High Density Heterotrophic Culture Of Chlorella Vulgaris

Chlorella has been applied in many fields because of its rich, all-round and balanced nutrition, nontoxicity and many important physiological functions. Heterotrophic culture takes more advantages than autophototrophic culture and is paid more and more attentions to present. To culture Chlorella cells under the heterotrophic conditions can make the biomass of Chlorella increase largely, shorten the culture cycle and decrease the harvesting cost. If Chlorella cells grow in the fed-batch heterotrophic conditions and also, Chlorella cells of high density will be obtained. So heterotrophic culture will promote the applications and developments of Chlorella.In this paper, the heterotrophic culture of C. vulgaris was studied systematically, and its experiment in middle scale with high density of C. vulgaris was successful. All of the obtained results may be useful for the experiment in large scale. The main results are followed.1. In the experiments of optimizing the medium and the growth conditions for the heterotrophic culture of C. vulgaris. (1) As for carbon sources, glucose and levulose are better, as for nitrogen sources, KN0₃ and NH₄NO₃ are better. Glycine (Gly) can be used as the sole nitrogen source and stimulate the cell growth, bovine serum albumin (BSA) has also the stimulating effect on the cell growth. (2) 10g.L^-1 glucose and 1.6g. L^-1 KNO₃ are the proper initial concentrations in the medium. The concentrations of glucose and N0₃^- should be controlled between the ranges from 2.45g.L^-1 to 6.17g. L^-1 and equal to or less than 0.44g. L^-1 respectively in the fed-batch culture, and the most appropriate ratio carbon to nitrogen is 41. 2. (3) C. vulgaris uptakes P0₄³- a little. (4) The inoculum size should be much larger and the optimum initial pH is 6.5.