外源CdS纳米粒子对大肠杆菌生长的影响

Effect of exogenous CdS nanoparticle on the growth of Escherichia coli

摘要:

半导体纳米材料在光激发下产生光电子和空穴，会影响微生物生长，其中空穴的氧化性将对菌体造成损伤，而光电子的作用可能会促进微生物代谢。本研究以大肠杆菌(Escherichia coli)作为研究对象，通过OD₆₀₀和菌落形成单位(colony forming unit,CFU)的测定，评价添加外源硫化镉(cadmium sulfide,CdS)纳米粒子后大肠杆菌的生长变化；结合对胞内氧化酶活力、丙酮酸和丙二醛浓度的测定，及相关基因的实时荧光定量PCR分析，说明CdS对大肠杆菌代谢的影响。结果表明，在光照条件下，CdS的加入使大肠杆菌OD₆₀₀提升了32.4%，丙酮酸积累量提高了34.6%；分裂蛋白基因ftsZ上调，并维持在50%以上，三羧酸循环关键酶基因icdA和gltA相对表达量上调86%和103%。这表明微生物可利用半导体光电子，促进自身生长代谢。研究结果有助于加深对纳米粒子与微生物相互作用的认识。

Abstract:

Semiconductor nanoparticles generate photoelectrons and photo-induced holes under light excitation, and thus may influence the growth of microbial cells. The highly oxidative holes may severely damage the cells, while the photoelectrons may promote microbial metabolism. In this study, we evaluated the effect of exogenous cadmium sulfide (CdS) nanoparticles on bacterial growth using OD₆₀₀ and colony forming unit (CFU) as indicators. The oxidase activities, the concentration of pyruvate and malondialdehyde, and the expression of relevant genes assessed by real-time fluorescent quantitative PCR were analyzed to investigate the effect of excited CdS on cellular metabolism. The results showed that the OD₆₀₀ and pyruvate accumulation of E.coli increased by 32.4% and 34.6%, respectively, under light conditions. Moreover, the relative expression level of the division protein gene ftsZ was increased more than 50%, and the tricarboxylic acid cycle pathway gene icdA and gltA increased by 86% and 103%, respectively. The results indicated that photoelectrons could be used by microorganisms, resulting in promoted growth and metabolism. This study gives a deep insight into the interaction between nanoparticles and bacteria.