In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall.
The Firmicutes are a phylum of bacteria, most of which have gram-positive cell wall structure. A few, however, such as Megasphaera, Pectinatus, Selenomonas and Zymophilus, have a porous pseudo-outer membrane that causes them to stain gram-negative. Scientists once classified the Firmicutes to include all gram-positive bacteria, but have recently defined them to be of a core group of related forms called the low-G+C group, in contrast to the Actinobacteria. They have round cells, called cocci, or rod-like forms (bacillus).
Enterobacter is a genus of common Gram-negative, facultatively anaerobic, rod-shaped, non-spore-forming bacteria of the family Enterobacteriaceae. It is the type genus of the order Enterobacterales. Several strains of these bacteria are pathogenic and cause opportunistic infections in immunocompromised hosts and in those who are on mechanical ventilation. The urinary and respiratory tracts are the most common sites of infection. The genus Enterobacter is a member of the coliform group of bacteria. It does not belong to the fecal coliforms group of bacteria, unlike Escherichia coli, because it is incapable of growth at 44.5 °C in the presence of bile salts. Some of them show quorum sensing properties.
The genus Selenomonas constitutes a group of motile crescent-shaped bacteria within the Veillonellaceae family and includes species living in the gastrointestinal tracts of animals, in particular the ruminants. A number of smaller forms discovered with the light microscope are now in culture but many, especially the large selenomonads are not, owing to their fastidious and incompletely known growth requirements.
Night eating syndrome (NES) is an eating disorder, characterized by a delayed circadian pattern of food intake. Although there is some degree of comorbidity with binge eating disorder, it differs from binge eating in that the amount of food consumed in the night is not necessarily objectively large nor is a loss of control over food intake required. It was originally described by Albert Stunkard in 1955 and is currently included in the other specified feeding or eating disorder category of the DSM-5. Research diagnostic criteria have been proposed and include evening hyperphagia and/or nocturnal awakening and ingestion of food two or more times per week. The person must have awareness of the night eating to differentiate it from the parasomnia sleep-related eating disorder (SRED). Three of five associated symptoms must also be present: lack of appetite in the morning, urges to eat at night, belief that one must eat in order to fall back to sleep at night, depressed mood, and/or difficulty sleeping.
Kruppel-like factor 13, also known as KLF13, is a protein that in humans is encoded by the KLF13 gene.
The Synergistetes is a recently recognized phylum of anaerobic bacteria that show Gram-negative staining and have rod/vibrioid cell shape. Although Synergistetes have a diderm cell envelope, the genes for various proteins involved in lipopolysaccharides biosynthesis have not yet been detected in Synergistetes, indicating that they may have an atypical outer cell envelope. The Synergistetes inhabit a majority of anaerobic environments including animal gastrointestinal tracts, soil, oil wells, and wastewater treatment plants and they are also present in sites of human diseases such as cysts, abscesses, and areas of periodontal disease. Due to their presence at illness related sites, the Synergistetes are suggested to be opportunistic pathogens but they can also be found in healthy individuals in the microbiome of the umbilicus and in normal vaginal flora. Species within this phylum have also been implicated in periodontal disease, gastrointestinal infections and soft tissue infections. Other species from this phylum have been identified as significant contributors in the degradation of sludge for production of biogas in anaerobic digesters and are potential candidates for use in renewable energy production through their production of hydrogen gas. All of the known Synergistetes species and genera are presently part of a single class (Synergistia), order (Synergistiales) and family (Synergistaceae).
The Chloroflexi or Chlorobacteria are a phylum of bacteria containing isolates with a diversity of phenotypes, including members that are aerobic thermophiles, which use oxygen and grow well in high temperatures; anoxygenic phototrophs, which use light for photosynthesis ; and anaerobic halorespirers, which uses halogenated organics as electron acceptors.
The Veillonellaceae are a family of the Clostridia, formerly known as Acidaminococcaceae. Bacteria in this family are grouped together mainly based on genetic studies, which place them among the Firmicutes. Supporting this placement, several species are capable of forming endospores. However, they differ from most other Firmicutes in having Gram-negative stains. The cell wall composition is peculiar.
Actinomyces gerencseriae is a species in the genus Actinomyces once known as Actinomyces israelii serovar II.
Well studied Periodontal pathogens are bacteria that have been shown to significantly contribute to periodontitis.
The Negativicutes are a class of bacteria in the phylum Firmicutes, whose members have a peculiar cell wall with a lipopolysaccharide outer membrane which stains gram-negative, unlike most other members of the Firmicutes. Although several neighbouring Clostridia species also stain gram-negative, the proteins responsible for the unusual diderm structure of the Negativicutes may have actually been laterally acquired from Proteobacteria. Additional research is required to confirm the origin of the diderm cell envelope in the Negativicutes.
Acidaminococcus is a genus in the phylum Firmicutes (Bacteria), whose members are anaerobic diplococci that can use amino acids as the sole energy source for growth. Like other members of the class Negativicutes, they are gram-negative, despite being Firmicutes, which are normally gram-positive.
Akkermansia is a genus in the phylum Verrucomicrobia (Bacteria). The genus was first proposed in 2004 by Muriel Derrien and others, with the type species Akkermansia muciniphila.
Eubacterium acidaminophilum is a Gram-positive bacterium species in the genus Eubacterium, notable for being an amino acid-degrading obligate anaerobe producing or utilizing H2 or formate. It is rod-shaped and motile by a polar to subpolar flagellum. Its type strain is al-2. It produces several relevant enzymes.
Pectinatus frisingensis is a species of anaerobic, Gram-negative, rod-shaped bacteria first isolated from spoilt beer.
Selenomonas lacticifex is a species of anaerobic, Gram-negative, rod-shaped bacteria first isolated from spoilt beer.
Zymophilus paucivorans is a species of anaerobic, Gram-negative, rod-shaped bacteria first isolated from spoilt beer. It is the type species of its genus.
Propionispira raffinosivorans is a motile, obligate anaerobic, gram-negative bacteria. It was originally isolated from spoiled beer and believed to have some causative effect in beer spoilage. Since then, it has been taxonomically reclassified and proven to play a role in anaerobic beer spoilage, because of its production of acids, such as acetic and propionic acid, during fermentation
Thermanaerovibrio acidaminovorans is a moderately thermophilic and anaerobic bacterium from the genus of Thermanaerovibrio which has been isolated from granular methanogenic sludge from Breda in the Netherlands.
