Investigation of technological characteristics of Lactobacillus casei strain CE28.26 and Lactobacillus acidophilus strain BCRC10695 and determination of their antimicrobial activity against foodborne pathogenic bacteria

Dairy-based traditional fermented foods have rich sources of native lactic flora which isolation. The aim of this study was to identify and investigate the technological and antimicrobial properties of Lactobacillus casei and Lactobacillus acidophilus isolated from local yogurt in Behbahan. After isolation, Gram and catalase tests was done and identification was performed by 16S rRNA gene analysis method. Then, their technological properties such as acidification, proteolytic, lipolytic and autolytic activity, resistance to acid and heat, and finally their antimicrobial activity against foodborne pathogens were examined. The results of the sequencing showed that the two isolates belonged to Lactobacillus casei strain CE28.26 and Lactobacillus acidophilus strain BCRC106955. The proteolytic activity of isolates was investigated by agar test and o-phthaldialdehyde method and the results showed that both isolates have the ability to hydrolyze casein. Also, no lipolytic activity was observed for any of the bacteria but isolates had high acidification activity. Studies of autolytic activity have shown that both sides have relatively good levels of this feature. The results showed the resistance of the strains decreased when the acidity production increased. So that the isolates could not grow in pH 3. Also, the study of temperature resistance showed with increasing the temperature and time, the resistance of isolates decreased. The results showed that L. acidophilus had more antimicrobial activity. The highest resistance and sensitivity were belonged to Pseudomonas aeruginosa and Staphylococcus aureus respectively. Due to the appropriate technological properties of Lactobacillus casei and Lactobacillus acidophilusisolates, they can be used as adjuncts culture in target industries such as dairy.