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A hemicellulose is one of a number of heteropolymers, such as arabinoxylans, present along with cellulose in almost all terrestrial plant cell walls. While cellulose is crystalline, strong, and resistant to hydrolysis, hemicelluloses have random, amorphous structure with little strength. They are easily hydrolyzed by dilute acid or base as well as a myriad of hemicellulase enzymes.
The phylum Bacteroidota is composed of three large classes of Gram-negative, nonsporeforming, anaerobic or aerobic, and rod-shaped bacteria that are widely distributed in the environment, including in soil, sediments, and sea water, as well as in the guts and on the skin of animals.
Lacticaseibacillus casei is an organism that belongs to the largest genus in the family Lactobacillaceae, a lactic acid bacteria (LAB), that was previously classified as Lactobacillus casei-01. This bacteria has been identified as facultatively anaerobic or microaerophilic, acid-tolerant, non-spore-forming bacteria. The taxonomy of this group has been debated for several years because researchers struggled to differentiate between the strains of L. casei and L. paracasei. It has recently been accepted as a single species with five subspecies: L. casei subsp. rhamnosus, L. casei subsp. alactosus, L. caseisubsp. casei'', L. casei subsp. tolerans, and L. casei subsp. pseudoplantarum. The taxonomy of this genus was determined according to the phenotypic, physiological, and biochemical similarities.
Thermus thermophilus is a Gram-negative bacterium used in a range of biotechnological applications, including as a model organism for genetic manipulation, structural genomics, and systems biology. The bacterium is extremely thermophilic, with an optimal growth temperature of about 65 °C (149 °F). Thermus thermophilus was originally isolated from a thermal vent within a hot spring in Izu, Japan by Tairo Oshima and Kazutomo Imahori. The organism has also been found to be important in the degradation of organic materials in the thermogenic phase of composting. T. thermophilus is classified into several strains, of which HB8 and HB27 are the most commonly used in laboratory environments. Genome analyses of these strains were independently completed in 2004.
Xylan is a type of hemicellulose, a polysaccharide consisting mainly of xylose residues. It is found in plants, in the secondary cell walls of dicots and all cell walls of grasses. Xylan is the third most abundant biopolymer on Earth.
Gliding motility is a type of translocation used by microorganisms that is independent of propulsive structures such as flagella, pili, and fimbriae. Gliding allows microorganisms to travel along the surface of low aqueous films. The mechanisms of this motility are only partially known.
Cytophaga is a genus of Gram-negative, gliding, rod-shaped bacteria. This bacterium is commonly found in soil, rapidly digests crystalline cellulose C. hutchinsonii is able to use its gliding motility to move quickly over surfaces. Although the mechanism for this is not known, there is a belief that the flagella is not used
Butyrivibrio is a genus of bacteria in Class Clostridia. Bacteria of this genus are common in the gastrointestinal systems of many animals. Genus Butyrivibrio was first described by Bryant and Small (1956) as anaerobic, butyric acid-producing, curved rods. Butyrivibrio cells are small, typically 0.4 – 0.6 µm by 2 – 5 µm. They are motile, using a single polar or subpolar monotrichous flagellum. They are commonly found singly or in short chains but it is not unusual for them to form long chains. Despite historically being described as Gram-negative, their cell walls contain derivatives of teichoic acid, and electron microscopy indicates that bacteria of this genus have a Gram-positive cell wall type. It is thought that they appear Gram-negative when Gram stained because their cell walls thin to 12 to 18 nm as they reach stationary phase.
Clostridium phytofermentans is an obligately anaerobic, rod-shaped spore-forming, Gram-positive bacterium in the family Lachnospiraceae. It is a model organism of interest for its ability to rapidly ferment diverse plant polysaccharides including cellulose, hemicellulose, and pectin to ethanol, acetate, and hydrogen. The C. phytofermentans 4.8 Mb genome has been fully sequenced, revealing it contains over 170 enzymes in the CAZy database, though one hydrolase appears to be essential for degrading cellulose.
Alpha-L-arabinofuranosidase is an enzyme with systematic name alpha-L-arabinofuranoside arabinofuranohydrolase. This enzyme catalyses the following chemical reaction
Acidobacterium capsulatum is a bacterium. It is an acidophilic chemoorganotrophic bacterium containing menaquinone. It is gram-negative, facultative anaerobic, mesophilic, non-spore-forming, capsulated, saccharolytic and rod-shaped. It is also motile by peritrichous flagella. Its type strain is JCM 7670.
Clostridium stercorarium is a cellulolytic thermophilic bacterium. It is anaerobic, spore-forming and saccharoclastic, with cells being rod-shaped and 0.7 to 0.8 by 2.7 to 7.7 µm in size. Its genome has been sequenced.
Clostridium straminisolvens is a moderately thermophilic, aerotolerant and cellulolytic bacterium. It is non-motile, spore-forming, straight or slightly curved rod, with type strain CSK1T. Its genome has been sequenced.
Spirochaeta thermophila is a fairly recently discovered free-living, anaerobic, spirochaete that seems to be the most thermophilic of the Spirochaetales order. The type species was discovered in 1992 in Kuril islands, Russia and described in Aksenova, et al. It has been isolated in the sediments and water columns of brackish aquatic habitats of various ponds, lakes, rivers, and oceans. This organism is identified as a new species based on its unique ability to degrade cellulose, xylan, and other α- and β-linked sugars and use them as the sole carbon source by encoding many glycoside hydrolases. It is presumed to secrete cellulases to break down plant-matter around it but there has been little work on the characterization of the enzymes responsible for this.
Cellulosimicrobium cellulans is a Gram-positive bacterium from the genus of Cellulosimicrobium. Cellulosimicrobium cellulans can cause rare opportunistic infections. The strain EB-8-4 of this species can be used for stereoselective allylic hydroxylation of D-limonene to (+)-trans-carveol.
Polaribacter is a genus in the family Flavobacteriaceae. They are gram-negative, aerobic bacteria that can be heterotrophic, psychrophilic or mesophilic. Most species are non-motile and species range from ovoid to rod-shaped. Polaribacter forms yellow- to orange-pigmented colonies. They have been mostly adapted to cool marine ecosystems, and their optimal growth range is at a temperature between 10 and 32 °C and at a pH of 7.0 to 8.0. They are oxidase and catalase-positive and are able to grow using carbohydrates, amino acids, and organic acids.
Komagataeibacter xylinus is a species of bacteria best known for its ability to produce cellulose, specifically bacterial cellulose.
Bacteroides caccae is a saccharolytic gram-negative bacterium from the genus Bacteroides. They are obligate anaerobes first isolated from human feces in the 1980s. Prior to their discovery, they were known as the 3452A DNA homology group. The type strain is now identified as ATCC 43185.
Cytophaga hutchinsonii is a bacterial species in the genus Cytophaga. C. hutchinsonii is an aerobic, gram-negative, soil, microorganism that exhibits gliding motility, enabling it to move quickly over surfaces and is capable of cellulose degradation.
Cytophagales is an order of non-spore forming, rod-shaped, Gram-negative bacteria that move through a gliding or flexing motion. These chemoorganotrophs are important remineralizers of organic materials into micronutrients. They are widely dispersed in the environment, found in ecosystems including soil, freshwater, seawater and sea ice. Cytophagales is included in the Bacteroidota phylum.
References
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