Dilute acid pretreatment and enzymatic hydrolysis of sorghum biomass for sugar recovery—A statistical approach.

Sorghum is one of the commercially feasible lignocellulosic biomass and has a great potential of being sustainable feedstock for renewable energy. As with any lignocellulosic biomass, sorghum also requires pretreatment which increases its susceptibility to hydrolysis by enzymes for generating sugars which can be further fermented to alcohol. In the present study, sorghum biomass was evaluated for deriving maximum fermentable sugars by optimizing various pretreatment parameters using statistical optimization methods. Pretreatment studies were done with H2SO4, followed by enzymatic saccharification. The efficiency of the process was evaluated on the basis of production of the total reducing sugars released during the process. Compositional analysis was done for native as well as pretreated biomass and compared. The biomass pretreated with the optimized conditions could yield 0.408 g of reducing sugars /g of pretreated biomass upon enzymatic hydrolysis. The cellulose content in the solid portion obtained after pretreatment using optimised conditions was found to be increased by 43.37% with lesser production of inhibitors in acid pretreated liquor.

The effect of nitrogen and potassium fertilizers on growth parameters and carbohydrate contents of sweet sorghum cultivars.

Sweet sorghum is tolerant to high temperature and drought and can be considered as an alternative crop to sugar beet and maize in Iran. In this study, the effects of nitrogen and potassium fertilizers on growth parameters including stem height, stem diameter, stem fresh weight, total fresh weight; carbohydrate contents including total sugar, brix value, sucrose content and purify; and juice extract of two sweet sorghum cultivars were determined. Three rates of N-fertilizer (0, 90, 180 kg urea ha(-1)) and two rates of K fertilizer (0 and 50 kg potassium sulfate ha(-1)) assigned as main plots and two sweet sorghum cultivars (Rio and Keller) as subplots. Growth parameters at soft dough and physiological maturity stages and carbohydrate contents at physiological maturity stage were determined. Results showed that application of 180 kg urea ha(-1) as compared to control at physiological maturity significantly (p < 0.01) increased stem height (12.65%), stem fresh weight (24.57%), total fresh weight (78.22%), total sugar (39.25%), sucrose content (9%) and juice extract (34.96%). Application of 50 kg potassium sulfate ha(-1) increased (p < 0.05) stem fresh weight (24.33%), total fresh weight (25.44%), total sugar (10.50%), and juice extract (9%) at physiological maturity. The highest growth parameters, carbohydrate contents and juice extract were obtained with the application of 180 kg urea ha(-1) and 50 kg potassium sulfate ha(-1) using cultivar (cv) Keller. The best results were taken with the application of both fertilizers.

Simple and economical assay systems for evaluation of phosphinothricin resistant transgenics of sorghum, Sorghum bicolor. (L.) Moench., and pearl millet, Pennisetum glaucum (L.) R. Br.

Five simple and rapid methods for evaluation of sorghum and pearl millet transgenics resistant to herbicide phosphinothricin (used as selectable marker) were studied. For rapid in vitro selection, three assays (establishment of sensitivity curves for embryogenic calli, determination of lethal doses for seed germination, and a rapid screening of cut young leaves based on the colour change of the medium) were established. For rapid screening of transgenic progeny, effects of in vivo Basta leaf spray and dip tests were studied at three different morphological stages. For all the above assays, LD50, and LD100 values were higher for pearl millet than sorghum. However, in both the crops, genotype effect was not significant. The assays standardized in the study were found to be effective for rapid, economical and mass-scale identification and characterization of transgenic plants of sorghum and pearl millet.