Improved production of carotenoid-free welan gum in a genetic-engineered Alcaligenes sp. ATCC31555

Abstract

To improve the production of welan gum and obtain a carotenoid-free strain while reducing the fermentation and post-treatment costs. The vitreoscilla globin (vgb) gene combined with the β-galactosidase (lacZ) promoter was inserted into the phytoene synthase (crtB) gene region of the chromosome in Alcaligenes sp. ATCC31555. When the recombinant strain was grown in a 5l fermentor, welan gum was produced at 24±0.4gl(-1) compared to 21g±0.4gl(-1) in the wild type. Furthermore, the carotenoid-free welan gum produced using Alcaligenes sp. ATCC31555 VHb strain was less expensive with improved properties. Alcaligenes sp. ATCC31555 VHb strain was a better neutral welan-producing strain with a higher production than the wild-type strain.