The production of ethanol from cellulosic materials via hydrolyzing enzymes - cellulases, presents a promising replacement for the depleting petroleum. However, for it to be an economically feasible option there is an immediate need to improve the activity range of cellulases available in the market and/or identify novel cellulases that are superior to the latter. Fungi and bacteria produce cellulases that have an activity range which is reflective of the environmental conditions that host them.  Mangrove sediments in the Arabian Gulf are characterized by high salinities and temperatures, and they also receive large cellulosic litter annually. This motivated us to characterize the microbial communities associated with mangrove sediments because they are a potential source of novel cellulases.  Our overarching hypothesis is that resident cellulose degrading populations produce enzymes that are active at a wide range of temperatures and salinities – thereby these cellulases may exhibit superior activity when compared to market available cellulases. The objective of this study is to characterize microbial communities of mangrove sediments pre and post enrichment using cellulose as a carbon source.  Temporal changes in microbial community structures as a result of enrichment are being monitored using Denaturing Gradient Gel Electrophoresis (DGGE) analysis of 16S rRNA genes followed by sequencing of unique bands.