Antioxidant Activities of Pediococcus Acidilactici GR-66 and Proposed Chromium (VI)-reducing Mechanism

Abstract

Chromium (Cr), one of the most common heavy metals in industry, is an environmental pollutant and has been recognized as a carcinogen to humans. Some probiotics can reduce oxidative stress induced by Cr (VI), but the underlying mechanism has not been fully uncovered. In this study, five probiotic strains have been identified from fermented milk of yak and assessed their antioxidant capability. P.acidilactici  GR-66 demonstrates the greatest antioxidant capability in vitro and then was orally administered to mice for 3 weeks as the treatment to Cr(VI) exposure. Results manifest that GR-66 can significantly alleviate Cr (VI)-induced inflammation and oxidative stress in vivo. Since the colonization number of GR-66 is less than 1%, GR-66 was not directly involved in intestinal Cr (VI) remediation but adjusted the gut microbiota. Sequencing of GR-66 recognized gene comp998 encoded enzyme that has been later aligned with NCBI database and identified a structure similar to flavodoxin 2HAY. Thus, we proposed that the comp998 reduce Cr (VI) to Cr (III) by transferring electrons through FMN.