Gene cloning and characterization of an aldehyde dehydrogenase from long-chain alkane-degrading Geobacillus thermoleovorans B23
Geobacillus thermoleovorans B23 is capable of degrading long-chain alkanes at 70°C. Bt-aldh, an aldehyde dehydrogenase gene in B23, was located in the upstream region of p21 whose expression level was dramatically increased when alkane degradation was started (Kato et al. 2009, BMC Microbiol 9:60). Like p21, transcription level of Bt-aldh was also increased upon alkane degradation. Bt-Aldh (497 aa, MW = 53,886) was overproduced in Escherichia coli, purified, and characterized biochemically. Bt-Aldh acted as an octamer, required NAD+ as a coenzyme, and showed high activity against aliphatic long-chain aldehydes such as tetradecanal. The optimum condition for activity was 50–55°C and pH 10.0. The activity was elevated to two- to threefold in the presence of 2 mM Ba2+, Ca2+, or Sr2+, while Mg2+ and Zn2+ inhibited the enzyme activity. Bt-Aldh represents thermophilic aldehyde dehydrogenases responsible for degradation of long-chain alkanes.
KeywordsLong-chain alkane degradation Aldehyde dehydrogenase Geobacillus thermoleovorans (Extreme) thermophilic microorganisms and their enzymology Biochemical characterisation Biodegradation of pollutants Biotechnology of thermophiles Enzymology Gene cloning and expression Isolation and characterization Thermophiles and thermophilic enzymes
This work was supported by a grant from the Program for Promotion of Basic Research Activities for Innovative Biosciences (PROBRAIN), NEDO, and KAKENHI (19380189) to MM.
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