Pellicle formation in Shewanella oneidensis

Yili Liang,Jingrong Chen,Guanzhou Qiu,Xueduan Liu,Haichun Gao,Zhili He,Jizhong Zhou,Lin Wu,Yangyang Dong

doi:10.1186/1471-2180-10-291

Yili Liang, Jingrong Chen + Show 7 more

Open Access

https://doi.org/10.1186/1471-2180-10-291

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Abstract

BackgroundAlthough solid surface-associated biofilm development of S. oneidensis has been extensively studied in recent years, pellicles formed at the air-liquid interface are largely overlooked. The goal of this work was to understand basic requirements and mechanism of pellicle formation in S. oneidensis.ResultsWe demonstrated that pellicle formation can be completed when oxygen and certain cations were present. Ca(II), Mn(II), Cu(II), and Zn(II) were essential for the process evidenced by fully rescuing pellicle formation of S. oneidensis from the EDTA treatment while Mg (II), Fe(II), and Fe(III) were much less effective. Proteins rather than DNA were crucial in pellicle formation and the major exopolysaccharides may be rich in mannose. Mutational analysis revealed that flagella were not required for pellicle formation but flagellum-less mutants delayed pellicle development substantially, likely due to reduced growth in static media. The analysis also demonstrated that AggA type I secretion system was essential in formation of pellicles but not of solid surface-associated biofilms in S. oneidensis.ConclusionThis systematic characterization of pellicle formation shed lights on our understanding of biofilm formation in S. oneidensis and indicated that the pellicle may serve as a good research model for studying bacterial communities.

Highlights

Solid surface-associated biofilm development of S. oneidensis has been extensively studied in recent years, pellicles formed at the air-liquid interface are largely overlooked
Certain metal cations are required for pellicle formation in S. oneidensis On the basis that metal cations are of general importance in biofilm formation, we examined the effects of certain metal cations on pellicle formation of S. oneidensis
No noticeable difference in growth between samples containing 0.3 mM EDTA and the non-EDTA control. All these results indicate that EDTA at the tested concentration has a detrimental effect on pellicle formation of S. oneidensis

Summary

Introduction

Solid surface-associated biofilm development of S. oneidensis has been extensively studied in recent years, pellicles formed at the air-liquid interface are largely overlooked. Many factors, including extracellular organelles such as flagella and type IV pili, secreted proteins, and chemical agents supplemented in media such as iron and phosphate, have been shown to play important roles in biofilm formation [5]. Effects of these factors on the biofilm formation process depend on the bacterium under study. It has been suggested that variation in effects of these factors on biofilm formation by particular species of bacteria may be reflection of the different environmental niches where they live [14,17,18,19]

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