In:
Microbiology, Microbiology Society, Vol. 160, No. 2 ( 2014-02-01), p. 270-278
Abstract:
Haem-dependent catalase is an antioxidant enzyme that degrades H 2 O 2 , producing H 2 O and O 2 , and is common in aerobes. Catalase is present in some strictly anaerobic methane-producing archaea (methanogens), but the importance of catalase to the antioxidant system of methanogens is poorly understood. We report here that a survey of the sequenced genomes of methanogens revealed that the majority of species lack genes encoding catalase. Moreover, Methanosarcina acetivorans is a methanogen capable of synthesizing haem and encodes haem-dependent catalase in its genome; yet, Methanosarcina acetivorans cells lack detectable catalase activity. However, inducible expression of the haem-dependent catalase from Escherichia coli (EcKatG) in the chromosome of Methanosarcina acetivorans resulted in a 100-fold increase in the endogenous catalase activity compared with uninduced cells. The increased catalase activity conferred a 10-fold increase in the resistance of EcKatG-induced cells to H 2 O 2 compared with uninduced cells. The EcKatG-induced cells were also able to grow when exposed to levels of H 2 O 2 that inhibited or killed uninduced cells. However, despite the significant increase in catalase activity, growth studies revealed that EcKatG-induced cells did not exhibit increased tolerance to O 2 compared with uninduced cells. These results support the lack of catalase in the majority of methanogens, since methanogens are more likely to encounter O 2 rather than high concentrations of H 2 O 2 in the natural environment. Catalase appears to be a minor component of the antioxidant system in methanogens, even those that are aerotolerant, including Methanosarcina acetivorans . Importantly, the experimental approach used here demonstrated the feasibility of engineering beneficial traits, such as H 2 O 2 tolerance, in methanogens.
Type of Medium:
Online Resource
ISSN:
1350-0872
,
1465-2080
DOI:
10.1099/mic.0.070763-0
Language:
English
Publisher:
Microbiology Society
Publication Date:
2014
detail.hit.zdb_id:
2008736-6
detail.hit.zdb_id:
1180712-X
SSG:
12
