Isolation and Identification of Lactobacillus Strains from Behbahan Local Cheeses and Investigation of Technological and Antimicrobial Properties of These Strains against Major Food Pathogens

Nowadays, use of lactic acid bacteria in foods to induce health effects is increasing. The aim of this study was to isolate and identify lactic acid bacteria from local cheeses in Behbahan, Iran, as well as assessing their technological and antimicrobial properties.

Lactobacillus spp. were identified using biochemical tests. After grouping the bacterial isolates based on their carbohydrate fermentation profiles, bacteria were identified using 16S rRNA gene sequencing technique. The bacterial acid production, autolytic and lipolytic activities were assessed as well. Antimicrobial activity of the strains with the best response to technological tests was investigated against pathogenic bacteria.

The Lactobacillus population of local cheeses from Behbahan belonged to five bacterial species of Lactobacillus sakei, Lactobacillus paraplantarum, Lactobacillus agilis, Lactobacillus helveticus and Lactobacillus salivarius. The bacterial ability to lower the pH was assessed at 30 °C for 3, 6 and 24 h. Except L. paraplantarum and Lactobacillus salivarius, which decreased pH less than 0.4 U within 3 h, the other strains showed abilities to produce appropriate acid quantities within a short time. The highest acid production belonged to Lactobacillus helveticus strain with decreases of 0.66 U pH within 3 h. All strains showed good autolytic activities. Based on the results, four strains showed lipolytic activities; of which, the highest lipolytic activity belonged to Lactobacillus helveticus and the lowest belonged to Lactobacillus salivarius. Results of antimicrobial assessments showed that acidic and neutralized supernatants of Lactobacillus helveticus included effects on all pathogenic strains. In general, Escherichia coli and Staphylococcus aureus were the most resistant and the most susceptible strains, respectively.

Based on the results, Lactobacillus helveticus showed the best technological and antimicrobial properties for use as an adjunct culture in dairy industries.