Abstract
Thraustochytrids are osmoheterotrophic protists that are emerging as a promising group of oleaginous microorganisms due to their high DHA, EPA and palmitic acid production. Squalene, a triterpene hydrocarbon known for its antioxidant, antitumorigenic and emollient properties, is accumulated in some strains of thraustochytrids especially in the genus Aurantiochytrium. Thraustochytrids can produce extracellular enzymes to degrade organic matter as their means of nutrition. Many studies attempt to grow thraustochytrids in cost-effective substrates such as lignocellulosic biomass. As the first step towards cellulose utilization, we genetically modified Aurantiochytrium sp. strain 18W-13a to express and secrete a highly active cellulase, β-glucosidase from Aspergillus aculeatus (AaBgl). The transformant strain, AaBgl+, exhibited increasing growth and enzyme activity under cellobiose as the sole carbon source. Native PAGE zymogram showed an active β-glucosidase enzyme in the supernatant of the AaBgl+ strain. Both wild-type and AaBgl+ strains can produce squalene and fatty acids DHA and DPA. This work is one of the first reports in targeted secretion of a functional enzyme in thraustochytrids. Moreover, enhanced expression of cellulases has never been done in thraustochytrids. We hope that this study could pave way for establishing consolidated bioprocessing thraustochytrid strains.
Published Version
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