Environmental and Genetic Determinants of Biofilm Formation in Paracoccus Denitrificans

dc.contributor.authorKumar, Santoshen_US
dc.contributor.authorSpiro, Stephenen_US
dc.contributor.utdAuthorKumar, Santoshen_US
dc.contributor.utdAuthorSpiro, Stephenen_US
dc.date.accessioned2018-10-17T22:38:39Z
dc.date.available2018-10-17T22:38:39Z
dc.date.created2017-09-06en_US
dc.date.issued2018-10-17
dc.description.abstractThe genome of the denitrifying bacterium Paracoccus denitrificans predicts the expression of a small heme-containing nitric oxide (NO) binding protein, H-NOX. The genome organization and prior work in other bacteria suggest that H-NOX interacts with a diguanylate cyclase that cyclizes GTP to make cyclic di-GMP (cdGMP). Since cdGMP frequently regulates attached growth as a biofilm, we first established conditions for biofilm development by P. denitrificans. We found that adhesion to a polystyrene surface is strongly stimulated by the addition of 10 mM Ca²⁺ to rich media. The genome encodes at least 11 repeats-in-toxin family proteins that are predicted to be secreted by the type I secretion system (TISS). We deleted the genes encoding the TISS and found that the mutant is almost completely deficient for attached growth. Adjacent to the TISS genes there is a potential open reading frame encoding a 2,211-residue protein with 891 Asp-Ala repeats. This protein is also predicted to bind calcium and to be a TISS substrate, and a mutant specifically lacking this protein is deficient in biofilm formation. By analysis of mutants and promoter reporter fusions, we show that biofilm formation is stimulated by NO generated endogenously by the respiratory reduction of nitrite. A mutant lacking both predicted diguanylate cyclases encoded in the genome overproduces biofilm, implying that cdGMP is a negative regulator of attached growth. Our data are consistent with a model in which there are H-NOX-dependent and -independent pathways by which NO stimulates biofilm formation. IMPORTANCE The bacterium Paracoccus denitrificans is a model for the process of denitrification, by which nitrate is reduced to dinitrogen during anaerobic growth. Denitrification is important for soil fertility and greenhouse gas emission and in waste and water treatment processes. The ability of bacteria to grow as a biofilm attached to a solid surface is important in many different contexts. In this paper, we report that attached growth of P. denitrificans is stimulated by nitric oxide, an intermediate in the denitrification pathway. We also show that calcium ions stimulate attached growth, and we identify a large calcium binding protein that is required for growth on a polystyrene surface. We identify components of a signaling pathway through which nitric oxide may regulate biofilm formation. Our results point to an intimate link between metabolic processes and the ability of P. denitrificans to grow attached to a surface.en_US
dc.description.departmentSchool of Natural Sciences and Mathematicsen_US
dc.identifier.bibliographicCitationKumar, Santosh, and Stephen Spiro. 2017. "Environmental and genetic determinants of biofilm formation in paracoccus denitrificans." mSphere 2(5), doi:10.1128/mSphereDirect.00350-17en_US
dc.identifier.issn2379-5042en_US
dc.identifier.issue5en_US
dc.identifier.urihttp://hdl.handle.net/10735.1/6199
dc.identifier.volume2en_US
dc.language.isoenen_US
dc.publisherAmer Soc Microbiologyen_US
dc.relation.urihttp://dx.doi.org/10.1128/mSphereDirect.00350-17en_US
dc.rightsCC BY 4.0 (Attribution)en_US
dc.rights©2017 The Authorsen_US
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/en_US
dc.sourcemSphere
dc.subjectEscherichia colien_US
dc.subjectHeterotrophic Processesen_US
dc.subjectBacteriaen_US
dc.subjectAnaerobic bacteria--Growthen_US
dc.subjectMicrobiologyen_US
dc.subjectBiofilmsen_US
dc.subjectDenitrificationen_US
dc.subjectNitric oxideen_US
dc.subjectParacoccus denitrificansen_US
dc.titleEnvironmental and Genetic Determinants of Biofilm Formation in Paracoccus Denitrificansen_US
dc.type.genrearticleen_US

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