The Agar-degrading Enzymatic System of Marine Bacterium Agarivorans sp.HZ105

doi:10.13560/j.cnki.biotech.bull.1985.2015.01.024

Abstract

Abstract: Three agarase genes（hz1, hz2, hz3）of 2 988 bp, 1 437 bp and 1 362 bp respectively, were cloned from strain Agarivorans sp.HZ105. These three agarase genes（hz1, hz2, hz3）encoded agarase HZ1, HZ3 and HZ4 and belonged to glycoside hydrolase family GH50, GH118 and GH16, respectively. The agarase genes of strain HZ105 were linked with vector pET-32a（+）and then were transfered to Escherichia coli BL21（DE3）. These agarase genes were successfully expressed in E. coli cells and their recombinant agarases were prepared. Agarose degradations of the recombinant agarases were studied. Agarase HZ1 could degrade agarose and neoagarooligosaccharides with high degrees of polymerization（8, 10, 12 and 14）into neoagarobiose and neoagarotetraose. Agarase HZ3 digested agarose to produce neoagarooligosaccharides with high degrees of polymerization, while agarase HZ4 decomposed agarose and neoagarooligosaccharides with high degrees of polymerization to yield neoagarotetraose and neoagarohexaose. Therefore, strain HZ105 might produce firstly agarases HZ3 and HZ4 to degrade agarose into neoagarooligosaccharides with high degrees of polymerization, and the products of agarases HZ3 and HZ4 would be then digested into neoagarooligosaccharides with low degrees of polymerization by agarase HZ1 and another agarase（HZ2）from strain HZ105 reported previously by our research group. Strain HZ105 is the first reported strain that produces four agarases and this study is the first report of the agar-degrading enzymatic system in the genus Agarivorans. The results could enrich the knowledge about the bacterial agar-degrading enzymatic system and the roles of the agarases in the system. The application of agarases from strain HZ105 should also benift from this study.

Key words: agarase, gene cloning, Agarivorans, enzymatic system, degradation products

Lin Bokun, Lu Guoyong, Song Yan, Xie Ruiquan, Chen Honglin, Hu Zhong. The Agar-degrading Enzymatic System of Marine Bacterium Agarivorans sp.HZ105[J]. Biotechnology Bulletin, 2015, 31(1): 160-166.

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