Inducible expression of agar-degrading genes in a marine bacterium Catenovulum maritimus Q1.sup.T and characterization of a [beta]-agarase

Agar-degrading bacteria are crucial drivers for the carbon cycle in the marine environments due to their ability that use algae as a carbon source. Although numerous agar-degrading bacteria and agarases have been reported, little is known about expression levels of agar-degrading genes in wild strai...

Full description

Saved in:
Bibliographic Details
Published in:Applied microbiology and biotechnology 2020-12, Vol.104 (24), p.10541
Main Authors: Xu, Zhen-Xing, Yu, Pei, Liang, Qi-Yun, Mu, Da-Shuai, Du, Zong-Jun
Format: Article
Language:English
Subjects:
Agar
Analysis
Chemical properties
Enzymes
Gene expression
Genetic aspects
Identification and classification
Marine bacteria
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Agar-degrading bacteria are crucial drivers for the carbon cycle in the marine environments due to their ability that use algae as a carbon source. Although numerous agar-degrading bacteria and agarases have been reported, little is known about expression levels of agar-degrading genes in wild strains. Here, the genome of an agar-hydrolyzing marine bacterium, Catenovulum maritimus Q1.sup.T, was sequenced and annotated with 11 agarase and 2 neoagarooligosaccharide hydrolase genes. Quantitative PCR revealed that all the annotated agar-degrading genes were expressed consistently that initially upregulated and then gradually downregulated under agarose induction. Moreover, the presence of glucose inhibited the agar-degrading ability, in terms of both gene expression and enzymatic activity. These facts indicated the agar-degrading ability of wild bacteria was mainly induced by agarose and repressed by the available carbon source. Additionally, a [beta]-agarase, AgaQ1, belonging to the GH16 family, with high expression in strain Q1.sup.T, was cloned and characterized. Biochemical analysis showed that the recombinant AgaQ1 was substrate-specific, yielding neoagarotetraose and neoagarohexaose as the main products. It exhibited optimal activity at 40 °C, pH 8.0, and an agarose concentration of 1.6% (w/v). Besides, AgaQ1 showed a high-specific activity (757.7 U/mg) and stable enzymatic activity under different ion or agent treatments; thus, AgaQ1 has great potential in industrial applications.
ISSN:0175-7598
1432-0614
DOI:10.1007/s00253-020-10969-2