Lactic acid bacteria exhibit similar antioxidant capacities in Caenorhabditis elegans- and Campylobacter jejuni-infected mice

Abstract

Caenorhabditis elegans (C. elegans) is increasingly used as a model organism to screen probiotics for ageing research. In this study, a C. elegans lifespan analysis model exposed to H₂O₂ and juglone (for chronic and acute assays) was used to preselect lactic acid bacteria (LAB) with resistance to oxidative stress. The mechanism of oxidative stress protection was analyzed. Seven out of ten LAB strains screened for namely 427, X13, 9-5, 422, Z5, G14 and H29M-8M demonstrated higher levels of protection to C. elegans, ranging from 70% to 85% survival rate, in comparison to the inactive strains 408, 13-7 and 430 (35% to 45% survival rate). The survival rates of the seven oxidative stress tolerant strains were correlated to increase in catalase (CAT), superoxide dismutase (SOD) and malondialdehyde (MDA) levels and decrease in reactive oxygen species (ROS) expression in C. elegans during H₂O₂ and juglone exposure. In addition, the transcription of mitogen-activated protein kinase (MAPK) and Nrf2-Keap1-ARE pathway related genes was elevated in the oxidative stress protection of LAB isolates. Finally, a significant correlation was found between the ability of these LAB strains to protect C. elegans from H₂O₂ or juglone exposure and their antioxidative ability in Campylobacter jejuni-infected mice. Thus the results indicated that the oxidative stress-based lifespan model of C. elegans is useful for screening of LAB with antioxidant efficacy in pathogen-infected mammals.