Sphingomonas was defined in 1990 as a group of Gram-negative, rod-shaped, chemoheterotrophic, strictly aerobic bacteria. They possess ubiquinone 10 as their major respiratory quinone, contain glycosphingolipids (GSLs), specifically ceramide, instead of lipopolysaccharide (LPS) in their cell envelopes, and typically produce yellow-pigmented colonies. The GSL serves to protect the bacteria from antibacterial substances. Unlike most Gram-negative bacteria, Sphingomonas cannot carry endotoxins due to the lack of lipopolysaccharides, and has a hydrophobic surface characterized by the short nature of the GSL's carbohydrate portion. [2]
By 2001, the genus included more than 20 species that were quite diverse in terms of their phylogenetic, ecological, and physiological properties. As a result, Sphingomonas was subdivided into different genera: Sphingomonas, Sphingobium , Novosphingobium , Sphingosinicella , and Sphingopyxis . These genera are commonly referred to collectively as sphingomonads. Distinct from other sphingomonads, Sphingomonas genomic structure includes a unique lipid formation, major 2-OH fatty acids, homospermidine as the primary polyamine, and signature nucleotide bases within the 16S rRNA gene. The bacteria holds 3914 proteins, 70 organizational RNA, and 3,948,000 base pairs (incomplete observation). [2]
The sphingomonads are widely distributed in nature, having been isolated from many different land and water habitats, as well as from plant root systems, clinical specimens, and other sources; this is due to their ability to survive in low concentrations of nutrients, as well as to metabolize a wide variety of carbon sources. Numerous strains have been isolated from environments contaminated with toxic compounds, where they display the ability to use the contaminants as nutrients. [2]
Some of the sphingomonads (especially Sphingomonas paucimobilis) also play a role in human disease, primarily by causing a range of mostly nosocomial, non-life-threatening infections that typically are easily treated by antibiotic therapy. [3] [4] In contrast, the seed-endophytic strain Sphingomonas melonis ZJ26 that can be naturally enriched in certain rice cultivars, confers diseases resistance against a bacterial pathogen and is vertically transmitted among plant generations via their seeds. [5]
Due to their biodegradative and biosynthetic capabilities, sphingomonads have been used for a wide range of biotechnological applications, from bioremediation of environmental contaminants to production of extracellular polymers such as sphingans (e.g., gellan, welan, and rhamsan) used extensively in the food and other industries. [6] The shorter carbohydrate moiety of GSL compared to that of LPS results in the cell surface being more hydrophobic than that of other Gram-negative bacteria, probably accounting for both Sphingomonas' sensitivity to hydrophobic antibiotics and its ability to degrade hydrophobic polycyclic aromatic hydrocarbons. [2] One strain, Sphingomonas sp. 2MPII, can degrade 2-methyl phenanthrene. [7] In May 2008, Daniel Burd, a 16-year-old Canadian, won the Canada-Wide Science Fair in Ottawa after discovering that Sphingomonas can degrade over 40% of the weight of plastic bags (polyethylene) in less than three months. [8]
A Sphingomonas sp. strain BSAR-1 expressing a high activity alkaline phosphatase (PhoK) has also been applied for bioprecipitation of uranium from alkaline solutions. The precipitation ability was enhanced by overexpressing PhoK protein in E. coli . This is the first report of bioprecipitation of uranium under alkaline conditions. [9]
Wine, developed through the alcoholic fermentation of grapes, is an alcoholic beverage that is sensorially characterized by micro-bacteria and a host of other environmental factors. While historic variables such as location, temperature, soil quality, and winemaking practices play a role in altering the taste of a wine, microbial biogeography plays a significant role in the quality of wine. A terroir , comprising the aforementioned characteristics, influences the quality of the wine grapes based on the unique vineyard region that it originates from. [10] The bacterial diversity of the grapes anticipates a wine’s chemical structure. The management of these microbial factors, within the fermentation process, allows producers to control the prevalence of desirable regional attributes.
While most microbiota cannot survive the wine fermentation process, Sphingomonas, found in soil, grape leaves, and on fermentation surfaces, can survive this process. The pigmentation, stress resistance levels, unique restorative DNA system, and low nutrient necessity allows further growth in the phyllosphere. [11] As the grape matures, the microbial count increases due to nutrient availability and expansion of its surface area. [10] Researchers at the University of California, Davis observed an increase in abundance of the Sphingomonas bacteria from finished wines cultivated within Napa and Sonoma Counties, California. [12] This indicates that Sphingomonas is a biomarker for the chemical composition of wine. Sphingomonas is found throughout the wine fermentation process indicating a relationship between the bacteria and microbial terroir of the wines. [13] [14]
Pseudomonadota is a major phylum of Gram-negative bacteria. The renaming of several prokaryote phyla in 2021, including Pseudomonadota, remains controversial among microbiologists, many of whom continue to use the earlier name Proteobacteria, of long standing in the literature. The phylum Proteobacteria includes a wide variety of pathogenic genera, such as Escherichia, Salmonella, Vibrio, Yersinia, Legionella, and many others. Others are free-living (non-parasitic) and include many of the bacteria responsible for nitrogen fixation.
Sphingomonadaceae are a gram-negative bacterial family of the Alphaproteobacteria. An important feature is the presence of sphingolipids in the outer membrane of the cell wall. The cells are ovoid or rod-shaped. Others are also pleomorphic, i.e. the cells change the shape over time. Some species from Sphingomonadaceae family are dominant components of biofilms.
Lactobacillales are an order of gram-positive, low-GC, acid-tolerant, generally nonsporulating, nonrespiring, either rod-shaped (bacilli) or spherical (cocci) bacteria that share common metabolic and physiological characteristics. These bacteria, usually found in decomposing plants and milk products, produce lactic acid as the major metabolic end product of carbohydrate fermentation, giving them the common name lactic acid bacteria (LAB).
Bacteria 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 the first life forms to appear on Earth, and are present in most of its habitats. Bacteria inhabit soil, water, acidic hot springs, radioactive waste, and the deep biosphere of Earth's crust. Bacteria play a vital role in many stages of the nutrient cycle by recycling nutrients and the fixation of nitrogen from the atmosphere. The nutrient cycle includes the decomposition of dead bodies; bacteria are responsible for the putrefaction stage in this process. In the biological communities surrounding hydrothermal vents and cold seeps, extremophile bacteria provide the nutrients needed to sustain life by converting dissolved compounds, such as hydrogen sulphide and methane, to energy. Bacteria also live in mutualistic, commensal and parasitic relationships with plants and animals. Most bacteria have not been characterised and there are many species that cannot be grown in the laboratory. The study of bacteria is known as bacteriology, a branch of microbiology.
Sphingomonas paucimobilis is a strictly aerobic Gram-negative bacterium that has a single polar flagellum with slow motility. The cell size is around 0.7 x 1.4 μm. It is usually found in soil. As with the other members of the genus, its biochemistry is remarkable in possession of ubiquinone 10 as its major respiratory quinone, and of glycosphingolipids instead of lipopolysaccharides in its cell envelope. It has been implicated in various types of clinical infections.
Symbiotic culture of bacteria and yeast (SCOBY) is a culinary symbiotic fermentation culture (starter) consisting of lactic acid bacteria (LAB), acetic acid bacteria (AAB), and yeast which arises in the preparation of sour foods and beverages such as kombucha. Beer and wine also undergo fermentation with yeast, but the lactic acid bacteria and acetic acid bacteria components unique to SCOBY are usually viewed as a source of spoilage rather than a desired addition. Both LAB and AAB enter on the surface of barley and malt in beer fermentation and grapes in wine fermentation; LAB lowers the pH of the beer/wine while AAB takes the ethanol produced from the yeast and oxidizes it further into vinegar, resulting in a sour taste and smell. AAB are also responsible for the formation of the cellulose SCOBY.
Faecalibacterium is a genus of bacteria. The genus contains several species including Faecalibacterium prausnitzii, Faecalibacterium butyricigenerans, Faecalibacterium longum, Faecalibacterium duncaniae, Faecalibacterium hattorii, and Faecalibacterium gallinarum. Its first known species, Faecalibacterium prausnitzii is gram-positive, mesophilic, rod-shaped, and anaerobic, and is one of the most abundant and important commensal bacteria of the human gut microbiota. It is non-spore forming and non-motile. These bacteria produce butyrate and other short-chain fatty acids through the fermentation of dietary fiber. The production of butyrate makes them an important member of the gut microbiota, fighting against inflammation.
Propionibacterium freudenreichii is a gram-positive, non-motile bacterium that plays an important role in the creation of Emmental cheese, and to some extent, Jarlsberg cheese, Leerdammer and Maasdam cheese. Its concentration in Swiss-type cheeses is higher than in any other cheese. Propionibacteria are commonly found in milk and dairy products, though they have also been extracted from soil. P. freudenreichii has a circular chromosome about 2.5 Mb long. When Emmental cheese is being produced, P. freudenreichii ferments lactate to form acetate, propionate, and carbon dioxide
(3 C3H6O3 → 2 C2H5CO2 + C2H3O2 + CO2).
A soda lake or alkaline lake is a lake on the strongly alkaline side of neutrality, typically with a pH value between 9 and 12. They are characterized by high concentrations of carbonate salts, typically sodium carbonate, giving rise to their alkalinity. In addition, many soda lakes also contain high concentrations of sodium chloride and other dissolved salts, making them saline or hypersaline lakes as well. High pH and salinity often coincide, because of how soda lakes develop. The resulting hypersaline and highly alkalic soda lakes are considered some of the most extreme aquatic environments on Earth.
Sphingomonas parapaucimobilis is a species of bacteria. Its type strain is JCM 7510.
Sphingomonas yanoikuyae is a short rod-shaped, strictly aerobic, Gram-negative, non-motile, non-spore-forming, chemoheterotrophic species of bacteria that is yellow or off-white in color. Its type strain is JCM 7371. It is notable for degrading a variety of aromatic compounds including biphenyl, naphthalene, phenanthrene, toluene, m-, and p-xylene. S. yanoikuyae was discovered by Brian Goodman on the southern coast of Papua New Guinea. However, Sphingomonas have a wide distribution across freshwater, seawater, and terrestrial habitats. This is due to the bacteria's ability to grow and survive under low-nutrient conditions as it can utilize a broad range of organic compounds.
Geobacter sulfurreducens is a gram-negative metal and sulphur-reducing proteobacterium. It is rod-shaped, aerotolerant anaerobe, non-fermentative, has flagellum and type four pili, and is closely related to Geobacter metallireducens. Geobacter sulfurreducens is an anaerobic species of bacteria that comes from the family of bacteria called Geobacteraceae. Under the genus of Geobacter, G. sulfurreducens is one out of twenty different species. The Geobacter genus was discovered by Derek R. Lovley in 1987. G. sulfurreducens was first isolated in Norman, Oklahoma, USA from materials found around the surface of a contaminated ditch.
Sphingobium japonicum is a hexachlorocyclohexane-degrading bacteria with type strain MTCC 6362T. Its genome has been sequenced.
Sphingobium indicum is a hexachlorocyclohexane-degrading bacteria with type strain MTCC 6364T. Its genome has been sequenced.
Sphingobium francense is a hexachlorocyclohexane-degrading bacteria with type strain MTCC 6363T.
Acetobacter fabarum is a bacterium that was first identified from fermenting cocoa beans in Ghana.
Exometabolomics, also known as 'metabolic footprinting', is the study of extracellular metabolites and is a sub-field of metabolomics.
Pseudobutyrivibrio is a Gram-negative, anaerobic and non-spore-forming bacterial genus from the family of Lachnospiraceae.
Blastomonas is a Gram-negative, photoheterotrophic, strictly aerobic and non-spore-forming bacteria genus from the family of Sphingomonadaceae.
Hydrocarbonoclastic bacteria are a heterogeneous group of prokaryotes which can degrade and utilize hydrocarbon compounds as source of carbon and energy. Despite being present in most of environments around the world, several of these specialized bacteria live in the sea and have been isolated from polluted seawater.