Adaptive remodelling of blue pigmenting Pseudomonas fluorescens pf59 proteome in response to different environmental conditions

Pseudomonas species are considered among the most important food spoilers thanks to the versatility to utilize a wide range of carbon sources and to grow under different environments. In the present study, proteomic responses of the blue pigmenting strain Pseudomonas fluorescens pf59, chosen as representative strain of P. fluorescens to application of environmental conditions such as low temperature (10 °C vs 30 °C) and extended incubation time (120 h vs 24 h), were evaluated under different culture media (Tryptic Soy Broth/Agar and Potato Dextrose Broth/Agar). In addition, bacterial growth dynamics, blue pigment production and biofilm formation of P. fluorescens pf59 were investigated. The relative amount of some proteins categories, such as those related to carbohydrate and energy metabolism, post-translational modifications, and fatty acid biosynthesis, was modulated in response to different environmental conditions. In particular, temperature influenced protein synthesis more than culture medium, modulating the abundance of several proteins. In addition, at 120 h of incubation, aldehyde dehydrogenase, peroxiredoxin, outer membrane protein W, and ATP-dependent chaperone ClpB were over-synthesized in both culture media. Production of blue pigment was found only after 120 h of incubation at 10 °C, using Potato Dextrose media. In this condition, we found a relationship between the blue colour appearance and the over-expression of four proteins involved in redox balance and osmotic-shock defence response. Our work contributes to the knowledge of proteome dynamics used by P. fluorescens underlying the microbial responses to various environmental conditions. The results provide useful indications to improve the efficacy of intervention methods to inhibit the survival of microorganisms in foods.