Antioxidant capacities of Bacillus endophyticus ST-1 and Ketogulonicigenium vulgare 25B-1 in vitamin C fermentation

ABSTRACT

Ketogulonicigenium vulgare and Bacillus play an important role in the two-step fermentation of vitamin C. Resolving the interaction between the two strains, not only can reduce the production cost and improve the productivity gains of vitamin C, but also can give significant clues for the study of complex microbial consortia. We analyzed some physiological properties, antioxidant-related enzyme activities and gene expression patterns of Bacillus endophyticus ST-1 and Ketogulonicigenium vulgare 25B-1 in vitamin C mono- and co-culture fermentation systems before and after B. endophyticus ST-1 sporulation. B. endophyticus ST-1 accelerated the growth and caused excessive accumulation of reactive oxygen species in K. vulgare 25B-1, resulting in oxidative stress. Oxidative stress signals could be transmitted to B. endophyticus ST-1, resulting in the upregulation of sodA, katE and gp genes, which are related to oxidation resistance and regulation of the oxidation–reduction state. The release of spores and the lysis of B. endophyticus ST-1 cells provided a favourable oxidation–reduction state for K. vulgare 25B-1 growth. The expression of sodB, grxC, gor and zwf genes in K. vulgare 25B-1 was gradually upregulated, leading to increased antioxidant capacity. B. endophyticus ST-1 regulates the oxidation–reduction state in the vitamin C fermentation system, thereby enhancing the antioxidant capacities of K. vulgare 25B-1.

KEYWORDS:

• Ketogulonicigenium vulgare
• oxidation-reduction state
• oxidative stress
• reactive oxygen species

Disclosure statement

The authors report no conflicts of interest.

Additional information

Funding

This work was supported by the National Science Foundation of China under grant number 31370077, Liaoning Higher Education Scientific Research Fund under grant number L2015482 and Shenyang Science and Technology Project under grant number F16-205-1-23.