Focussed metabolism of ß-glucans by the soil Bacteroidetes Chitinophaga pinensis.

The genome and natural habitat of Chitinophaga pinensis suggest the ability to degrade a wide variety of carbohydrate-based biomass. Complementing our earlier investigations into the hydrolysis of some plant polysaccharides, we now show that C. pinensis can grow directly on spruce wood and fungal fruiting body. Growth was stronger on fungal material, although secreted enzyme activity was high in both cases, and all biomass-induced secretomes showed a predominance of ß-glucanase activities. We therefore conducted a screen of growth on and hydrolysis of ß-glucans isolated from different sources. Most non-crystalline ß-glucans supported good growth, with variable efficiency of polysaccharide deconstruction and oligosaccharide uptake, depending on the polysaccharide backbone linkage. In all cases, ß-glucan was the only type of polysaccharide that could be effectively hydrolysed by secreted enzymes. This contrasts with the secretion of a broad range of enzyme activities we observed during growth on complex heteroglycans. Our findings imply a role for C. pinensis in the turnover of multiple types of biomass, and suggest that the species may have two metabolic modes: a 'scavenging mode' where multiple different types of glycan may be degraded, and a more 'focussed mode' of ß-glucan metabolism. The significant accumulation of some types of ß-gluco-oligosaccharide in growth medium may be due to the lack of an appropriate transport mechanism, and we propose that this is due to the specificity of expressed Polysaccharide Utilisation Loci. We present a hypothetical model for ß-glucan metabolism by C. pinensis that suggests the potential for nutrient sharing among the microbial litter community. [ABSTRACT FROM AUTHOR]