Abstract
There is an urgent requirement for sustainable sources of food and feed due to world population growth. Aquaculture relies heavily on the fish meal and fish oils derived from capture fisheries, challenging sustainability of the production system. Furthermore, substitution of fish oil with vegetable oil and fish meal with plant seed meals in aquaculture feeds reduces the levels of valuable omega-3 long chain polyunsaturated fatty acids such as eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids, and lowers the nutritional value due to the presence of phytate. Addition of exogenous phytase to fish feed is beneficial for enhancing animal health and reducing phosphorus pollution. We have engineered the marine diatom Phaeodactylum tricornutum, accumulating high levels of EPA and DHA together with recombinant proteins: the fungal Aspergillus niger PhyA or the bacterial Escherichia coli AppA phytases. The removal of the N-terminal signal peptide further increased phytase activity. Strains engineered with fcpA and CIP1 promoters showed the highest level of phytase activity. The best engineered strain achieved up to 40,000 phytase activity units (FTU) per gram of soluble protein, thus demonstrating the feasibility of development of multifunctionalized microalgae to simultaneously produce industrially useful proteins and fatty acids to meet the demand of intensive fish farming activity.
Highlights
The rise in world population is driving demand for high-quality protein and hydrocarbon production for both human and animal consumption
Seo et al, 2015 reported that use of the endogenous elongation factor 2 (EF2) promoter isolated from P. tricornutum resulted in a 1.2-fold increase in transgene expression compared with the fcp promoter in light conditions, and that EF2-mediated expression was stable in P. tricornutum throughout light and dark cycles[29]
A study characterising transgene expression using an algal virus promoter of a putative replication-associated (VP3) gene from Chaetoceros lorenzianus-infecting DNA virus (ClP1) showed that promoter activity remained stable through a photoperiod, and in cells grown in low nutrient culture conditions[30]
Summary
The rise in world population is driving demand for high-quality protein and hydrocarbon production for both human and animal consumption. Www.nature.com/scientificreports storage form of phosphate in plants, accounting for ~80% of the total phosphorus[6] Monogastric animals such as poultry, swine and fish are incapable of digesting phytate from plant-derived feeds as they lack a phytase enzyme[7]. The poor digestibility of phosphorous from phytate in animal feeds creates animal waste comparatively rich in phytate which can be released by bacterial or fungal action to become an environmental pollutant For these reasons, phytase enzyme is widely used as an animal feed additive in diets of swine, poultry and fish to increase the uptake of phytate-derived phosphorus and reduce the environmental burden resulting from phytate rich waste. Phaeodactylum tricornutum is a marine diatom that accumulates up to 35% EPA and traces of DHA It contains 49% protein and is used to feed fish larvae and molluscs. DHA content in the transgenic Pt_OtElo[5] strain was increased up to eight-fold compared to that of wild type (WT) cells
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
