The marine-derived polysaccharide WL gum produced by Sphingomonas sp. WG showed commercial utility potential in ink, food, and oil industries. A β-1,4-glucuronosyltransferase WelK was predicted to catalyze the transfer of glucuronic acid from UDP-glucuronic acid to glucosyl-α-pyrophosphorylpolyprenol intermediate in the WL gum biosynthesis process. Its function was evaluated by bioinformatical analysis, gene knocking out, and overexpressing strategies. Compared to the wild strain, the WL gum production and broth viscosity of the mutant ∆welK were decreased by 71.5% and 99.2% when cultured for 48 h. The gene disruption led to the failure of product preparation. Homologous expression of welK in the native organism can effectively improve WL gum production. When glucose concentration was 6.7%, the WL gum production by the welK-overexpressing strain cultured for 60 h and 84 h reached 32.65 and 43.13 g/L, 134.1%, and 114% of the wild strain. The polysaccharide composition and qRT-PCR analysis showed that the glucuronic acid content was closely related to the expression level of welK. Thus, WelK was proved to play a critical role in the WL gum synthesis and will be an attractive target for metabolic engineering. Our experiment provided a genetic manipulation method for the functional characterization of genes in Sphingomonas sp. WG.

鞘氨醇单胞菌属产生的海洋来源的多糖 WL 胶。WG 在油墨、食品和石油行业显示出商业效用潜力。预计 β-1,4- 葡萄糖醛酸转移酶 WelK 在 WL 胶生物合成过程中催化葡萄糖醛酸从 UDP-葡萄糖醛酸转移到葡萄糖基-α-焦磷酰聚异戊二烯醇中间体。通过生物信息学分析、基因敲除和过表达策略评估其功能。与野生菌株相比，当培养 48 小时时，突变体∆welK的 WL 树胶产量和肉汤粘度分别降低了 71.5% 和 99.2%。基因破坏导致产品制备失败。welK 的同源表达在原生生物中可以有效提高WL胶的产量。当葡萄糖浓度为6.7%时，培养60 h和84 h的welK过表达菌株的WL胶产量分别达到野生菌株的32.65和43.13 g/L，分别为134.1%和114%。多糖组成和qRT-PCR分析表明，葡萄糖醛酸含量与welK的表达水平密切相关。因此，WelK 被证明在 WL 胶合成中起着关键作用，并将成为代谢工程的一个有吸引力的目标。我们的实验为鞘氨醇单胞菌中基因的功能表征提供了一种遗传操作方法。工作组。