Meganema perideroedes

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Description and Significance

Genome Structure

Cell Structure, Metabolism and Life Cycle





Domain: Bacteria

Phylum: Proteobacteria

Class: Alphaproteobacteria

Order: Rhizobiales

Family: Methylobacteriaceae

Species: Meganema

Description and significance

Filamentous bacteria in the class Alphaproteobacteria, identified in sludge from an industrial wastewater treatment plant. Phylogenetic analysis of the 16S rRNA showed that the strain forms a monophyletic cluster with five strains in the same Alphaproteobacteria class. However, Meganema perideroedes is phenotypically different from its closest relative, filamentous bacteria Brevundimonas vesicularis. The optimum temperature of growth is 30 degrees celcius with a salinity of 2% NaCl. Meganema perideroedes was studied in depth because its filamentous morphology, Nostocoida limicola Type II, often causes bulking problems in activated sludge wastewater treatment plants. In order to find efficient control methods, knowledge of the physiology and ecology of the bacteria is important.

Genome Structure

The size of the bacteria in megabase pairs or (Mb) is 3.41. The guanine and cytosine percentage is GC% 67.2. - 42.9 mol% of G+C content- specific strain Number of Genes 3,134 Number of Proteins 3,084 Total Sequence Length 3,409,949 Number of Scaffold 17 Number of Chromosomes 0 Number of plasmids 0 Entire genome has been sequenced

Cell Structure, Metabolism and Life Cycle

Cell Structure Characteristics

The cell structure appears to be bent/curled, occasionally tangled filaments that are not motile or branched. The filament length measures to be greater than 200 micrometers with the diameter being about 1.4-2.0 micrometers. The septa is visible but the sheath and any attached growth are absent. Cell shape varies from spherical, discoid or ovoid shaped. Other granules may be present but there is no sulfur storage. The cell is Gram negative and Neisser negative even though some cells would stain Gram positive.


Many of the isolates that have been observed of this bacteria are Gram negative bacteria. These bacteria are oxidase and catalase-positive and obligate aerobic. It has been observed that the bacteria under aerobic conditions consume acetate and glucose. They also have a high substrate uptake capability. Many filamentous bacteria have a high substrate affinity and this one follows that characteristic. Using MAR-FISH all substrates were offered and that main ones that were taken up were acetate, propionate, butyrate, oleic acid, and glucose. There was also an uptake of sugars and amino acids.

When nitrate is an electron acceptor cannot grow anaerobically.


Found in the sludge of industrial wastewater treatment plants. Five strains were isolated from the sludge and 16S rRNA analysis showed that the strains form a monophyletic cluster. Meganema perideroedes consumes acetate and glucose under aerobic conditions with an unusually high substrate uptake.


Known habitat is a mixture of activated sludges

Uptake of Substrates Under Aerobic Conditions

M. perideroedes Microcolonies in sludge flocs

Formate − +

Acetate ++ +

Propionate ++ ++

Butyrate + ++

Pyruvate − ++

Oleic acid ++ +

Glucose ++ ++

Galactose + ++

Mannose + +

Glycine + +

Leucine + ++

Ethanol − ++

Bicarbonate + thiosulfate − +

−: No silver grains (no substrate uptake). +: Few silver grains, but clearly positive. ++: Positive, many silver grains.

Uptake of Substrates Under Anaerobic Conditions

Table 2.  Uptake of organic substrates by M. perideroedes under conditions where nitrate or nitrite serve as electron acceptor and anaerobic conditions as investigated by MAR

  Nitrate Nitrite Anaerobic

  M. perideroedes Floca M. perideroedes Floca M. perideroedes Floca

Formate − + − + − +

Acetate + + + + − +

Propionate + + − + − +

Butyrate − + − + − +

Oleic acid − + − + − +

Glucose + + + + − +

Galactose + + − + − +

Mannose − + − + − +

Glycine − + − + − +

Leucine − ++ − ++ − +

−: No silver grains (no substrate uptake). +: Few silver grains, but clearly positive. ++: Positive, many silver grains.

aMicrocolonies in sludge flocs.


Kragelund, C., Nielsen, J. L., Thomsen, T. R. and Nielsen, P. H. (2005), Ecophysiology of the filamentous Alphaproteobacterium Meganema perideroedes in activated sludge. FEMS Microbiology Ecology, 54: 111–112. doi: 10.1016/j.femsec.2005.03.002

Thomsen, T. R.. "Meganema perideroedes gen. nov., sp. nov., a filamentous alphaproteobacterium from activated sludge." International Journal of Systematic and Evolutionary Microbiology (): 1865-1868. Print.


David Bur

Danielle Stawkey