Determination of relationship between production of some metabolites and bifidogenic growth stimulator (BGS) activity by propionic acid bacteria

In this study, we investigated total acid, organic acid, exopolysaccharide (EPS) production, antimicrobial activity, autoaggregation and coaggregation ability, bifidogenic growth stimulator (BGS) activities of 31 strains of propionic acid bacteria isolated from cheese. Different types of media were used for determination of per centage acid production of the strains and maximum acid production was seen in skimmilk. Propionic, acetic and lactic acid amounts of the strains which produce higher total acid were analysed by HPLC in these media and determined that propionic acid production was higher than both acetic and lactic acid. The highest propionic acid producer strain was Propionibacterium thoenii 72 (15.50 ± 0.15 mg/ml) in modified skimmilk. We studied EPS production of propionic acid bacteria in different media and determined EPS production in E-YEL-G was higher than other media. Antimicrobial activities of the strains against Escherichia coli ATCC 35218 and Staphylococcus aureus ATCC 25923 which is pathogen microorganisms were determined cultivating in SM and YEL-G. According to this antimicrobial activity against Escherichia coli ATCC 35218 was higher than Staphylococcus aureus ATCC 25923 in both media. Autoaggregation and coaggregation abilities with Escherichia coli ATCC 35218 and Staphylococcus aureus ATCC 25923 of the strains which produced higher amounts of EPS were determined. When P. acidipropionici 75 has high autoaggregation ability (%49±4) and coaggregation ability with Escherichia coli ATCC 35218 (%19±1); P. freudenreichii spp. freudenreichii 21 and P. freudenreichii spp. freudenreichii 31-4 have high coaggregation ability with S. aureuss ATCC 25923 (%16±5). Positive correlatios has been obtained between production of acid and antimicrobial activity (p<0,01). We determined the highest bifidogenic growth stimulator (BGS) activity of propionic acid bacteria by P. thoenii 72 strain against Bifidobacterium breve A28 and no effect has been obtained from sonication, enzymes, pH or heat to BGS activity. There is not any correlations between acid, EPS production, antimicrobial activity, autoaggregation, coaggregation ability and BGS activity of strains which used fort his study.