Characterization and Transcriptome Analysis of a Long-Chain n -Alkane-Degrading Strain Acinetobacter pittii SW-1.

Strain sw-1, isolated from 7619-m seawater of the Mariana Trench, was identified as by 16S rRNA gene and whole-genome sequencing. sw-1 was able to efficiently utilize long-chain -alkanes (C-C), but not short- and medium-chain -alkanes (C-C). The degradation rate of C was 91.25%, followed by C, C, C, C, and C with the degradation rates of 89.30%, 84.03%, 80.29%, 30.29%, and 13.37%, respectively. To investigate the degradation mechanisms of -alkanes for this strain, the genome and the transcriptome analyses were performed. Four key alkane hydroxylase genes (, , , and ) were identified in the genome. Transcriptomes of strain sw-1 grown in C or CHCOONa (NaAc) as the sole carbon source were compared. The transcriptional levels of and , respectively, increased 78.28- and 3.51-fold in C compared with NaAc, while and did not show obvious change. The expression levels of other genes involved in the synthesis of unsaturated fatty acids, permeases, membrane proteins, and sulfur metabolism were also upregulated, and they might be involved in -alkane uptake. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) confirmed that expression was significantly induced by C, C, and C, and induction extent by C and C was higher than that with C Furthermore, expression was only induced by C, and expression was not induced by any of -alkanes. In addition, sw-1 could grow with 0%-3% NaCl or 8 out of 10 kinds of the tested heavy metals and degrade -alkanes at 15 °C. Taken together, these results provide comprehensive insights into the degradation of long-chain -alkanes by isolated from the deep ocean environment.