The invention relates to a
microorganism and a microbial
fermentation process thereof, in particular to a
chromium-rich
yeast culture and a
fermentation process thereof. The process is characterized by selecting and screening
Candida tropicalis and
saccharomyces cerevisiae tolerant of high
chromium and carrying out production through a liquid-
solid two-phase
fermentation process. The process flow comprises that: high-
chromium-tolerant (trivalent) strains are screened; the strains are progressively expanded and cultured; liquid fermentation is performed to transform inorganic chromium, wherein the content of the inorganic chromium in a culture medium is 0.05 to 0.4 percent, preferably 0.1 to 0.2 percent, and the time of fermentation and transformation is 12 to 48 hours, preferably 18 to 26hours; after the liquid fermentation is over, culture solution and a
solid culture medium are mixed according to the weight ratio of 1:3-1.5:1, preferably 1:1, and are subjected to
solid aerobic fermentation for 16 to 36 hours, preferably 16 to 24 hours; after the solid aerobic fermentation is over, solid anaerobic fermentation is performed to break the wall of
yeast at a temperature kept between40 and 60 DEG C for 6 to 24 hours, preferably at 50 DEG C for 6 to 10 hours; and a finished product after
drying contains organic chromium accounting for 0.05 to 0.3 percent. The proportion of transforming the inorganic chromium into the organic chromium by utilizing a technique of the invention is more than 85 percent, and no
hexavalent chromium is detected. The chromium-rich
yeast culture produced in the invention has the characteristics of simple process, low production cost, good product quality and the like, has the double function of organic chromium and
probiotic feed, and can be used for feed of
livestock, poultry and aquatic products.