Bacterial reporter strains for D-xylose content analysis in arabinoxylans

A pair of ice nucleation and fluorescence reporter strains induced specifically by d-xylose were developed and optimized, to monitor d-xylose content in hydrolyzed arabinoxylans samples. Reporter strains were developed by fusing the Escherichia coli xylose isomerase promoter P (xylA) to the promoterless native inaZ gene of Pseudomonas syringae and synthetic gfp gene of Aequorea victoria and transferring final constructs to E. coli DH5 alpha. Because of relatively low initial response toward the target analyte, signal improvement by promoter region length adjustment has been implemented. In both cases, this approach proved to be successful, although the manner in which reporter strains have responded to it was dissimilar. The specificity and quantitative response of obtained reporter strains have been confirmed, and the response ranges for NIxylA100 and gfpxylA300 have been established as 9 x 10(-6)-9 x 10(-1) g l(-1) and 9 x 10(-3)-9 g l(-1), respectively. The performance of developed reporter strains has been assessed in comparison with high-performance anion-exchange chromatography and demonstrated 15-18 % difference between data obtained with reporter strains and chromatography analysis, which for microbial sensors is an acceptable dissimilarity. The developed microbial reporter strains present an alternative for other analytical methods used for monosaccharide quantification and enable quantification of d-xylose in arabinoxylans samples.