Heat shock proteins 70 (Hsp70) are potential thermal stress markers as they play a pivotal role in safeguarding cells against heat shock-induced damage. The Hsp70s are present in several variants with each containing its peculiar importance due to their specific functions such as cell protection during elevated thermal stress. The present investigation evaluated the gene expression profiles of all Hsp70 genes in Glaciozyma antarctica PI12 during a heat wave condition. In this study, we exposed G. antarctica PI12 cells to a realistic heat wave to understand the impacts of the extraordinary, unprecedented heat waves that hit Antarctica at nearly 40°C above the average in 2022. The experiment was carried out through eight days where cells were exposed gradually at 0, 2, 4, 8, 12, 16, 20, 25 and 30°C. The gene expression profiles were obtained during the simulated heat wave along with non-stressed control treatments by real-time PCR. Out of the six Hsp70 genes in G. antarctica PI12, five were expressed under the conditions tested. Among the expressed genes, gahsp70-1, gahsp70-5, and gahsp70-6 showed significant upregulation. Specifically, their expression levels increased by five- to eightfold after exposure to heat shock at 4°C. Gene expression patterns at 20°C and 30°C also showed induction with the highest at 3.6 folds and 5.8 folds, respectively. These results indicate that the expression of Hsp70 genes in G. antarctica PI12 was inducible under thermal stress, indicating their importance in cells during the heat waves. These results conclude that the gene expression patterns of Hsp70 during heat waves contribute vital information on thermal adaptation in the Antarctic marine ecosystem under climate stress.

The human movement to and from Antarctica has increased significantly in recent decades, particularly to the South Shetland Islands, King George Island (KGI), and Deception Island (DCI). Such movements may result in unintentional soil transfer to other warmer regions, such as tropical countries. However, the ability of Antarctic bacteria to survive in tropical climates remained unknown. Hence, the objectives of this work were (i) to determine the bacterial diversity of the soils at the study sites on the two islands, and (ii) to determine if simulated tropical-like growth climate conditions would impact overall diversity and increase the abundance of potentially harmful bacteria in the Antarctic soils. KGI and DCI soils were incubated for 12 months under simulated tropical conditions. After 6 and 12-months, samples were collected and subjected to metagenomic DNA extraction, 16S rDNA amplification, sequencing, and alignment analysis. The 12-month denaturing gradient gel electrophoresis (DGGE) analysis revealed changes in fingerprinting patterns and bacterial diversity indices. Following that, bacterial diversity analyses for KGI and DCI soils were undertaken using V3-V4 16S rDNA amplicon sequencing. Major bacterial phyla in KGI and DCI soils comprised Actinobacteria, Proteobacteria, and Verrucomicrobia. Except for Proteobacteria in KGI soils and Acidobacteria and Chloroflexi in DCI soils, most phyla in both soils did not acclimate to simulated tropical conditions. Changes in diversity were also observed at the genus level, with Methylobacterium spp. predominating in both soils after incubation. After the 12-month incubation, the abundance of potentially pathogenic bacteria such as Mycobacterium, Massilia, and Williamsia spp. increased. Overall, there was a loss of bacterial diversity in both Antarctic soils after 12 months, indicating that most bacteria from both islands' sampling sites cannot survive well if the soils were accidentally transported into warmer climates.