Arxula adeninivorans
Microscopic representation of B. adeninivorans cells cultured at 30 ° C (a), 37 ° C. (b) 42 ° C (C) and 45 ° C ( d). You can see the transition from normal yeast cells in filamentous cells from 42 ° C] ]
Blastobotrys adeninivorans also Arxula adeninivorans is a dimorphic yeast species with unusual properties. It was first described in the mid-1980s and initially called Trichosporon adeninivorans.
Basics
After their discovery in the Netherlands strains of this species were, inter alia, found in Siberia and South Africa. They were isolated from soil samples and Holzhydrolysaten. After detailed phylogenetic comparisons with related yeast species Arxula adeninivorans was renamed in 2007 in Blastobotrys adeninivorans. The former scientific name but is used more often. All B. adeninivorans strains have unusual biochemical activities. You are able to in addition to various sugars amines, adenine (hence the name adeninivorans ) and other purines to use as the sole carbon source. Furthermore, they can assimilate nitrate and are thermo tolerant, ie they can grow up to 48 ° C at temperatures. A special characteristic of biotechnological importance is a temperature-dependent dimorphism. At temperatures above 42 ° C, a reversible transformation of normal yeast cells in filamentous forms ( similar to that of fungi ) is induced. Yeast forms recur in lowering the cultivation temperature back below 42 ° C. With the change of morphology differences in the secretion of proteins and in the modification ( attachment of sugar chains) are connected ( see figure in Taxobox ).
Biotechnological potential
Applications in biotechnology
A company and an academic institution to use this yeast for such applications. Here as an example two genetically modified strains and their application: in both cases, several plasmids were transferred with different protein genes simultaneously in the yeast. In the first example, a strain was provided by genetic engineering with the ability to produce a degradable by biological means plastic material, namely PHA ( polyhydroxyalkanoate ). This required a new synthetic route consisting of three enzymatic steps, are transferred to the yeast. The corresponding genes phbA, phbB, and phbC were isolated from the bacterium Ralstonia eutropha and appropriate, usable for the yeast form integrated into plasmids. These plasmids were introduced into the yeast, and the thus produced was genetically modified organism capable of producing the plastic material effectively. In the second example, a biosensor for the detection of estrogen in environmental samples was developed. For this purpose, the active chain of estrogen has been imitated in yeast. First, a gene for the human estrogen receptor alpha ( hERalpha ) was transferred to the yeast on a first plasmid. Such a receptor recognizes and binds the hormone. The receptor interact upon binding of the estrogen with a second gene, which is activated by this interaction. Such a " reporter gene" was transferred to a second plasmid in the yeast. The " reporter gene" includes the manufacturing instructions for the manufacture of an easily detected with simple test protein, such as an enzyme or a dye, this gene was in this case as a fusion to a control element in front of, a promoter, which was so modified to receptor to / hormone could recognize complex. Such a modified strain can 'll cultured in the presence of some water samples. The concentration can then ( as color intensity or enzyme activity) can be accurately determined in correlation to the amount of the reporter gene.