Misplaced Pages

#537462

26-454: The Eggerthellaceae are a family of Gram-positive , rod- or coccus-shaped Actinomycetota . It is the sole family within the order Eggerthellales. The name Eggerthellaceae is derived from the Latin term Eggerthella , referring to the type genus of the family and the suffix "-ceae," an ending used to denote a family. Together, Eggerthellaceae refers to a family whose nomenclatural type

52-399: A cytoplasmic membrane and an outer cell membrane; they contain only a thin layer of peptidoglycan (2–3 nm) between these membranes. The presence of inner and outer cell membranes defines a new compartment in these cells: the periplasmic space or the periplasmic compartment. These bacteria have been designated as diderm bacteria . The distinction between the monoderm and diderm bacteria

78-621: A monophyletic clade and that no loss of the outer membrane from any species from this group has occurred. In the classical sense, six gram-positive genera are typically pathogenic in humans. Two of these, Streptococcus and Staphylococcus , are cocci (sphere-shaped). The remaining organisms are bacilli (rod-shaped) and can be subdivided based on their ability to form spores . The non-spore formers are Corynebacterium and Listeria (a coccobacillus), whereas Bacillus and Clostridium produce spores. The spore-forming bacteria can again be divided based on their respiration : Bacillus

104-972: A number of bacterial taxa (viz. Negativicutes , Fusobacteriota , Synergistota , and Elusimicrobiota ) that are either part of the phylum Bacillota or branch in its proximity are found to possess a diderm cell structure. However, a conserved signature indel (CSI) in the HSP60 ( GroEL ) protein distinguishes all traditional phyla of gram-negative bacteria (e.g., Pseudomonadota , Aquificota , Chlamydiota , Bacteroidota , Chlorobiota , " Cyanobacteria ", Fibrobacterota , Verrucomicrobiota , Planctomycetota , Spirochaetota , Acidobacteriota , etc.) from these other atypical diderm bacteria, as well as other phyla of monoderm bacteria (e.g., Actinomycetota , Bacillota , Thermotogota , Chloroflexota , etc.). The presence of this CSI in all sequenced species of conventional LPS ( lipopolysaccharide )-containing gram-negative bacterial phyla provides evidence that these phyla of bacteria form

130-793: A recipient host bacterium). In transformation, the genetic material passes through the intervening medium, and uptake is completely dependent on the recipient bacterium. As of 2014 about 80 species of bacteria were known to be capable of transformation, about evenly divided between gram-positive and gram-negative bacteria ; the number might be an overestimate since several of the reports are supported by single papers. Transformation among gram-positive bacteria has been studied in medically important species such as Streptococcus pneumoniae , Streptococcus mutans , Staphylococcus aureus and Streptococcus sanguinis and in gram-positive soil bacteria Bacillus subtilis and Bacillus cereus . The adjectives gram-positive and gram-negative derive from

156-508: A single membrane, but stain gram-negative due to either lack of the peptidoglycan layer, as in the mycoplasmas , or their inability to retain the Gram stain because of their cell wall composition—also show close relationship to the gram-positive bacteria. For the bacterial cells bounded by a single cell membrane, the term monoderm bacteria has been proposed. In contrast to gram-positive bacteria, all typical gram-negative bacteria are bounded by

182-455: A surface layer called an S-layer . In gram-positive bacteria, the S-layer is attached to the peptidoglycan layer. Gram-negative bacteria's S-layer is attached directly to the outer membrane . Specific to gram-positive bacteria is the presence of teichoic acids in the cell wall. Some of these are lipoteichoic acids, which have a lipid component in the cell membrane that can assist in anchoring

208-402: Is a facultative anaerobe , while Clostridium is an obligate anaerobe . Also, Rathybacter , Leifsonia , and Clavibacter are three gram-positive genera that cause plant disease. Gram-positive bacteria are capable of causing serious and sometimes fatal infections in newborn infants. Novel species of clinically relevant gram-positive bacteria also include Catabacter hongkongensis , which

234-428: Is ambiguous as it refers to three distinct aspects (staining result, envelope organization, taxonomic group), which do not necessarily coalesce for some bacterial species. The gram-positive and gram-negative staining response is also not a reliable characteristic as these two kinds of bacteria do not form phylogenetic coherent groups. However, although Gram staining response is an empirical criterion, its basis lies in

260-427: Is an emerging pathogen belonging to Bacillota . Transformation is one of three processes for horizontal gene transfer , in which exogenous genetic material passes from a donor bacterium to a recipient bacterium, the other two processes being conjugation (transfer of genetic material between two bacterial cells in direct contact) and transduction (injection of donor bacterial DNA by a bacteriophage virus into

286-1550: Is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN). Coriobacteriales Slackia Cryptobacterium Denitrobacterium Senegalimassilia Eggerthella Gordonibacter Adlercreutzia Anaerosomataceae Parvivirga Atopobiaceae Raoultibacter Denitrobacterium Coriobacteriaceae Rubneribacter Xiamenia Zhang et al. 2022 Eggerthella Gordonibacter Paraeggerthella Arabiibacter Enteroscipio Cryptobacterium Slackia Berryella Ellagibacter Senegalimassilia Adlercreutzia Slackia Wade et al. 1999 " Anaerotardibacter " Afrizal et al. 2022 Cryptobacterium Nakazawa et al. 1999 Denitrobacterium Anderson et al. 2000 " Ca. Aveggerthella " Gilroy et al. 2021 Berryella Wylensek et al. 2021 " Phoenicibacter " Bilen et al. 2019 Ellagibacter Beltran et al. 2018 Senegalimassilia corrig. Lagier et al. 2014 " Ca. Aphodovivens " Gilroy et al. 2021 Parvibacter Clavel et al. 2013 Adlercreutzia Maruo et al. 2008 Raoultibacter Traore et al. 2022 Gordonibacter Wurdemann et al. 2009 Enteroscipio Danylec et al. 2018 Arabiibacter Lo et al. 2023 Rubneribacter Danylec et al. 2018 Gram-positive bacteria The Gram stain

SECTION 10

#1732775776538

312-426: Is because the thick layer of peptidoglycan in the bacterial cell wall retains the stain after it is washed away from the rest of the sample, in the decolorization stage of the test. Conversely, gram-negative bacteria cannot retain the violet stain after the decolorization step; alcohol used in this stage degrades the outer membrane of gram-negative cells, making the cell wall more porous and incapable of retaining

338-863: Is between 43.4 and 66.3 mol%. Analysis of genome sequences identified 13 conserved signature indels (CSIs) in diverse proteins that are exclusively present in different Eggerthellaceae species. The proteins containing these CSIs are: contaexcinuclease ABC subunit UvrC, DNA polymerase III subunit alpha, ribonuclease III , tRNA (N6-isopentenyl adenosine(37)-C2)-methylthiotransferase (MiaB), peptide chain release factor 2, 16S rRNA (cytosine(1402)-N(4))-methyltransferase, elongation factor Tu , UDP-N-acetylglucosamine 1-carboxyvinyltransferase DNA polymerase III subunit epsilon, UDP-glucose 4-epimerase and DNA-directed RNA polymerase subunit alpha. The identified CSIs provide reliable and important means to distinguish members of Eggerthellaceae from all other Coriobacteriia as well as other bacteria. The currently accepted taxonomy

364-407: Is supported by conserved signature indels in a number of important proteins (viz. DnaK, GroEL). Of these two structurally distinct groups of bacteria, monoderms are indicated to be ancestral. Based upon a number of observations including that the gram-positive bacteria are the major producers of antibiotics and that, in general, gram-negative bacteria are resistant to them, it has been proposed that

390-564: Is the genus Eggerthella . Members of this family are mostly anaerobic, non-motile (with the exception of some Gordonibacter and Senegalimassilia species that exhibit motility), asaccharolytic and do not form spores. Eggerthellaceae species are commonly isolated from human and animal faeces and other human sources such as the colon, vagina, oral cavity and blood. Some species have also been isolated from human samples of periodontal or endodontic infections, Crohn's disease and severe blood bacteremia. The G+C content for Eggerthellaceae species

416-421: Is used by microbiologists to place bacteria into two main categories, Gram-positive (+) and Gram-negative (-). Gram-positive bacteria have a thick layer of peptidoglycan within the cell wall, and Gram-negative bacteria have a thin layer of peptidoglycan. Gram-positive bacteria take up the crystal violet stain used in the test, and then appear to be purple-coloured when seen through an optical microscope . This

442-418: The absence of the outer membrane. In general, the following characteristics are present in gram-positive bacteria: Only some species have a capsule , usually consisting of polysaccharides . Also, only some species are flagellates , and when they do have flagella , have only two basal body rings to support them, whereas gram-negative have four. Both gram-positive and gram-negative bacteria commonly have

468-501: The archetypical diderm bacteria where the outer cell membrane contains lipopolysaccharide, and the diderm bacteria where outer cell membrane is made up of mycolic acid . In general, gram-positive bacteria are monoderms and have a single lipid bilayer whereas gram-negative bacteria are diderms and have two bilayers. Exceptions include: Some Bacillota species are not gram-positive. The class Negativicutes, which includes Selenomonas , are diderm and stain gram-negative. Additionally,

494-413: The crystal violet stain. Their peptidoglycan layer is much thinner and sandwiched between an inner cell membrane and a bacterial outer membrane , causing them to take up the counterstain ( safranin or fuchsine ) and appear red or pink. Despite their thicker peptidoglycan layer, gram-positive bacteria are more receptive to certain cell wall –targeting antibiotics than gram-negative bacteria, due to

520-468: The gram-positive bacteria was challenged, with major implications for the therapeutic and general study of these organisms. Based on molecular studies of the 16S sequences, Woese recognised twelve bacterial phyla . Two of these were gram-positive and were divided on the proportion of the guanine and cytosine content in their DNA . The high G + C phylum was made up of the Actinobacteria , and

546-471: The kingdom Monera was divided into four divisions based primarily on Gram staining: Bacillota (positive in staining), Gracilicutes (negative in staining), Mollicutes (neutral in staining) and Mendocutes (variable in staining). Based on 16S ribosomal RNA phylogenetic studies of the late microbiologist Carl Woese and collaborators and colleagues at the University of Illinois , the monophyly of

SECTION 20

#1732775776538

572-626: The low G + C phylum contained the Firmicutes . The Actinomycetota include the Corynebacterium , Mycobacterium , Nocardia and Streptomyces genera. The (low G + C) Bacillota, have a 45–60% GC content, but this is lower than that of the Actinomycetota. Although bacteria are traditionally divided into two main groups, gram-positive and gram-negative, based on their Gram stain retention property, this classification system

598-401: The marked differences in the ultrastructure and chemical composition of the bacterial cell wall, marked by the absence or presence of an outer lipid membrane. All gram-positive bacteria are bounded by a single-unit lipid membrane, and, in general, they contain a thick layer (20–80 nm) of peptidoglycan responsible for retaining the Gram stain. A number of other bacteria—that are bounded by

624-526: The outer cell membrane in gram-negative bacteria (diderms) has evolved as a protective mechanism against antibiotic selection pressure. Some bacteria, such as Deinococcus , which stain gram-positive due to the presence of a thick peptidoglycan layer and also possess an outer cell membrane are suggested as intermediates in the transition between monoderm (gram-positive) and diderm (gram-negative) bacteria. The diderm bacteria can also be further differentiated between simple diderms lacking lipopolysaccharide,

650-437: The peptidoglycan. Along with cell shape , Gram staining is a rapid method used to differentiate bacterial species. Such staining, together with growth requirement and antibiotic susceptibility testing, and other macroscopic and physiologic tests, forms a basis for practical classification and subdivision of the bacteria (e.g., see figure and pre-1990 versions of Bergey's Manual of Systematic Bacteriology ). Historically ,

676-531: The surname of Hans Christian Gram ; as eponymous adjectives , their initial letter can be either capital G or lower-case g , depending on which style guide (e.g., that of the CDC ), if any, governs the document being written. Cryptobacterium Cryptobacterium is a genus of Actinomycetota , in the family Coriobacteriaceae . Up to now there is only one species of this genus known ( Cryptobacterium curtum ). This Actinomycetota -related article

#537462