atpD expression of probiotic Lactobacillus plantarum 91 under acidic environment

Archana Chandran, Sunita Grover, V.K. Batish

Abstract


Lactobacillus plantarum is a flexible and versatile microorganism that inhabits a wide variety of environmental niches, including the human gastrointestinal (GI) tract. Strains of Lactobacillus plantarum have proven ability to survive gastric transit and can colonize the intestinal tract of humans and other mammals. The ability of these microorganisms to grow in harsh environment prevailing in is linked to their ability to resist acidic conditions in the stomach of healthy humans. Changes in pH in the environment have been reported to influence the expression of many genes and atp operon is chiefly involved in the acid tolerance of probiotic lactobacilli in the gut. The atpD genes are included in the category of housekeeping genes. However, the regulation of this pH-inducible phenotype has not been clearly established at the molecular level. In this study the influence of low pH on inducible gene expression in Lactobacillus plantarum 91 was investigated both in vitro and in vivo. Logarithmic phase cultures were exposed to pH 2.5, 2.0 and 1.5 for various time intervals and cultured for monitoring survivability. The cultures were able to survive at pH 1.5 to an appreciable level even after 1-3 h. In vivo study was carried out by feeding L.plantarum cultures to mice followed by isolation of bacterial RNA from stomach at different time intervals. The isolated RNA was reverse transcribed and the resultant cDNAs were subjected to RT-qPCR and the products were resolved by electrophoresis. TheatpDgene was significantly up-regulated to 1.48, 2.04 and 3.05 folds after 15, 30 and 60 min. transit in the stomach of mice. This result clearly demonstrates that atpD gene expression is essential for survival of probiotic bacteria under acidic environment prevailing in the stomach

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Keywords


Lactobacillus plantarum, Probiotic, atpD, Acid tolerance

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A KAU publication [CODEN: JTAGEI; ISSN 0971-636X; eISSN 0973-5399]