Cetobacterium somerae | |
---|---|
Scientific classification | |
Domain: | |
Phylum: | |
Class: | |
Order: | |
Family: | |
Genus: | |
Species: | C. somerae |
Binomial name | |
Cetobacterium somerae Finegold et al. 2003 [1] | |
Type strain | |
ATCC BAA-474, CCUG 46254, WAL 14325 [2] | |
Synonyms | |
Cetobacterium someriae [2] |
Cetobacterium somerae [2] is a microaerotolerant, Gram-negative, and rod-shaped anaerobic bacteria found in the gastrointestinal tract of fish living in freshwater ecosystems. [3] The bacteria is also immobile and non-spore forming. [4] [3] C. somerae was first isolated from the feces of children with Autism spectrum disorder. [3] Members of bacteria within the Cetobacterium genus tend to dominate the microbiota of fish in freshwater ecosystems. [5] Cetobacterium somerae also produces vitamin B-12 within the gastrointestinal tract of fish in order to provide nutritional support for growth. [5]
Cetobacterium somerae traces from a unique lineage. The taxonomic classification is as follows: Bacteria, Fusobacteriota, Fusobacteriia, Fusobacteriales, Fusobacteriaceae, Cetobacterium , and lastly, Cetobacterium somerae. [6] The closest species is Cetobacterium ceti , the only other species within the genus Cetobacterium . The sequence similarity shared with Cetobacteium ceti is 98%. [3] Leptotrichia buccalis , 'Sebaldella termitidis, Sneathia sanguinegens , Streptobacillus moniliformis , Propionigenium species, Ilyobacter species, and Fusobacterium species were among the other species that shared phylogenetic relationships with Cetobacterium somerae. [3] Of these, Fusobacterium species has the most sequence similarity for the whole genome, at 93%, while Sneathia sanguinegens has the lowest, at 82%. [3]
From 2000 to 2002, in the VA Medical Center West Los Angeles and UCLA School of Medicine, a team of researchers led by Sydney M. Finegold discovered the species Cetobacterium somerae. [3] At Rush Children's Hospital in Chicago, two children between 47-51 months old with late-onset autism who were given oral vancomycin medication had four strains of an unknown gram-negative, rod-shaped bacterium extracted from their feces. [3] Phenotypic characterization including biochemical tests, [7] cellular fatty acid analysis, and antibiotic susceptibility testing was performed on the isolates by Finegold's team. [3] To dilute the stool samples, they were combined under anaerobic circumstances with peptone broth. [3] Plates of diluted samples were placed on different media and incubated with particular gas conditions. [3] Standard tests and commercial systems were used to evaluate biochemical parameters and measure bile sensitivity. [3] Acid production and substrate utilization were investigated. [3] Cellular fatty acids and DNA G + C concentration were examined for chemotaxonomy in species identification. [3] Using 16S rRNA gene sequencing, database searches, and relatedness-based tree construction were all part of the phylogenetic analysis process. [3] An evaluation of the groupings' stability was conducted using maximum parsimony and bootstrap analysis (Finegold et al., 2003). Both maximum parsimony and bootstrap analyses are performed specifically for examining phylogenetic trees. Maximum parsimony is an approach to minimize the number of evolutionary steps required to allot data onto branches of a phylogenetic tree. [8] On the other hand, bootstrap analyses are a method to determine the confidence intervals for a phylogenetic tree. [9] 16S rRNA gene sequencing and phylogenetic analysis showed the isolates represented a novel species within the genus Cetobacterium, distinct from but closely related to Cetobacterium ceti. [3] Based on the phenotypic and phylogenetic evidence, the researchers proposed in 2003 to classify the new bacterium as Cetobacterium somerae, naming the type strain WAL 14325T. [2] [3]
Cetobacterium somerae is also found to be in the intestinal tracts of freshwater fish. [10] In 2008, a group of researchers from Japan used fishing sampling locations such as the Fisheries Research Laboratory of the Saitama Prefectural Agriculture and Forestry Research Center to isolate anaerobic bacteria from the intestine contents of various freshwater fishes like goldfish, tilapia, catfish, common carp and grass carp. [10] Standard anaerobic culture techniques [11] on various media like Fusobacterium modified agar, Bacteroides agar and fradiomycin- Clostridium welchii agar were used. [10] Phenotypic characterization such as biochemical tests, fermentation products, G+C content, and 16S rRNA gene sequencing were used to identify the microbial strains. [10] They identified these previous "Bacteroides type A" isolates as actually being Cetobacterium somerae based on their analyses. [10]
In 2023, a published study recorded the first bacteremia case involving Cetobacterium somerae for necrotizing cholecystitis, a condition concerning the inflammation of the gallbladder, in a human patient. [12] The study describes that Cetobacterium somerae cannot grow in the presence of oxygen and relies on anaerobic respiration. [12] Through the fermentation of carbohydrates, it yields large amounts of acetate and only trace amounts of propionate and butyrate. [12] It has been proposed to increase fish's intestinal consumption of carbohydrates by producing acetate. [12] It can synthesize vitamin B12, which could "promote fish health”. [12]
There are two types of bacteria species within the genus of Cetobacterium: Cetobacterium ceti and Cetobacterium somerae. [13] In 2014, an experiment was conducted in order to determine the importance of microorganisms on the gut health of various fish species. [13] Both of the C. ceti and C. somerae bacterial species used in the study are found in abundance in the guts of several different warmwater fish species that are deemed economically valuable in the aquaculture industry. [13] However, analyses of the gut flora of the fish using 16s rRNA sequencing established that the C. somerae bacterial species was the most prevalent microorganism in all of the fish species even though the microbial gut distribution of the fish samples all varied greatly in abundance. [13] C. somerae makes up 70% of the gut bacteria of several freshwater fish species, including tilapia, bass, bluegill, and carp. [12] It's not known to cause infections in fish, but it seems to be a potentially mutualistic bacteria in fish intestines. [12]
The Cetobacterium somerae currently has three strains being isolated: ATCC BAA-474, MGYG-HGUT-01458, and CS2105-BJ. [14] However only the CS2105-BJ has a finished sequence as computed by the IMG (Integrated Microbial Genome) dataset. [14] The whole genome of the CS2105-BJ strain Cetobacterium somerae bacteria was sequenced in 2023 and has a size of 2.97 Mb. [15] 28.83% of the total nucleotides are G+C base pairs as sequenced by the PacBio sequencing technology. [15] The strain has 2901 total genes and 94.35% of the total genes code for the production of proteins. [15] 1.55% of the total gene count serves as regulatory proteins to assist in gene expression. [15] According to the KEGG (Kyoto Encyclopedia of Genes and Genomes) database, the bacterial strain has a circular chromosome and contains six plasmids. [16]
Analysis of the genome using Illumina sequencing technology showed that the Cetobacterium somerae contains no pathogenic potential to cause disease in host organisms such as fish due to a lack of toxins and adhesins that will allow the bacteria to infect a host. [17] However, in 2023, the first human infection of C. somerae infection was identified via 16s rRNA gene sequencing. [12] The introduction of 16s rRNA gene sequencing has provided a culture-independent method of identifying microorganisms. [18] In the past, it was difficult to isolate obligate anaerobic bacteria due to their need for an anoxic environment. [18] The current pathogenicity of C. somerae in human hosts is therefore uncertain and research is further being conducted to interpret the mechanisms. [12]
The Cetobacterium somerae bacteria has potential benefits and implications in the health of fish species. Namely, C. somerae fermentation products can potentially replace fish meal as an adjuvant with plant protein for fish food. [19] Scientists have also long considered plant proteins as an alternative source to fish meal due to sustainability issues associated with fish meal. [20] Fish meal production yields an abundance of phosphorus, which contributes to anoxic environments via algal blooms that can kill fish. [20] However, despite the fact that plant-based fish food is considered more sustainable, its usage is cautioned because plant proteins have been shown to negatively affect fish metabolism via antinutritional factors, which restrict nutrient uptake and induce metabolic inhibition. [21] However, the fermentation product of the C. somerae is a potential source of supplemental fish feed that can mitigate the inhibitory effects of plant proteins and therefore reduces toxic effects from antinutritional factors in fish species consuming plant protein within aquatic ecosystems. [19] For example, a study on carp fish contrasting finely ground plant proteins, or uPPs (ultra-processed proteins), in comparison to the fermentation product of a C. somerae bacterial strain showed that the uPPs contributed to increased inflammation and an increase of liver enzymes that contribute to fatty liver disease in the carp fish. [19] However, utilizing the uPPs in conjunction with the fermentation product of the C. somerae bacteria reduced the amount of inflammation and fatty liver disease, showing that the C. somerae fermentation product offsets the negative effects of the plant proteins. [19]
The effects of Cetobacterium somerae as an alleviating agent has been further studied in carp hepatotoxicity induced from pesticides. [22] For example, the pesticide trichlorfon has been shown to heighten enzymatic activity that contributes to liver disease in carp fish and also negatively alters the microflora in the carp’s gut. [22] Astragalus polysaccharides, a polysaccharide derived from the Astragalus propinquus plant has shown to have synergistic effects when used in combination with Cetobacterium somerae. [22] The pair mitigates hepatotoxicity caused by trichloron by reducing fat synthesis and regulating gut microbiota of the carp fish. [22]
The scientific advancement of Cetobacterium somerae on human health has recently been found as a potential source of a biomarker for colorectal cancer. [23] The prevalence of certain bacterial organisms in the human gut may be used as a source of a noninvasive biomarker for the presence of colorectal cancer. [23] This is helpful because the more invasive detectors of colorectal cancer via colonoscopy can be economically disadvantageous for certain populations. [23] For example, the simultaneous presence of the bacterial species Prevotella copri , Gemella morbillorum , Parvimonas micra , Cetobacterium somerae, and Pasteurella stomatis in the gut microbiota is a strong predictor of colorectal cancer. [23]
Acetobacter is a genus of acetic acid bacteria. Acetic acid bacteria are characterized by the ability to convert ethanol to acetic acid in the presence of oxygen. Of these, the genus Acetobacter is distinguished by the ability to oxidize lactate and acetate into carbon dioxide and water. Bacteria of the genus Acetobacter have been isolated from industrial vinegar fermentation processes and are frequently used as fermentation starter cultures.
Bacillus safensis is a Gram-positive, spore-forming, and rod bacterium, originally isolated from a spacecraft in Florida and California. B. safensis could have possibly been transported to the planet Mars on spacecraft Opportunity and Spirit in 2004. There are several known strains of this bacterium, all of which belong to the Bacillota phylum of Bacteria. This bacterium also belongs to the large, pervasive genus Bacillus. B. safensis is an aerobic chemoheterotroph and is highly resistant to salt and UV radiation. B. safensis affects plant growth, since it is a powerful plant hormone producer, and it also acts as a plant growth-promoting rhizobacteria, enhancing plant growth after root colonization. Strain B. safensis JPL-MERTA-8-2 is the only bacterial strain shown to grow noticeably faster in micro-gravity environments than on the Earth surface.
Bacteroides is a genus of Gram-negative, obligate anaerobic bacteria. Bacteroides species are non endospore-forming bacilli, and may be either motile or nonmotile, depending on the species. The DNA base composition is 40–48% GC. Unusual in bacterial organisms, Bacteroides membranes contain sphingolipids. They also contain meso-diaminopimelic acid in their peptidoglycan layer.
16S ribosomal RNA is the RNA component of the 30S subunit of a prokaryotic ribosome. It binds to the Shine-Dalgarno sequence and provides most of the SSU structure.
Microbiota are the range of microorganisms that may be commensal, mutualistic, or pathogenic found in and on all multicellular organisms, including plants. Microbiota include bacteria, archaea, protists, fungi, and viruses, and have been found to be crucial for immunologic, hormonal, and metabolic homeostasis of their host.
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.
Thermococcus celer is a Gram-negative, spherical-shaped archaeon of the genus Thermococcus. The discovery of T. celer played an important role in rerooting the tree of life when T. celer was found to be more closely related to methanogenic Archaea than to other phenotypically similar thermophilic species. T. celer was the first archaeon discovered to house a circularized genome. Several type strains of T. celer have been identified: Vu13, ATCC 35543, and DSM 2476.
Hydrogenobacter thermophilus is an extremely thermophilic, straight rod (bacillus) bacterium. TK-6 is the type strain for this species. It is a Gram negative, non-motile, obligate chemolithoautotroph. It belongs to one of the earliest branching order of Bacteria. H. thermophilus TK-6 lives in soil that contains hot water. It was one of the first hydrogen oxidizing bacteria described leading to the discovery, and subsequent examination of many unique proteins involved in its metabolism. Its discovery contradicted the idea that no obligate hydrogen oxidizing bacteria existed, leading to a new understanding of this physiological group. Additionally, H. thermophilus contains a fatty acid composition that had not been observed before.
Microbial phylogenetics is the study of the manner in which various groups of microorganisms are genetically related. This helps to trace their evolution. To study these relationships biologists rely on comparative genomics, as physiology and comparative anatomy are not possible methods.
Rhodoferax is a genus of Betaproteobacteria belonging to the purple nonsulfur bacteria. Originally, Rhodoferax species were included in the genus Rhodocyclus as the Rhodocyclus gelatinous-like group. The genus Rhodoferax was first proposed in 1991 to accommodate the taxonomic and phylogenetic discrepancies arising from its inclusion in the genus Rhodocyclus. Rhodoferax currently comprises four described species: R. fermentans, R. antarcticus, R. ferrireducens, and R. saidenbachensis. R. ferrireducens, lacks the typical phototrophic character common to two other Rhodoferax species. This difference has led researchers to propose the creation of a new genus, Albidoferax, to accommodate this divergent species. The genus name was later corrected to Albidiferax. Based on geno- and phenotypical characteristics, A. ferrireducens was reclassified in the genus Rhodoferax in 2014. R. saidenbachensis, a second non-phototrophic species of the genus Rhodoferax was described by Kaden et al. in 2014.
Campylobacter showae is a Gram-negative, chemoheterotrophic, microaerophilic, motile bacteria belonging to the Campylobacter Genus. The type strain of this species, SU A4, was first isolated from plaque samples taken from the gingival crevices of the human oral cavity but has since also been found in colonic tissues and stool. Since its discovery, C. showae has been implicated in various medical conditions including Crohn's disease, periodontitis, inflammatory bowel disease, and ulcerative colitis due to its pathogenic nature.
Oscillibacter valericigenes is a species of mesophilic bacterium identified in the alimentary canal of Japanese Corbicula clams. It is Gram-negative and anaerobic, with a straight to slightly curved rod-like morphology, and is motile with petritrichous flagella. It was not observed in culture to form spores.
Microbial DNA barcoding is the use of DNA metabarcoding to characterize a mixture of microorganisms. DNA metabarcoding is a method of DNA barcoding that uses universal genetic markers to identify DNA of a mixture of organisms.
Deinococcus aerius is an anaerobic bacterium that can be found in the atmosphere above the island of Japan. Living in such conditions makes these bacteria highly resistant to desiccation, UV-C, and gamma radiation. Although previously unidentified as strain TR0125, this bacterium was determined to be Deinococcus aerius by 16S rRNA sequencing.
Thermodesulfobacterium hveragerdense is a bacterial species belonging to genus Thermodesulfobacterium, which are thermophilic sulfate-reducing bacteria. This species is found in aquatic areas of high temperature, and lives in freshwater like most, but not all Thermodesulfobacterium species It was first isolated from hotsprings in Iceland.
Christensenella hongkongensis is a species of clinically relevant gram-positive coccobacilli, first isolated from patients in Hong Kong and Canada in 2006. Although the species remains relatively rare, it has a high mortality rate of up to 50%. Christensenella is thought to be broadly distributed globally, as it has been isolated from patient blood cultures around the world including Hong Kong, South Korea, New Zealand, Canada, Sweden, France and Italy. Fewer than 15 cases of C. hongkongensis have been observed worldwide.
Peptidiphaga gingivicola is a Gram-positive, non-spore forming, coccus shaped bacterium. Coccus are spherical and generally round in shape. Coccus are differentiated by their groupings that can range from chains, groups, or grape-like clusters. Peptidiphaga gingivicola was observed to grow in groups of 2-5 cocci between 0.2-0.9 mm in diameter. Growth was observed when cultured under anaerobic conditions between 33 and 40 degrees celsius on Blood Brucella agar for 4 days. Peptidiphaga gingivicola has been cultured from patients with periodontal disease, primarily caused by bacterial plaque formation on the gum and teeth of the oral cavity. The microbe is known to break down peptides of the gum causing tissue damage and tooth decay, leading to serious implications for oral health.
Fervidicoccus fontis is an extremophilic, coccus-shaped archaeaon known for thriving in high-temperature environments. It was discovered in Russia's Uzon Caldera and exhibits anaerobic, organotrophic metabolism, primarily fermenting organic compounds like peptides and yeast extract. Genetically distinct with no more than 89% similarity to its closest relatives, F. fontis is the sole species within the order Fervidicoccales and genus Fervidicoccus, but ongoing research suggests potential new species. It plays a significant role in biotechnological applications due to its lipid-hydrolyzing capabilities, contributing to industries ranging from wastewater treatment to pharmaceuticals.
Actinomyces massiliensis is an anaerobic, mesophilic, Gram-positive bacterium originally isolated from a human blood sample and belonging to the genus Actinomyces.