Microbial oil accumulation and cellulase secretion of the endophytic fungi from oleaginous plants

Abstract

This research was designed to screen for strains that produce microbial oil by using straw as the substrate. One hundred and forty-one isolates of endophytic fungi were obtained from stems of seven oleaginous plant species. Sixty-nine isolates (48.9% of the total isolates) could be clearly seen having lipid bodies in their hyphae when examined with optical microscopy. Twenty-six isolates which had bigger and more oil bodies in their hyphae were selected for further research. These Isolates belong to five genera including Microsphaeropsis, Phomopsis, Cephalosporium, Sclerocystis and Nigrospora. Their oil contents ranged from 21.3 to 35.0% of dry cell weights when cultured in potato dextrose broth. When cultured on the solid-state medium composed of steam-exploded wheat straw (20% w/w), wheat bran (5%) and water (75%) they were able to produce cellulase and microbial oil with yields of 0.31-0.69 filter paper unit and 19-42 mg/g initial dry substrate, respectively. These results show that some endophytic fungi isolated from the oleaginous plants have the abilities of accumulating oil and producing cellulase simultaneously. They may be potential microbial oil producers by utilising straw as the substrate.