THE CHEMICAL COMPOSITION OF CHLORELLA; EFFECT OF ENVIRONMENTAL CONDITIONS

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Abstract
The degree of reduction of the total organic matter of plant material is designated the R-value. This value is detd. from the elementary composition of the material; it is proportional to the heat of combustion and is an expression of the energy content of the material. The approx. carbohydrate, protein and lipid content of the plant material was calculated from the elementary analysis and the R-value. C. pyrenoidosa cells grown under different environmental conditions vary widely in composition. The lipid content, for example, varied from 4.5 to 85.6% of the dry wt. The environmental factors, CO2 concn., aerobic and anaerobic atmospheres, mineral nutrients, illumination and temp, influence the composition of Chlorella. The R-value and lipid content increase concurrently. In general, cells of low lipid content are produced when the fixed N in the medium is above 0.001 [image]. Below this concn., cells of higher lipid content can be obtained. High light intensity also favors high lipid content. The effects of N concn. and illumination are interrelated. The storage of energy by cultures under different conditions is discussed. Chlorella of high lipid content apparently carries on photosynthesis with a chlorophyll content 1/500 to 1/2000 that of cells of low lipid content.