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–С₃₀n-alkanes (В-1024), С₁₀, C₁₁, and С₁₃–С_19,22n-alkanes (1017), and C₁₁–C₂₉n-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 ladAα_B23, ladAβ_B23, 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.