Biotechnological potential of mangrove sediments: Identification and functional attributes of thermostable and salinity-tolerant ß-glucanase.

Microorganisms native to mangroves are expected to contain enzymes capable of hydrolyzing different carbon sources. However, most of these microorganisms aren't cultivable; hence, alternative techniques as metagenomics are tools for studying and obtaining some of the natural genomes, genes and enzymes of biotechnological interest. The ß-glucanase was produced using a metagenomic clone of mangrove sediments and detected by functional screening on carboxymethylcellulose substrate. The enzyme was purified by cation exchange chromatography. The peptides detected by mass spectrometry showed 20% identity with the polypeptide deduced from the genomic fragment sequenced. The ORF identified as BglfosD9 possessed 729 bp and the encoded protein showed predicted MW and pI of 28kD and 6.8, respectively. The enzyme was active in a wide range of pH (5-10) with optimum pH at 8, had relative activity greater than 50% at all temperatures tested (5-90 °C), was stable at temperatures of 5, 50 and 90 °C and showed excellent relative activity at high NaCl concentrations. This ß-glucanase also showed high relative activity in the presence of SDS and it could hydrolyze ß-glucan, CMC and Avicel as substrates. These findings support the idea of a new thermostable and active enzyme at basic pH from metagenomic library of mangrove sediment.