Biosynthesis of Chondroitin in Engineered .

Chondroitin, the precursor of chondroitin sulfate, which is an important polysaccharide, has drawn significant attention due to its applications in many fields. In the present study, a heterologous biosynthesis pathway of chondroitin was designed in a GRAS (generally recognized as safe) strain . and genes with host codon preference were synthesized and driven by promoter P, which was confirmed as a strong promoter via GFPuv reporter assessment. In a lactate dehydrogenase () deficient host, intracellular chondroitin titer increased from 0.25 to 0.88 g/l compared with that in a wild-type host. Moreover, precursor enhancement via overexpressing precursor synthesizing gene further improved chondroitin titers to 1.09 g/l. Chondroitin production reached 1.91 g/l with the engineered strain ΔL-CgCAU in a 5-L fed-batch fermentation with a single distribution M of 186 kDa. This work provides an alternative, safe and novel means of producing chondroitin for industrial applications.