Multifunctional properties of Lactobacillus plantarum strains isolated from fermented cereal foods

Abstract

Strains of Lactobacillus plantarum were studied for starter cultures and probiotic functions with the overall aim of selecting multifunctional cultures that could bring about fermentation of cereals as well as rendering health benefits. Two L. plantarum strains previously isolated from West African fermented cereals were sub-typed using RAPD-PCR; these strains carried different plasmid profiles ranging from 2 to 50 kb and showed variation in carbohydrate fermentation patterns. RT-PCR analysis showed that the gene coding for rhamnosidase was expressed by both strains, but the amylase gene was only expressed by L. plantarum ULAG11. L. plantarum ULAG24 demonstrated antagonism to food borne pathogens and expressed all nine genes associated with plantaricin biosynthesis while only 3 genes of the plantaricin operon were identified in the strain ULAG11. Both L. plantarum strains were similar in their resistance to acid (pH 2.0) and were tolerant to bile salt concentration of 0.3% (w/v) and were able to grow under anaerobic environment. Adhesion assays indicated that L. plantarum ULAG24 adhered to HT29 cell line and competitively excluded Salmonella enterica LT2. In vivo analysis showed limited colonisation of BALB/c mice gut, but stimulation of IFNγ (1.2 ng/ml) and IL10 (3.4 ng/ml) by L. plantarum ULAG24 was observed. This shows that L. plantarum ULAG24 possesses probiotic functions as well as plantaricin production potential, while expression of amylase enzyme was detected in L. plantarum ULAG11. The identified diverse functional attributes among L. plantarum strains showed that these two strains could be used for industrial processing of fermented cereals in W. Africa with added benefits of the strains having probiotic potential for human health.