Project description:The transcriptional responses of Prevotella ruminicola were determined during growth on 20 different carbohydrate sources including mono-, di- and tri- saccharides, oligosaccharides, polymeric xylan and complete plant material with the aim of obtaining a more complete understanding of the number of genes and metabolic networks associated with carbohydrate catabolism by this organism
Project description:Feruloyl esterases (Faes) constitute a subclass of carboxyl esterases that specifically hydrolyze the ester linkages between ferulate and polysaccharides in plant cell walls. Until now, the described microbial Faes were mainly from fungi. In this study, we report that Cellulosilyticum ruminicola H1, a previously described fibrolytic rumen bacterium, possesses three different active feruloyl esterases, FaeI, FaeII, and FaeIII. Phylogenetic analysis classified the described bacterial Faes into two types, FaeI and FaeII in type I and FaeIII in type II. Substrate specificity assays indicated that FaeI is more active against the ester bonds in natural hemicelluloses and FaeIII preferentially attacks the ferulate esters with a small moiety, such as methyl groups, while FaeII is active on both types of substrates. Among the three feruloyl esterase genes, faeI was the only one induced significantly by xylose and xylan, while pectin appeared to moderately induce the three genes during the late log phase to stationary phase. Western blot analysis determined that FaeI and FaeIII were secreted and cytoplasmic proteins, respectively, whereas FaeII seemed to be cell associated. The addition of FaeI and FaeII but not FaeIII enhanced the activity of a xylanase on maize cob, suggesting a synergy of the former two with xylanase. Hence, we propose that the three feruloyl esterases work in concert to hydrolyze ferulate esters in natural hemicelluloses.
Project description:The transcriptional responses of Prevotella ruminicola were determined during growth on 20 different carbohydrate sources including mono-, di- and tri- saccharides, oligosaccharides, polymeric xylan and complete plant material with the aim of obtaining a more complete understanding of the number of genes and metabolic networks associated with carbohydrate catabolism by this organism All microarray hybridizations and subsequent scanning was undertaken using a two colour system (Cy3 and Cy5): 34 samples
