Applied Microbiology and Biotechnology, Vol.98, No.7, 2947-2953, 2014
Production of darabitol from raw glycerol by Candida quercitrusa
To promote the effective use of raw glycerol (a by-product of biodiesel production), 110 yeast strains that produce d-arabitol from glycerol were isolated from environmental samples. Among them, strain 17-2A was an effective d-arabitol producer in the presence of 250 g/l glycerol and was identified as Candida quercitrusa based on morphological, physicochemical, and phylogenetic analyses. C. quercitrusa type strain NBRC1022 produced the greatest quantity of d-arabitol (41.7 g/l) when the ability to produce d-arabitol from raw glycerol was compared among C. quercitrusa 17-2A and its phylogenetically related strains in flask culture. Under optimized culture conditions, strain NBRC1022 produced d-arabitol at a concentration of 58.2 g/l after a 7-day cultivation in 250 g/l glycerol, 6 g/l yeast extract, and 2 g/l CaCl2. The culture conditions were further investigated with raw glycerol using a jar fermenter; the concentration of d-arabitol reached 67.1 g/l after 7 days and 85.1 g/l after 10 days, respectively, which corresponded to 0.40 g/g of glycerol. To our knowledge, the present d-arabitol yield from glycerol is higher than reported previously using microbial production.