Assessment of chitin decomposer diversity within an upland grassland

The breakdown of chitin within an acidic upland grassland was studied. The aim was to provide a molecular characterisation of microorganisms involved in chitin degradation in the soil using soil microcosms and buried litter b ags containing chitin. The investigation involved an examination of the eff ects of liming on the microbial communities within the soil and their chiti nolytic activity. Microcosm experiments were designed to study the influenc e of lime and chitin enrichment on the grassland soil bacterial community e x situ under controlled environmental conditions. Bacterial and actinomycet e counts were determined and total community DNA was extracted from the mic rocosms and from chitin bags buried at the experimental site. PCR based on specific 16S rRNA target sequences provided products for DGGE analysis to d etermine the structure of bacterial and actinomycete communities. Chitinase activity was assessed spectrophotometrically using chitin labelled with re mazol brilliant violet. Both liming and chitin amendment increased bacteria l and actinomycete viable counts and the chitinase activity. DGGE band patt erns confirmed changes in bacterial populations under the influence of both treatments. PCR products amplified from DNA isolated from chitin bags were cloned and sequenced. Only a few matched known species but a prominent col oniser of chitin proved to be Stenotrophomonas maltophilia.