Vegetos

Abstract

An economic nutrient medium by varying the composition and substituting some of the components with economic chemical fertilizers of the selected Chu-13 medium for the isolated green alga Botryococcus braunii from Udaisagar Lake, Udaipur, Rajasthan was devised in this study. The devised medium contained fairly low concentrations of a few nutrients, NaNO₃ (0.2 g/L), single super phosphate (0.028 g/L), MgSO₄.7H₂O (0.12 g/L) and mureate of potash (0.05 g/L). The medium was prepared in treated sewage water or in tap water or in distilled water supplemented with 3.6 g/L soil extract and costs about 1/10^th ( 107.82/KL) the cost of the Chu-13 medium ( 1,049.26/KL). During the formulation of the medium, influence of sodium nitrate, magnesium sulphate and single super phosphate on biomass and hydrocarbon production by the organism were investigated. Variation in the concentration of other constituents of Chu-13 medium adversely affected the parameters, biomass and hydrocarbon content, important for commercial biofuel purpose. Decrease in the concentration of NaNO₃ and MgSO₄ from the control values found in Chu-13 medium exhibited marked positive effects on hydrocarbon content, maximum values being observed at their 40% concentrations (0.13 g/L NaNO₃ and 0.08 g/L MgSO₄.7H₂O); whereas, highest biomass yields were found at their 60% concentrations (0.2 g/L NaNO₃ and 0.12 g/L MgSO₄.7H₂O). In contrast, biomass and hydrocarbon content were not much affected when the concentration of single super phosphate (SSP) was reduced up to 40% as phosphorus (0.028 g/L SSP) to the value found in Chu-13 medium, but at 20% (0.014 g/L SSP) and lower concentrations, significant reduction in both the parameters was observed. The devised economic medium can be effectively exploited for the commercial cultivation of the alga for biofuel purpose by monitoring the concentrations of a few nutrients NaNO₃, MgSO₄.7H₂O and SSP to obtain maximum yield of biomass and hydrocarbon.