title: Driving carbon flux through exogenous butyryl-CoA: Acetate CoA-transferase to produce butyric acid at high titer in Thermobifida fusca.
abstract: Butyric acid, a 4-carbon short chain fatty acid, is widely used in chemical, food, and pharmaceutical industries. The low activity of butyryl-CoA: acetate CoA-transferase in Thermobifida fusca muS, a thermophilic actinobacterium whose optimal temperature was 55°C, was found to hinder the accumulation of high yield of butyric acid. In order to solve this problem, an exogenous butyryl-CoA: acetate CoA-transferase gene (actA) from Thermoanaerobacterium thermosaccharolyticum DSM571 was integrated into the chromosome of T. fusca muS by replacing celR gene, forming T. fusca muS-1. We demonstrated that on 5g/L cellulose, the yield of butyric acid by the engineered muS-1 strain was increased by 42.9 % compared to the muS strain. On 100g/L of cellulose, the muS-1 strain could consume 90.5% of total cellulose in 144h, with 33.2g/L butyric acid produced. Furthermore, on the mix substrates including the major components of biomass: cellulose, xylose, mannose and galactose, 70.4g/L butyric acid was produced in 168h by fed-batch fermentation. To validate the ability of fermenting biomass, the muS-1 strain was grown on the milled corn stover ranging from 200 to 250μm. The muS-1 strain had the highest butyrate titer 17.1g/L on 90g/L corn stover.
authors.affiliation: National Engineering Laboratory for Cereal Fermentation Technology (NELCF), Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; The Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China. Electronic address: dengyu@jiangnan.edu.cn.
authors.forename: Yu
authors.initials: Y
authors.lastname: Deng
authors.affiliation: National Engineering Laboratory for Cereal Fermentation Technology (NELCF), Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; The Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China.
authors.forename: Yin
authors.initials: Y
authors.lastname: Mao
authors.affiliation: School of Pharmaceutical Science, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China. Electronic address: zhangxj@jiangnan.edu.cn.
authors.forename: Xiaojuan
authors.initials: X
authors.lastname: Zhang
mesh_terms: D000192:Actinomycetales / Q000187:drug effects / Q000378:metabolism*; D000214:Acyl Coenzyme A / Q000378:metabolism*; D000332:Aerobiosis / Q000187:drug effects; D061249:Batch Cell Culture Techniques; D019149:Bioreactors / Q000382:microbiology; D020148:Butyric Acid / Q000378:metabolism*; D002244:Carbon / Q000378:metabolism*; D002482:Cellulose / Q000494:pharmacology; D002876:Chromosomes, Bacterial / Q000235:genetics; D015256:Coenzyme A-Transferases / Q000235:genetics / Q000378:metabolism*; D005285:Fermentation / Q000187:drug effects; D005818:Genetic Engineering; D016254:Mutagenesis, Insertional / Q000235:genetics; D014866:Waste Products; D003313:Zea mays / Q000737:chemistry
chemical_list: D000214:Acyl Coenzyme A; D014866:Waste Products; D020148:Butyric Acid; C024343:butyryl-coenzyme A; D002244:Carbon; D002482:Cellulose; D015256:Coenzyme A-Transferases
keywords: Butyric acid; Butyryl-CoAacetate CoA-transferase; Chromosome integration; Metabolic engineering