Inducible expression of agar-degrading genes in a marine bacterium Catenovulum maritimus Q1T and characterization of a ß-agarase.
Appl Microbiol Biotechnol
; 104(24): 10541-10553, 2020 Dec.
Article
en En
| MEDLINE
| ID: mdl-33104843
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 Q1T, 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 ß-agarase, AgaQ1, belonging to the GH16 family, with high expression in strain Q1T, 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. KEY POINTS: ⢠The genome of C. maritimus Q1T was sequenced and annotated with 11 agarases and 2 Nabh genes. ⢠The expression of agar-degrading genes in the strain C. maritimus Q1T was induced by agarose. ⢠Glucose was the carbon source utilized prior to agarose for bacterial growth. ⢠A ß-agarase, AgaQ1, with high expression and activity was identified.
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1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Alteromonadaceae
Idioma:
En
Revista:
Appl Microbiol Biotechnol
Año:
2020
Tipo del documento:
Article
País de afiliación:
China
Pais de publicación:
Alemania