模拟失重环境对大肠杆菌K12表型异质性亚群菌株的影响

Effect of simulated weightlessness on Escherichia coli K12 phenotypic heterogeneous strains

摘要:

【背景】我国未来几年深空探索任务将呈“井喷式”发展，微生物对于航天活动的影响越来越引起关注，而国内外少有表型异质性亚群的研究。【目的】从表型异质性的角度探讨低剪切力模拟失重环境(low-shear modeled microgravity，LSMMG)和低剪切力正常重力环境(low-shear normal gravity，LSNG)对大肠杆菌K12造成的影响。【方法】利用旋转细胞培养系统模拟失重环境对大肠杆菌K12进行连续传代培养，从单克隆形态、颜色以及菌体形态等方面挑选出表型异质性的亚群菌株，对不同菌株进行增殖速率、抗生素耐药性、生物被膜形成、环境压力抵抗力以及细胞毒性的测定，以此评估低剪切力和模拟失重环境对大肠杆菌K12的影响。【结果】利用旋转细胞培养系统连续传代培养，总共分离出4株形态不同的表型异质性亚群菌株，其中2株来自模拟失重组(M1，Ma)，另外2株来自正常重力对照组(N1，Na)；4株亚群与原始菌株(P)相比，在增殖速率、生物被膜形成、环境压力抵抗力和细胞毒性方面均有增强或减弱的明显变化，对于抗生素的耐药性无明显变化。【结论】低剪切力模拟失重环境以及存在低剪切力的正常重力环境均能引起大肠杆菌表型异质性变化，与原始菌株相比，表型异质性亚群菌株在分化上并没有统一的方向，但仍需警惕那些可能对人类造成危害的变化表型。

Abstract:

[Background] The exploration mission of deep space exploration in China in the next few years will be a “well blowout” development. The impact of microorganisms on space activities will attract more and more attention. However, there are few studies on phenotypic heterogeneity at home and abroad. [Objective] To investigate the effect of low-shear modeled microgravity (LSMMG) and low-shear normal gravity (LSNG) on the large intestine from the perspective of phenotypic heterogeneity Bacillus K12 caused by the impact. [Methods] The continuous culture of Escherichia coli K12 was simulated by a rotating cell culture system to simulate the environment of weightlessness. The phenotypic heterogeneity subtypes were selected from the morphology, color and morphology of the cells. The proliferation rate of different strains, antibiotic resistance, biofilm formation, environmental pressure resistance, and cytotoxicity were measured to assess the effects of low shear stress and simulated weightlessness on E. coli K12. [Results] Four strains with different phenotypic heterogeneity were isolated by continuous culture in rotating cell culture system. Two of them were from simulated weightlessness group (M1, Ma) and the other two were from normal gravity control group (N1, Na). Compared with the original strain (P), the four sub-populations showed significant changes in proliferation rate, biofilm formation, environmental pressure resistance and cytotoxicity, and their antibiotic resistance has no significant changes. [Conclusion] Low shear stress can induce the phenotypic heterogeneity of Escherichia coli in both simulated weightlessness environment and normal gravity environment with low shear stress. Compared with the original strain, the phenotypic heterogeneity strains are differentiated. There is no unifying direction, but we still need to be alert to the changing phenotypes that could be harmful to humans.