Sphaerotilus natans explained

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]

Further reading

External links

Notes and References

  1. Fair, Geyer & Okun p.32-31
  2. Pellegrin . V . Juretschko . S . Wagner . M . Cottenceau . G . 1999 . Morphological and Biochemical Properties of a Sphaerotilus sp. Isolated From Paper Mill Slimes . . 65 . 1 . 156–62 . 10.1128/AEM.65.1.156-162.1999 . 9872774 . 90997. 1999ApEnM..65..156P .
  3. The Sphaerotilus-Leptothrix group of bacteria. . 281433. 1978. Van Veen. WL. Mulder. EG. Deinema. MH . 42. 2. 329–56. 10.1128/MMBR.42.2.329-356.1978 . 353479.
  4. Hammer p.55
  5. Web site: Sphaerotilus natans. Environmental Business Specialists LLC. 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 . 10.1016/j.ecolind.2024.111949 . 1470-160X. free . 2024EcInd.16111949E .
  7. Curtis . EJ . May 1969 . Sewage fungus: Its nature and effects . Water Research . 3 . 5 . 289–311 . 10.1016/0043-1354(69)90084-0 . 1969WatRe...3..289C . 0043-1354.
  8. Gray . NF . November 1985 . Heterotrophic Slimes in Flowing Waters . Biological Reviews . 60 . 4 . 499–548 . 10.1111/j.1469-185X.1985.tb00621.x . 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 . 10.2166/nh.2023.114 . 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 . 25042522 . 0043-1303.
  11. Betz pp.288&289