Bioethanol Production from Ammonia Pretreated Rice Straw

Rice straw is produced in large quantity throughout the world. Rice straw is a leading feedstock for bioethanol production. Diluted ammonia pretreatment for one week at room temperature was found to be effective pretreatment. This pretreated rice straw was acid hydrolyzed and subsequently fermented with Saccharomyces cerevisiae CP11 strain. 1.5% ammonia pretreatment at room temperature for one week resulted 82.4% delignification and 78.49% of acid hydrolysis. Acid hydrolysate was fermented with maximum ethanol concentration 5.70 % with an ethanol yield of 0.46g/g and fermentation efficiency of 90.6%. Diluted ammonia pretreatment at higher temperature has reduced delignification, saccharification and fermentation efficiency with more phenols and furfurals

SPECTROPHOTOMETRIC METHOD FOR THE DETERMINATION OF IODATE USING METHYLENE BLUE AS A CHROMOGENIC REAGENT

A simple, rapid and sensitive spectrophotometric method has been developed for the determination of iodate (IO3-) in table salt and sea water. The proposed method is based on the reaction of iodate with potassium iodide in an acid medium to liberate iodine. The liberated iodine bleaches the blue color of methylene blue and is measured at 665.6 nm. This decrease in absorbance is directly proportional to the iodate concentration and obeys Beer's law in the range of 0.5-14 μgmL–1 of IO3-. The molar absorptivity, Sandell's sensitivity, detection limit and quantitation limit of the method were found to be 1.24 x 104 L mol-1cm–1, 1.41 x 10-2 μgcm-2, 0.048 μgmL–1 and 0.145 μgmL-1, respectively. The optimum reaction conditions and other analytical conditions were evaluated. The effect of interfering ions on the determination has been described. The proposed method has been successfully applied to the determination of the iodate in the table salt and sea water. KEY WORDS: Iodate determination, Methylene blue, Spectrophotometry, Table salt, Sea water Bull. Chem. Soc. Ethiop. 2006, 20(1), 143-147

Role of Heat Shock Proteins and Plasma Membrane on Thermotolerance in Saccharomyces cerevisiae-VS3 Strain

Aim: Study of HSPs synthesis after heat and cold shock and explanation of thermotolerance by the transport of HSPs to the plasma membrane. Methods and Results: Physical (cold and heat shock) and chemical (lignocaine) damage to plasma membrane was achieved in thermotolerant and mesophilic strains of Saccharomyces cerevisiae. In shocked yeasts K+ ion efflux, leakage of UV280 absorbing material, HSP expression profile and viability at 25 and 45°C were studied. Physical/chemical shock was given for 30 minutes and subsequently yeasts were incubated at 25°C to avoid further membrane damage by stress. In thermotolerant strain, membrane damage increased up to 70 minutes (30 min of shock and 40 min at 25°C) and reduced thereafter. De-novo HSPs in membrane were noted at 60 minutes and reached maximum at 80 minutes in thermotolerant strain. In mesophilic yeast, de-novo HSPs were not synthesized and leakage was continuous up to the studied period (100 minutes). Conclusion: These de-novo HSPs are transported to the membrane for restoring the membrane integrity and to prevent the leakage. The thermotolerant strain can grow at higher temperatures compared to mesophilic strain due to more production of HSPs and HSP associated membrane damage reversal. Significance and Impact of the Study: Several reports established the role of HSPs in thermotolerance but their mode of action is not well characterized. The current method explains the mechanism for acquiring thermotolerance in yeast

Spectrophotometric determination of dissolved oxygen in water

593-595A simple, rapid and sensitive spectrophotometric method has been developed for the determination of dissolved oxygen (DO) in river water samples. The method is based on the reaction of dissolved oxygen with manganous sulphate in alkaline iodide-azide solution and the liberation of iodine by manganese dioxide. The liberated iodine bleaches the violet colour of azure B which is measured at 644 nm. The decrease in absorbance is directly proportional to dissolved oxygen concentration and obeys Beer’s law in the range 0.2-1.4 gmL-1. The molar absorptivity, Sandell’s sensitivity, detection limit and quantitation limit of the method were found to be 5.86 104 Lmol-1 cm-1, 3.66 10-3 g/cm2, 0.030 and 0.090 gmL-1, respectivel

<b>Spectrophotometric method for the determination of iodate using methylene blue as a chromogenic reagent</b>

A simple, rapid and sensitive spectrophotometric method has been developed for the determination of iodate (IO₃^-) in table salt and sea water. The proposed method is based on the reaction of iodate with potassium iodide in an acid medium to liberate iodine. The liberated iodine bleaches the blue color of methylene blue and is measured at 665.6 nm. This decrease in absorbance is directly proportional to the iodate concentration and obeys Beer's law in the range of 0.5-14 μgmL^-1 of IO₃^-. The molar absorptivity, Sandell's sensitivity, detection limit and quantitation limit of the method were found to be 1.24 x 10⁴ L mol^-1cm^-1, 1.41 x 10^-2 μgcm^-2, 0.048 μgmL^-1 and 0.145 μgmL^-1, respectively. The optimum reaction conditions and other analytical conditions were evaluated. The effect of interfering ions on the determination has been described. The proposed method has been successfully applied to the determination of the iodate in the table salt and sea water

Spectrophotometric determination of arsenic in environmental and biological samples

36-40A simple and sensitive spectrophotometric method has been developed for the determination of arsenic using variamine blue as a chromogenic reagent. The method is based on the reaction of arsenic(III) with potassium iodate in acid medium to liberate iodine, which oxidizes variamine blue to form a violet coloured species having an absorption maximum at 556 nm. Beer’s law is obeyed in the range 0.2-14 μg mL-1 of As(III). The molar absorptivity, Sandell’s sensitivity, detection limit and quantitation limit were found to be 1.43104 L mol-1cm-1, 5.2610-2 μg cm-2, 0.022 and 0.072 μg mL-1, respectively. The optimum reaction conditions and other analytical parameters were evaluated. The proposed method has been successfully applied for the determination of arsenic in various environmental and biological samples

Sequential cellulase production, saccharification and ethanol fermentation using rice straw

616-620This study presents alkali pretreated rice straw for cellulase production using Aspergillus niger CP1 by solid state fermentation (SSF). On 8th day, 140±2.4 IU g/l dry substrate (ds) carboxy methyl cellulose CMCase), 15±1.2 IU g/l ds filter paper activity (FPA) and 24±1.1 IU g/l ds â-glucosidase activities were noted. On extraction of 120 g material with 1 l of 0.1 mol/l citrate buffer, 5.9±0.12 IU ml/l CMCase, 0.62±0.001 IU ml/l FPA and 1.11±0.002 IU/ml â-glucosidase were obtained. When extracted enzyme was used for saccharification of 120 g fresh pretreated rice straw containing 100 g holocellulose, 45±0.2 g, sugars (50 g/l) were released in 900 ml hydrolysate to give 45% hydrolysis. Hydrolysate after yeast fermentation gave 15.6±0.05 g/l ethanol with a yield of 0.4±0.011 g/l/h and 78% fermentation efficiency. In sequential enzyme production, saccharification and fermentation studies, on 8thday of cellulase production by SSF, temperature was shifted from 28±1°C to 55°C for 36 h, and 76% hydrolysis was achieved. When A. niger in hydrolysate was inactivated and used, 68±0.83 g/l ethanol and 92% fermentation efficiency were obtained. Hydrolysate used without inactivation of A. niger gave 61.65±0.78 g/l ethanol and 85% fermentation efficiency