Construction of high-guluronate-containing-alginate producing mutant of Pseudomonas sp. QDA
富含古罗糖醛酸的褐藻多糖生产菌株的构建

Pseudomonas sp.QDA,which was isolated from seawater,has the ability of producing extracellular alginate.In order to obtain the high-guluronate-containing alginate,C-5-mannuronan epimerase gene(algG) of Pseudomonas sp.QDA was cloned by PCR and ligated in to plasmid pMF54Km.The resulting plasmid pMF54Km-algG was transferred to QDA by triparental mating,and an algG over-expressing strain,QDA-G,was obtained.The results of 1H-NMR showed that the M/G ratio of alginate fragments by QDA-G was 0.38 and the content of guluronate was 74.2%,about 26.4% higher than that of wild strain QDA.The genetic stability of QDA-G was good.No significant changes were found in M/G ratio of alginate fragments of QDA-G after 20 passages.