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The article presents the results of a study of some adaptive properties of a bacterial isolate from wheat bran, identified by the 16S rRNA gene as an Arthrobacter agilis strain. According to the literature data, A. agilis does not belong to the dominant bacterial species of wheat microbial associations and activates growth at low ambient temperatures. The studied A. agilis strain showed poor growth in a microbial consortium when an aqueous suspension of wheat bran, partially fermented at 28 ± 1°C by the native microbiota, was plated on a dense MPA medium and produced the pigment after three weeks of storage at 4 ± 1°C. Moderate growth of bacteria without increased pigmentation was observed during its subsequent transfer after low-temperature storage on agar media containing carbohydrates and nitrogen compounds, mineral salts, and vitamins that were more easily utilized than native bran. The growth of colonies upon plating on such media increased in the series: thermally fermented wheat bran → HMF agar → LB (without salt). It was revealed that the A. agilis strain, which was not typical of the wheat bran microflora, under the influence of osmotic and/or temperature shock (in response to a sharp change in the NaCl concentration and/or a difference in ambient temperatures) produced pigments both in agar and liquid cultures. According to the results of spectral analysis, the pigment was assigned to carotenoids and tentatively identified as bacterioruberin. Quantitative evaluation showed that, under stress conditions during submerged cultivation, the studied strain A. agilis wb28 was able to synthesize the pigment at the level of 52.8 mg/L (17.2 mg/g biomass). [ABSTRACT FROM AUTHOR]

Among the living organisms, microscopic fungi are unique in their ability to occupy diverse ecological niches due to the evolutionarily formed mechanisms of adaptation to a broad range of climatic and technogenic factors. One approach to understanding the mechanisms of adaptation to changing environmental conditions is associated with lipid metabolism. The review provides a critical analysis of publications and our own experimental data on the variability of micromycete lipids under the influence of stress factors and of the possible related adaptive mechanisms. The functional, structural, and quantitative changes in fungal lipids were analyzed under the conditions of osmotic, thermal, and cold influences, as well as toxicity. Biochemical variations in the composition of phospholipids and other membrane lipids are characterized as diverse and ambiguous, depending on the degree of exposure, the initial lipid composition, genetic resistance of fungi, and their ability to adapt to extreme conditions. The role of lipid metabolism in the overall integral response of fungal cells to stress is discussed. [ABSTRACT FROM AUTHOR]

The composition of the membrane lipids and cytosol soluble carbohydrates under three kinds of unfavorable impacts (osmotic, oxidative, and cold) was studied. Changes in the composition of the membrane lipids, specifically, increasing content of phosphatidic acids and decreasing levels of phosphatidylcholines and phosphatidylethanolamines, were the general response to the impacts. The degree of fatty acid unsaturation increased in all dominant phospholipids under osmotic shock, only in cardiolipins and phosphatidic acids under oxidative stress, and only in phosphatidylcholines under cold shock. Increased sterol content was observed only under cold and osmotic treatments. No general pattern was revealed in the composition of cytosol carbohydrates in response to stresses. Oxidative stress had almost no effect on the carbohydrate composition, while osmotic and cold treatments resulted in increased glycerol content and decreased total carbohydrate content. The mechanisms of fungal response to various stress impacts are discussed. [ABSTRACT FROM AUTHOR]

Data available in the literature concerning the response of mesophilic bacteria to cold shock at the level of DNA transcription, translation, and chromosome dynamics, i.e., in terms of cell biology, are analyzed. Relevant molecular mechanisms and particular regulatory systems within the framework of a general cell response to cold shock are considered. It is suggested that a short-term response to cold shock is necessary for bacteria to transit to a viable but nonculturable state and/or for their physiological and genetic adaptation to psychrotrophic life. It is emphasized that cell responses to cold and heat shocks are different and that DNA dynamics (i.e., its supercoiling, multiple bending, and condensation) and the rearrangement of the protein-synthesizing apparatus of cells (including the induction of alternative translational mechanisms) may play a central role in cell response to cold shock. The role of molecular chaperones in cold shock response is presumably of less importance than it is in the case of heat shock. [ABSTRACT FROM AUTHOR]

The response of aerobically grown Escherichia coli cells to the cold shock induced by the rapid lowering of growth temperature from 37 to 20°C was found to be basically the same as the oxidative stress response. The enhanced sensitivity of cells deficient in two superoxide dismutases, Mn-SOD and Fe-SOD, and the increased expression of the Mn-SOD gene, sodA, in response to cold stress were interpreted as both oxidative and cold stresses are due to a rise in the intracellular level of superoxide anion. The long-term cultivation of E. coli at 20°C was also accompanied by the typical oxidative stress response reactions—an enhanced expression of the Mn-SOD and catalase HPI genes and a decrease in the intracellular level of reduced glutathione (GSH) and in the GSH/GSSG ratio. [ABSTRACT FROM AUTHOR]