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Characterization of a biosurfactant-producing Leclercia sp. B45 with new transcriptional patterns of alkB gene

Shuai, Yiying, Zhou, Hanghai, Mu, Qinglin, Zhang, Dongdong, Zhang, Ning, Tang, Jingchun, Zhang, Chunfang
Annals of microbiology 2019 v.69 no.2 pp. 139-150
Fourier transform infrared spectroscopy, Leclercia, biodegradation, biosurfactants, carbon, enzymes, gas chromatography-mass spectrometry, gene expression regulation, genes, hexadecane, metabolism, pH, quantitative polymerase chain reaction, reverse transcriptase polymerase chain reaction, salinity, temperature, transcription (genetics)
To investigate the hydrocarbon-degrading ability, biosurfactant-producing capacity, and alkane monooxygenase system of Leclercia spp. A bacterial strain classified as Leclercia sp. B45 was isolated, and its biosurfactant-producing capacity, hydrocarbon-degrading ability, and alkane hydroxylase (alkB) gene transcriptional patterns were evaluated by TLC, FTIR, GC-MS, and RT-qPCR, respectively. Strain B45 showed active biosurfactant-producing ability, which was preferentially induced by C16. The extracted biosurfactant tolerated a wide range of salinity, pH, and temperature. The degradation rate of n-decane (C10), n-hexadecane (C16), and octacosane (C28) by strain B45 could reach 92.6%, 94.1%, and 67.8%, respectively. Furthermore, the alkB transcription levels in the strain B45 with C10, C16, or C28 as a carbon source were distinctly higher than those of the control group during the late exponential and stationary phases. The relative alkB transcript copy number decreased with the increase in alkane chain length, which is consistent with B45 strain biodegradation kinetics. Leclercia sp. B45 showed excellent n-alkane degradation performance and biosurfactant-producing capacity. Meanwhile, the alkB gene in Leclercia sp. B45 is likely to represent a novel gene, whose transcription level was significantly upregulated when induced by n-alkane. These results provide new insights into alkane metabolism mechanism in Leclercia sp. B45.