Determination Of Biomass, Protein, Carbohydrate And Lipid

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Determination of biomass, protein, carbohydrate and lipid For the estimation of dry biomass, 2 ml culture was removed on 10th day from each flask, and absorbance measured at 750 nm spectrophotometrically (Shimadzu UV mini 1601, Japan) and converted to dry biomass using the regression equation Dry biomass (mg ml-1) = Abs750+0.0378/0.0009 (R2 =0.995; P< 0.001) based on a standard curve constructed depending on Abs 750 vs dry biomass. To determine dry biomass 10 ml microalgal culture with known Abs750 ranging from 0.1 to 0.5 were filtered through pre-combusted (100oC, 4 h) and pre-weighed glass microfiber filters (GE Healthcare, UK) and rinsed with 5 ml of 0.5M ammonium formate. The filters were dried at 100oC for 4 h, cooled in a…show more content…
Optimization of medium composition and culture conditions Experimental design Selection of significant variables by Plackett-Burman design The screening of significant variables influencing biomass production of Chaetoceros muelleri was accomplished by Plackett-Burman experimental design using the statistical software Design Expert (version 6.0.9, Stat-Ease Inc, Minneapolis, MN). Three nutritional parameters (nitrate, phosphate, and silicate) and four physicochemical parameters (temperature, pH, salinity, and agitation speed) were screened, having each variable tested at two levels, as minimum (-) and maximum (+). The minimum and maximum limits of the variables were nitrate (A):7.5-150 mg l-1 ; phosphate (B): 0.5-10 mg l-1; silicate (C): 3-60 mg l-1; temperature (D): 20-30oC; pH (E): 6-9; salinity (F): 15-40 ppt and agitation speed (G): 100-200 rpm. For screening the above variables, microalgal culture having absorbance of 0.2 at 750 nm was inoculated to a final concentration of 10% (v/v) to 100 ml medium in 250 ml conical flasks having varying composition as formulated by Plackett-Burman design. The design matrix, consisted of 11 variables with 12 runs (N), with D1 to D4 as the dummy variables was used to evaluate the standard errors (SE) (Table 1) . The experimental cultures were incubated in triplicate for 10 days in a shaker
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