Probiotic Potential of Bacillus Strains Isolated from an Acidic Fermented Food Idli

Present study is intended to assess the probiotic properties of Bacillus spp. isolated from idli batter, a traditional fermented food of Southern India and Sri Lanka. A total of 32 isolates were screened for potential pathogenic behaviour through haemolysis assay, DNase activity and antibiotics sensitivity. Two of the isolates were found to be potentially safe and identified as Bacillus spp. These strains were characterized for in vitro probiotic attributes and antioxidant activity. Both the strains showed strong acid and bile tolerance, transit tolerance, lysozyme tolerance, cell surface hydrophobicity, auto-aggregation, co-aggregation, biofilm formation potential and adhesion to human colon adenocarcinoma (HT 29) cell line demonstrating potential probiotic ability. These strains also exhibited considerable cholesterol binding, thermostability, β-galactosidase production, proteolytic, amylolytic and lipolytic activity. Cell-free supernatant inhibited the biofilm formation by Pseudomonas aeruginosa (KT266804) to 90%. Intact cells showed significant DPPH (41%), hydroxyl (31%), radical scavenging activity and lipid peroxidation inhibition (20.38%), while cell-free extracts exhibited significant superoxide anion radical scavenging activity (16.25%). Results revealed that isolates could be potential probiotic candidate after further assessment of in vivo probiotic properties and safety evaluation and could be utilised as starter cultures in functional foods.

Production of a highly concentrated probiotic culture of Lactococcus lactis CECT 539 containing high amounts of nisin

In this study, probiotic biomass and nisin productions by Lactococcus lactis CECT 539 were followed in two realkalized fed-batch cultures in diluted whey (DW) supplemented with KH₂PO₄ up to a total phosphorus concentration of 0.459 g/L. Increased biomass (5.12 g/L, 2.18 × 10¹⁰ CFU/mL) and nisin (235.23 BU/mL) concentrations were obtained in the culture fed concentrated whey and concentrated mussel processing waste (CMPW) medium supplemented with glucose up to a concentration of 400 g/L (CMPW + G medium) compared with similar fed-batch fermentations in DW medium. In the second fed-batch fermentation, the feeding medium CMPW + G was supplemented with KH₂PO₄ up to a TP concentration of 3.21 g/L. With this approach, increased production of biomass (5.49 g/L, 2.33 × 10¹⁰ CFU/mL) and nisin (257.59 BU/mL) was obtained. Considering the substantial availability of these wastes at very low prices from local dairy and mussel processing plants in Galicia, their use as culture media could offer an attractive alternative for a low-cost production of probiotic biomass and nisin at a high scale.

Screening of Oxalate Degrading Lactic Acid Bacteria of Food Origin

A screening for oxalate degrading abilities was initially carried on within Lactic Acid Bacteria cultures of different food origin. Seventy-nine strains were drop-inoculated onto MRS agar plates containing calcium oxalate. By comparing colonies diameters, 31 strains were used to inoculate, in parallel, MRS and MRS modified by sodium oxalate addition. Differences in the strains’ growth were assessed by colony forming unit counts. For two strains, the growth in oxalate enriched medium was significantly higher; while, for eleven strains an opposite behaviour was recorded. Two strains – probiotic Lactobacillus rhamnosus LbGG and Enterococcus faecalis 59 – were chosen. The first strain appeared to be able to metabolize oxalate more efficiently than the other tested cultures, while strain 59 appeared unable to gather advantage by oxalates and, indeed, appeared to be inhibited by the salt presence in the medium. Outcomes revealed that higher glucose concentrations may favour oxalates utilization. In MRS with oxalate, but without glucose, citrate was completely metabolized. Evaluation along time confirmed that the oxalate degradation is more significant in presence of glucose. Outcomes may represent a good start for the development of a safe and even probiotic culture able to lower the oxalates content of food.