Transcriptomic profiling of Pseudomonas migulae revealed gene regulatory properties during biodegradation of aromatic hydrocarbons under cold stress

Bacterial strains within the genus <i>Pseudomonas</i> have often been characterized for their ability to biodegrade aromatic hydrocarbon pollutants, as well as high adaptability to diverse environmental stresses, including cold stress. In this study, a newly isolated bacterium, <i>Pseudomonas migulae</i> strain HY-2, which can grow at 10 °C by utilizing the aromatic hydrocarbon pollutant <i>p</i>-hydroxybenzoic acid (PHBA) as the sole carbon source, was employed as a model to investigate bacterial gene regulatory properties during cold stress adaptation and aromatic hydrocarbon biodegradation. Complete genome sequencing and transcriptomic analysis under cold conditions revealed that strain HY-2 up-regulates at least ten types of chaperone proteins potentially involved in transcriptional, translational and post-translational regulation to maintain protein homeostasis. Transcriptomic data also suggested that cold-induced biofilm formation was enhanced by exogenous polyamines, spermidine or putrescine, which was confirmed through subsequent bioassays. It is hypothesized that exogenous polyamines, commonly supplied by surrounding organisms, enhance biofilm formation in <i>Pseudomonas</i>, thereby aiding in cold stress resistance. Notably, expressions of functional genes responsible for PHBA biodegradation in strain HY-2 were mostly unaffected by cold stress - only three genes, including a PHBA transporter gene, were significantly up-regulated while the neighbouring 10 genes were unaffected - resulting in minimal impact on growth efficiency at 10 °C. These findings provide new insights into the genetic properties of cold adaptation and stress resilience in <i>Pseudomonas</i> and reaffirm the potential of this genus for bioremediation applications in natural environments without the need for extensive anthropogenic intervention.