Heterologous protein expression in pseudoalteromonas haloplanktis TAC125

The Antarctic strain Pseudoalteromonas haloplanktis TAC125 is considered one of the model organisms of cold-adapted bacteria, and during last years, it has been exploited as an alternative expression system for recombinant protein production. P. Haloplanktis TAC125 was the first Antarctic bacterium in which an efficient geneexpression technology was set up, and several generations of cold-adapted gene-expression vectors allow the production of recombinant proteins either by constitutive or inducible systems and to address the product toward any cell compartment or to the extracellular medium. Moreover, the development of synthetic media and efficient fermentation schemes, to upscale the recombinant protein production in automatic bioreactors, makes the industrial application of P. Haloplanktis TAC125 more achievable and concrete. The cellular physicochemical conditions and folding processes in P. Haloplanktis TAC125 are quite different from those observed in canonical mesophilic hosts and allowed the production of several difficult-to-express protein products, some of which are of human origin. The recently reported possibility to produce proteins within a range of temperature from 15 to -2.5 °C enhances the chances to improve the conformational quality and solubility of recombinant proteins. This chapter outlines main features and potentiality of this unconventional protein production platform

Acidithiobacillus ferrivorans SS3 presents little RNA transcript response related to cold stress during growth at 8 A degrees C suggesting it is a eurypsychrophile

Acidithiobacillus ferrivorans is an acidophilic bacterium that represents a substantial proportion of the microbial community in a low temperature mining waste stream. Due to its ability to grow at temperatures below 15 °C, it has previously been classified as ‘psychrotolerant’. Low temperature-adapted microorganisms have strategies to grow at cold temperatures such as the production of cold acclimation proteins, DEAD/DEAH box helicases, and compatible solutes plus increasing their cellular membrane fluidity. However, little is known about At. ferrivorans adaptation strategies employed during culture at its temperature extremes. In this study, we report the transcriptomic response of At. ferrivorans SS3 to culture at 8 °C compared to 20 °C. Analysis revealed 373 differentially expressed genes of which, the majority were of unknown function. Only few changes in transcript counts of genes previously described to be cold adaptation genes were detected. Instead, cells cultured at cold (8 °C) altered the expression of a wide range of genes ascribed to functions in transcription, translation, and energy production. It is, therefore, suggested that a temperature of 8 °C imposed little cold stress on At. ferrivorans, underlining its adaptation to growth in the cold as well as suggesting it should be classified as a ‘eurypsychrophile’