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Psychrophilic organisms possess several adaptive strategies which allow them to sustain life at low temperatures between −20 to 20°C. Studies on Antarctic psychrophiles are interesting due to the multiple stressors that exist on the permanently cold continent. These organisms produce, among other peculiarities, cold-active enzymes which not only have tremendous biotechnological potential but are valuable models for fundamental research into protein structure and function. Recent innovations in omics technologies such as genomics, transcriptomics, proteomics and metabolomics have contributed a remarkable perspective of the molecular basis underpinning the mechanisms of cold adaptation. This review critically discusses similar and different strategies of cold adaptation in the obligate psychrophilic yeast, Glaciozyma antarctica PI12 at the molecular (genome structure, proteins and enzymes, gene expression) and physiological (antifreeze proteins, membrane fluidity, stress-related proteins) levels. Our extensive studies on G. antarctica have revealed significant insights towards the innate capacity of- and the adaptation strategies employed by this psychrophilic yeast for life in the persistent cold. Furthermore, several cold-active enzymes and proteins with biotechnological potential are also discussed. [ABSTRACT FROM AUTHOR]

Microbes living in the polar regions have some common and unique strategies to respond to thermal stress. Nevertheless, the amount of information available, especially at the molecular level is lacking for some organisms such as Antarctic psychrophilic yeast. For instance, it is not known whether molecular chaperones in Antarctic yeasts play similar roles to those from mesophilic yeasts when they are exposed to heat stress. Therefore, this project aimed to determine the gene expression patterns and roles of molecular chaperones in Antarctic psychrophilic Glaciozyma antarctica PI12 that was exposed to heat stress. G. antarctica PI12 was grown at its optimal growth temperature of 12°C and later exposed to heat stresses at 16°C and 20°C for 6 hours. Transcriptomes of those cells were extracted, sequenced and analyzed. Thirty-three molecular chaperone genes demonstrated differential expression of which 23 were up-regulated while 10 were down-regulated. Functions of up-regulated molecular chaperone genes were related to protein binding, response to a stimulus, chaperone binding, cellular response to stress, oxidation, and reduction, ATP binding, DNA-damage response and regulation for cellular protein metabolic process. On the other hand, functions of down-regulated molecular chaperone genes were related to chaperone-mediated protein complex assembly, transcription, cellular macromolecule metabolic process, regulation of cell growth and ribosome biogenesis. The findings provided information on how molecular chaperones work together in a complex network to protect the cells under heat stress. It also highlights the evolutionary conserved protective role of molecular chaperones in psychrophilic yeast, G. antarctica, and mesophilic yeast, Saccharomyces cerevisiae. [ABSTRACT FROM AUTHOR]