Cellulolytic activities of a novel fomitopsis sp. and aspergillus tubingensis isolated from Philippine mangroves

The ability to deconstruct plant cell wall polysaccharides is inherent in fungal endophytes. As such, discovering organisms that secrete potent cocktails of carbohydrate-active enzymes may hold the key to deconstructing waste agricultural biomass for industrial applications. Based on CMC-Congo red plate based assay, two fungal isolates derived from mangrove trees (JB10 and JB11) showed high enzymatic indices (as high as 5.6 ± 0.18 for JB10). Both isolates were then grown in potato dextrose (PD), carboxymethylcellulose(CMC), and beechwood xylan (XY), and the corresponding endoglucanase, xylanase, and β-glucosidase activities of the enzymes present in crude culture supernatants were determined. JB11 showed significant increase in endoglucanase activity (0.36 ± 0.04 U/mL) in PD, while JB10 endoglucanase activity was similar between the three media. Interestingly, xylanase activity of both isolates was relatively high (ranging 0.26-1.0 U/mL), with JB10 xylanase activity five-fold higher in PD. Lastly, there was 2-4 fold increase detected in β-glucosidase activities (0.59-0.8 U/mL) in both isolates when grown in CMC or XY media. Phylogenetic analysis of the ITS sequences show that JB11 is Aspergillus tubingensis, while JB10 is a novel Fomitopsis sp. isolate.