航天器组装环境中极端微生物的筛选与特性

Screening and characterization of extremophiles in spacecraft assembly environment

航天器在进入太空飞行前需要对微生物进行严格把控.航天器组装、集成与测试厂房(AIT厂房)是航天器携带微生物的重要环境来源之一,因其装配洁净室具有通风干燥、营养物质匮乏等不利于微生物生长繁殖的特性,因此航天器潜在携带的都是能够适应极端环境的极端微生物.针对我国某AIT厂房内部空气与表面环境,通过平板培养并应用细菌16S序列分析共鉴定出13株细菌,分别对其进行了各种极端环境耐受力测试以及抗生素耐药性和成膜能力测试.这些细菌全都来自厚壁菌门Firmicutes和变形菌门Proteobacteria,且其中9株都属于芽孢杆菌属(Bacillus).13株细菌均为耐盐耐酸耐碱微生物,且大部分细菌能在80℃热激和紫外光照射下存活.除了一株在表面环境中分离得到的Sphingomonassp.JCM7513对所有测试的抗生素均不敏感,具有极强的耐药性之外,其余的12株细菌对大部分β-内酰胺类抗生素敏感,但对四环类抗生素和红霉素具有较强的耐药性.分离到的细菌绝大部分具有很强的生物被膜形成能力.本研究表明在航天器组装环境中存在一定数量的极端微生物,为了保护航天器免受生物腐蚀和行星保护的正向污染,需要有更加有效的监测和消杀方法.(图6表3参29)

Spacecrafts need to strictly control microorganisms before entering space flight. The Spacecraft Assembly, Integration, and Test Center(AITC) is an important environmental source for spacecrafts to carry microorganisms. The assembly clean room has characteristics of ventilation, dryness, and lack of nutrients that are not conducive to the growth and reproduction of microorganisms, except for extremophiles. In this study,based on the internal air and surface environment of the AITC in China, 13 strains of bacteria were identified by plate culture and 16S sequence analysis, and their extreme environmental tolerance, antibiotic resistance, and film-forming ability were tested. All these bacteria belonged to the Firmicutes and Proteobacteria phyla, and nine strains belonged to the Bacillus genus. All 13 strains of bacteria were salt-tolerant, acid-tolerant, and alkalitolerant, and 69.2% of the bacteria survived heat shock at 80 ℃. Among these, one strain of Sphingomonas sp.JCM7513 isolated from the surface environment was insensitive to all the tested antibiotics and had strong drug resistance, while the other 12 strains were sensitive to most β-lactam antibiotics but had strong resistance to tetracyclic antibiotics and erythromycin. Most of the isolated bacteria exhibited strong biofilm-forming abilities.The study showed that there are a certain number of extremophiles in the spacecraft assembly environment.To protect spacecrafts from biological corrosion and planetary protection forward pollution, more effective monitoring and elimination methods are needed.