Isolation and characterization of probiotic bacteria from fruit pulp, screening of probiotic properties and production of bacteriocin and probiotic curd

Abstract

The present study was investigated to isolate probiotic lactic acid bacteria from Actinidia deliciosa (kiwi fruit) pulp. A total of eight isolates were found and two of them were probiotic LAB strains. The both A2 and A5 isolates strains were Gram-positive, catalase and oxidase negative, non-spore forming, non-motile, rod or short cocci shaped bacteria. The A2 and A5 strains both survived well in conditions of low pH, 0.4% phenol and high bile salt concentrations. They could grow at different temperatures and were resistant to different NaCl concentrations. A study was also conducted on the various probiotic and safety attributes of isolates. Bacteriocins, a kind of ribosomal protein produced by LAB, were estimated using the Folin-Lowery method. The formation of bacteriocins was influenced by various physical and chemical factors. The result demonstrates that the optimum conditions for the production of bacteriocins by the A2 strain were glucose as carbon source, pH 6.5, 2% NaCl and 1% bile salts. For the A5 strain, sucrose as a carbon source, pH 6.5, 1% NaCl and 1% bile salt were optimum conditions for bacteriocin production. Study was also conducted on exopolysaccharide (EPS) production, adhesion characteristics, antagonistic activity and antibiotic sensitivity. Probiotic curd (Dahi) formation was done and several parameters of curd like pH, total lactic acid concentration and water-holding capacity were all investigated.