Sewage fungus

Last updated
A photo of sewage fungus found in the River Crane (London, England) Sewage fungus (River Crane, England, UK).jpg
A photo of sewage fungus found in the River Crane (London, England)

Sewage fungus [1] (also known as undesirable river biofilms, URBs) is a polymicrobial biofilm (a microbial mat) that proliferates in saprobic rivers [2] and has been frequently used as a bioindicator [3] [4] of organic river pollution for the past century. [5] Its presence has been strongly associated with discharges of untreated or inadequately treated sewage, [6] [7] [8] [9] yet its presence extends beyond these areas, with contributors including airport de-ice fluid runoff, [10] [11] [12] papermill effluents, [13] and agricultural runoff. [14] [15]

Contents

The name "sewage fungus" is somewhat of a misnomer, [5] as these growths are not primarily fungal in nature. Instead, they are complex polymicrobial mats bound within a matrix of extracellular polymeric substances. The bacterial taxa most frequently associated with this phenomenon include Sphaerotilus natans , Zoogloea spp., Beggiatoa spp., and Rhodoferax spp. [11] [16] [17]

Environmental Impacts

In addition to being a bioindicator of organic pollution in rivers and playing a vital role utilizing excess organic carbon in fluvial systems, sewage fungus causes significant ecological impacts through direct and indirect ecological pathways.

Sewage fungus thrives in the low dissolved oxygen (DO) environment of an organically polluted river. [4] [17] [18] [19] Whilst DO is required for sewage fungus growth, it readily outcompetes other benthic organisms at low DO, [20] [21] [22] quickly smothering riverbeds, greatly altering the benthic habitat for invertebrates [23] [24] and fish spawning. [2] [25] [26] The dominating growth of sewage fungus also reduces hyporheic exchange flows, an important part of a rivers self-cleaning system. [27] [28] Similar river biofilms are also reported to accumulate heavy metals [29] [30] and other toxic substances. [31] within their matrix causing ecological impacts throughout the food web. [32] [33] As a heterotroph, sewage fungus uses considerably higher DO than an aquatic macrophyte of the same mass, [34] it can maintain DO concentrations below thresholds required for other organisms. Once sewage fungus becomes established, it is difficult to remove, [35] unless all sources of organic nutrients (pollution) are addressed, causing a further loss in biodiversity [36] and other flora and fauna [37] [38] in the river. These ecological impacts and the striking visible presence of sewage fungus growth on a riverbed further affects people's perceptions and use of rivers. [7] [39]

Microbial composition

Sewage fungus is a type of microbial mat, the specific composition of which is affected by the available nutrients (especially organic carbon sources) and the environmental drivers of each unique occurrence. However, several key taxa are reported as highly frequent and dominant within sewage fungus.

Sphaerotilus natans , has been strongly associated with this phenomenon since it was first studied [5] and continues to be regarded as a key sewage fungus organism. [11] [12] Consequently, Sphaerotilus has been used seemingly synonymously with sewage fungus and a series of laboratory studies use S. natans as sewage fungus. [25] [40] [41]

Other key taxa include the bacteria Zoogloea spp., Beggiatoa spp., Thiothrix spp., Flavobacterium spp. , and Flexibacter spp. . [16] [17] However, fungi (e.g., Leptomitus lacteus, Geotrichum candidum , and Fusarium aquaeductuum), algae (e.g., Cladophora glomerata) along with archaea and protozoa (e.g., Carchesium polypinum) also form integral and important pasts of the biofilm.

Recent genomic studies of sewage fungus composition have identified some of these taxa within airport de-icer implicated occurrences but have also identified new taxa not previously associated with sewage fungus: Rhodoferax as a dominant component of sewage fungus, [11] and the presence of Thiothrix. [12]

Drivers of sewage fungus

Alongside the complex nutrient utilisation requirements of sewage fungus, there are several key environmental drivers including substrate type, flow velocity, temperature, shading/sunlight, and water chemistry (e.g. pH).

Flowing water is a requirement for sewage fungus growth, to provide a constant replenishment of nutrients. [2] [4] [42] However, if the velocity of the river is too fast, then growths are scoured away, especially on more readily mobilised substrates. In turn, the specific flow of the river shapes the morphotype and structure of the biofilm. [43] Intrinsically the substrate affects the upper limit of flow as more stable riverbeds are less readily mobilised in periods of higher flows. Surfaces such as large cobbles, anthropogenic litter (e.g., bricks), and concrete channels facilitate excellent sewage fungus growth, whereas fine sediments and gravel provide a less stable substrate.

Related Research Articles

<span class="mw-page-title-main">Biofilm</span> Aggregation of bacteria or cells on a surface

A biofilm is a syntrophic community 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 polymeric substances (EPSs). The cells within the biofilm produce the EPS components, which are typically a polymeric combination of extracellular polysaccharides, proteins, lipids and DNA. Because they have a three-dimensional structure and represent a community lifestyle for microorganisms, they have been metaphorically described as "cities for microbes".

<span class="mw-page-title-main">Mycelium</span> Vegetative part of a fungus

Mycelium is a root-like structure of a fungus consisting of a mass of branching, thread-like hyphae. Its normal form is that of branched, slender, entangled, anastomosing, hyaline threads. Fungal colonies composed of mycelium are found in and on soil and many other substrates. A typical single spore germinates into a monokaryotic mycelium, which cannot reproduce sexually; when two compatible monokaryotic mycelia join and form a dikaryotic mycelium, that mycelium may form fruiting bodies such as mushrooms. A mycelium may be minute, forming a colony that is too small to see, or may grow to span thousands of acres as in Armillaria.

<span class="mw-page-title-main">Water pollution</span> Contamination of water bodies

Water pollution is the contamination of water bodies, with a negative impact on their uses. It is usually a result of human activities. Water bodies include lakes, rivers, oceans, aquifers, reservoirs and groundwater. Water pollution results when contaminants mix with these water bodies. Contaminants can come from one of four main sources. These are sewage discharges, industrial activities, agricultural activities, and urban runoff including stormwater. Water pollution may affect either surface water or groundwater. This form of pollution can lead to many problems. One is the degradation of aquatic ecosystems. Another is spreading water-borne diseases when people use polluted water for drinking or irrigation. Water pollution also reduces the ecosystem services such as drinking water provided by the water resource.

<span class="mw-page-title-main">Biofilter</span> Pollution control technique

Biofiltration is a pollution control technique using a bioreactor containing living material to capture and biologically degrade pollutants. Common uses include processing waste water, capturing harmful chemicals or silt from surface runoff, and microbiotic oxidation of contaminants in air. Industrial biofiltration can be classified as the process of utilizing biological oxidation to remove volatile organic compounds, odors, and hydrocarbons.

<i>Geobacter</i> Genus of anaerobic bacteria found in soil

Geobacter is a genus of bacteria. Geobacter species are anaerobic respiration bacterial species which have capabilities that make them useful in bioremediation. Geobacter was found to be the first organism with the ability to oxidize organic compounds and metals, including iron, radioactive metals, and petroleum compounds into environmentally benign carbon dioxide while using iron oxide or other available metals as electron acceptors. Geobacter species are also found to be able to respire upon a graphite electrode. They have been found in anaerobic conditions in soils and aquatic sediment.

Microbial intelligence is the intelligence shown by microorganisms. The concept encompasses complex adaptive behavior shown by single cells, and altruistic or cooperative behavior in populations of like or unlike cells mediated by chemical signalling that induces physiological or behavioral changes in cells and influences colony structures.

<span class="mw-page-title-main">Polyphosphate-accumulating organisms</span>

Polyphosphate-accumulating organisms (PAOs) are a group of microorganisms that, under certain conditions, facilitate the removal of large amounts of phosphorus from their environments. The most studied example of this phenomenon is in polyphosphate-accumulating bacteria (PAB) found in a type of wastewater processing known as enhanced biological phosphorus removal (EBPR), however phosphate hyperaccumulation has been found to occur in other conditions such as soil and marine environments, as well as in non-bacterial organisms such as fungi and algae. PAOs accomplish this removal of phosphate by accumulating it within their cells as polyphosphate. PAOs are by no means the only microbes that can accumulate phosphate within their cells and in fact, the production of polyphosphate is a widespread ability among microbes. However, PAOs have many characteristics that other organisms that accumulate polyphosphate do not have that make them amenable to use in wastewater treatment. Specifically, in the case of classical PAOs, is the ability to consume simple carbon compounds without the presence of an external electron acceptor by generating energy from internally stored polyphosphate and glycogen. Many bacteria cannot consume carbon without an energetically favorable electron acceptor and therefore PAOs gain a selective advantage within the mixed microbial community present in the activated sludge. Therefore, wastewater treatment plants that operate for enhanced biological phosphorus removal have an anaerobic tank prior to the other tanks to give PAOs preferential access to the simple carbon compounds in the wastewater that is influent to the plant.

<span class="mw-page-title-main">First flush</span> Initial surface runoff of a rainstorm

First flush is the initial surface runoff of a rainstorm. During this phase, water pollution entering storm drains in areas with high proportions of impervious surfaces is typically more concentrated compared to the remainder of the storm. Consequently, these high concentrations of urban runoff result in high levels of pollutants discharged from storm sewers to surface waters.

<span class="mw-page-title-main">Aerobic granular reactor</span>

Aerobic granular reactors (AGR) or Aerobic granular sludge (AGS) are a community of microbial organisms, typically around 0.5-3mm in diameter, that remove carbon, nitrogen, phosphorus and other pollutants in a single sludge system. It can also be used for wastewater treatments. Aerobic granular sludge is composed of bacteria, protozoa and fungi, which allows oxygen to follow in and biologically oxidize organic pollutants. AGS is a type of wastewater treatment process for sewages and/or industrial waste treatment. AGR was first discovered by UK engineers, Edward Ardern and W.T. Lockett who were researching better ways for sewage disposal. Another scientist by the name of Dr. Gilbert Fowler, who was at the University of Manchester working on an experiment based on aeration of sewage in a bottle coated with algae. Eventually, all three scientists were able to collaborate with one another to discover AGR/AGS.

<span class="mw-page-title-main">Flavobacteriia</span> Class of bacteria

The class Flavobacteriia is composed of a single class of environmental bacteria. It contains the family Flavobacteriaceae, which is the largest family in the phylum Bacteroidota. This class is widely distributed in soil, fresh, and seawater habitats. The name is often spelt Flavobacteria, but was officially named Flavobacteriia in 2012.

<i>Pepper mild mottle virus</i> Species of virus

Pepper mild mottle virus (PMMoV) is a plant pathogenic virus that occurs worldwide on species of field grown bell, hot and ornamental pepper species. It is caused by members of the plant virus genus Tobamovirus—otherwise known as the tobacco mosaic virus family. Tobamovirus are viruses that contain positive sense RNA genomes that infect plants. Symptoms of the disease vary depending on the cultivar. Typical symptoms include the chlorosis of leaves, stunting, and distorted and lumpy fruiting structures. The virus is spread by mechanical transmission and infected seeds. Avoidance is the best means of controlling the disease because once a plant is infected it cannot be treated. Only seeds that have been tested and treated for the pathogen should be planted.

<span class="mw-page-title-main">Extracellular polymeric substance</span> Gluey polymers secreted by microorganisms to form biofilms

Extracellular polymeric substances (EPSs) are natural polymers of high molecular weight secreted by microorganisms into their environment. EPSs establish the functional and structural integrity of biofilms, and are considered the fundamental component that determines the physicochemical properties of a biofilm. EPS in the matrix of biofilms provides compositional support and protection of microbial communities from the harsh environments. Components of EPS can be of different classes of polysaccharides, lipids, nucleic acids, proteins, lipopolysaccharides, and minerals.

<i>Thioploca</i> Genus of bacteria

Thioploca is a genus of filamentous sulphur-oxidizing bacteria, in the order Thiotrichales. They inhabit both marine and freshwater environments, forming vast communities off the Pacific coast of South America and in other areas with a high organic matter sedimentation and bottom waters rich in nitrate and poor in oxygen. Their cells contain large vacuoles that occupy more than 80% of the cellular volume, used to store nitrate to oxidize sulphur for anaerobic respiration in the absence of oxygen, an important characteristic of the genus. With cell diameters ranging from 15-40 μm, they are some of the largest bacteria known. They provide an important link between the nitrogen and sulphur cycles, because they use both sulfur and nitrogen compounds. They secrete a sheath of mucus which they use as a tunnel to travel between sulphide-containing sediment and nitrate-containing sea water.

<i>Sphaerotilus natans</i> Species of bacterium

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"

<span class="mw-page-title-main">Plastisphere</span> Plastic debris suspended in water and organisms which live in it

The plastisphere is a human-made ecosystem consisting of organisms able to live on plastic waste. Plastic marine debris, most notably microplastics, accumulates in aquatic environments and serves as a habitat for various types of microorganisms, including bacteria and fungi. As of 2022, an estimated 51 trillion microplastics are floating in the surface water of the world's oceans. A single 5mm piece of plastic can host 1,000s of different microbial species. Some marine bacteria can break down plastic polymers and use the carbon as a source of energy.

Comammox is the name attributed to an organism that can convert ammonia into nitrite and then into nitrate through the process of nitrification. Nitrification has traditionally been thought to be a two-step process, where ammonia-oxidizing bacteria and archaea oxidize ammonia to nitrite and then nitrite-oxidizing bacteria convert to nitrate. Complete conversion of ammonia into nitrate by a single microorganism was first predicted in 2006. In 2015 the presence of microorganisms that could carry out both conversion processes was discovered within the genus Nitrospira, and the nitrogen cycle was updated. Within the genus Nitrospira, the major ecosystems comammox are primarily found in natural aquifers and engineered ecosystems.

<span class="mw-page-title-main">Moving bed biofilm reactor</span> Type of wastewater treatment

Moving bed biofilm reactor (MBBR) is a type of wastewater treatment process that was first invented by Professor Hallvard Ødegaard at Norwegian University of Science and Technology in the late 1980s. The process takes place in an aeration tank with plastic carriers that a biofilm can grow on. The compact size and cheap wastewater treatment costs offers many advantages for the system. The main objective of using MBBR being water reuse and nutrient removal or recovery. In theory, wastewater will be no longer considered waste, it can be considered a resource.

Bioclogging or biological clogging refers to the blockage of pore space in soil by microbial biomass, including active cells and their byproducts such as extracellular polymeric substance (EPS). The microbial biomass obstructs pore spaces, creating an impermeable layer in the soil and significantly reducing water infiltration rates.

Jennifer Lee Stauber is an Australian ecotoxicologist and chief research scientist at the CSIRO Land and Water.

<span class="mw-page-title-main">Phytobenthos</span>

Phytobenthos (from Greek φυτόν and βένθος are autotrophic organisms found attached to bottom surfaces aquatic environments, such as rocks, sediments, or even other organisms. This photosynthetic community includes single-celled or filamentous cyanobacteria, microalgae, and macrophytes. Phytobenthos are highly diverse, and can be found in freshwater and marine environments, as well as transitional water systems. However, their distribution and availability still depend on the factors and stressors that exist in the environment. Because phytobenthos are autotrophs, they need to be able to subsist where it is still possible to perform photosynthesis. Similar to phytoplankton, phytobenthos contribute to the aquatic food web for grazers and heterotrophic bacteria, and researchers have also been studying their health as an indicator for water quality and environmental integrity of aquatic ecosystems.

References

  1. Exton, Ben; Hassard, Francis; Medina-Vaya, Angel; Grabowski, Robert C. (April 2024). "Undesirable river biofilms: The composition, environmental drivers, and occurrence of sewage fungus". Ecological Indicators. 161: 111949. doi: 10.1016/j.ecolind.2024.111949 . ISSN   1470-160X.
  2. 1 2 3 Curtis, E.J.C. (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.
  3. "Freshwater Biology and Ecology Handbook". Foundation for Water Research. Retrieved 2022-08-15.
  4. 1 2 3 Quinn, McFarlane (1985). "Sewage fungus as a monitor of water quality". Biological Monitoring in Freshwaters: Proceedings of a Seminar.
  5. 1 2 3 Butcher, R.W. (August 1932). "Contribution to our knowledge of the ecology of sewage fungus". Transactions of the British Mycological Society. 17 (1–2): 112–IN4. doi:10.1016/S0007-1536(32)80029-X.
  6. Chonova, Teofana; Labanowski, Jérôme; Cournoyer, Benoit; Chardon, Cécile; Keck, François; Laurent, Élodie; Mondamert, Leslie; Vasselon, Valentin; Wiest, Laure; Bouchez, Agnès (April 2018). "River biofilm community changes related to pharmaceutical loads emitted by a wastewater treatment plant". Environmental Science and Pollution Research. 25 (10): 9254–9264. doi:10.1007/s11356-017-0024-0. ISSN   0944-1344. PMID   28884270. S2CID   3997467.
  7. 1 2 Curtis, E.J.C.; Harrington, D.W. (June 1971). "The occurrence of sewage fungus in rivers in the United Kingdom". Water Research. 5 (6): 281–290. Bibcode:1971WatRe...5..281C. doi:10.1016/0043-1354(71)90173-4.
  8. Harrison, Heukelekian (1958). "Slime Infestation: Literature Review". Sewage and Industrial Wastes. 30 (10): 1278–1302. JSTOR   25033719 via JSTOR.
  9. Hammond, Peter; Suttie, Michael; Lewis, Vaughan T.; Smith, Ashley P.; Singer, Andrew C. (2021-03-11). "Detection of untreated sewage discharges to watercourses using machine learning". npj Clean Water. 4 (1). doi: 10.1038/s41545-021-00108-3 . ISSN   2059-7037. S2CID   232173162.
  10. Mericas, Dean; Sturman, Paul; Lutz, Michelle; Corsi, Steve; Cieciek, Chris; Boltz, Josh; Morgenroth, Eberhard; Airport Cooperative Research Program; Transportation Research Board (2014-11-03). Understanding Microbial Biofilms in Receiving Waters Impacted by Airport Deicing Activities. Washington, D.C.: Transportation Research Board. doi:10.17226/22262. ISBN   978-0-309-30809-0.
  11. 1 2 3 4 Exton, Benjamin; Hassard, Francis; Medina Vaya, Angel; Grabowski, Robert C. (2023-03-01). "Polybacterial shift in benthic river biofilms attributed to organic pollution – a prospect of a new biosentinel?". Hydrology Research. 54 (3): 348–359. doi: 10.2166/nh.2023.114 . ISSN   0029-1277. S2CID   257347315.
  12. 1 2 3 Nott, Michelle A.; Driscoll, Heather E.; Takeda, Minoru; Vangala, Mahesh; Corsi, Steven R.; Tighe, Scott W. (2020-01-22). Loiselle, Steven Arthur (ed.). "Advanced biofilm analysis in streams receiving organic deicer runoff". PLOS ONE. 15 (1): e0227567. Bibcode:2020PLoSO..1527567N. doi: 10.1371/journal.pone.0227567 . ISSN   1932-6203. PMC   6975536 . PMID   31968006.
  13. Roberts, J.C. (1978). "Sewage fungus growth in rivers below papermill discharges". New Processes for Wastewater Treatment and Recovery: 140–158.
  14. Rutt, G.P.; Pickering, T.D.; Reynolds, N.R.M. (1993). "The impact of livestock-farming on welsh streams: The development and testing of a rapid biological method for use in the assessment and control of organic pollution from farms". Environmental Pollution. 81 (3): 217–228. doi:10.1016/0269-7491(93)90205-3. PMID   15091808.
  15. Seager, J.; Jones, F.; Rutt, G. (February 1992). "Assessment and Control of Farm Pollution". Water and Environment Journal. 6 (1): 48–53. doi:10.1111/j.1747-6593.1992.tb00737.x. ISSN   1747-6585.
  16. 1 2 Geatches, Gething, Rutt (2014). 'Sewage fungus': A field and microscopic guide. Environment Agency and Natural Resources Wales.{{cite book}}: CS1 maint: multiple names: authors list (link)
  17. 1 2 3 Curtis, E.J.C.; Curds, C.R. (December 1971). "Sewage fungus in rivers in the United Kingdom: The slime community and its constituent organisms". Water Research. 5 (12): 1147–1159. Bibcode:1971WatRe...5.1147C. doi:10.1016/0043-1354(71)90080-7.
  18. Gray, N.F.; Hunter, Christine A. (January 1985). "Heterotrophic slimes in Irish rivers". Water Research. 19 (6): 685–691. doi:10.1016/0043-1354(85)90113-7.
  19. Hickey, Christopher W. (November 1988). "River oxygen uptake and respiratory decay of sewage fungus biofilms". Water Research. 22 (11): 1375–1380. Bibcode:1988WatRe..22.1375H. doi:10.1016/0043-1354(88)90093-0.
  20. Adeola, Samuel; Revitt, Michael; Shutes, Brian; Garelick, Hemda; Jones, Huw; Jones, Clive (2009-01-12). "Constructed Wetland Control of BOD Levels in Airport Runoff". International Journal of Phytoremediation. 11 (1): 1–10. doi:10.1080/15226510802363220. ISSN   1522-6514. S2CID   85164686.
  21. Turnbull, D.A.; Bevan, J.R. (1995). "The impact of airport de-icing on a river: The case of the Ouseburn, Newcastle upon Tyne". Environmental Pollution. 88 (3): 321–332. doi:10.1016/0269-7491(95)93446-7. PMID   15091545.
  22. United States Environmental Protection Agency (US EPA) (2000). "Preliminary Data Summary - Airport Deicing Operations (Revised)" (PDF).
  23. Hirsch (1958). "Biological evaluation of organic pollution of New Zealand streams". New Zealand Journal of Science. 1 (4): 500–553.
  24. Hynes (1960). The biology of polluted waters. Liverpool University Press.
  25. 1 2 Curtis, E.J.C.; Delves-Broughton, J.; Harrington, D.W. (June 1971). "Sewage fungus: studies of Sphaerotilus slimes using laboratory recirculating channels". Water Research. 5 (6): 267–279. Bibcode:1971WatRe...5..267C. doi:10.1016/0043-1354(71)90172-2.
  26. Smith, Lloyd L.; Kramer, Robert H. (July 1963). "Survival of Walleye Eggs in Relation to Wood Fibers and Sphaerotilus natans in the Rainy River, Minnesota". Transactions of the American Fisheries Society. 92 (3): 220–234. doi:10.1577/1548-8659(1963)92[220:SOWEIR]2.0.CO;2. ISSN   0002-8487.
  27. Magliozzi, Chiara; Grabowski, Robert C.; Packman, Aaron I.; Krause, Stefan (2018-11-30). "Toward a conceptual framework of hyporheic exchange across spatial scales". Hydrology and Earth System Sciences. 22 (12): 6163–6185. doi: 10.5194/hess-22-6163-2018 . ISSN   1607-7938.
  28. Lewandowski, Jörg; Arnon, Shai; Banks, Eddie; Batelaan, Okke; Betterle, Andrea; Broecker, Tabea; Coll, Claudia; Drummond, Jennifer; Gaona Garcia, Jaime; Galloway, Jason; Gomez-Velez, Jesus; Grabowski, Robert; Herzog, Skuyler; Hinkelmann, Reinhard; Höhne, Anja (2019-10-25). "Is the Hyporheic Zone Relevant beyond the Scientific Community?". Water. 11 (11): 2230. doi: 10.3390/w11112230 . hdl: 20.500.11850/382125 . ISSN   2073-4441.
  29. Decho, Alan W.; Visscher, Pieter T.; Reid, R. Pamela (2005), "Production and cycling of natural microbial exopolymers (EPS) within a marine stromatolite", Geobiology: Objectives, Concepts, Perspectives, Elsevier, pp. 71–86, doi:10.1016/b978-0-444-52019-7.50008-5, ISBN   978-0-444-52019-7 , retrieved 2023-10-10
  30. Flemming, Hans-Curt; Wingender, Jost (September 2010). "The biofilm matrix". Nature Reviews Microbiology. 8 (9): 623–633. doi:10.1038/nrmicro2415. ISSN   1740-1526. PMID   20676145. S2CID   28850938.
  31. Flemming, Hans-Curt; Wingender, Jost; Szewzyk, Ulrich; Steinberg, Peter; Rice, Scott A.; Kjelleberg, Staffan (September 2016). "Biofilms: an emergent form of bacterial life". Nature Reviews Microbiology. 14 (9): 563–575. doi:10.1038/nrmicro.2016.94. ISSN   1740-1526. PMID   27510863. S2CID   4384131.
  32. Friedman, Barry A.; Dugan, Patrick R. (May 1968). "Identification of Zoogloea species and the Relationship to Zoogloeal Matrix and Floc Formation". Journal of Bacteriology. 95 (5): 1903–1909. doi:10.1128/jb.95.5.1903-1909.1968. ISSN   0021-9193. PMC   252226 . PMID   5650090.
  33. Patrick, F; Loutit, M (1976). "Passage of metals in effluents, through bacteria to higher organisms". Water Research. 10 (4): 333–335. Bibcode:1976WatRe..10..333P. doi:10.1016/0043-1354(76)90176-7.
  34. Gray, N (1987). Sewage Fungus in Irish Rivers: A Guide to Identification, Evaluation and Control. Trinity College, University of Dublin.
  35. McKinney, Ross E. (2004-03-11). Environmental Pollution Control Microbiology (0 ed.). CRC Press. doi:10.1201/9780203025697. ISBN   978-1-135-52187-5.
  36. Hartwell, S. Ian; Jordahl, David M.; Evans, Joyce E.; May, Eric B. (August 1995). "Toxicity of aircraft de-icer and anti-icer solutions to aquatic organisms". Environmental Toxicology and Chemistry. 14 (8): 1375–1386. doi:10.1002/etc.5620140813.
  37. Pillard, David A (February 1995). "Comparative toxicity of formulated glycol deicers and pure ethylene and propylene glycol to Ceriodaphnia dubia and Pimephales promelas". Environmental Toxicology and Chemistry. 14 (2): 311–315. doi:10.1002/etc.5620140217.
  38. Pillard, D. A.; DuFresne, D. L. (1999-07-01). "Toxicity of Formulated Glycol Deicers and Ethylene and Propylene Glycol to Lactuca sativa, Lolium perenne, Selenastrum capricornutum, and Lemna minor". Archives of Environmental Contamination and Toxicology. 37 (1): 29–35. doi:10.1007/s002449900486. ISSN   0090-4341. PMID   10341039. S2CID   12747431.
  39. Gray, N. F. (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. S2CID   83810613.
  40. Dias, FF; Dondero, NC; Finstein, MS (August 1968). "Attached Growth of Sphaerotilus and Mixed Populations in a Continuous-flow Apparatus". Applied Microbiology. 16 (8): 1191–99. doi:10.1128/am.16.8.1191-1199.1968. ISSN   0003-6919. PMC   547617 . PMID   4877499.
  41. Dias, FF; Heukelekian, H (September 1967). "Utilization of Inorganic Nitrogen Compounds by Sphaerotilus natans Growing in a Continuous-Flow Apparatus". Applied Microbiology. 15 (5): 1083–86. doi:10.1128/am.15.5.1083-1086.1967. ISSN   0003-6919. PMC   547145 . PMID   16349722.
  42. Phaup, JD (October 1968). "The biology of Sphaerotilus species". Water Research. 2 (9): 597–614. Bibcode:1968WatRe...2..597P. doi:10.1016/0043-1354(68)90065-1.
  43. Besemer, K; Singer, G; Limberger, R; Chlup, AK; Hochedlinger, G; Hödl, I; Baranyi, C; Battin, TJ (August 2007). "Biophysical Controls on Community Succession in Stream Biofilms". Applied and Environmental Microbiology. 73 (15): 4966–74. Bibcode:2007ApEnM..73.4966B. doi:10.1128/AEM.00588-07. ISSN   0099-2240. PMC   1951047 . PMID   17557861.