Project description:we studied the functional composition of a packed-bed nitrifying bioreactor inoculated with a co-culture of Nitrosomonas europaea (ATCC 25978) and Nitrobacter winogradskyi (ATCC 25391) after 840 days of operation.
2023-09-18 | PXD030632 | Pride
Project description:Nitrifying microbes of shrimp culture systems
Project description:The effects of the aromatic hydrocarbons benzene and toluene on Nitrosomonas europaea, a nitrifying bacterium that plays an important role in the removal of nitrogen from wastewater treatment plants, were studied in batch reactors. Exposure to 20 M toluene and 40 M benzene resulted in a 50% reduction in nitrifying activity after 1 h. However, Affymetrix microarray experiments detected no significant changes in gene expression in toluene exposed cells. Cells exposed to benzene were found to up-regulate a gene cluster (NE 1545 - NE 1551). This gene cluster appears to be involved with fatty-acid metabolism, lipid and membrane protein biosynthesis. TEM experiments reveal that cells exposed to benzene decrease the thickness of their membrane and the membrane becomes more structured. Keywords: stress response, benzene, toluene
Project description:Nitrification, the oxidation of ammonia via nitrite to nitrate, has always been considered to be a two-step process catalysed by chemolithoautotrophic microorganisms oxidizing either ammonia or nitrite. No known nitrifier carries out both steps, although complete nitrification should be energetically advantageous. This functional separation has puzzled microbiologists for a century. Here we report on the discovery and cultivation of a completely nitrifying bacterium from the genus Nitrospira, a globally distributed group of nitrite oxidizers. The genome of this chemolithoautotrophic organism encodes the pathways both for ammonia and nitrite oxidation, which are concomitantly activated during growth by ammonia oxidation to nitrate. Genes affiliated with the phylogenetically distinct ammonia monooxygenase and hydroxylamine dehydrogenase genes of Nitrospira are present in many environments and were retrieved on Nitrospira contigs in new metagenomes from engineered systems. These findings fundamentally change our picture of nitrification and point to completely nitrifying Nitrospira as key components of nitrogen-cycling microbial communities.
2019-03-15 | PXD013103 | Pride
Project description:Microbial community diversity of the enriched culture