtypes of ARG in yogurt samples. A total of 44 ARG subtypes in pasteurized yogurt were potentially hosted by 36 bacterial genera, and in probiotic yogurt, 63 ARG were expected to be hosted by 86 bacterial species from 37 genera. These findings indicate potential safety issues in fermented dairy products and emphasize the need for a more hygienic environment when processing probiotic yogurt.

Latilactobacillus curvatus FFZZH5L isolated from pickled cowpea enhanced antioxidant activity in Caenorhabditis elegans by upregulating the level of glutathione S-transferase

Latilactobacillus curvatus is a potential probiotic that possesses beneficial health properties and fermentation traits; however, the extent of understanding of the antioxidant activities of L. curvatus is limited. This study investigates the antioxidant activities of a new L. curvatus FFZZH5L strain. The strain exhibits broad tolerance to acids, bases and salts and demonstrated good adaption to the gastrointestinal environment, with a survival rate of 45% after 24 h of treatment in artificial gastrointestinal juice. Moreover, L. curvatus FFZZH5L exhibits inhibitory effects on Staphylococcus aureus, with a self-aggregation rate of 34.8% and a co-aggregation rate of 82.2%. In vitro, the DPPH radical scavenging ability and GSH-px enzyme activity of L. curvatus FFZZH5L reach 64.27% and 15.95 U mL-1, respectively. Treatment of C. elegans with L. curvatus FFZZH5L in vivo significantly extended the organism's lifespan. Furthermore, the activity of SOD, GSH-px and T-AOC was increased by 33.6%, 43.4% and 58.3%, respectively. Feeding C. elegans with L. curvatus FFZZH5L decreased the MDA, lipofuscin and ROS levels by 9%-36.4%. L. curvatus FFZZH5L effectively protected C. elegans against juglone-induced oxidative stress damage and led to a significant increase in the organism's survival under heat stress. The RT-qPCR analysis suggests that feeding C. elegans with L. curvatus FFZZH5L upregulates the expression levels of antioxidant-related genes including glutathione S-transferase 4 (gst-4), gst-1, gst-10, sod-3, sod-5, and sod-10 in C. elegans. Our investigation confirms the probiotic and antioxidant properties of L. curvatus, indicating its potential application in functional foods and the pharmaceutical industry.

Unraveling multifunction of low-temperature Daqu in simultaneous saccharification and fermentation of Chinese light aroma type liquor

Chinese liquor is produced by a representative simultaneous saccharification and fermentation process. Daqu, as a starter of Chinese liquor fermentation, affects both saccharification and fermentation. However, it is still unclear how Daqu contributed to the simultaneous saccharification and fermentation process. Here, using Chinese light aroma type liquor as a case, we identified low-temperature Daqu-originated enzymes and microorganisms that contributed to the simultaneous saccharification and fermentation using metaproteomic analysis combined with amplicon sequencing analysis. α-Amylase and glucoamylase accounted for 95 % of total saccharifying enzymes and were identified as key saccharifying enzymes. Lichtheimia was the key producer of these two enzymes (> 90 %) in low-temperature Daqu. Daqu contributed 90 % α-amylase and 99 % glucoamylase to the initial liquor fermentation. These two enzymes decreased by 35 % and 49 % until day 15 in liquor fermentation. In addition, Daqu contributed key microbial genera (91 % Saccharomyces, 6.5 % Companilactobacillus) and key enzymes (37 % alcohol dehydrogenase, 40 % lactic acid dehydrogenase, 56 % aldehyde dehydrogenase) related with formations of ethanol, lactic acid and flavour compounds to the initial liquor fermentation. The average relative abundances of these fermentation-related key microorganisms and enzymes increased by 2.78 times and 1.29 times till day 15 in liquor fermentation, respectively. It indicated that Daqu provided saccharifying enzymes for starch hydrolysis, and provided both enzymes and microorganisms associated with formations of ethanol, lactic acid and flavour compounds for liquor fermentation. This work illustrated the multifunction of low-temperature Daqu in the simultaneous saccharification and fermentation of Chinese light aroma type liquor. It would facilitate improving liquor fermentation by producing high-quality Daqu.

Food-Grade Bacteria Combat Pathogens by Blocking AHL-Mediated Quorum Sensing and Biofilm Formation

Disrupting bacterial quorum sensing (QS) signaling is a promising strategy to combat pathogenic biofilms without the development of antibiotic resistance. Here, we report that food-associated bacteria can interfere with the biofilm formation of a Gram-negative pathogenic bacterium by targeting its AHL (acyl-homoserine lactone) QS system. This was demonstrated by screening metabolic end-products of different lactobacilli and propionibacteria using Gram-negative and biofilm-forming Chromobacterium violaceum as the QS reporter and our anti-QS microscale screening platform with necessary modifications. The method was optimized in terms of the inoculation technique and the concentrations of D-glucose and L-tryptophan, two key factors controlling the synthesis of violacein, a purple pigment indicating the activation of the QS system in C. violaceum. These improvements resulted in ca. 16-times higher violacein yields and enabled revealing anti-QS effects of Lactobacillus acidophilus, Lentilactobacillus kefiri, Lacticaseibacillus rhamnosus and Propionibacterium freudenreichii, including new cheese-associated strains. Our findings also suggest that acetate and propionate excreted by these species are the main factors that interrupt the QS-mediated signaling and subsequent biofilm growth without affecting the cell viability of the C. violaceum reporter. Thus, the present study reports a revised anti-QS screening method to accurately define new bacteria with an ability to combat pathogens in a safe and sustainable way.

Metagenomic Analysis of Liquor Starter Culture Revealed Beneficial Microbes' Presence

Wines are complex matrices famous for their pleasant aroma and exceptional flavor. Baijiu (white wine) is a traditional Chinese liquor with a soft mouthfeel, fragrant taste, and long-lasting aftertaste. Baijiu is distilled from sorghum and wheat via solid fermentation. As in wines, the microbial ecosystem of Baijiu is a key decisive factor influencing aroma and consumer preferences. Microbial diversity in Baijiu has been intensively investigated. It is important to note that probiotics are a mixture of bacteria and yeast primarily intended to improve health. Our study aimed to characterize the microbial ecosystem of Zaopei Baijiu Daqu (ZBD) starter cultures for specific microbes with probiotic properties. The DNA samples of ZBD starters were analyzed using a metagenomic 16S rRNA approach to characterize the bacterial and ITS for fungal diversity. Weissella cibaria was the most dominant species in the bacterial community, while Saccharomycopsis fibuligera was the most abundant fungal species. Furthermore, functional prediction analysis identified unique pathways associated with microbial diversity relevant to functional innovation. These associated pathways include fermentation, amino acid metabolism, carbohydrate metabolism, energy metabolism, and membrane transport. This study identified beneficial microbes in the starter culture, opening a path for further in-depth analysis of those microbes by isolating and evaluating them for a valuable role in in vitro and in vivo studies.

Phenotype-genotype analysis of Latilactobacills curvatus from different niches: Carbohydrate metabolism, antibiotic resistance, bacteriocin, phage fragments and linkages with CRISPR-Cas systems

The potential probiotic function of Latilactobacills curvatus has attracted the attention of researchers. To explore the differences in the genomes of L. curvatus, nine strains were isolated from various sources, including feces and fermented vegetables and compared with 25 strains from the NCBI database. The findings indicated that the average genome size, GC content, and CDS of L. curvatus were 1.94 MB, 41.9%, and 1825, respectively. Its core genome is associated with transcription, translation, carbohydrate transport and metabolism, and defense functions. The pan-genome of L. curvatus was in a closed state. The genetic diversity of L. curatus is mainly manifested in its ability to use carbohydrates, antibiotic resistance, bacteriocin operon, and polymeric regularly interspaced short palindromic repeats (CRISPR)-Cas for bacterial immunity. The CRISPR system of 34 strains of L. curvatus was predominantly found to be of the IIA type with a few IIC and IE types. These findings will contribute to a better understanding of this species.

Microbiological Characterization of Greek Galotyri Cheese PDO Products Relative to Whether They Are Marketed Fresh or Ripened

Galotyri is the most popular traditional Greek PDO soft acid-curd cheese. This study compared the microbial numbers and types and characterized the lactic acid bacteria (LAB) biota of two artisan-type Galotyri PDO cheese varieties, one marketed fresh (Brand-K) and the other ripened (Brand-Z). Two retail batches of each cheese variety were analyzed, and a total of 102 LAB isolates were biochemically identified. LAB (7.2–9.3 log CFU/g) prevailed in all cheeses, followed by yeasts (5.8–6.8 log CFU/g). Typical starter strains of Streptococcus thermophilus and Lactobacillus delbrueckii were the most abundant species in all batches. However, the fresh Brand-K cheeses had 1–3 log units higher thermophilic starter LAB counts than the ripened Brand-Z cheeses, which contained a more diverse viable LAB biota comprising Lacticaseibacillus paracasei, Leuconostocmesenteroides, Lentilactobacillus (L. diolivorans, L. kefiri, L. hilgardii), Pediococcusinopinatus/parvulus, few spontaneous nonstarter thermophilic streptococci and lactobacilli, and Enterococcus faecium and E. faecalis at higher subdominant levels.Conversely, the fresh Brand-K cheeses were enriched in members of the Lactiplantibacillus plantarum group; other LAB species were sporadically isolated, including Lactococcus lactis. All retail cheeses were safe (pH 3.9–4.0). No Salmonella spp. or Listeria monocytogenes were detected in 25-g samples by culture enrichment; however, Listeria innocua and coagulase-positive staphylococci (850 CFU/g) survived in one ripened batch. Gram-negative bacteria were <100 CFU/g in all cheeses. In conclusion, ripening reduced the starter LAB viability but increased the nonstarter LAB species diversity in the present Galotyri PDO market cheeses.

Enhancing Bioactive Components of Euryale ferox with Lactobacillus curvatus to Reduce H2O2-Induced Oxidative Stress in Human Skin Fibroblasts

This study investigated the effects of Lactobacillus curvatus fermentation on the oxidative stress attenuating effects of Euryale ferox on H₂O₂-induced human skin fibroblasts (HSF). The results showed that Lactobacillus curvatus fermentation (i) increases the content of the various bioactive components of Euryale ferox and is found to have smaller molecular weights of polysaccharides and polypeptides; (ii) increases the overall intracellular and extracellular antioxidant capacity of H₂O₂-induced HSF while reducing reactive oxygen species (ROS) levels. Superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) all showed simultaneous increases in activity. Aside from that, the Nrf2 and MAPK signaling pathways are activated to regulate downstream-associated proteins such as the Bax/Bcl-2 protein ratio, matrix metalloproteinase 1 (MMP-1) activity, and human type I collagen (COL-1). These results suggested that the fermentation of Euryale ferox with Lactobacillus curvatus enhances its antioxidant capacity and attenuates apoptosis and senescence caused by oxidative stress.

Effects of Lactobacillus curvatus HY7602-Fermented Antlers in Dexamethasone-Induced Muscle Atrophy

This study assessed the improvements yielded by Lactobacillus curvatus HY7602-fermented antlers (FA) in dexamethasone-induced muscle atrophy and the effects of bioactive compounds increased by fermentation. Dexamethasone-treated C2C12 myoblast cells were treated with FA and non-fermented antlers (NFA). FA showed inhibitory effects on muscle protein degradation in the C2C12 cells. Hsb:ICR mice were orally administered saline (control(CON) and dexamethasone only (DEX)), oxymetholone (DEX+OXY), NFA (DEX+NFA), and FA (DEX+FA) via gavage. Before the end of the experiment, dexamethasone was intraperitoneally (IP) injected into the mice, except in the control group, to induce muscle atrophy. Compared with the DEX group, the DEX+FA group exhibited a significant prevention in the reduction of hindlimb strength, calf thickness, calf muscle weight, and the cross-sectional area of muscle fibers (p < 0.05). The FA-induced improvements in muscle atrophy were associated with a decreased gene expression of protein degradation and growth inhibition, and an increased gene expression of protein synthesis and growth factors. Sialic acid, a bioactive compound associated with muscles, was increased by 51.41% after fermentation and suppressed the expression of protein degradation genes in the C2C12 cells. L. curvatus HY7602-fermented antlers with increased sialic acid after fermentation may therefore be useful for preventing and improving muscle atrophy.

Mechanism of high D-aspartate production in the lactic acid bacterium Latilactobacillus sp. strain WDN19

D-Aspartate (D-Asp) is a useful compound for a semisynthetic antibiotic and has potentially beneficial effects on humans. Several lactic acid bacteria (LAB) species produce D-Asp as a component of cell wall peptidoglycan. We previously isolated a LAB strain (named strain WDN19) that can extracellularly produce a large amount of D-Asp. Here, we show the factors that contribute to high D-Asp production ability. Strain WDN19 was most closely related to Latilactobacillus curvatus. The D-Asp production ability of strain WDN19 in a rich medium was 13.7-fold higher than that of L. curvatus DSM 20019. A major part of D-Asp was synthesized from L-Asp contained in the medium by aspartate racemase (RacD). During their cultivation, the RacD activity in strain WDN19 was higher than in strain DSM 20019, especially much higher in the early exponential growth phase because of the higher racD transcription and the higher activity of RacD itself of strain WDN19. In a synthetic medium, the extracellular production of D,L-Asp was observed in strain WDN19 but not in strain DSM 20019. The addition of L-asparagine (L-Asn) to the medium increased and gave D,L-Asp production in strains WDN19 and DSM 20019, respectively, suggesting L-Asp synthesis by L-asparaginase (AsnA). The L-Asn uptake ability of the strains was similar, but the AsnA activity in the middle exponential and early stationary growth phases and intracellular D,L-Asp was much higher in strain WDN19. In their genome sequences, only an aspartate aminotransferase gene was found among L-Asp-metabolizing enzymes, except for RacD, but was disrupted in strain WDN19 by transposon insertion. These observations indicated that the high D-Asp production ability of strain WDN19 was mainly based on high RacD and AnsA activities and L-Asp supply. KEY POINTS: • Strain WDN19 was suggested to be a strain of Latilactobacillus curvatus. • Extracellular high d-Asp production ability was not a common feature of L. curvatus. • High d-Asp production was due to high RacD and AnsA activities and l-Asp supply.

Probiotic-mediated p38 MAPK immune signaling prolongs the survival of Caenorhabditis elegans exposed to pathogenic bacteria

The host-microbiota cross-talk represents an important factor contributing to innate immune response and host resistance during infection. It has been shown that probiotic lactobacilli exhibit the ability to modulate innate immunity and enhance pathogen elimination. Here we showed that heat-inactivated probiotic strain Lactobacillus curvatus BGMK2-41 stimulates immune response and resistance of the Caenorhabditis elegans against Staphylococcus aureus and Pseudomonas aeruginosa. By employing qRT-PCR and western blot analysis we showed that heat-inactivated BGMK2-41 activated PMK-1/p38 MAPK immunity pathway which prolongs the survival of C. elegans exposed to pathogenic bacteria in nematode killing assays. The C. elegans pmk-1 mutant was used to demonstrate a mechanistic basis for the antimicrobial potential of BGMK2-41, showing that BGMK2-41 upregulated PMK-1/p38 MAPK dependent transcription of C-type lectins, lysozymes and tight junction protein CLC-1. Overall, this study suggests that PMK-1/p38 MAPK-dependent immune regulation by BGMK2-41 is essential for probiotic-mediated C. elegans protection against gram-positive and gram-negative bacteria and could be further explored for development of probiotics with the potential to increase resistance of the host towards pathogens.

Screening and Identification of Latilactobacillus curvatus Z12 From Rumen Fluid of an Adult Female Sika Deer as a Potential Probiotic for Feed Additives

Lactic acid bacteria (LAB) are the main microorganisms used as probiotics against gastrointestinal inflammation. The objective of this study was to evaluate the potential probiotic characteristics (antimicrobial activity, artificial gastrointestinal model resistance, cell surface hydrophobicity, and autoaggregation ability) and safety characteristics (hemolytic activity, antimicrobial resistance, and in vivo safety) of LAB isolated from the rumen fluid of an adult female sika deer. Two isolated strains identified as Latilactobacillus curvatus Z12 and Z19 showed good antimicrobial activity against enteropathogenic Escherichia coli (ATCC25922), Salmonella typhi (ATCC14028), and Staphylococcus aureus (ATCC25923). In addition, L. curvatus Z12 exhibited higher artificial gastrointestinal model resistance, cell surface hydrophobicity and autoaggregation ability than L. curvatus Z19. Therefore, regarding safety characteristics, only L. curvatus Z12 was evaluated. Upon assessment of safety, L. curvatus Z12 was negative for hemolytic activity and susceptible to penicillin G and cefamandole. Furthermore, an in vivo safety assessment showed that high-dose L. curvatus Z12 (109 CFU/mL) supplementation not only had no adverse effects on body weight gain, feed intake, and organ coefficients of treated mice but also played a key role in promoting the immune system maturation of treated mice. This research revealed that L. curvatus Z12 possesses desirable probiotic characteristics and could be used as a potential probiotic feed additive to improve sika deer health.

Isolation, identification and characterization of L actobacillus species diversity from Meekiri: traditional fermented buffalo milk gels in Sri Lanka

Traditional fermented buffalo milk gel; Meekiri, is a popular buffalo milk-derived product in Sri Lanka. Predominantly, it is produced using the back-slopping (adding a small amount of the previous fermentate) technique, following the life-long traditions available at the cottage level. Hence, diverse and unclassified starter cultures are likely to be established across the varying geographical regions of Meekiri production. In the present study, we aimed to elucidate the diversity of lactic acid bacteria (LAB) and their characteristics including probiotic properties from major Meekeri production areas (n = 22) in Sri Lanka. Lactic acid bacteria was isolated from locally produced Meekiri samples (n = 23) and characterized based on morphological, biochemical, physiological profiles and potential of probiotic properties. The isolates revealed five different colony and cell morphologies and were classified as heterofermenters, homofermenters and facultative heterofermenters based on CO2 production using glucose. None of the isolates showed the ability to grow either at 5 °C or 0 °C, while 71 % and 100 % survival of the isolates were observed at 15 °C and 45 °C, respectively. Amplified ribosomal DNA restriction analysis (ARDRA) primarily grouped the isolates into three distinct clusters based on their DNA banding patterns. Subsequently, 16S rRNA sequencing of isolates revealed the presence of four species namely, Limosilactobacillus fermentum (n = 18), Latilactobacillus curvatus (n = 2), Lactobacillus acidophilus (n = 2) and Lactiplantibacillus plantarum (n = 1) and in the phylogenetic analysis, it was represented by four distinctive clades. All the isolated species demonstrated promising probiotic potential with antibiotic sensitivity, antimicrobial properties, bile acid tolerance and acid tolerance. In conclusion, traditional back-slopping Meekiri in Sri Lanka contains diverse LAB, with a negligible geographical variation at species-level. Our work provides a strong foundation and insights into future applications in starter culture development for the fermentation of buffalo's milk.

Application of Latilactobacillus curvatus into Pickled Shrimp (Litopenaeus Vannamei)

Latilactobacillus curvatus has a strong carbohydrate fermentative ability and antibacterial ability. It is considered as a promising probiotic by its excellent fermentation attributes and health advantages. Pickled shrimp derived from the fermentation process is highly appreciated by its unique texture, taste and flavor. However, this product is easily decomposed by spoilage bacteria especially Staphylococcus. This research evaluated the inoculation of L. curvatus (0.1-0.5 %) and different fermentation temperatures (28-30 oC) on the reduction of Staphylococcus aureus, pH and overall acceptance of the pickled shrimp after 6 weeks of fermentation. Results showed that the fermentation process should be conducted at 29 oC with 0.3 % Latilactobacillus curvatus (at initial density 9 log cfu/ml) to reduce pH to 3.70, completely against Staphylococcus aureus, obtain the highest sensory score (8.91).

In silico comparative genomics analysis of Lactiplantibacillus plantarum DW12, a potential gamma-aminobutyric acid (GABA)-producing strain

Gamma-aminobutyric acid (GABA) is an amino that plays a major role as a neurotransmitter. It iscommonly produced by lactic acid bacteria (LAB) naturally found in fermented food and fruit. Lactiplantibacillus plantarum DW12 is a high potential GABA-producing strain isolated from a fermented beverage. In this study, to highlight its ability to produce GABA, we sequenced the genome of L. plantarum DW12 and then performed comprehensive bioinformatics and meta-analysis to compare the genomic data of previously published genomes. Also, the evolutionary analysis among L. plantarum species was demonstrated using pan-genome analysis against 576 genomes from the database. As a result, the DW12 genome comprises one circular chromosome of 3,217,574 bp. It contains several genes that encode for the production of antimicrobial compounds including plantaricin A, E, F, J, K, and N. The glutamic acid decarboxylase (GAD) operon was found in the DW12 genome, suggests a high potential of producing GABA in this strain. Therefore, L. plantarum DW12 could be a good candidate as a starter culture in the beverage and food industries due to its safety aspects and ability to produce GABA.