Pu•biome

Sphaerotilus natans

Bacteria

Overview

Sphaerotilus natans is a Gram-negative, non-spore-forming, strictly aerobic, motile, filamentous bacterium. It has been detected in at least 2 gut microbiome compilation studies or metastudies. Sphaerotilus natans is likely to be transient and not a long-term gut coloniser. (Pellegrin1999; vanVeen1978)

This organism has been recovered from human faeces and sewage. The risk classification (www.baua.de) for this organism is 1, i.e., low risk of infection and spread. Pathogenicity status unknown, or very unlikely to be pathogenic. Likely to be transient and not a long-term gut commensal.

QUIRKS

Obligate aerobe; unlikely to be a gut coloniser.

GENERAL CHARACTERISTICS (Pellegrin1999); (vanVeen1978);

	Character	Response
🧂	Salt tolerance:	tolerates 0.2% salt;
pH	Acidity tolerance:	tolerates pH 6.5; tolerates pH 8.1; Grows optimally at pH 7.5.
🌡	Temperature tolerance:	grows at 15℃; grows at 40℃; Grows optimally at 30℃.
⥅	Substrates assimilated or utilised:	ethanol; fructose; gluconate; glucose; glycerol; inositol; maltose; methanol; ribose; sucrose; trehalose; butyrate; fumarate; glycerate; 3-hydroxybutyrate; lactate; malate; malonate; oxalate; propionate; pyruvate; quinate; succinate; butanol;
±	Strain-dependent substrate utilisation:	galactose; lactose; mannitol; rhamnose; sorbitol; xylose; acetate; citrate; D-tartrate;
	Active enzymes:	catalase;
±	Strain-dependent active enzymes:	arginine dihydrolase; β-galactosidase; oxidase;

SPECIAL FEATURES

	Character	Response
±	ONPG test:	strain dependent
±	Nitrate:	strain dependent
✗	Nitrite:	not reduced

NOTES

Sphaerotilus Natans

https://www.ebsbiowizard.com/resources/micro-gallery/#SphaerotilusNatans

Sphaerotilus natans, S. natans for short, is a type of filamentous bacteria found in many activated sludge processes and in aerated stabilization basins (ASBs). It is commonly found in systems where there is a low dissolved oxygen concentration, nutrient deficiency, especially phosphorus, and/or in the presence of soluble, readily-metabolizable substrates, like organic acids or simple sugars. It is also common in complete mix systems where the wastewater and biomass are completely mixed throughout the aeration basin.

S. natans should be identified by filamentous bacteria identification by trained personnel. By using activated sludge microscopic examination techniques, microbiologists will look for the following characteristics of this filament: straight or smoothly-curved trichomes that extend from the floc and resemble spaghetti, sausage-shaped rods or round-ended rods, clear cell septa, and a tight sheath. The filament length ranges from 100 to greater than 500 microns in length and around 1.5 microns in diameter. Because of the long length of these filaments, they can cause filamentous bridging of the floc or open floc structure. The filament is not motile and usually does not have attached growth unless is it not growing. If attached growth is present, it is not substantial. S. natans has Gram and Neisser negative staining reactions. It presents itself with false branching, where the filaments appear to be branched but are actually just lying very close together. In this case, there is no continuous flow of cytoplasm between the two filaments. While many filaments can metabolize sulfates and incorporate them as elemental sulfur in the cells, this filament does not contain sulfur granules.

S. natans can cause filamentous bulking sludge in industrial wastewater treatment plants that contain easily degradable materials, like sugars or organic acids. It can be temporarily controlled by chlorination of the filaments and concurrent wasting. However, the root cause for the bulking has to be corrected to prevent the filament from returning. During chlorination, empty sheaths or empty cells are observed within the filaments. Bulking episodes are identified by microscopic examination and settling analyses.

Details

GENERAL

Lineage	Physiology	General	Growth Tolerances	Hydrol./digest./degr.
Phylum: Proteobacteria Class: Betaproteobacteria Order: Burkholderiales Family: Burkholderiales genera incertae sedis Genus: Sphaerotilus	Gram stain: neg O₂ Relation.: strictly aerobic Spore: No spore Motility: Swimming Morphology: Filamentous	Health: Unknown Source: human faeces and sewage	Opt. T: 30℃ Low T(℃): 15(+) Mid T(℃): 40(+) NaCl 0.5-2%: 0.2(+) Opt. pH: 7.5 pH 6.0-8.0: 6.5(+) pH >8: 8.1(+)

SUBSTRATE ASSIMILATION & UTILISATION

Monosaccharide util/assim	Oligosaccharide util/assim	Other carboh. util/assim	Amino acid util/assim	Organic acid util/assim
Arabinose: neg Fructose: + Galactose: d Glucose: + Rhamnose: d Ribose: + Xylose: d	Cellubiose: neg Lactose: d Maltose: + Raffinose: neg Sucrose: + Trehalose: +	Cellulose: neg Ethanol: + Gluconate: + Glycerol: + Inositol: + Inulin: neg Mannitol: d Methanol: + Sorbitol: d Starch: neg		Acetate: d Butyrate: + Citrate: d Fumarate: + Glycerate: + 3-Hydroxybutyrate: + Lactate: + Malate: + Malonate: + Propionate: + Pyruvate: + Quinate: + Succinate: + D-Tartrate: d

ENZYME ACTIVITY

Enzymes: General	Enzymes: Carbohydrate	Enzymes: Protein	Enzymes: Arylamidases	Enzymes: Esters/fats
Oxidase: d Catalase: +	β-Galactosidase: d	ArgDH: d LysDC: neg OrnDC: neg

References

SPECIFIC REFERENCES FOR SPHAEROTILUS NATANS

Pellegrin1999 - Morphological and biochemical properties of a Sphaerotilus sp. Isolated from paper mill slimes.

vanVeen1978 - The Sphaerotilus-Leptothrix group of bacteria.

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GUT MICROBIOME COMPILATIONS AND METASTUDIES FOR SPHAEROTILUS NATANS

De2020 - Metagenomic analysis of gut microbiome and resistome of diarrheal fecal samples from Kolkata, India, reveals the core and variable microbiota including signatures of microbial dark matter.

Yang2020 - Species-Level Analysis of Human Gut Microbiota With Metataxonomics.

Yang2020a - Establishing high-accuracy biomarkers for colorectal cancer by comparing fecal microbiomes in patients with healthy families