Isolation and Biochemical and Molecular Identification of Lactobacillus Plantarum ‎Bacteria from Rhizosphere of Lenjan Rice

Probiotics refers to a group of living microorganisms that have beneficial effects on host health. Lactobacilli are one of the most important probiotic bacteria. The stimulatory effects of the immune system, besides reduction of gastrointestinal infections and the risk of inflammation of intestines in humans and animals, are some of Lacobacillus benefits. The effect of rhizospher bacteria, like Lactobacillus, on production of plant hormones, dissolving plant nutrient, facilitates the absorption of nutrients (like nitrogen), and the reduction of plant diseases were reported. Isolation of Lactobacillus has been reported of various sources of dairy and non-dairy sources. The purpose of this study was to investigate the presence of L. plantarum, one of most important probiotic bacteria, in rice rhizosphere, along with examination of the morphological, molecular, biochemical and probiotic properties of the isolated microorganisms. Sampling of rhizosphere rice variety was carried out in Lenjan (Lenjan, Isfahan) carried out. Dillutions of samples were transferred to MES medium. Biochemical test, as sugar fermentation and enzyme activity, performed on gram-positive isolate bacilli. The ability of bacteria to grow in presence of Bile salt, and different pH and temperatures was investigated. Antibiotic resistance of isolates was examined. Specific primers of L. plantarum was used for molecular identification. Of 16 microorganisms, isolated from the rice's rhizosphere, there were 10 bacillus-shaped bacteria, which eight gram-positive isolates were oxidase and catalase negative (characteristic of Lactobacillus species). Sugar fermentation experiments identified six isolates with L. plantarum characteristics. Molecular experiments with the specific primers of L. plantarum confirmed the results. The bacteria grew very well (similar to control samples) in acidic medium at pH 3.5, 40ºC, and in presence of 0.3% bile. Resistance to seven of 12 antibiotics was detected. Discussion and conclusion: The present study showed that rhizosphere of rice is the natural source for isolationof L. plantarum.