Versatile biotechnological applications of Euglena gracilis

Euglena gracilis is a freshwater protist possessing secondary chloroplasts of green algal origin. Various physical factors (e.g. UV) and chemical compounds (e.g. antibiotics) cause the bleaching of E. gracilis cells-the loss of plastid genes leading to the permanent inability to photosynthesize. Bleaching can be prevented by antimutagens (i.e. lignin, vitamin C and selenium). Besides screening the mutagenic and antimutagenic activity of chemicals, E. gracilis is also a suitable model for studying the biological effects of many organic pollutants. Due to its capability of heavy metal sequestration, it can be used for bioremediation. E. gracilis has been successfully transformed, offering the possibility of genetic modifications for synthesizing compounds of biotechnological interest. The novel design of the next generation transgenic expression cassettes with respect to the specificities of euglenid gene expression is proposed. Moreover, E. gracilis is a natural source of commercially relevant bioproducts such as (pro)vitamins, wax esters, polyunsaturated fatty acids and paramylon (beta-1,3-glucan). One of the highest limitations of large-scale cultivation of E. gracilis is its disability to synthesize essential vitamins B-1 and B-12. This disadvantage can be overcome by co-cultivation of E. gracilis with other microorganisms, which can synthesize sufficient amounts of these vitamins. Such co-cultures can be used for the effective accumulation and harvesting of Euglena biomass by bioflocculation.

Automated summary

Euglena gracilis, a freshwater protist, has secondary chloroplasts derived from green algae and can undergo bleaching due to various physical and chemical factors. It can be used as a model organism to study the effects of pollutants and for bioremediation. Genetic modifications have been successfully applied to E. gracilis for the synthesis of biotechnological compounds. Large-scale cultivation is limited by the inability to synthesize essential B-vitamins, but co-cultivation with other microorganisms can overcome this disadvantage.