Construction and potential application of bacterial superoxide dismutase expressed in Bacillus subtilis against mycotoxins.

Xueqian Dong,Yonggang Zhang,Chunyu Yang,Wei Wang,Hongyu Han,Tianyi Jiang,Yanmin Zhang,Shashi Kant Bhatia

doi:10.1371/journal.pone.0260047

Abstract

Oxidative stress, which could be evoked by numerous inducements including mycotoxins like deoxynivalenol (DON), cause severe damages to organisms. Antioxidants are promising protectants against oxidative stress that could be applied in pharmaceutical, cosmetic, and food and feed industries. In this study, a thermostable and acidophilic superoxide dismutase (AaSOD) was used to develop an antioxidant product that can potentially protect organisms from oxidative stress related damages. The enzyme was successfully expressed as an extracelluar protein in Bacillus subtilis with a high yield. To obtain a feasible protocol for industrial production of AaSOD, the fermentation mediums that are commonly used for culturing B. subtilis were screened, the feasibility of expressing AaSOD without antibiotic as selection pressure was confirmed, and the effect of using lactose as an inducer instead of isopropyl-β-d-thiogalactoside (IPTG) was investigated. Batch fermentation was conducted to validate the optimized conditions for AaSOD production, and 6530 U mL-1 of SOD activity was obtained in the fermentation broth. The dry powder product of AaSOD with an activity of 22202 U g-1 was prepared by spray-drying and was administrated on zebrafish to test its function as a protectant against DON, and thus gained a significant redress of the reactive oxygen species (ROS) accumulation induced by DON. Taken together, this study provides a feasible protocol to prepare the AaSOD-based antioxidant product that is potentially applied in livestock industry.

Highlights

Mycotoxins, a structurally diverse group of toxic compounds with mostly small molecular weight, are mainly produced as secondary metabolites by various fungal species under suitable temperature and humidity conditions [1]
The yield of protein was estimated to be 87.5 mg L-1, which was comparable to the yield by using E. coli for intracellular expression in our previous study [17]
The aim of this study is to develop a potential antioxidant enzyme product (AaSOD) that is suitable for oral administration of animals, by releasing the oxidative damages from the mycotoxins such as DON

Summary

Introduction

Mycotoxins, a structurally diverse group of toxic compounds with mostly small molecular weight, are mainly produced as secondary metabolites by various fungal species under suitable temperature and humidity conditions [1]. Many mycotoxins have been identified and characterized, and several classes of them received extensive attention, including.

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