Gluten hydrolyzing activity of Bacillus spp isolated from sourdough

Bennur Somashekharaiah Rashmi,Mahanthesh Vasudha,Patil Prakash,Palegar Krishnappa Somaraja,Devaraja Gayathri,Kumar S Sunil,Chidanandamurthy Thippeswamy Swamy,Chakra Siddappa Prashantkumar

doi:10.1186/s12934-020-01388-z

Abstract

BackgroundCeliac disease is an intestinal chronic disorder with multifactorial etiology resulting in small intestinal mucosal injuries and malabsorption. In genetically predisposed individuals with HLA DQ2/DQ8 molecules, the gluten domains rich in glutamine and proline present gluten domains to gluten reactive CD4+ T cells causing injury to the intestine. In the present experimental design, the indigenous bacteria from wheat samples were studied for their gluten hydrolyzing functionality.ResultsProteolytic activity of Bacillus spp. was confirmed spectrophotometrically and studied extensively on gliadin-derived synthetic enzymatic substrates, natural gliadin mixture, and synthetic highly immunogenic 33-mer peptide. The degradation of 33-mer peptide and the cleavage specificities of the selected isolates were analyzed by tandem mass spectrometry. The gluten content of the sourdough fermented by the chosen bacterial isolates was determined by R5 antibody based competitive ELISA. All the tested isolates efficiently hydrolyzed Z-YPQ-pNA, Z-QQP-pNA, Z-PPF-pNA, and Z-PFP-pNA and also cleaved 33-mer immunogenic peptide extensively. The gluten content of wheat sourdough was found to be below 110 mg/kg.ConclusionIt has been inferred that four Bacillus spp especially GS 188 could be useful in developing gluten-reduced wheat food product for celiac disease prone individuals.

Highlights

Celiac disease is an intestinal chronic disorder with multifactorial etiology resulting in small intestinal mucosal injuries and malabsorption
The selected eight isolates were further subjected for the evaluation of enzymatic cleavage specificities using synthetic gliadin epitope derived tripeptide analogs namely: Z-YPQ-pNA, Z-QQP-pNA, Z-PPF-pNA and Z-PFP-pNA in which amino terminal was modified with benzyloxycarbonyl (Z) and served as protective group whereas carboxy terminal with p-nitro anilide served as reporter group
Z-YPQ-pNA was most efficiently cleaved by all the 8 isolates the substrates such as, Z-QQPpNA, Z-PPF-pNA and Z-PFP-pNA were cleaved with variation (Fig. 2)

Summary

Introduction

Celiac disease is an intestinal chronic disorder with multifactorial etiology resulting in small intestinal mucosal injuries and malabsorption. CD is one of the HLA linked disorders and the genes encoding for HLA-DQ molecules namely DQ (α1*0501, β1*02)/DQ2 or to a lesser extent DQ (α1*03, β1*0302)/DQ8 which are present on antigen presenting cells, are considered as principal genetic factors responsible for CD. These HLA molecules preferentially present tissue transglutaminase (tTG) deamidated proline- and glutamine-rich peptides to gluten reactive C D4+ T cells causing intestinal damage, which can be characterized by partial and subtotal villous atrophy with hyperplastic crypts, increased intra epithelial lymphocytes and mononuclear infiltration in the lamina propria [3,4,5]. The prevalence of CD has increased significantly over the past two decades, especially around 1 in 100 of the general population with female to male ratio ranging

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