In vitro screening and characterization of lactic acid bacteria from Lithuanian fermented food with potential probiotic properties

Screening of lactic acid bacteria from the milk of Sahiwal cows and characterization of their probiotic potential for preventing bovine mastitis

Antibiotic therapy has been the most popular line of treatment for the control of mastitis worldwide during the last few decades. Alternative and sustainable treatments must be developed because pathogens are becoming more resistant to antibiotics, leading to the development and spread of antimicrobial resistance (AMR). The aim of the current investigation was to isolate lactic acid bacteria (LAB) with probiotic potential that can inhibit mastitis-causing pathogens to prevent bovine mastitis. Milk samples were collected from Sahiwal cows, and a total of 150 bacteria were isolated, of which 76 were found to be catalase negative, and resistant to vancomycin. Twenty-three isolates displayed greater acid and bile tolerance, with > 90% survivability, and were molecularly characterized by 16S rRNA partial sequencing. The autoaggregation percentages for SML7 and SML41 were greater (p<0·05) 80.38±0.19% and 80.28±0.04%, respectively. SML10 (92.04±0.26 μmol/mL) had the highest (p<0.05) ferric-reducing antioxidant power (FRAP) activity, while SML20 (52.1±0.99%) had the highest 1,1 diphenyl 2 picrylhydrazyl (DPPH) scavenging activity. All the strains were nonhemolytic or nonmucinolytic. The highest antimicrobial activity was observed in several strains (SML41, SML63, SML76, and SML60) against common mastitis-causing pathogens, namely, E. coli ATCC25922, Staphylococcus aureus ATCC25923, Enterococcus faecalis NCDC114, Streptococcus agalactiae NCDC208, and Enterococcus faecium NCDC124. The coaggregation efficacy of SML20 with S. aureus was the highest (67.69±1.21%), while SML41 showed the highest (69.75±0.29%) coaggregation efficacy with E. faecalis NCDC114 and SML63 (68.078±0.26) with S. agalactiae NCDC208. Overall, seven distinct lactic acid bacterial clusters were identified by cluster analysis of the phylogenetic tree as follows: Enterococcus hirae (1), Limosilactobacillus reuteri (1), Pediococcus acidilactici (4), Weissella confusa (11), Lactobacillus helveticus (3), Limosilactobacillus balticus (2), and Lacticaseibacillus rhamnosus (1). The Lactobacillus helveticus SML41, Lactobacillus helveticus SML60, Weissella confusa SML61, Lacticaseibacillus rhamnosus SML63, Weissella confusa SML64, and Pediococcus acidilactici SML76 isolates were found to possess the most desirable characteristics of potential probiotics based on principal component analysis (PCA). Therefore, the strains chosen in the current investigation demonstrated techno-functional characteristics that rendered them appropriate for probiotic use to treat and prevent intramammary infections in dairy cattle in a sustainable manner.

Draft genome sequence data of Lactiplantibacillus plantarum 33C isolated from Lithuanian fermented food

This strain was isolated from traditionally (homemade) fermented Lithuanian cherry tomatoes. The genome consists of 55 contigs with a total size of 3,326,119 bp, an N50 of 170738, and a GC% of 44.3 %. According to the COG annotation, most of these proteins were divided into three categories related to transcription (K category: 307), amino acid transport and metabolism (E category: 222), and carbohydrate transport and metabolism (G category: 268). No genes associated with antimicrobial resistance or virulence factors were identified. The data presented here can be used in comparative genomics to identify antimicrobial resistance genes and virulence factors that may be present in relevant Lactobacillus species. PlasmidFinder server revealed the presence of plasmid pR18 (assessment number JN601038) in the genome that has lincomycin resistance, can be transferred from one bacterium to another, and is one of the most common plasmids in the genera Bacillus and Lactobacillus. The draft genome sequence data have been deposited with NCBI under Bioproject under accession number PRJNA947394.

Research progress in isolation and identification of rumen probiotics

With the increasing research on the exploitation of rumen microbial resources, rumen probiotics have attracted much attention for their positive contributions in promoting nutrient digestion, inhibiting pathogenic bacteria, and improving production performance. In the past two decades, macrogenomics has provided a rich source of new-generation probiotic candidates, but most of these "dark substances" have not been successfully cultured due to the restrictive growth conditions. However, fueled by high-throughput culture and sorting technologies, it is expected that the potential probiotics in the rumen can be exploited on a large scale, and their potential applications in medicine and agriculture can be explored. In this paper, we review and summarize the classical techniques for isolation and identification of rumen probiotics, introduce the development of droplet-based high-throughput cell culture and single-cell sequencing for microbial culture and identification, and finally introduce promising cultureomics techniques. The aim is to provide technical references for the development of related technologies and microbiological research to promote the further development of the field of rumen microbiology research.

Biotechnological Potential and Safety Evaluation of Dextran- and Riboflavin-Producing Weisella cibaria Strains for Gluten-Free Baking

Gluten consumption causes several immunological and non-immunological intolerances in susceptible individuals. In this study, the dextran-producing Weissella cibaria BAL3C-5 and its derivative, the riboflavin-overproducing strain BAL3C-5 C120T, together with a commercial bakery yeast, were used to ferment gluten-free (GF)-doughs obtained from corn and rice flours at two different concentrations and supplemented with either quinoa, buckwheat, or chickpea to obtain laboratory-scale GF bread. The levels of dextran, riboflavin, and total flavins were determined in the fermented and breads. Both strains grew in fermented doughs and contributed dextran, especially to those made with corn plus quinoa (~1 g/100 g). The highest riboflavin (350-150 µg/100 g) and total flavin (2.3-1.75 mg/100 g) levels were observed with BAL3C-5 C120T, though some differences were detected between the various doughs or breads, suggesting an impact of the type of flour used. The safety assessment confirmed the lack of pathogenic factors in the bacterial strains, such as hemolysin and gelatinase activity, as well as the genetic determinants for biogenic amine production. Some intrinsic resistance to antibiotics, including vancomycin and kanamycin, was found. These results indicated the microbiological safety of both W. cibaria strains and indicated their potential application in baking to produce GF bread.