Bacteria

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 the air, 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

A flagellum (; : flagella) (Latin for 'whip' or 'scourge') is a hair-like appendage that protrudes from certain plant and animal sperm cells, from fungal spores (zoospores), and from a wide range of microorganisms to provide motility. Many protists with flagella are known as flagellates.

right|thumb|300px|The bright colors of Grand Prismatic Spring in [[Yellowstone National Park are produced by thermophiles, a type of extremophile.]]

right|thumb|350px|Schematic drawing of bacterial conjugation. 1- Donor cell produces pilus. 2- Pilus attaches to recipient cell, brings the two cells together. 3- The mobile plasmid is nicked and a single strand of DNA is then transferred to the recipient cell. 4- Both cells recircularize their plasmids, synthesize second strands, and reproduce pili; both cells are now viable donors. A pilus (Latin for 'hair'; : pili) is a hair-like cell-surface appendage found on many bacteria and archaea. The terms pilus and fimbria (Latin for 'fringe'; plural: fimbriae) can be used interchangeably, although

group of bacterial species

microorganisms which "breathe" sulfates

thumb|upright=2| Diverse microbial communities of characteristic microbiota are part of plant microbiomes, and are found on the outside surfaces and in the internal tissues of the host plant, as well as in the surrounding soil.

specialized anatomy and physiology of bacteria

a microbial organism's resistance to multiple antimicrobial drugs or a cancer cell's resistance to multiple cytostatics

thumb|right|320px|Mycobacterium tuberculosis (stained red) in tissue (blue).

thumb|upright|right|Gram-negative bacteria attempting to grow and divide in the presence of peptidoglycan synthesis-inhibiting antibiotics (e.g. penicillin) fail to do so, and instead end up forming spheroplasts. A spheroplast (or sphaeroplast in British usage) is a microbial cell from which the cell wall has been almost completely removed, as by the action of penicillin or lysozyme. According to some definitions, the term is used to describe Gram-negative bacteria. According to other definitions, the term also encompasses yeasts. The name spheroplast stems from the fact that after the microbe

The Thermomicrobia is a group of thermophilic green non-sulfur bacteria. Based on species Thermomicrobium roseum (type species) and Sphaerobacter thermophilus, this bacteria class has the following description:

alt=|thumb|377x377px|Some representative hopanoids: A. Diploptene, also called 22(29)-hopene B. Diplopterol, also called hopan-22-ol, the hydrated cyclomer of diploptene C. Bacteriohopanetetrol (BHT), a common extended hopanoid D. Hopane, the diagenetic product of A and B that results from reducing conditions during deposition and persists in the rock record. The diagenetic product of C would be an extended C35 hopane.Hopanoids are a diverse subclass of triterpenoids with the same hydrocarbon skeleton as the compound hopane. This group of pentacyclic molecules therefore refers to simple hopene

growth form of bacteria that lacks cell walls

polyphyletic group of bacteria that orient themselves along the magnetic field lines of Earth’s magnetic field

thumb|A SCOBY used for brewing kombucha thumb|Kombucha co-culture with SCOBY biofilm

DD-Transpeptidase (, DD-peptidase, DD-transpeptidase, DD-carboxypeptidase, D-alanyl-D-alanine carboxypeptidase, D-alanyl-D-alanine-cleaving-peptidase, D-alanine carboxypeptidase, D-alanyl carboxypeptidase, and serine-type D-Ala-D-Ala carboxypeptidase.) is a bacterial enzyme that catalyzes the transfer of the R-L-αα-D-alanyl moiety of R-L-αα-D-alanyl-D-alanine carbonyl donors to the γ-OH of their active-site serine and from this to a final acceptor. It is involved in bacterial cell wall biosynthesis, namely, the transpeptidation that crosslinks the peptide side chains of peptidoglycan strands.

study of the ecology of microorganisms

experiment showing that in bacteria, genetic mutations arise in the absence of selection, rather than being a response to selection.

In biology, axenic (, ) describes the state of a culture in which only a single species, variety, or strain of organism is present and entirely free of all other contaminating organisms. The earliest axenic cultures were of bacteria or unicellular eukaryotes, but axenic cultures of many multicellular organisms are also possible. Axenic culture is an important tool for the study of symbiotic and parasitic organisms in a controlled environment.

Flavodoxins (Fld) are small, soluble electron-transfer proteins. Flavodoxins contain flavin mononucleotide as prosthetic group. The structure of flavodoxin is characterized by a five-stranded parallel beta sheet, surrounded by five alpha helices. They have been isolated from prokaryotes, cyanobacteria, and some eukaryotic algae.

gluey polymers secreted by microorganisms to form biofilms

fat-loving bacteria

group of bacteria

microbiological method for rapid identification

term in biology

bacteria using nitrate and nitrite as a terminal electron acceptor

envelope that surrounds a bacterial cell and includes the cytoplasmic membrane and everything external, encompassing the periplasmic space, cell wall, and outer membrane if present

A piezophile (from Greek "piezo-" for pressure and "-phile" for loving) is an organism with optimal growth under high hydrostatic pressure, i.e., an organism that has its maximum rate of growth at a hydrostatic pressure equal to or above , when tested over all permissible temperatures. Originally, the term barophile was used for these organisms, but since the prefix "baro-" stands for weight, the term piezophile was given preference. Like all definitions of extremophiles, the definition of piezophiles is anthropocentric, and humans consider that moderate values for hydrostatic pressure are tho

corrosion caused or promoted by microorganisms

Ultramicrobacteria are bacteria that are smaller than 0.1 μm3 under all growth conditions. This term was coined in 1981, describing cocci in seawater that were less than 0.3 μm in diameter. Ultramicrobacteria have also been recovered from soil and appear to be a mixture of gram-positive, gram-negative and cell-wall-lacking species. Ultramicrobacteria possess a relatively high surface-area-to-volume ratio due to their small size, which aids in growth under oligotrophic (i.e. nutrient-poor) conditions. The relatively small size of ultramicrobacteria also enables parasitism of larger organisms; s

agricultural amendment

first organisms to be modified in the laboratory

Gracilicutes (Latin: gracilis, slender, and cutis, skin, referring to the cell wall) is a clade in bacterial phylogeny.

thumb|right|300px|Cross section though a soybean (Glycine max 'Essex') root nodule: The rhizobacteria, Bradyrhizobium|Bradyrhizobium japonicum, colonizes the roots and establishes a nitrogen-fixing symbiosis. This high-magnification image shows part of a cell with single bacteroids within their host plant. In this image, endoplasmic reticulum, dictysome, and cell wall can be seen.

form of motility in biology

cyanobacterial organellum

a process in which the presence of one nutrient source leads to a decrease in the frequency, rate, or extent of processes involved in the metabolism of other nutrient sources

An acetogen is a microorganism that generates acetate (CH3COO−) as an end product of either anaerobic respiration or fermentation. In a narrower sense, a homoacetogen is a bacterial or archaeal microorganism that performs anaerobic respiration and carbon fixation simultaneously through the reductive acetyl coenzyme A (acetyl-CoA) pathway – also known as the Wood-Ljungdahl pathway; they can produce acetyl-CoA (and from that, in most cases, acetate as the end product) from two molecules of carbon dioxide (CO2) and four molecules of molecular hydrogen (H2). This process is known as acetogenesis,

A bacteriome is a specialized organ, found mainly in some insects, that hosts endosymbiotic bacteria. Bacteriomes contain specialized cells, called bacteriocytes, that provide nutrients and shelter to the bacteria while protecting the host animal. In exchange, the bacteria provide essentials like vitamins and amino acids to the host insect. Bacteriomes also protect the bacteria from the host's immune system, with insects secreting antimicrobial peptides such as the coleoptericin secreted by weevils to keep bacteria within the bacteriome.

Bacteria that produce light through chemiluminescence

the generation of RNA transcripts of the genetic material in prokaryotes

Bioprecipitation is the concept of rain-making bacteria and was proposed by David Sands from Montana State University in the 1970s. This is precipitation that is beneficial for microbial and plant growth, it is a feedback cycle beginning with land plants generating small air-borne particles called aerosols that contain microorganisms that influence the formation of clouds by their ice nucleation properties. The formation of ice in clouds is required for snow and most rainfall. Dust and soot particles can serve as ice nuclei, but biological ice nuclei are capable of catalyzing freezing at much

Saccharibacteria, formerly known as TM7, is a major bacterial lineage. It was discovered through 16S rRNA sequencing .

Cable bacteria are filamentous bacteria that conduct electricity across distances over 1 cm in sediment and groundwater aquifers

adaptive mechanism

bacteria that are in a state of very low metabolic activity and do not divide, but are alive and have the ability to become culturable once resuscitated