Related Experiment Video
Updated: Aug 7, 2026
15:19
Development of Sulfidogenic Sludge from Marine Sediments and Trichloroethylene Reduction in an Upflow Anaerobic Sludge Blanket Reactor
Published on: October 15, 2015
Comamonas denitrificans sp. nov., an efficient denitrifying bacterium isolated from activated sludge
L Gumaelius1, G Magnusson, B Pettersson
1Department of Biotechnology, Royal Institute of Technology, Stockholm, Sweden.
Summary
Researchers identified novel denitrifying bacteria from wastewater, proposing a new species, Comamonas denitrificans, for efficient biological nutrient removal in activated sludge treatment.
Area of Science:
- Environmental Microbiology
- Wastewater Treatment Technologies
- Bacterial Taxonomy
Background:
- Denitrification is crucial for removing nitrogen from wastewater.
- Identifying efficient denitrifying bacteria is key to optimizing activated sludge processes.
- Biomarkers for effective denitrification are needed to monitor treatment efficacy.
Purpose of the Study:
- To isolate and characterize highly efficient denitrifying bacteria from activated sludge.
- To determine the taxonomic position of these novel isolates.
- To propose a new species for strains exhibiting superior denitrifying capabilities.
Main Methods:
- Isolation and screening of 1,500 bacterial strains from wastewater treatment plants.
- Characterization of denitrifying activity, including speed and lag phase.
- Analysis of nitrite reductase type (cd1-type).
- 16S ribosomal DNA (rDNA) sequencing and phylogenetic analysis.
- Determination of phenotypic characteristics like colony morphology and growth patterns.
Main Results:
- Five high-performing denitrifying strains were isolated, showing rapid denitrification without a lag phase.
- All selected strains possessed the cd1-type nitrite reductase and were Gram-negative rods.
- Phylogenetic analysis based on 16S rDNA sequences placed these strains within the genus Comamonas.
- Four strains (110, 123T, 2.99g, P17) showed high similarity (>99.7%) to each other, distinct from known strains (<96.7%).
- Strain 123T was designated as the type strain for the proposed new species, Comamonas denitrificans sp. nov.
Conclusions:
- A new species, Comamonas denitrificans, is proposed for four highly similar, efficient denitrifying strains.
- These bacteria hold potential as biomarkers and key players in enhanced biological nutrient removal in wastewater treatment.
- Further taxonomic investigation is required for strain 5.38g due to phenotypic differences.
More Related Videos
Related Concept Videos
01:30Environmental Applications of Microorganisms
Microorganisms play a pivotal role in maintaining ecosystem balance by recycling essential elements such as carbon, nitrogen, and phosphorus, as well as supporting processes like bioremediation, wastewater treatment, and biofuel production.Microbes in Elemental CyclesIn the carbon cycle, microorganisms decompose organic matter, releasing carbon dioxide via aerobic respiration. This carbon dioxide is subsequently used by photosynthetic organisms to synthesize organic compounds, closing the...
01:15Metabolism of Chemolithotrophs
Chemolithotrophs are microorganisms that obtain energy by oxidizing inorganic molecules such as hydrogen gas (H₂), ammonia (NH₃), reduced sulfur compounds (H₂S, S²⁻), and ferrous iron (Fe²⁺). Unlike heterotrophic organisms that rely on organic carbon, chemolithotrophs transfer electrons from these inorganic donors to the electron transport chain (ETC), generating a proton motive force (PMF) that drives ATP synthesis through oxidative phosphorylation. However, because inorganic electron donors...
01:22Inorganic Nitrogen Assimilation
Nitrogen is an essential element in biological systems, forming a crucial component of proteins, nucleic acids, and other cellular constituents. Many bacteria and archaea acquire nitrogen in the form of nitrate (NO₃⁻) or ammonia (NH₃), which are then assimilated into biomolecules through specific enzymatic pathways.Assimilatory Nitrate ReductionWhen nitrate enters the cell, it undergoes a two-step reduction process known as assimilatory nitrate reduction. Initially, the enzyme nitrate reductase...
01:26Bacterial Phylum Proteobacteria
Proteobacteria, one of the largest and most diverse bacterial phyla, encompasses a wide range of Gram-negative bacteria distinguished by their outer membrane composed of lipopolysaccharides. These microorganisms exhibit various metabolic capabilities, including phototrophy, chemolithotrophy, and heterotrophy, and thrive in diverse environments from soil to aquatic systems and host-associated niches. The phylum is divided into six classes: Alphaproteobacteria, Betaproteobacteria,...
01:26Microbes and the Nitrogen Cycle
The nitrogen cycle is a complex biogeochemical process critical to maintaining the balance of nitrogenous compounds in ecosystems. This cycle involves multiple microbial-mediated transformations through which nitrogen changes oxidation states, supporting essential ecological functions and contributing to plant and microbial growth.Nitrogen Fixation and AmmonificationNitrogen fixation initiates the cycle by converting inert atmospheric nitrogen (N₂) into bioavailable ammonia (NH₃), a process...
01:18Deep Sea Microbial Ecology
The deep ocean and its underlying sediments represent vast, largely unexplored microbial habitats that extend far beyond the sunlit photic zone. The photic (euphotic) zone typically spans the upper ~100–200 meters of pelagic waters in the open ocean, but its depth varies geographically and seasonally, where sufficient light supports photosynthetic life. Below this lies the deep sea, spanning roughly 1000–6000 meters (bathypelagic to abyssal zones), with deeper hadal trenches extending beyond...