Author: Herr Dr. Amoneit
Last saved by: Saritas, Sevim
Company: Hewlett-Packard

Production of Lipids and Protein by Schizochytrium aggregatum under Different Growth Conditions
Carolina Shene, Daniela Vergara, Marcelo Garcés, Department of Chemical Engineering, Universidad de La Frontera, Temuco, Chile

Consumption of long chain polyunsaturated fatty acids (LC-PUFA) belonging to the omega-3 family such as docosahexaenoic acid (C22:6n-3, DHA) has several positive effect on the health of humans and animals. At present cold water fish and their oils are the main source of LC-PUFA. Marine protists belonging to the Labyrinthulomycetes among which is S. aggregatum, can be alternatives for the microbial production of lipids containing DHA. The aim of this work was to test the effect of the carbon and nitrogen sources, their concentrations, percentage of artificial sea water (ASW) and other factors of the growth medium on the production of lipids by an isolated Labyrinthulomycetes strain showing high similitude (97.4%) to S. aggregatum, according to its 18s rRNA sequence. In shaking flask experiments the strain was able to grow (1.7-4.8 g/L, after 4 days) on glucose, sucrose, maltose, soluble starch and glycerol at 20 g/l; biomass with the highest lipid content (16.8±0.7%) was that grown in glycerol whereas the highest biomass concentration (7.9±0.5 g/l) was obtained with soluble starch. Corn steep liquor enhanced the lipid content in the biomass cultivated with glucose (20±0.2%). Negligible growth was observed when ASW and pH were below 50% and 5, respectively. In order to increase biomass concentration and lipid productivity the culture (200 ml, initial glucose concentration 20 g/L) was fed with starch (4 g) every 4 days. Under these conditions biomass concentration, lipids and DHA productivity were 41.5±1.3 g/l, 1.3±0.2 g/(l d) and 350±15 mg/(l d), respectively.
Proteins synthesized by the strain cultivated in glucose and starch, on which biomass yields were significantly different, were submitted to two-dimensional gel electrophoresis. Image analysis suggests that the carbon source induce differential protein expression.
Acknowledgments. The authors thank Dirección de Investigación at Universidad de La Frontera for the economic support provided through Convenios de Desempeño I, II and GAP.