# Cell Response to Oxidative Stress in Antarctic Filamentous Fungi
## 6 Low Temperature-Induced Oxidative Stress in Antarctic Fungi  
Among the mentioned harsh parameters of growth in Antarctica, the temperature plays an important role in the realization of oxidative stress in fungi [1,123]. The cold temperatures result in a decline in the metabolic activity of microorganisms, which leads to a reduction in the utilization of ATP and the accumulation of electrons at specific points within the respiratory chain (see Figure 1) [153]. The situation gives rise to a rapid increase in the production of ROS [Figure 8]. There are data that support the modification of metabolic pathways to ensure some species survive under cold stress conditions. The findings suggest the presence of a multifaceted interaction between physiological and biochemical mechanisms that contribute to the adaptation of these species to low-temperature environments [154]. Reduced metabolic activity in response to cold stress has been observed in the fungal strains _P. chrysogenum_[155], _Mrakia psychrophilia_[156], and _Mortierella isabellina_[157]. [PERSON] [50] demonstrated significant metabolite changes in the carbon-metabolite pathway (glycolysis, pentose-phosphate pathway, and TCA cycle) in the Antarctic basidiomycetous yeast _Mrakia blollopis_ grown at 10 and 3 \({}^{\circ}\)C. Proteomic analysis of fungal strains belonging to the genus _Pseudogymnoascus_ revealed a positive correlation between protein levels and transcription levels in certain pathways when subjected to low-temperature stress, indicating an up-regulation of chaperones and pathways associated with energy metabolism [11; 154]. Moreover, the expression of cold-responsive genes, such as the FRO1 gene, as well as the accumulation of ROS, can be influenced by the disruption of mitochondrial function in plants [158]. [PERSON] and [PERSON] [159] propose a model that elucidates the relationship between temperature stress and ROS production. This model is primarily based on the disruption of cellular homeostasis and the uncoupling of metabolic processes. The scientific literature contains only a very small number of studies that make a connection between low temperatures and oxidative stress in fungi (Table 2). As shown by [PERSON] et al. [160], a rapid reduction in growth temperature from 30 to 10 \({}^{\circ}\)C increased H\({}_{2}\)O\({}_{2}\) levels in _S. cerevisiae_, coinciding with increased transcripts of genes responsible for antioxidant defense. Similar results have been reported for the _S. cerevisiae_ BY4743 strain growth at low temperatures (10-15 \({}^{\circ}\)C) [161]. The authors suggested that the suboptimal temperature caused an enhanced level of ROS and induction of the antioxidant response. Temperature changes induced ROS generation in plant pathogen _A. flavus_[162]. A transient temperature downshift from 30 \({}^{\circ}\)C to 10 \({}^{\circ}\)C or 4 \({}^{\circ}\)C resulted in a significant increase in \({}^{\bullet}\)O\({}_{2}\)\({}^{-}\) and H\({}_{2}\)O\({}_{2}\) levels within both the intact cells and mitochondria of the Antarctic strains _Penicillium_ sp. 161 and _A. glaucus_ 363 [163]. The reduction in temperature to 4 \({}^{\circ}\)C resulted in a more pronounced elevation of ROS levels compared to the conditions at 10 \({}^{\circ}\)C. Furthermore, the mesophilic strain _A. glaucus_ 363 exhibited a more vigorous ROS production process in contrast to the psychrotolerant _Penicillium_ sp. 161. Similar results have been reported for the Antarctic strains _P. griseofuluum_ P29 and _P. chrysogenum_ P27 [164], as well as for _P. waksmanii_ m12 and _P. olsonii_ p14 [165]. An association between cold stress and ROS generation has been reported on two strains of the cold-adapted oleaginous yeast _Rhodosporidium kratochvilovae_[166]. In the psychrophilic fungus _Pseudogymnoascus_ _panorum_, increased levels of unsaturated fatty acids allow membrane function to be maintained under high ROS levels at low temperatures [76]. Figure 8: Molecular mechanism of cold stress realization.