Cellulolytic microorganisms are considered as a key player in various environments to degrade the plant biomass. Cellulases are used in various applications in industries like biofuels, food and beverages and medical applications. 

These microorganisms can be isolated from various environments such as soils, insect gut, mammalian rumen, and oceans. The Red Sea has a unique environment in terms of high seawater temperature, high salinity, low nutrients, and high bio-diversity. However, there is little information regarding cellulases genes in the Red Sea environment. 

The aim of the study was to examine if the Red Sea can be a potential resource for bio-prospecting of microbial cellulases, by isolation and characterization of cellulase-producing microorganisms from the Red Sea environment. Three bacterial strains were successfully isolated from plankton fraction and seaweed surface. The isolated strains were identified as Bacillus paralichiniformis and showed strong cellulase activity. These results suggest that these four isolates secreted active cellulases. 

Next, we compared the expression of cellulase genes under cellulase-inducing and non-inducing condition, and identified several cellulase genes that were upregulated during the cellulolysis from each isolate. These genes are expected to play important roles in their cellulolysis.