Polyol accumulation by Aspergillus oryzae at low water activity in solid-state fermentation.
Polyol accumulation and metabolism were examined in Aspergillus oryzae cultured on whole wheat grains or on wheat dough as a model for solid-state culture. In solid-state fermentation (SSF), water activity (a(w)) is typically low resulting in osmotic stress. In addition to a high level of mannitol, which is always present in the cells, A. oryzae accumulated high concentrations of glycerol, erythritol and arabitol at relatively low a(w) (0.96-0.97) in SSF. Accumulation of such a mixture of polyols is rather unusual and might be typical for SSF. A. oryzae mycelium accumulating various polyols at low a(w) contained at least four distinct polyol dehydrogenases with highest activities toward glycerol, erythritol, D-arabitol and mannitol. NADP(+)-dependent glycerol dehydrogenase activity correlated very well with glycerol accumulation. A similar correlation was observed for erythritol and NADP(+)-erythritol dehydrogenase suggesting that NADP(+)-dependent glycerol and erythritol dehydrogenases are involved in biosynthesis of glycerol and erythritol, respectively, and that these enzymes are induced by osmotic stress.
Ruijter
George J G
GJG
Wageningen University, Laboratory of Microbiology, Dreijenlaan 2, 6703HA Wageningen, The Netherlands.|Wageningen Centre for Food Sciences, PO Box 557, 6700AN Wageningen, The Netherlands.
Visser
Jaap
J
Wageningen Centre for Food Sciences, PO Box 557, 6700AN Wageningen, The Netherlands.
Rinzema
Arjen
A
Wageningen University, Food and Bioprocess Engineering Group, PO Box 8129, 6700EV Wageningen, The Netherlands.|Wageningen Centre for Food Sciences, PO Box 557, 6700AN Wageningen, The Netherlands.
D001236:Aspergillus oryzae / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D001939:Bread / Q000382:microbiology; D003470:Culture Media; D004896:Erythritol / Q000378:metabolism; D005285:Fermentation; D015966:Gene Expression Regulation, Fungal; D005990:Glycerol / Q000378:metabolism; D008353:Mannitol / Q000378:metabolism; D025282:Mycelium / Q000201:enzymology; D009249:NADP / Q000378:metabolism; D009997:Osmotic Pressure; D011108:Polymers / Q000378:metabolism*; D013401:Sugar Alcohol Dehydrogenases / Q000235:genetics / Q000378:metabolism; D013402:Sugar Alcohols / Q000378:metabolism; D014908:Triticum / Q000382:microbiology; D014867:Water
D003470:Culture Media; D011108:Polymers; D013402:Sugar Alcohols; C024617:polyol; D014867:Water; D008353:Mannitol; D009249:NADP; D013401:Sugar Alcohol Dehydrogenases; D005990:Glycerol; D004896:Erythritol; C014999:arabitol