Abstract—

At the International Space Station (ISS), artificial living conditions are created and maintained to satisfy human needs, these conditions are also favorable for the growth of numerous microorganisms, molds and bacteria. Among the microorganisms detected on the ISS are those from the automicroflora of crew members, and a significant number of spore-forming bacteria. In most cases, this group of microorganisms gives rise to strains that are able to colonize, grow and reproduce on interior materials and equipment of stations, and may be involved in biodestructive processes. These bacteria show increased resistance to various stress factors, for example, DNA-damaging and oxidizing agents. The molecular mechanisms of this resistance to stress are poorly understood. As part of the sanitary-microbiological monitoring of the ISS habitat, the Bacillus licheniformis 24 strain was isolated. Here, we demonstrated that this strain has increased resistance to hydrogen peroxide and Paraquat when compared to the “terrestrial” B. licheniformis B-10956 strain. B. licheniformis 24 overexpressed genes encoding enzymes that neutralize reactive oxygen species, such as KatX catalase and the superoxide dismutases SodA and SodF. Apart from this, in comparison with B. licheniformis B-10956, of B. licheniformis 24 cells had lower hydrogen sulfide production that was associated with sharply reduced expression of the cysIJ operon that encodes sulfite reductase. The results indicate that enzymatic antioxidant protective systems make a more significant contribution to the hyper-resistance of Bacillus strains to oxidizing agents than components of non-enzymatic systems, such as hydrogen sulfide.

中文翻译：

---

地衣芽孢杆菌24株对氧化应激的高抗性与酶促抗氧化系统基因的过表达相关。

摘要-

在国际空间站（ISS），创造并维持了人工生活条件以满足人类的需求，这些条件也有利于多种微生物，霉菌和细菌的生长。在国际空间站上检测到的微生物中，有来自机组人员自发菌群的微生物，还有大量的孢子形成细菌。在大多数情况下，这类微生物产生的菌株能够在车站的内部材料和设备上定殖，生长和繁殖，并可能参与生物破坏过程。这些细菌显示出对各种压力因素（例如，DNA破坏剂和氧化剂）的抗性增强。这种抗压力的分子机制了解甚少。作为国际空间站栖息地卫生微生物监测的一部分，分离出地衣芽孢杆菌24菌株。在这里，我们证明了与“陆地”地衣芽孢杆菌B-10956菌株相比，该菌株对过氧化氢和百草枯具有增强的抗性。地衣芽孢杆菌24个过表达的基因编码的酶可中和活性氧，例如KatX过氧化氢酶和超氧化物歧化酶SodA和SodF。除此之外，与地衣芽孢杆菌B-10956相比，地衣芽孢杆菌24细胞的硫化氢生成量较低，这与cysIJ的表达急剧降低有关编码亚硫酸还原酶的操纵子。结果表明，酶抗氧化剂保护系统对芽孢杆菌菌株对氧化剂的高抗性比非酶系统的组分（如硫化氢）做出了更大的贡献。