Environmental and Genetic Determinants of Biofilm Formation in <named-content content-type="genus-species">Paracoccus denitrificans</named-content>

ABSTRACT The 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 t...

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Autores principales:	Santosh Kumar, Stephen Spiro
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2017
Materias:	biofilm cyclic di-GMP denitrification flavohemoglobin H-NOX nitric oxide Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/daa744937464462aaf8792683b0095e2
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spelling	oai:doaj.org-article:daa744937464462aaf8792683b0095e22021-11-15T15:22:05ZEnvironmental and Genetic Determinants of Biofilm Formation in <named-content content-type="genus-species">Paracoccus denitrificans</named-content>10.1128/mSphereDirect.00350-172379-5042https://doaj.org/article/daa744937464462aaf8792683b0095e22017-10-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mSphereDirect.00350-17https://doaj.org/toc/2379-5042ABSTRACT The 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.Santosh KumarStephen SpiroAmerican Society for Microbiologyarticlebiofilmcyclic di-GMPdenitrificationflavohemoglobinH-NOXnitric oxideMicrobiologyQR1-502ENmSphere, Vol 2, Iss 5 (2017)
institution	DOAJ
collection	DOAJ
language	EN
topic	biofilm cyclic di-GMP denitrification flavohemoglobin H-NOX nitric oxide Microbiology QR1-502
spellingShingle	biofilm cyclic di-GMP denitrification flavohemoglobin H-NOX nitric oxide Microbiology QR1-502 Santosh Kumar Stephen Spiro Environmental and Genetic Determinants of Biofilm Formation in <named-content content-type="genus-species">Paracoccus denitrificans</named-content>
description	ABSTRACT The 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.
format	article
author	Santosh Kumar Stephen Spiro
author_facet	Santosh Kumar Stephen Spiro
author_sort	Santosh Kumar
title	Environmental and Genetic Determinants of Biofilm Formation in <named-content content-type="genus-species">Paracoccus denitrificans</named-content>
title_short	Environmental and Genetic Determinants of Biofilm Formation in <named-content content-type="genus-species">Paracoccus denitrificans</named-content>
title_full	Environmental and Genetic Determinants of Biofilm Formation in <named-content content-type="genus-species">Paracoccus denitrificans</named-content>
title_fullStr	Environmental and Genetic Determinants of Biofilm Formation in <named-content content-type="genus-species">Paracoccus denitrificans</named-content>
title_full_unstemmed	Environmental and Genetic Determinants of Biofilm Formation in <named-content content-type="genus-species">Paracoccus denitrificans</named-content>
title_sort	environmental and genetic determinants of biofilm formation in <named-content content-type="genus-species">paracoccus denitrificans</named-content>
publisher	American Society for Microbiology
publishDate	2017
url	https://doaj.org/article/daa744937464462aaf8792683b0095e2
work_keys_str_mv	AT santoshkumar environmentalandgeneticdeterminantsofbiofilmformationinnamedcontentcontenttypegenusspeciesparacoccusdenitrificansnamedcontent AT stephenspiro environmentalandgeneticdeterminantsofbiofilmformationinnamedcontentcontenttypegenusspeciesparacoccusdenitrificansnamedcontent
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Environmental and Genetic Determinants of Biofilm Formation in <named-content content-type="genus-species">Paracoccus denitrificans</named-content>

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