Transcriptional Profiling Suggests that Multiple Metabolic Adaptations are Required for Effective Proliferation of Pseudomonas aeruginosa in Jet Fuel

Abstract

Fuel is a harsh environment for microbial growth. However, some bacteria can grow well due to their adaptive mechanisms. Our goal was to characterize the adaptations required for Pseudomonas aeruginosa proliferation in fuel. We have used DNA-microarrays and RT-PCR to characterize the transcriptional response of P. aeruginosa to fuel. Transcriptomics revealed that genes essential for medium- and long-chain n-alkane degradation including alkB1 and alkB2 were transcriptionally induced. Gas chromatography confirmed that P. aeruginosa possesses pathways to degrade different length n-alkanes, favoring the use of n-C11-18. Furthermore, a gamut of synergistic metabolic pathways, including porins, efflux pumps, biofilm formation, and iron transport, were transcriptionally regulated. Bioassays confirmed that efflux pumps and biofilm formation were required for growth in jet fuel. Furthermore, cell homeostasis appeared to be carefully maintained by the regulation of porins and efflux pumps. The Mex RND efflux pumps were required for fuel tolerance; blockage of these pumps precluded growth in fuel. This study provides a global understanding of the multiple metabolic adaptations required by bacteria for survival and proliferation in fuel-containing environments. This information can be applied to improve the fuel bioremediation properties of bacteria.

Enzyme-mediated biodegradation of long-chain n-alkanes (C32 and C40) by thermophilic bacteria

“…shows higher degradation rates of the hexadecane and benzo[e]pyrene both aliphatic and polyaromatic hydrocarbon at 70°C that was isolated from Hot springs (Feitkenhauer et al 2003). While, Pseudomonas aeruginosa normally metabolize the alkanes through oxidation process and it has two alkane hydroxylases (alkB1 and alkB2), cytochrome P450 and other essential electron transfer proteins that allow it to metabolize long-chain alkanes (Gunasekera et al 2013). Similarly, G. stearothermophilus are reported to contain hydroxylase enzyme and gene-encoding alkane monooxygenase are responsible for degradation of long-chain alkanes (C 12 -C 31 ) (Sakai et al 1994;Wang et al 2006;Liu et al 2010;).…”

Transcriptomic Analyses Elucidate Adaptive Differences of Closely Related Strains of Pseudomonas aeruginosa in Fuel

“…aeruginosa ATCC 33988, isolated from a fuel tank in Oklahoma, is highly adapted to hydrocarbon-containing environments and is considered to be an efficient alkane degrader (5,6). The 6.4-Mb genome of strain ATCC 33988 has 5,975 predicted coding sequences (7).…”

“…In contrast, the genome of P. aeruginosa PAO1, an important opportunistic human pathogen, is 6.26 Mb in size (8), with 5,696 genes (Pseudomonas Genome Database). Although there is a high degree of genome similarity between these two strains, including the presence of the long-chain alkane monooxygenase genes alkB1 and alkB2 (5,7,9), the growth of the PAO1 strain in jet fuel is markedly slower than that of ATCC 33988. In particular, we noticed the PAO1 strain exhibits a reduced growth rate and a longer lag phase than ATCC 33988 when hydrocarbons are its sole carbon source.…”

“…When the fuel-adapted strain P. aeruginosa ATCC 33988 was grown in Jet A fuel and its transcriptome compared with that of cells grown in glycerol, a large number of genes were differentially expressed (5). Upon exposure to fuel, strain ATCC 33988 transcriptionally regulated several genes that included genes encoding efflux pumps (mexCD-OprJ, mexEF-OprN, and mexAB-oprN) and porins (oprF and oprG), extracellular polysaccharides (algD operon and pel operon), and genes associated with biofilm formation, production of siderophores, such as pyoverdine (pvcA-F) and pyochelin (pchC, pchD, and pchF) for iron acquisition, and a range of transcriptional regulator proteins (e.g., Fur and Hfq).…”

The Effects of Storage on Turbine Engine Fuels

“…It has been shown that several adaptations are needed for Pseudomonas aeruginosa to metabolize jet fuel [33]. When jet fuel is the available carbon source, the bacteria alter their metabolism through transcriptional regulation to favor the use of parainic hydrocarbons of the C 11 -C 13 length as a food source [34].…”