Deng Jun-Jin, Hu Jing-Yi, Han Xue-Ying, Li Yang, Luo Xiao-Chun, Wang Zhi-Lin, Li Jia-Zhou
Agro-Biological Gene Research Center, State Key Laboratory of Swine and Poultry Breeding Industry, Guangdong Key Laboratory for Crop Germplasm Resources Preservation and Utilization, Guangdong Academy of Agricultural Sciences, No. 20 Jinying Road, Tianhe, Guangzhou, Guangdong 510640, China; Institute of Animal Science, Guangdong Academy of Agricultural Sciences, State Key Laboratory of Livestock and Poultry Breeding, The Key Laboratory of Animal Nutrition and Feed Science in South China, Ministry of Agriculture and Rural Affairs, Guangdong Key Laboratory of Animal Breeding and Nutrition, No. 1 Dafeng Street, Wushan Road, Tianhe, Guangzhou, Guangdong 510640, China.
School of Biology and Biological Engineering, South China University of Technology, Guangzhou Higher Education Mega Center, Panyu, Guangzhou, Guangdong 510006, China.
J Hazard Mater. 2023 Sep 15;458:131707. doi: 10.1016/j.jhazmat.2023.131707. Epub 2023 May 29.
Animal farming copiously generates indoles, which contribute to odor and pose a challenge for deodorization. While biodegradation is widely accepted, there is a lack of suitable indole-degrading bacteria for animal husbandry. In this study, we aimed to construct genetically engineered strains with indole-degrading abilities. Enterococcus hirae GDIAS-5 is a highly efficient indole-degrading bacterium, which functions via a monooxygenase YcnE presumably contributes to indole oxidation. However, the efficiency of engineered Escherichia coli expressing YcnE for indole degradation is lower than that of GDIAS-5. To improve its efficacy, the underlying indole-degradation mechanisms in GDIAS-5 were analyzed. An ido operon that responds to a two-component indole oxygenase system was identified. In vitro experiments showed that the reductase component of YcnE, YdgI, can improve the catalytic efficiency. The reconstruction of the two-component system in E. coli exhibited higher indole removal efficiency than GDIAS-5. Furthermore, isatin, the key intermediate metabolite in indole degradation, might be degraded via a novel isatin-acetaminophen-aminophenol pathway involving an amidase whose coding gene is located near the ido operon. The two-component anaerobic oxidation system, upstream degradation pathway, and engineering strains investigated in this study provide important insights into indole degradation metabolism and offer efficient resources for achieving bacterial odor elimination.
