Sphaerotilus natans is an aquatic periphyton bacterial organism associated with polluted water. These tightly sheathed filamentous bacteria colonies are commonly but inaccurately known as "sewage fungus"[1]

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 growing within a long, tubular sheath. An adhesive basal element at one end of the filament can aid attachment to solid surfaces.[2] 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.[3] Individual mature cells swarm out of the protective tube to colonize new sites.[4] Each motile mature cell has an intertwined bundle of flagella 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 as 10 to 30 strands with diameters of 12.5 to 16 nm each. S. natans stores reserves of poly- beta -hydroxybutyrate as internal bioplastic globules making up 30 to 40% of the dry weight of a colony.[3] Gram and Neisser staining reactions are negative.[5]

Habitat

S. natans requires dissolved simple sugars or organic acids as a food supply, but needs less phosphorus than many competing organisms and can tolerate low oxygen concentrations.[5] Capability to deposit elemental sulfur intracellularly in the presence of hydrogen sulfide is believed to be a detoxifying mechanism. S. natans requires either cobalamin or methionine as a trace nutrient.[3] S. natans filaments can aid development of a periphyton biofilm trapping suspended particles and stabilizing colonies of other organisms including Klebsiella and Pseudomonas.[2]

S. natans is described as a key taxon in sewage fungus, a polymicrobial biofilm that proliferates in rivers with a high organic loading[6][7][8] such as from sewage discharges, industrial effluents or runoff from airport de-icing.[9] It is also implicated in active sludge bulking[10]

Significance

Sphaerotilus natans is often associated with a buoyant floc (or "bulking sludge") causing poor solids separation in activated sludge clarifiers of secondary sewage treatment.[4] Metal surfaces covered with S. natans may experience accelerated corrosion if the slime creates a barrier causing differential oxygen concentrations.[11] S. natans slimes may reduce quality of paper produced by paper mills that use recycled water.[2]

References

  1. ^ Fair, Geyer & Okun p.32-31
  2. ^ a b c Pellegrin, V; Juretschko, S; Wagner, M; Cottenceau, G (1999). "Morphological and Biochemical Properties of a Sphaerotilus sp. Isolated From Paper Mill Slimes". Applied and Environmental Microbiology. 65 (1): 156–62. Bibcode:1999ApEnM..65..156P. doi:10.1128/AEM.65.1.156-162.1999. PMC 90997. PMID 9872774.
  3. ^ a b c Van Veen, WL; Mulder, EG; Deinema, MH (1978). "The Sphaerotilus-Leptothrix group of bacteria". Microbiological Reviews. 42 (2): 329–56. doi:10.1128/MMBR.42.2.329-356.1978. PMC 281433. PMID 353479.
  4. ^ a b Hammer p.55
  5. ^ a b "Sphaerotilus natans". Environmental Business Specialists LLC. Retrieved 2012-09-26.
  6. ^ Exton, B; Hassard, F; Medina-Vaya, A; Grabowski, RC (April 2024). "Undesirable river biofilms: The composition, environmental drivers, and occurrence of sewage fungus". Ecological Indicators. 161: 111949. Bibcode:2024EcInd.16111949E. doi:10.1016/j.ecolind.2024.111949. ISSN 1470-160X.
  7. ^ Curtis, EJ (May 1969). "Sewage fungus: Its nature and effects". Water Research. 3 (5): 289–311. Bibcode:1969WatRe...3..289C. doi:10.1016/0043-1354(69)90084-0. ISSN 0043-1354.
  8. ^ Gray, NF (November 1985). "Heterotrophic Slimes in Flowing Waters". Biological Reviews. 60 (4): 499–548. doi:10.1111/j.1469-185X.1985.tb00621.x. ISSN 1464-7931.
  9. ^ Exton, B; Hassard, F; Medina-Vaya, A; Grabowski, RC (March 2023). "Polybacterial shift in benthic river biofilms attributed to organic pollution – a prospect of a new biosentinel?". Hydrology Research. 54 (3): 348–59. doi:10.2166/nh.2023.114 – via IWA Publishing.
  10. ^ Richard, M; Hao, O; Jenkins, D (1985). "Growth Kinetics of Sphaerotilus Species and Their Significance in Activated Sludge Bulking". Journal (Water Pollution Control Federation). 57 (1): 68–81. ISSN 0043-1303. JSTOR 25042522.
  11. ^ Betz pp.288&289

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) ISBN 0-471-34726-4
Allikas: https://en.wikipedia.org/wiki/Sphaerotilus
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