Evaluating the Effect of Diversity of Lactobacillus plantarum Strains Isolated from Different on Their Antagonistic, Antioxidant and Aggregation Activities

Lactic acid bacteria are usually involved in the preparation of fermented foods and can produce different metabolites according to their strain type. The aim of this study was to evaluate the antimicrobial, antioxidant and aggregation activities of 10 different strains of Lactobacillus plantarum isolated from native fermented foods including Koozeh cheese, fermented olives, sourdough and camel milk. In this study, the antibacterial activity of 10 different strains of L. plantarum and their cell free supernatants against four pathogens were evaluated by agar-spot and well diffusion methods, respectively. The antifungal activity of the studied strains against two molds was investigated by overlay method. Additionally, auto-aggregation, co-aggregation and hydrophobicity tests of different strains were performed separately. The antioxidant activity of the strains and the cell free supernatants was also evaluated by the DPPH radical scavenging assay. The results showed that all strains had antimicrobial and antifungal activities against the indicator microorganisms and their activity level was different depending on the L. plantarum strains. Also, among the indicator pathogenic bacteria and molds, Escherichia coli and Aspergillus flavus, respectively were the most susceptible. The results of tests related to the surface cellular characteristics of the bacteria showed that the L. plantarum strains are very similar in terms of auto-aggregation, hydrophobicity and antioxidant properties. Indigenous L. plantarum strains and their metabolites can be suggested as a biopreservative in the food and drug industries, but more in-vitro and in-vivo tests should be carried out in this field.