Phaffia yeast is a new genus of Basidiomycetes. Phaffia yeast is relatively special in Basidiomycetes, mainly in its ability to ferment sugars, and contains astaxanthin, astaxanthin is a kind of carotenoid that have a wide range of application in health care products, pharmaceuticals, cosmetics material, food additives.
This makes Phaffia yeast different from the other red yeast’s strictly aerobic characterstic, pigments are mainly the ²-carotene and monocyclic carotenoids. Shortly after found astaxanthin in Phaffia yeast, people began to study the feasibility of its application and its effects on the organism pigment formation and get good results.
For high-yielding astaxanthin’s breeding, now astaxanthin manufacturer has pay attention to astaxanthin oversynthesized Mutants. In recent years, scientists in this area have been made a lot of progress. Such as get the Phaffia yeast mutant strain, the astaxanthin content increased 232%, reaching 1500 mg/kg dry cells. Use alcohol waste medium screening phaffia yeast NRRLY-17269 mutants JB2, in 5 liter fermentor trials, every per kg dry cells obtained (2010 ± 170) mg of carotenoids production. In addition, the studies of using recombinant DNA technology to build high-yielding astaxanthin genetically engineered bacteria has already started, and in the transformation of the yeast Phaffia system, the key enzymes and enzyme genes encoding biosynthesis astaxanthin pathway has also made some progress.
The production of astaxanthin not only related to species, but also related to the culture conditions. Use yeast Phaffia strains UCD67-210 as an experimental, study several important parameters that effect the fermentation, such as: pn value, temperature, type and concentration of carbon, oxygen and light and so on. Get the optimum fermentation parameters: pH value 5.0, temperature 20 ~ 22, best carbon is fiber two-phase. Sugar concentration exceeding 1.5 % would reduce the unit weight of cell astaxanthin content, but due to the increase of biomass, per unit volume astaxanthin contained also increase, dissolve oxygen up to 3.6 to 108 mmol/l • hours, but the light has little effect on astaxanthin. In researching continuous culture Phaffia yeast pH line control, it was found that the glucose pH (5.02) is higher than the medium pH (5.00), Phaffia yeast growth is relatively slow (0.055 - 1 hour); and add sugar the pH value control in 4.98, the growth speed up to 0.095 to 1 hour. It was also found, the time interval has a major impact on the growth of the yeast. When the yeast Phaffia NCHU ~ FS501 study glucose concentration reached 35g/l, astaxanthin yield can reach 16.33 mg/l; when glucose concentration at or more than 45g/l, astaxanthin formation is inhibited.
Reduce fermentation costs, in addition to the low production of astaxanthin, another adverse factor impact the commercial applications of Phaffia yeast make Phaffia yeast’s medium cost relatively high. Some cheap food processing wastes, such as alfalfa Chih purple residue will effectively promote yeast growth, however, will also inhibit the formation of astaxanthin. This inhibition is due to the presence of saponins. Use starch and alcohol waste screened NRRLY-17269 Phaffia yeast mutant JB2, and carotenoid yield cultured in alcohol can up to 1330 to 1750 mg/kg dry matter, which makes the medium cost greatly reduce. At present, the extraction of astaxanthin is broken in various ways first, and then extracted with an organic solvent. Chinese scholars with acid treatment cells, extracted with acetone, the effect is good.
Source:http://www.cosprm.com
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