fliY基因失活减弱沙福芽孢杆菌ST7菌株的锰氧化能力

Inactivation of fliY attenuates the manganese-oxidizing capacity of Bacillus safensis ST7

摘要:

【背景】沙福芽孢杆菌ST7菌株具有较强的锰氧化能力，但其分子机制不清楚。【目的】着重研究鞭毛马达开关蛋白基因(fliY)对沙福芽孢杆菌锰氧化能力的影响。【方法】根据同源重组原理，以沙福芽孢杆菌ST7菌株为起始菌株，构建fliY基因敲除的突变株△fliY，测定菌落迁徙、细菌生物膜和锰氧化率等，研究fliY基因突变后菌株的运动能力、生物膜生成和锰氧化能力是否发生变化。【结果】经克隆测序，证实突变株△fliY中fliY基因的后半段被卡纳霉素抗性基因取代，fliY基因失活；与野生型菌株ST7相比，突变株△fliY在全营养的LB培养基中生长变化不大，但在含锰的PYCM培养基中，突变株的生长速度减慢、菌落较小、生物膜生成量显著下降，运动性和锰氧化能力分别下降65%和20%。【结论】fliY基因不仅影响菌株的生长和运动，而且参与细菌的趋化和锰氧化等生物学过程。

Abstract:

[Background] Bacillus safensis ST7 has strong ability of oxidizing manganese, the molecular mechanism of which, however, remains unclear. [Objective] The aim is to study the effect of the flagellar motor switch protein FliY on the manganese-oxidizing ability of B. safensis. [Methods] Based on the principle of homologous recombination, a fliY -deleted mutant (△fliY) was constructed using B. safensis ST7 as the starting strain. The changes in mobility, biofilm formation, and manganese-oxidizing capacity of △fliY were evaluated based on colony migration, biofilm production, and Mn(II)-oxidizing rate. [Results] After cloning and sequencing, it was confirmed that fliY was inactivated with the last part replaced by kanamycin resistance gene in △fliY. The growth of △fliY in LB medium was similar to that of the starting strain. However, △fliY showed retarded logarithmic growth, small colonies, and reduced biofilm production in the PYCM medium containing Mn(II). The motility and Mn(II)-oxidizing rate of △fliY decreased by about 65% and 20%, respectively. [Conclusion] The gene fliY not only affects the growth and motility but also participates in biological processes such as chemotaxis and manganese oxidation of B. safensis.