Study Of AlgL And AlgG From Pseudomonas Sp.QDA

Alginate is a polymer ofα-L-guluronate(G) andβ-D-mannuronate(M), which are linked together to form polymannuronate, polyguluronate, or alternating M&G blocks in the linear molecular. Alginates and derivatives have been widely used in pharmaceutical and food industries. The ratio of M/G is an important factor on the efficiency of the alginate bioactivity. Alginates with high M contents exhibit high activity on anti-tumor and stimulate murine haematopoiesis, while alginates with high G content show anti-AIDS activity. Recently, alginate bioconversion including alginate biosynthesis, enzymatic degradation and modification has attracted attention on their potential for expanding the uses of alginate. In this study, the alginate lyase gene algL and polymannuronate C-5 epimerase gene algG from Pseudomonas sp. QDA were studied with their function on alginate bioconversion using DNA recombination method.Firstly, AlgL overexpressed stain was established. The expression vector pMF36-Ka-algL and control plasmid pMF36-Ka were constructed and transformed into Pseudomonas sp. QDA by electroporation methods. The alginate production in algL overexpressed strain was almost the same as wild type QDA, but the molecular weight of alginate was reduced dramatically. It provides a new method for preparation of alginate oligosaccharide. Interestingly, In Pseudomonas genus, alginate with high molecular weight plays a key role in the formation of biofilm, which provides a protective barrier against host immune defenses and antibiotic resistance. The biofilm formation of the algL overexpressed QDA is less than that of the wide type QDA because of the degradation of alginate on mutant strain. In addition, the algL overexpressed QDA is more sensitive to antibiotics than the wild type QDA. Our result indicated that alginate lyase may be used as an adjuvant therapeutic medicine for the treatment of disease associated with Pseudomonas infection.In bacteria, alginate is first synthesized as poly-mannuronan, and then G residues...