Bacteriocins from lactic acid bacteria are ribosomal synthesized antibacterial proteins/peptides having wide range of applications. Lactobacillus pentosus SJ65, isolated from fermented Uttapam batter (used to prepare south Indian pan cake), produces bacteriocin having a broad spectrum of activity against pathogens. Optimization studies are of utmost important to understand the source of utilization and the conditions to enhance the production of metabolites. In the present study, an attempt was made to identify the parameters involved for maximal production of antimicrobial compounds especially bacteriocin from the isolate L. pentosus SJ65. Initially, optimal conditions, such as incubation period, pH, and temperature were evaluated. Initial screening was done using methodology one-variable-at-a-time (OVAT) for various carbon and nitrogen sources. Further evaluation was carried out statistically using Plackett-Burman design and the variables were analyzed using response surface methodology using central composite design. The optimum media using tryptone or soy peptone, yeast extract, glucose, triammonium citrate, MnSO4, dipotassium hydrogen phosphate and tween 80 produced maximum bacteriocin activity.

Lactic acid bacteria (LAB) are protective and generally recognized as safe (GRAS) organisms. The antimicrobial compounds produced by LAB act effectively against several pathogenic organisms, hence they are well-employed as food preservative. This study aims at isolation and characterization of potent bacteriocinogenic lactobacilli from fermented Uttapam batter. Eighteen bacilli showing wide spectrum of inhibitory property against Gram positive and negative organisms were grouped using RAPD, physiological and biochemical characteristics. Eight bacteriocinogenic potent isolates having variation were further identified using 16S rRNA gene sequencing and belonged to Lactobacillus plantarum with 99% sequence homology. Using multiplex PCR the isolates were identified using various molecular tools as Lactobacillus pentosus, L. plantarum ssp. argentoratensis, L. plantarum and L. plantarum ssp. plantarum. These isolates have to be evaluated further for several applications, that turns out to be beneficial for humans.

Probiotic lactic acid bacteria are health promoters and have been traditionally consumed without the knowledge that they have beneficial properties. These bacteria mainly involve in secreting antimicrobials, enhance immune-modulatory effects, and preserve the intestinal epithelial barrier by competitively inhibiting the pathogenic organisms. The aim of this study was to investigate the in vitro probiotic properties of Lactobacillus pentosus, Lactobacillus plantarum, Lactobacillus plantarum ssp. argentoratensis, and Lactobacillus plantarum ssp. plantarum isolated from fermented Uttapam batter. The isolates produced bacteriocins that were effective against several pathogens. All the isolates exhibited tolerance to bile, gastric, and intestinal conditions. Beneficial properties like cholesterol assimilation and production of enzymes such as β-galactosidase, phytase and bile hydrolase varied among the isolates. Four isolates from each sub-species effectively adhered to Caco-2 cells and prevented pathogen adhesion. Using these strains, the soy milk was fermented, which exhibited higher antioxidant activity, 2,2-diphenylpicrylhydrazyl (DPPH) scavenging activity and decreased phytate content when compared to unfermented soy milk. Thus, these probiotic isolates can be successfully used for formulation of functional foods that thereby help to improvise human health.

Humans and lactic acid bacteria (LAB) have allied relationships for thousands of years, where LAB has been involved in food preservations as well as in preserving human health against several pathogens. This study aims at partial purification of bacteriocins from Lactobacillus pentosus SJ65 isolated from fermented Uttapam batter, a South Indian fermented food source, their characterization and mode of action. The bacteriocin was purified using various strategies such as acetone precipitation, gel permeation and hydrophobic interaction chromatography. The bacteriocin was stable at acidic and neutral pH and up to 100C and exhibited a wide spectrum of activity against clinically relevant gram-positive and gram-negative pathogens. However, Tris-tricine sodium dodecyl sulfate, native polyacrylamide gel electrophoresis and its gel half activity assay against Listeria monocytogenes showed that the purified bacteriocin is composed of two independent peptides with molecular weight of 3.9 and 1.6 kDa. PRACTICAL APPLICATIONSBacteriocins, proteinaceous antimicrobial compounds from lactic acid bacteria, are receiving attention for their contribution in food preservation. In addition, interests are created for their use against human bacterial, fungal infections and cancer treatment. To date, only nisin and pediocin have been approved by the United States Food and Drug Administration for use in food industries as preservatives and marketed worldwide. Other bacteriocins such as lactacins, plantaricins, pentocins, etc., are in their own lines of progress for several applications. Bacteriocins are advantageous being less toxic, having broad spectrum of activity and exhibiting antimicrobial activity at nanomolar concentrations. Thus, bacteriocins can be a potential drug candidate for replacing antibiotics to treat drug-resistant pathogens in the future.

Lactic acid bacteria are known to produce numerous antimicrobial compounds that are active against various pathogens. Here, we have purified and characterized a novel low-molecular-weight (LMW) antimicrobial compound produced by Lactobacillus and Pediococcus isolated from fermented idly and uttapam batter. The LMW compound was extracted from cell-free supernatant using ice-cold acetone, purified by gel permeation and hydrophobic interaction chromatography. It exhibited antimicrobial activity against Gram-positive and Gram-negative pathogenic bacteria sparing the probiotic strains like Lactobacillus rhamnosus. The molecular weight of the LMW compound was identified as 204 Da using LC-MS-ESI. In addition, the structure of the compound was predicted using spectroscopic methods like FTIR and NMR and identified as 2-hydroxyl indole-3-propanamide. The LMW compound was differentiated from its related compound, tryptophan, by Salkowski reaction and thin-layer chromatography. This novel LMW compound, 2-hydroxyl indole-3-propanamide, may have an effective application as an antibiotic which can spare prevailing probiotic organisms but target only the pathogenic strains.