The aim of this study was to identify genes involved in long-chain alkane degradation in Dietzia sp. DQ12-45-1b. Functional genes were annotated by genome analysis. Induction of alkane hydroxylase genes by C28 n-alkane was analyzed by using quantitative real-time PCR in wild-type Dietzia sp. DQ12-45-1b and its alkW1 gene knockout mutant strain M 5-5. From the genome of Dietzia sp. DQ12-45-1b, two homologues, G1 and G2 genes were annotated, which showed 50% amino acid sequence similarity with AlmA from Acinetobacter sp. DSM17874, and 48% amino acid sequence similarity with LadA from Geobacillus thermodenitrificans NG80-2, respectively. In addition, G1 showed 71% amino acid sequence similarity with G1a, and G2 showed 34% and 87% amino acid sequence similarities with G2a and G2ß, respectively, which were annotated from Dietzia sp. E1 genome. In addition, the alkW1 gene knockout strain M 5-5 could grow with C28 n-alkane as the sole carbon source, indicating the presence of potential long-chain alkane hydroxylase gene(s) other than alkW1 in Diezia sp. DQ12-45-1b. Accordingly, induction of G1 and G2 genes was observed when Dietzia ap. DQ12-45-1b and alkW1 knockout mutant strain M 5-5 grew with C28 n-alkane as sole carbon source. The results indicated that G1 and G2 genes are mostly responsible for the degradation of long-chain alkanes in Dietzia sp. DQ12-45-1b, which has unique multiple alkane hydroxylase systems. 相似文献
Petroleum hydrocarbons, mainly consisting of n-alkanes and polycyclic aromatic hydrocarbons (PAHs), are considered as priority pollutants and biohazards in the environment, eventually affecting the ecosystem and human health. Though many previous studies have investigated the change of bacterial community and alkane degraders during the degradation of petroleum hydrocarbons, there is still lack of understanding on the impacts of soil alkane contamination level. In the present study, microcosms with different n-alkane contamination (1%, 3% and 5%) were set up and our results indicated a complete alkane degradation after 30 and 50 days in 1%- and 3%-alkane treatments, respectively. In all the treatments, alkanes with medium-chain length (C11-C14) were preferentially degraded by soil microbes, followed by C27-alkane in 3% and 5% treatments. Alkane contamination level slightly altered soil bacterial community, and the main change was the presence and abundance of dominant alkane degraders. Thermogemmatisporaceae, Gemmataceae and Thermodesulfovibrionaceae were highly related to the degradation of C14- and C27-alkanes in 5% treatment, but linked to alkanes with medium-chain (C11-C18) in 1% treatment and C21-alkane in 3% treatment, respectively. Additionally, we compared the abundance of three alkane-monooxygenase genes, e.g., alk_A, alk_P and alk_R. The abundance of alk_R gene was highest in soils, and alk_P gene was more correlated with alkane degradation efficiency, especially in 5% treatment. Our results suggested that alkane contamination level showed non-negligible effects on soil bacterial communities to some extents, and particularly shaped alkane degraders and degrading genes significantly. This study provides a better understanding on the response of alkane degraders and bacterial communities to soil alkane concentrations, which affects their biodegradation process.
