Physiological Characterization of an n-Butane-Utilizing Bacterium, Alcaligenes sp.

Abstract

An n-butane-utilizing bacterium was isolated from soil contaminated with petroleum and identified as Alcaligenes sp. by 16S-rDNA sequence homology. The bacterial isolate grew on gaseous alkane (n-butane), liquid alkane (n-hexane, n-octane or n-decane) or liquid alkane mixture (kerosene, C10~C16) as the sole carbon source, but did not grow on glucose, lactate or pyruvate. The specific activities of butane monooxygenase, butanol dehydrogenase, butyraldehyde dehydrogenase, lactate dehydrogenase, pyruvate dehydrogenase, isocitrate dehydrogenase and malate dehydrogenase were 6.97±0.42, 2.54±0.28, 3.78±0.31, 0.003±0.00, 0.007±0.00, 0.51±0.03 and 0.65±0.04 μM mg protein-1 min-1, respectively. In tests of n-butane, n-hexane, n-octane and ndecane oxygenation with crude enzyme extracted from bacterial cells grown on kerosene, NADH was oxidized to NAD+ coupled to production of n-butanol, n-hexanol, n-octanol and n-decanol. However, monooxygenase activity was relatively higher when the substrate for the enzyme assay was same as that used for growth than when the substrate and growth medium differed. This suggests that Alcaligenes sp. may produce specific monooxygenases dependent on the n-alkane species used as the growth substrate.