Evaluation of some biological activities of Euglena gracilis biomass produced by a fed-batch culture with some crop fertilizers

The feasibility of growing Euglena gracilis in some crop fertilizers was investigated and some biological activities of the produced biomass were evaluated. A fed-batch mixotrophic culture was done in an airlift photobioreactor operated at an aeration rate of 0.2 vvm. A final biomass concentration of 2.6 gL-1 obtained with NPK15:15:15 after 96 h of cultivation was significantly lower than the 5.7 gL-1 obtained with BGII medium under the same culture condition. There was no significant effect of supplementing conventional rat feeds with Euglena biomass or captopril (an antihypertensive drug) on the body weight of the rats. However, supplementation with Euglena biomass had significant (P<0.05) effects on some biological activities such as, inhibition of angiotensin converting enzyme (ACE), hypocholesterolaemic activity and increase in red blood count (P<0.05). Analysis of the dried algal biomass showed a protein content of 33.327%, fat content of 16.4%, poly unsaturated fatty acid (PUFA) content of 51.33 mgKOH/g, and vitamin E content of 171.3 mg/100 g. Key words: Mixotrophic, angiotensin converting enzyme, hypocholesterolaemic activity, photobioreactor.