Figure 2From: Xylitol production from xylose mother liquor: a novel strategy that combines the use of recombinant Bacillus subtilis and Candida maltosaIdentification of recombinant B. subtilis carrying the xylose isomerase gene disruption. A, PCR identification of two recombinant B. subtilis strains carrying the xylose isomerase gene disruption (lanes 1 and 2) and two wild-type B. subtilis strains (lanes 3 and 4). To create the recombinant strains, the 1.4-kb DNA was amplified using two sets of primers (see Method and Materials); B, HPLC analysis of the xylose isomeric reaction. The xylose isomeric reaction with the crude extract from strain BSxyl (xylA disrupted); DNA markers from the bottom of the gel are in the following order: 500 bp, 1 kb, 1.5 kb, and 2 kb. B, HPLC analysis of the xylose isomeric reaction with the crude extract from recombinant (I) and wild-type B. subtilis 168 (II). No D-xylulose was detected after incubation with the crude extract from the xylA- gene-disrupted strain BSxyl (I), while D-xylulose could be detected using the crude extract from the control strain B. subtilis 168 as enzyme and xylose as substrate (II). C, TLC assay of the culture medium of recombinant BSxyl (i) and B. subtilis 168 (ii). The culture medium consisted of LB and 10 g L-1 xylose. The spot in 1 represents 1 μL of 10 g L-1 xylose standard, and the spots in 2, 3, 4, and 5 show 1 μL of each sample taken at 0, 8, 16, and 24 h.Back to article page