Possible Nonconductive Role of Geobacter sulfurreducens Pilus Nanowires in Biofilm Formation

Department of Microbiology, University of Massachusetts, Amherst, MA 01003, USA.
Journal of Bacteriology (Impact Factor: 2.81). 04/2007; 189(5):2125-7. DOI: 10.1128/JB.01284-06
Source: PubMed


Geobacter sulfurreducens required expression of electrically conductive pili to form biofilms on Fe(III) oxide surfaces, but pili were also essential
for biofilm development on plain glass when fumarate was the sole electron acceptor. Furthermore, pili were needed for cell
aggregation in agglutination studies. These results suggest that the pili of G. sulfurreducens also have a structural role in biofilm formation.

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Available from: Gemma Reguera, Sep 22, 2014
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    • "Pili are known to have an important role in biofilm formation (Moreira et al., 2006; Reguera et al., 2007; Oxaran et al., 2012; Snider et al., 2012), but also for the conductive properties of Geobacter biofilms (Summers et al., 2010; Malvankar "
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    ABSTRACT: Interspecies exchange of electrons enables a diversity of microbial communities to gain energy from reactions that no one microbe can catalyze. The first recognized strategies for interspecies electron transfer were those that relied on chemical intermediates that are recycled through oxidized and reduced forms. Well-studied examples are interspecies H2 transfer and the cycling of sulfur intermediates in anaerobic photosynthetic communities. Direct interspecies electron transfer (DIET) in which two species establish electrical contacts is an alternative. Electrical contacts documented to date include electrically conductive pili, as well as conductive iron minerals and conductive carbon moieties such as activated carbon and biochar. Interspecies electron transfer is central to the functioning of methane-producing microbial communities. The importance of interspecies H2 transfer in many methanogenic communities is clear, but under some circumstances DIET predominates. It is expected that further mechanistic studies and broadening investigations to a wider range of environments will help elucidate the factors that favor specific forms of interspecies electron exchange under different environmental conditions.
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    • "La capacidad de las especies Geobacter para transferir electrones desde y hacia electrodos permite obtener electricidad a partir de materia orgánica [8], o el uso de electrodos como donador de electrones para la reducción de contaminantes tales como; nitrato, uranio y disolventes clorados [9] -[11]. Además estas bacterias son capaces de fabricar Pili, que pueden ser útiles en el desarrollo de dispositivos en la industria de microelectrónica [12] "

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    • "(iii) non-conductive nanowires as a foremost structural factor for cell aggregation and biofilm formation as described for pili of metal-reducing bacteria , e.g. Geobacter sulfurreducens (Reguera et al., 2007). "
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    ABSTRACT: The colonisation of activated zeolites (i.e. clinoptilolites) as carriers for microorganisms involved in the biogas process was investigated. Zeolite particle sizes of 1.0-2.5mm were introduced to anaerobic laboratory batch-cultures and to continuously operated bioreactors during biogas production from grass silage. Incubation over 5-84 days led to the colonisation of zeolite surfaces in small batch-cultures (500 ml) and even in larger scaled and flow-through disturbed bioreactors (28 l). Morphological insights were obtained by using scanning electron microscopy (SEM). Single strand conformation polymorphism (SSCP) analysis based on amplification of bacterial and archaeal 16S rRNA fragments demonstrated structurally distinct populations preferring zeolite as operational environment. via sequence analysis conspicuous bands from SSCP patterns were identified. Populations immobilised on zeolite (e.g. Ruminofilibacter xylanolyticum) showed pronounced hydrolytic enzyme activity (xylanase) shortly after re-incubation in sterilised sludge on model substrate. In addition, the presence of methanogenic archaea on zeolite particles was demonstrated.
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