摘要
Abstract
Fatty acids,as crucial industrial chemicals,are faced with sustainability challenges with regards to their conventional production methods.Herein,we employed Corynebacterium glutamicum(C.glutamicum)as a platform to systematically enhance fatty acid synthesis efficiency via multidimensional metabolic engineering strategies,including markerless gene knockout or integration by the suicide plasmid pK18mobsacB.First,overexpression of zwf(glucose-6-phosphate dehydrogenase),a key gene in the pentose phosphate pathway(PPP),resulted in the generation of strain NC-fl.This strain could maintain normal growth and glucose consumption rates.More importantly,it could increase intracellular NADPH levels by 41.14％.Total fatty acid production reached(356.58±25.66)mg/L,representing a 15.05％improvement over the strain NC-e6.Subsequently,attenuation of gltA expression,encoding a key TCA cycle enzyme,in strain NC-f2 redirected acetyl-CoA flux towards fatty acid biosynthesis.As a result of this metabolic shift,both cell growth and glucose consumption rates decreased,while the total fatty acid production could be improved by 32.71％.Knockout of the polyketide synthase gene pks13 was performed to block mycolic acid synthesis,then accordingly enhance fatty acid accumulation.Such a new strain NC-f3 led to a 21.98％increase in total fatty acid production compared to strain NC-f2.Finally,the strain NC-f4,with overexpression of the thioesterase gene Cgl2451,exhibited enhanced fatty acid hydrolysis.The yield of fatty acid could reach(651.01±62.6)mg/L in this case,representing a 12.78％increase relative to NC-f3 and a 110.04％increase relative to NC-e6.Overall,optimization using multiple metabolic engineering strategies significantly enhanced the capability of fatty acid synthesis in C.glutamicum.关键词
谷氨酸棒杆菌/脂肪酸/NADPH/柠檬酸合酶/硫酯酶Key words
Corynebacterium glutamicum/fatty acid/NADPH/citrate synthase/thioesterase分类
化学化工
