Glutathione biosynthesis and activity of dependent enzymes in food grade lactic acid bacteria harboring multidomain bifunctional fusion gene (gshF).

AIMS: To assess glutathione (GSH) biosynthesis ability and activity of dependent enzymes in food grade lactic acid bacteria and correlating with genomic information on glutathione system in LAB.

METHODS AND RESULTS: Whole genome sequences of twenty-six food grade LAB were screened for presence/absence of set of genes involved in de novo glutathione system. Multiple strains of S. thermophilus (37), Lb. casei (37), Lb. rhamnosus (4), Lb. paracasei (8) Lb. plantarum (23) & Lb. fermentum (22) were screened for biochemical evidence of GSH system. Multiple sequence analysis of GshF sequences was carried out for comparing the genomic signatures between GSH producing and non-producing species.

CONCLUSIONS: Streptococcus thermophilus was found to have de novo glutathione biosynthesis as well as import ability. Lactobacillus spp. were negative for GSH synthesis but could import it from the medium. All the species exhibited prolific glutathione reductase and peroxidase activity. Sequence analysis revealed absence of key amino acid residues as well as a truncated N-terminal region in lactobacilli.

SIGNIFICANCE AND IMPACT OF THE STUDY: The study provides a comprehensive view on status of an important antioxidative system (the glutathione system) in LAB and is expected to serve as a primer for future work on mechanistic role of GSH in the group. This article is protected by copyright. All rights reserved.