Detection of n-alkane biodegradation genes alkB and ladA in thermophilic hydrocarbon-oxidizing bacteria of the genera Aeribacillus and Geobacillus

Abstract

Ability to degrade crude oil n-alkanes was revealed in new strains of thermophilic bacilli isolated from petroleum reservoirs and a hot spring: Geobacillus toebii В-1024, Geobacillus sp. 1017, and Aeribacillus pallidus 8m3. The strains utilized С10–С30 n-alkanes (В-1024), С10, C11, and С13–С19,22 n-alkanes (1017), and C11–C29 n-alkanes (8m3). In all three strains, PCR amplification with specific degenerate oligonucleotide primers revealed the alkB gene encoding rubredoxin-dependent alkane monooxygenase. In strains В-1024 and 1017, fragments of the genes homologous to the ladA gene determining flavin-dependent alkane monooxygenase were also amplified. Nucleotide sequences of these genes were practically identical to those of the genes ladAαB23, ladAβB23, and ladB B23, which were revealed previously in Geobacillus thermoleovorans strain B23. For the latter strain, activity of respective enzymes in the oxidation of long-chain n-alkanes has been shown. Thus, simultaneous presence of the alkB and ladA genes coding alkane monooxygenases responsible for oxidation of medium-chain and long-chain n-alkanes in thermophilic bacilli was revealed for the first time.