Antimicrobial Activities and Biopreservation Potential of Lactic Acid Bacteria (LAB) from Raw Buffalo (Bubalus bubalis) Milk

Transcriptional Analysis and Identification of a Peptidoglycan Hydrolase (PGH) and a Ribosomal Protein with Antimicrobial Activity Produced by Lactiplantibacillus paraplantarum

The growing challenge of antibiotic resistance has intensified the search for new antimicrobial agents. Promising alternatives include peptidoglycan hydrolases (PGHs) and certain ribosomal proteins, both of which exhibit antimicrobial activity. This study focuses on a Lactiplantibacillus paraplantarum strain, isolated from fermented meat, capable of inhibiting pathogens such as Listeria innocua, Salmonella Typhimurium, Escherichia coli, Staphylococcus aureus, and Weissella viridescens. The highest growth and antimicrobial activity were observed at a high nitrogen concentration (5.7 g/L). Two antimicrobial proteins were identified: the 50S ribosomal protein L14 (RP uL14) and 6-phospho-N-acetylmuramidase (MupG), a PGH. Partial purification and characterization of these proteins were achieved using SDS-PAGE, zymography, and LC-MS/MS. Transcriptional data (RT-qPCR) showed that higher nitrogen concentrations enhanced MupG expression, while increased carbon concentrations boosted RP uL14 expression. These findings highlight the importance of nutritional sources in maximizing the production of novel antimicrobial proteins, offering a potential path to develop effective alternatives against antibiotic-resistant bacteria.

Evaluating the Probiotic Profile, Antioxidant Properties, and Safety of Indigenous Lactobacillus spp. Inhabiting Fermented Green Tender Coconut Water

This study isolated and characterized four indigenous lactic acid bacterial strains from naturally fermented green tender coconut water: Lactiplantibacillus plantarum CWJ3, Lacticaseibacillus casei CWM15, Lacticaseibacillus paracasei CWKu14, and Lacticaseibacillus rhamnosus CWKu-12. Notably, among the isolates, Lact. plantarum CWJ3 showed exceptional acid tolerance, with the highest survival rate of 37.34% at pH 2.0 after 1 h, indicating its higher resistance against acidic gastric conditions. However, all strains exhibited robust resistance to bile salts, phenols, and NaCl, with survival rates exceeding 80% at given concentrations. Their optimal growth at 37 °C and survival at 20 °C and 45 °C underscored adaptability to diverse environmental conditions. Additionally, all strains showed sustainable survival rates in artificial saliva and simulated gastrointestinal juices, with Lact. plantarum CWJ3 exhibiting significantly higher survival rate (70.66%) in simulated gastric juice compared to other strains. Adherence properties were particularly noteworthy, especially in Lact. rhamnosus CWKu-12, which demonstrated the highest hydrophobicity, coaggregation with pathogens and autoaggregation, among the strains. The production of exopolysaccharides, particularly by Lact. plantarum CWJ3, enhanced their potential for gut colonization and biofilm formation. Various in vitro antioxidative assays using spectrophotometric methods revealed the significant activity of Lact. plantarum CWJ3, while antimicrobial testing highlighted its efficacy against selected foodborne pathogens. Safety assessments confirmed the absence of biogenic amine production, hemolytic, DNase, and gelatinase activities, as well as the ability to hydrolase the bile salt. Furthermore, these non-dairy probiotics exhibited characteristics comparable to dairy derived probiotics, demonstrating their potential suitability in developing novel probiotic-rich foods and functional products.

Bio-Preservation Potential and Antimicrobial Activity of Bacteriocin-Producing Lactic Acid Bacteria Isolated from Ethiopian Traditional Fermented Dairy Products

This study aimed to assess the antibacterial activity and bio-preservation capability of bacteriocin-producing LAB isolated from Ethiopian traditional fermented dairy products in raw milk from Jimma town. Bacteriocin-producing LAB were tested for their antimicrobial activity against various foodborne pathogens, including Staphylococcus aureus, Escherichia coli, Listeria monocytogenes, and Salmonella typhimurium. The results showed that probiotic LAB isolates inhibited foodborne pathogens (E. coli, S. aureus, and L. monocytogenes), with inhibition zones ranging from 22.00 ± 0.57 to 34.13 ± 0.57. Enterococcus faecium and Lactococcus lactis demonstrated possible antagonistic effects against E. coli, while Pediococcus pentosaceus had a 34.13 ± 0.57 mm inhibitory zone against Pseudomonas aeruginosa. The isolates also showed co-aggregation potential with the pathogens, with Lactococcus lactis isolates and their combinations demonstrating the best co-aggregation capabilities against the investigated pathogens. The bio-preservative assay showed that putative probiotic isolates (L. lactis JULABE35, E. faecium JULABE 23, and P. pentosaceus JULABE05) were efficient in decreasing Listeria monocytogenes in raw milk. After 7-8 days, milk samples diagnosed with these isolates showed complete reduction of Listeria monocytogenes. The bio-preservation capability of bacteriocin-producing LAB on raw milk extended the shelf life of milk at 4 °C storage for ten days, compared to six days for milk samples without probiotic LAB. The milk samples preserved with probiotic and bacteriocin-producing isolates showed good proximate analysis, showing significant variation with milk kept without bacteriocin-producing isolates. The isolated chemicals employed in this study can be used as food additives or food preservatives, indicating potential applications in Ethiopian traditional fermented dairy products.

Harnessing the Health and Techno-Functional Potential of Lactic Acid Bacteria: A Comprehensive Review

This review examines the techno-functional properties of lactic acid bacteria (LABs) in the food industry, focusing on their potential health benefits. We discuss current findings related to the techno-functionality of LAB, which includes acidification, proteolytic and lipolytic features, and a variety of other biochemical activities. These activities include the production of antimicrobial compounds and the synthesis of exopolysaccharides that improve food safety and consumer sensory experience. LABs are also known for their antioxidant abilities, which help reduce oxidative reactions in foods and improve their functional properties. In addition, LABs' role as probiotics is known for their promising effects on gut health, immune system modulation, cholesterol control, and general wellbeing. Despite these advantages, several challenges hinder the effective production and use of probiotic LABs, such as maintaining strain viability during storage and transport as well as ensuring their efficacy in the gastrointestinal tract. Our review identifies these critical barriers and suggests avenues for future research.

Isolation and characterization of lactic acid bacteria producing a potent anti-listerial bacteriocin-like inhibitory substance (BLIS) from chhurpi, a fermented milk product

Nowadays, the bacteriocin industries have seen significant growth, supplanting chemical preservatives in its ability to improve the shelf-life and safety of food. The increasing customer desire to use natural preservatives has fueled advancing bacteriocin research. The objective of this study was to identify lactic acid bacteria (LAB) that produce bacteriocin-like inhibitory substance (BLIS) and have strong anti-listerial activity. We have identified and analyzed a LAB obtained from chhurpi samples, a popular milk-derived product in the Himalayan regions of India and Nepal. The strain was studied and identified based on its morphological, biochemical, and physiological characteristics. Furthermore, the molecular 16s-rDNA analysis suggests that the strain was Lactococcus sp. RGUAM1 (98.2% similar to Lactococcus lactis subsp. hordniae NBRC 100931T). The isolated strain can produce a potent BLIS, which has shown efficacy against three gram-positive bacteria responsible for food spoilage, such as Listeria monocytogenes (MTCC 657), Staphylococcus aureus subsp. aureus (MTCC 87), Lactobacillus plantarum (MTCC 1407), Lactobacillus paraplantarum (MTCC 12904). The scanning electron microscope (SEM) image illustrates that the crude cell-free supernatant (CFS) disrupts the cell envelope, leading to the release of cellular contents and the clustering of cells. In addition, this BLIS can easily withstand a wide range of pH (2-12), temperature (up to 100 °C for 15 min), bile salt (0.3% W/V), salinity (4% W/V), and enzyme activity of 1600 AU/ml against Listeria monocytogenes. Our research offers a robust framework and valuable insights into bio-preservation and its potential applications in diverse food products.