EFFECTS OF SHIFTING PH IN THE STATIONARY-PHASE OF GROWTH ON THE CHEMICAL-COMPOSITION OF EUGLENA-GRACILIS

Effects of pH shifted in the stationary phase on the chemical composit ion of Euglena gracilis cells were examined. When the cells that were cultivated at fixed pH of 4.5 reached stationary phase, the pH of the culture was shifted to 2.0-8.5, and the cultivation was continued for 24 hours more. Shifting pH to below 3.0 and between 6.5 and 7.5 increa sed cellular protein and decreased paramylon. The maximum content of p rotein in the cells was 77.5% when the pH was shifted to 7.5. At shift ed pH of higher than 8.0, the protein content was greatly decreased an d the paramylon content was greatly increased. This technique of shift ing pH in the stationary phase did not improve the lipid content or fa tty acid composition in Euglena for use as a feed for larval fish. Ara chidonic acid, however, was found to be decreased in alkaline pH after shifting. This pH shifting technique that can improve the protein con tent in Euglena cells is useful for mass production of Euglena for use in the feed industry.