l-Ribulose production from l-arabinose by an l-arabinose isomerase mutant from Geobacillus thermodenitrificans

Abstract

Geobacillus thermodenitrificans, with a double-site mutation in L-arabinose isomerase, produced 95 g L-ribulose l(-1 ) from 500 g L-arabinose l(-1) under optimum conditions of pH 8, 70 degrees C, and 10 units enzyme ml(-1) with a conversion yield of 19% over 2 h. The half-lives of the mutated enzyme at 70 and 75 degrees C were 35 and 4.5 h, respectively.

Immobilization ofBacillus licheniformisL-Arabinose Isomerase for Semi-ContinuousL-Ribulose Production

“…This yield is higher than that (19%) catalyzed by L-AI mutant from G. thermodenitrificans. 24) To our knowledge, this is the first report demonstrating the feasibility of continuous production of L-ribulose with an immobilized enzyme. Immobilization of BLAI on Eupergit C might prove valuable as a cost-effective means of industrial-scale production of L-ribulose.…”

“…As listed in Table 4, although the K m of the immobilized BLAI was higher than that of the other L-AIs, its V max value was higher than that of the others. In addition, the immobilized BLAI had the longest t 1=2 , 707, 236, 106, and 6.6 times than that of free enzymes from Bacillus halodurans, 22) Geobacillus stearothermophilus, 22) Thermotoga neapolitana 23) and B. licheniformis, 5) and Geobacillus thermodenitrificans 24) respectively.…”

l -Ribose Production from l -Arabinose by Using Purified l -Arabinose Isomerase and Mannose-6-Phosphate Isomerase from Geobacillus thermodenitrificans

“…L-Ribose has been produced from L-ribulose using mannose-6-phosphate isomerase (MPI) from Bacillus subtilis with a conversion yield of 70% (17). In this study, the production of L-ribose from L-arabinose was demonstrated via a two-enzyme system from G. thermodenitrificans, in which L-ribulose was first produced from L-arabinose by AI and subsequently converted to L-ribose by MPI.The analysis of monosaccharides and the purification and thermostability of AI and MPI from G. thermodenitrificans (2) isolated from compost were performed as described previously (7,18,19). The cross-linked enzymes were obtained from the treatment of 0.5% glutaraldehyde (10, 16).…”

“…The analysis of monosaccharides and the purification and thermostability of AI and MPI from G. thermodenitrificans (2) isolated from compost were performed as described previously (7,18,19). The cross-linked enzymes were obtained from the treatment of 0.5% glutaraldehyde (10, 16).…”

“…L-Ribose isomerase from an Acinetobacter sp., which is most active with Lribose, showed poor efficiency in the conversion of L-ribulose to L-ribose (9). Recently, L-ribulose was produced with a conversion yield of 19% from the inexpensive sugar L-arabinose using L-arabinose isomerase (AI) from Geobacillus thermodenitrificans (18). L-Ribose has been produced from L-ribulose using mannose-6-phosphate isomerase (MPI) from Bacillus subtilis with a conversion yield of 70% (17).…”