Thormann Kai M, Saville Renée M, Shukla Soni, Pelletier Dale A, Spormann Alfred M
Department of Civil and Environmental Engineering, Stanford University, Stanford, CA 94305-5429, USA.
J Bacteriol. 2004 Dec;186(23):8096-104. doi: 10.1128/JB.186.23.8096-8104.2004.
Shewanella oneidensis MR-1 is a facultative Fe(III)- and Mn(IV)-reducing microorganism and serves as a model for studying microbially induced dissolution of Fe or Mn oxide minerals as well as biogeochemical cycles. In soil and sediment environments, S. oneidensis biofilms form on mineral surfaces and are critical for mediating the metabolic interaction between this microbe and insoluble metal oxide phases. In order to develop an understanding of the molecular basis of biofilm formation, we investigated S. oneidensis biofilms developing on glass surfaces in a hydrodynamic flow chamber system. After initial attachment, growth of microcolonies and lateral spreading of biofilm cells on the surface occurred simultaneously within the first 24 h. Once surface coverage was almost complete, biofilm development proceeded with extensive vertical growth, resulting in formation of towering structures giving rise to pronounced three-dimensional architecture. Biofilm development was found to be dependent on the nutrient conditions, suggesting a metabolic control. In global transposon mutagenesis, 173 insertion mutants out of 15,000 mutants screened were identified carrying defects in initial attachment and/or early stages in biofilm formation. Seventy-one of those mutants exhibited a nonswimming phenotype, suggesting a role of swimming motility or motility elements in biofilm formation. Disruption mutations in motility genes (flhB, fliK, and pomA), however, did not affect initial attachment but affected progression of biofilm development into pronounced three-dimensional architecture. In contrast, mutants defective in mannose-sensitive hemagglutinin type IV pilus biosynthesis and in pilus retraction (pilT) showed severe defects in adhesion to abiotic surfaces and biofilm formation, respectively. The results provide a basis for understanding microbe-mineral interactions in natural environments.
奥奈达希瓦氏菌MR-1是一种兼性铁（III）和锰（IV）还原微生物，是研究微生物诱导的铁或锰氧化物矿物溶解以及生物地球化学循环的模型。在土壤和沉积物环境中，奥奈达希瓦氏菌生物膜在矿物表面形成，对于介导这种微生物与不溶性金属氧化物相之间的代谢相互作用至关重要。为了深入了解生物膜形成的分子基础，我们在流体动力流动室系统中研究了在玻璃表面形成的奥奈达希瓦氏菌生物膜。初始附着后，微菌落的生长和生物膜细胞在表面的横向扩散在前24小时内同时发生。一旦表面覆盖几乎完成，生物膜的发育就会伴随着广泛的垂直生长，形成高耸的结构，从而产生明显的三维结构。发现生物膜的发育取决于营养条件，这表明存在代谢控制。在全局转座子诱变中，在筛选的15000个突变体中，有173个插入突变体被鉴定为在初始附着和/或生物膜形成的早期阶段存在缺陷。其中71个突变体表现出非游动表型，这表明游动运动性或运动元件在生物膜形成中起作用。然而，运动基因（flhB、fliK和pomA）的破坏突变并不影响初始附着，但影响生物膜发育成明显三维结构的进程。相比之下，在IV型菌毛生物合成和菌毛回缩（pilT）方面存在缺陷的突变体分别在与非生物表面的粘附和生物膜形成方面表现出严重缺陷。这些结果为理解自然环境中的微生物-矿物相互作用提供了基础。
