Global transcriptional response of solvent‐sensitive and solvent‐tolerant Pseudomonas putida strains exposed to toluene

Abstract

Summary Pseudomonas putida strains are generally recognized as solvent tolerant, exhibiting varied sensitivity to organic solvents. Pan‐genome analysis has revealed that 30% of genes belong to the core‐genome of Pseudomonas. Accessory and unique genes confer high degree of adaptability and capabilities for the degradation and synthesis of a wide range of chemicals. For the use of these microbes in bioremediation and biocatalysis, it is critical to understand the mechanisms underlying these phenotypic differences. In this study, RNA‐seq analysis compared the short‐ and long‐term responses of the toluene‐sensitive KT2440 strain and the highly tolerant DOT‐T1E strain. The sensitive strain activates a larger number of genes in a higher magnitude than DOT‐T1E. This is expected because KT2440 bears one toluene tolerant pump, while DOT‐T1E encodes three of these pumps. Both strains activate membrane modifications to reduce toluene membrane permeability. The KT2440 strain activates the TCA cycle to generate energy, while avoiding energy‐intensive processes such as flagellar biosynthesis. This suggests that KT2440 responds to toluene by focusing on survival mechanisms. The DOT‐T1E strain activates toluene degradation pathways, using toluene as source of energy. Among the unique genes encoded by DOT‐T1E is a 70 kb island composed of genes of unknown function induced in response to toluene.

Traits allowing resistance to organic solvents in Pseudomonas

“…The particular details on how cells reprogram their transcriptomes and adapt their physiology to face solvent loads must surely vary across strains and species. Future comparative studies similar to that performed by Molina-Santiago et al (2016) should throw more light on this. biology is supported by grant BIO2015-66203-P from the Spanish Ministry of Science and Competitiveness (MINECO/ FEDER).…”

“…Future comparative studies similar to that performed by Molina‐Santiago et al . () should throw more light on this.…”

“…More recently, the use of microarrays and proteomic analyses has become important. In an article in this issue of Environmental Microbiology (Molina‐Santiago et al ., ), authors searched for a more comprehensive view of Pseudomonas solvent resistance by comparing the short‐ and long‐term responses of the toluene‐sensitive P. putida strain KT2440 and the toluene‐resistant strain P. putida DOT‐T1E, when faced with a non‐lethal dose of toluene in a minimal salts medium containing glucose as the carbon source, work that involved RNA‐Seq global transcriptomic analyses. In addition to confirming our present understanding of how solvent‐tolerance is achieved, the results reported provide new perspectives and suggest new lines of research.…”

“…As shown by Molina‐Santiago et al . (), there are several ways by which these responses can come about. The particular details on how cells reprogram their transcriptomes and adapt their physiology to face solvent loads must surely vary across strains and species.…”

“…In summary, solvent-tolerance is a multifactorial response that involves the adaptation of membrane fluidity, the induction of functions allowing for a general stress response, the generation of extra energy or the redirection of that available, and the extrusion of solvents from cells. As shown by Molina-Santiago et al (2016), there are several ways by which these responses can come about. The particular details on how cells reprogram their transcriptomes and adapt their physiology to face solvent loads must surely vary across strains and species.…”