Crude Oil Degrading Fingerprint and the Overexpression of Oxidase and Invasive Genes for n-hexadecane and Crude Oil Degradation in the Acinetobacter pittii H9-3 Strain

Abstract

A crude oil-degrading bacterium named strain H9-3 was isolated from crude oil contaminated soil in the Northeastern area of China. Based on its morphological characteristics and 16S rDNA sequence analysis, strain H9-3 is affiliated to Acinetobacter pittii in the group of Gammaproteobacteria. The strain was efficient in removing 36.8% of the initial 10 g·L−1 of crude oil within 21 days. GC-MS was performed and a preference was shown for n-C10, n-C11, i-C14, i-C17, i-C34, n-C12, n-C13, n-C14, n-C27, n-C32 and i-C13, over n-C16, n-C18–C22, n-C24–n-C31, and n-C36. This can be regarded as the specific fingerprint for crude oil degradation by strain H9-3 of Acinetobacter pittii. In addition to crude oil, it was shown that soybean oil and phenols can be utilized as carbon sources by strain H9-3. It was also shown that aniline and α-naphthol cannot be utilized for growth, but they can be tolerated by strain H9-3. Methylbenzene was neither utilized nor tolerated by strain H9-3. Although n-hexadecane was not preferentially consumed by strain H9-3, during culture with crude oil, it could be utilized for growth when it is the sole carbon source. The degradation of some branched alkanes (i-C14, i-C17 and i-C34) and the preferential degradation of crude oil over phenols could be used as a reference for distinguishing A. pittii from A. calcoaceticus. The difference in gene expression was very significant and was induced by diverse carbon sources, as shown in the qRT-PCR results. The oxidation and adhesion events occurred at high frequency during alkane degration by Acinetobacter pittii strain H9-3 cells.

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