Polysaccharides, or polycarbohydrates, are the most abundant carbohydrates found in food. They are long-chain polymeric carbohydrates composed of monosaccharide units bound together by glycosidic linkages. This carbohydrate can react with water (hydrolysis) using amylase enzymes as catalyst, which produces constituent sugars. They range in structure from linear to highly branched. Examples include storage polysaccharides such as starch, glycogen and galactogen and structural polysaccharides such as cellulose and chitin.
Inulins are a group of naturally occurring polysaccharides produced by many types of plants, industrially most often extracted from chicory. The inulins belong to a class of dietary fibers known as fructans. Inulin is used by some plants as a means of storing energy and is typically found in roots or rhizomes. Most plants that synthesize and store inulin do not store other forms of carbohydrate such as starch. In the United States in 2018, the Food and Drug Administration approved inulin as a dietary fiber ingredient used to improve the nutritional value of manufactured food products. Using inulin to measure kidney function is the "gold standard" for comparison with other means of estimating glomerular filtration rate.
A fructan is a polymer of fructose molecules. Fructans with a short chain length are known as fructooligosaccharides. Fructans can be found in over 12% of the angiosperms including both monocots and dicots such as agave, artichokes, asparagus, leeks, garlic, onions, yacón, jícama, barley and wheat.
β-Amylase is an enzyme with the systematic name 4-α-D-glucan maltohydrolase. It catalyses the following reaction:
Galactosidases are enzymes that catalyze the hydrolysis of galactosides into monosaccharides.
The blue–white screen is a screening technique that allows for the rapid and convenient detection of recombinant bacteria in vector-based molecular cloning experiments. This method of screening is usually performed using a suitable bacterial strain, but other organisms such as yeast may also be used. DNA of transformation is ligated into a vector. The vector is then inserted into a competent host cell viable for transformation, which are then grown in the presence of X-gal. Cells transformed with vectors containing recombinant DNA will produce white colonies; cells transformed with non-recombinant plasmids grow into blue colonies.
Fructosides are glycosides where the glycone group is fructose.
The enzyme levan fructotransferase (DFA-IV-forming) catalyzes the following process:
In enzymology, a 2,1-fructan:2,1-fructan 1-fructosyltransferase is an enzyme that catalyzes the chemical reaction
In enzymology, a 6G-fructosyltransferase is an enzyme that catalyzes the chemical reaction
In enzymology, an amylosucrase is an enzyme that catalyzes the chemical reaction
In enzymology, a dextransucrase is an enzyme that catalyzes the chemical reaction
In enzymology, an inulosucrase is an enzyme that catalyzes the chemical reaction
In enzymology, a sucrose:sucrose fructosyltransferase is an enzyme that catalyzes the chemical reaction
Levan is a naturally occurring fructan present in many plants and microorganisms. This polymer is made up of fructose, a monosaccharide sugar, connected by 2,6 beta glycosidic linkages. Levan can have both branched and linear structures of relatively low molecular weight. Branched levan forms a very small, sphere-like structure with basal chains 9 units long. The 2,1 branching allows methyl ethers to form and create a spherical shape. The ends of levan also tend to contain a glucosyl residue. Branched levan tends to be more stable than linear polysaccharides. However, the amount of branching and length of polymerization tends to vary among different species. The shortest levan is 6-kestose, a chain of two fructose molecules and a terminal glucose molecule.
Plasmid-mediated resistance is the transfer of antibiotic resistance genes which are carried on plasmids. Plasmids possess mechanisms that ensure their independent replication as well as those that regulate their replication number and guarantee stable inheritance during cell division. By the conjugation process, they can stimulate lateral transfer between bacteria from various genera and kingdoms. Numerous plasmids contain addiction-inducing systems that are typically based on toxin-antitoxin factors and capable of killing daughter cells that don't inherit the plasmid during cell division. Plasmids often carry multiple antibiotic resistance genes, contributing to the spread of multidrug-resistance (MDR). Antibiotic resistance mediated by MDR plasmids severely limits the treatment options for the infections caused by Gram-negative bacteria, especially family Enterobacteriaceae. The global spread of MDR plasmids has been enhanced by selective pressure from antimicrobial medications used in medical facilities and when raising animals for food.
In molecular biology, glycoside hydrolase family 68 is a family of glycoside hydrolases.
In molecular biology, glycoside hydrolase family 27 is a family of glycoside hydrolases.
2,6-β-Fructan 6-levanbiohydrolase is an enzyme with systematic name (2→6)-β-D-fructofuranan 6-(β-D-fructosyl)-D-fructose-hydrolase. This enzyme catalyses the following chemical reaction
Kestose is a class of sugars that belongs to a group of fructooligosaccharides.
SacB counter-selection relies on the toxic product produced by the SacB gene. sacB comes from the gram-positive bacteria Bacillus subtilis and encodes the enzyme levansucrase that converts sucrose into a toxic metabolite in gram-negative bacteria. Plating on sucrose medium will select for cells that contain constructs that have lost the sacB gene. [1]
