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The unconventional adverse effects of fungal pretreatment on iturin A fermentation by Bacillus amyloliquefaciens CX-20 |
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| Authors: | Wenchao Chen Meng Wang Yangmin Gong Qianchun Deng Mingming Zheng Shouwen Chen Xia Wan Chen Yang Fenghong Huang |
| Institution: | 1. Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, Wuhan, 430062 China
Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture, Wuhan, 430062 China Oil Crops and Lipids Process Technology National & Local Joint Engineering Laboratory, Wuhan, 430062 China Hubei Key Laboratory of Lipid Chemistry and Nutrition, Wuhan, 430062 China;2. Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, Wuhan, 430062 China;3. Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Environmental Microbial Technology Center of Hubei Province, College of Life Sciences, Hubei University, Wuhan, 430062 China |
| Abstract: | Fungal pretreatment is the most common strategy for improving the conversion of rapeseed meal (RSM) into value-added microbial products. It was demonstrated that Bacillus amyloliquefaciens CX-20 could directly use RSM as the sole source of all nutrients except the carbon source for iturin A fermentation with high productivity. However, whether fungal pretreatment has an impact on iturin A production is still unknown. In this study, the effects of fungal pretreatment and direct bio-utilization of RSM for iturin A fermentation were comparatively analysed through screening suitable fungal species, and evaluating the relationships between iturin A production and the composition of solid fermented RSM and liquid hydrolysates. Three main unconventional adverse effects were identified. (1) Solid-state fermentation by fungi resulted in a decrease of the total nitrogen for B. amyloliquefaciens CX-20 growth and metabolism, which caused nitrogen waste from RSM. (2) The released free ammonium nitrogen in liquid hydrolysates by fungal pretreatment led to the reduction of iturin A. (3) The insoluble precipitates of hydrolysates, which were mostly ignored and wasted in previous studies, were found to have beneficial effects on producing iturin A. In conclusion, our study verifies the unconventional adverse effects of fungal pretreatment on iturin A production by B. amyloliquefaciens CX-20 compared with direct bio-utilization of RSM. |
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