''Sphaerotilus natans'' is an aquatic
periphyton
Periphyton is a complex mixture of algae, cyanobacteria, heterotrophic microbes, and detritus that is attached to submerged surfaces in most aquatic ecosystems. The related term Aufwuchs (German "surface growth" or "overgrowth") refers to the col ...
organism associated with polluted water. It forms colonies commonly known as "sewage fungus", but later identified as tightly sheathed filamentous
bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...
.
Morphology
Straight or smoothly curved filaments 1.5 µm in diameter and 100 to more than 500 µm in length are formed by rod-shaped cells with clear
septa
The Southeastern Pennsylvania Transportation Authority (SEPTA) is a regional public transportation authority that operates bus, rapid transit, commuter rail, light rail, and electric trolleybus services for nearly 4 million people in five coun ...
growing within a long, tubular sheath. An adhesive basal element at one end of the filament can aid attachment to solid surfaces.
The sheath offers some protection from predators, and the ability to anchor in flowing water allows access to a passing stream of food and nutrients.
Individual mature cells swarm out of the protective tube to colonize new sites.
[Hammer p.55] Each motile mature cell has an intertwined bundle of
flagella
A flagellum (; ) is a hairlike appendage that protrudes from certain plant and animal sperm cells, and from a wide range of microorganisms to provide motility. Many protists with flagella are termed as flagellates.
A microorganism may have f ...
appearing as a single flagellum consisting of a long filament with a short hook and a basal body complex, but it is distinguishable by
electron microscope
An electron microscope is a microscope that uses a beam of accelerated electrons as a source of illumination. As the wavelength of an electron can be up to 100,000 times shorter than that of visible light photons, electron microscopes have a hi ...
as 10 to 30 strands with diameters of 12.5 to 16 nm each. ''S. natans'' stores reserves of
poly- ''beta'' -hydroxybutyrate as internal globules making up 30 to 40% of the dry weight of a colony.
Gram and Neisser staining reactions are negative.
Habitat
''S. natans'' requires dissolved simple
sugar
Sugar is the generic name for sweet-tasting, soluble carbohydrates, many of which are used in food. Simple sugars, also called monosaccharides, include glucose, fructose, and galactose. Compound sugars, also called disaccharides or double ...
s or
organic acid
An organic acid is an organic compound with acidic properties. The most common organic acids are the carboxylic acids, whose acidity is associated with their carboxyl group –COOH. Sulfonic acids, containing the group –SO2OH, are rel ...
s as a food supply, but needs less
phosphorus
Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ear ...
than many competing organisms and can tolerate low
oxygen
Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...
concentrations.
Capability to deposit elemental
sulfur
Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...
intracellularly in the presence of
hydrogen sulfide
Hydrogen sulfide is a chemical compound with the formula . It is a colorless chalcogen-hydride gas, and is poisonous, corrosive, and flammable, with trace amounts in ambient atmosphere having a characteristic foul odor of rotten eggs. The unde ...
is believed to be a detoxifying mechanism. ''S. natans'' requires either
cobalamin
Vitamin B12, also known as cobalamin, is a water-soluble vitamin involved in metabolism. It is one of eight B vitamins. It is required by animals, which use it as a cofactor in DNA synthesis, in both fatty acid and amino acid metabolism. It ...
or
methionine
Methionine (symbol Met or M) () is an essential amino acid in humans. As the precursor of other amino acids such as cysteine and taurine, versatile compounds such as SAM-e, and the important antioxidant glutathione, methionine plays a critical ro ...
as a trace nutrient.
''S. natans'' filaments can aid development of a periphyton
biofilm
A biofilm comprises any syntrophic consortium of microorganisms in which cells stick to each other and often also to a surface. These adherent cells become embedded within a slimy extracellular matrix that is composed of extracellular ...
trapping suspended particles and stabilizing colonies of other organisms including ''
Klebsiella
''Klebsiella'' is a genus of Gram-negative, oxidase-negative, rod-shaped bacteria with a prominent polysaccharide-based capsule.
''Klebsiella'' species are found everywhere in nature. This is thought to be due to distinct sublineages developin ...
'' and ''
Pseudomonas
''Pseudomonas'' is a genus of Gram-negative, Gammaproteobacteria, belonging to the family Pseudomonadaceae and containing 191 described species. The members of the genus demonstrate a great deal of metabolic diversity and consequently are able ...
''.
Significance
''Sphaerotilus natans'' is often associated with a buoyant floc (or "bulking sludge") causing poor solids separation in
activated sludge
The activated sludge process is a type of biological wastewater treatment process for treating sewage or industrial wastewaters using aeration and a biological floc composed of bacteria and protozoa. It uses air (or oxygen) and microorganisms ...
clarifier
Clarifiers are settling tanks built with mechanical means for continuous removal of solids being deposited by sedimentation. A clarifier is generally used to remove solid particulates or suspended solids from liquid for clarification and/or thi ...
s of
secondary sewage treatment.
Metal surfaces covered with ''S. natans'' may experience accelerated
corrosion
Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engine ...
if the slime creates a barrier causing differential oxygen concentrations.
[Betz pp.288&289] ''S. natans'' slimes may reduce quality of paper produced by
paper mill
A paper mill is a factory devoted to making paper from vegetable fibres such as wood pulp, old rags, and other ingredients. Prior to the invention and adoption of the Fourdrinier machine and other types of paper machine that use an endless belt, ...
s using recycled water streams.
References
Further reading
* Betz Laboratories ''Handbook of Industrial Water Conditioning'' (7th Edition) Betz Laboratories (1976)
* Fair, Gordon Maskew, Geyer, John Charles & Okun, Daniel Alexander ''Water and Wastewater Engineering'' (Volume 2) John Wiley & Sons (1968)
* Hammer, Mark J. ''Water and Waste-Water Technology'' John Wiley & Sons (1975)
External links
Type strain of ''Sphaerotilus natans'' at Bac''Dive'' - the Bacterial Diversity Metadatabase
{{Taxonbar, from=Q290696
Aquatic ecology
Gram-negative bacteria
Comamonadaceae
Water pollution