%A Yang,Min %A Yu,Yuan %A Yang,Suxiao %A Shi,Xiaohui %A Mou,Haijin %A Li,Li %D 2018 %J Frontiers in Microbiology %C %F %G English %K alginate lyase,Microbulbifer,heterologous expression,Extracellular secretion,Thermal stability,poly-guluronic acid preference %Q %R 10.3389/fmicb.2018.02894 %W %L %M %P %7 %8 2018-November-29 %9 Original Research %# %! New PolyG-specific Alginate Lyase %* %< %T Expression and Characterization of a New PolyG-Specific Alginate Lyase From Marine Bacterium Microbulbifer sp. Q7 %U https://www.frontiersin.org/articles/10.3389/fmicb.2018.02894 %V 9 %0 JOURNAL ARTICLE %@ 1664-302X %X Alginate lyases play an important role in preparation of alginate oligosaccharides. Although a large number of alginate lyases have been characterized, reports on directional preparation of alginate oligosaccharides by alginate lyases are still rather less. Here, a gene alyM encoding a new alginate lyase AlyM was cloned from Microbulbifer sp. Q7 and expressed in Escherichia coli. AlyM exhibited the maximumactivity at pH 7.0 and 55°C and showed special preference to poly-guluronic acid (polyG). Glycine promoted the extracellular secretion of AlyM by 3.6 times. PBS and glycerol significantly improved the thermal stability of AlyM, the enzyme activity remained 75 and 78% after heat-treatment at 45°C for 2 h, respectively. ESI-MS analysis suggested that AlyM mainly produced oligosaccharides with degrees of polymerization (DP) of 2–5. The results of 1H-NMR showed that guluronic acid (G) occupied the reducing end of the end products, indicating that AlyM preferred to degrade the glycosidic bond at the G-X linkage. HPLC analysis showed that the hydrolysis products with a lower degree of polymerization contained more G. Therefore, AlyM shows good potential to produce alginate oligosaccharides with specific M/G ratio and molecular weights.