Levan Production in Shake Flask and Fermenter Influence of Feeding Strategy on Levan Yield and Molecular Weight Distribution

Effect of feeding strategy on levan production was studied in a shake flask and a 5 L lab scale fermenter. In a shake flask, levan specific substrate yield (YP/S) increased from 0.35 g levan/g sucrose to 0.48 g levan/g sucrose with repeated batch feeding. In a 3 L reactor, levan productivity of 7.18 g/L h was obtained with the fed-batch mode of fermentation. The gel permeation chromatography results indicate that higher initial sucrose concentration under the fed-batch mode operation resulted in the formation of low molecular weight fractions (4 and 10 kDa). Thus, fed-batch fermentation favors levan production resulting in higher yield and productivity and also affects the molecular weight distribution of the biopolymer

Response Surface Methodology: Optimisation of Antifungal Bioemulsifier from Novel Bacillus thuringiensis

An antifungal bioemulsifier compound was produced from a novel strain of Bacillus thuringiensis pak2310. To accentuate the production and as the first step to improve the yield, a central composite design (CCD) was used to study the effect of various factors like minimal salts (1X and 3X), glycerol concentration (2% and 4%), beef extract concentration (1% and 3%), and sunflower oil concentration (2% and 4%) on the production of bioemulsifier molecule and to optimize the conditions to increase the production. The E24 emulsification index was used as the response variable as the increase in surfactant production was seen to be proportional to increased emulsification. A quadratic equation was employed to express the response variable in terms of the independent variables. Statistical tools like student’s t-test, F-test, and ANOVA were employed to identify the important factors and to test the adequacy of the model. Under optimum conditions (1X concentration of minimal salts (MS), 2.6% glycerol (v/v), 1% beef extract (w/v), and 2% sunflower oil (v/v)) a 65% increase in yield was produced

Understanding the pyrolysis kinetics, thermodynamic, and environmental sustainability parameters of Sesamum indicum crop residue

In this work, the physiochemical characteristics, thermodynamics, and sustainability of the pyrolysis of Sesamum indicum biomass were assessed. The pyrolysis kinetics of sesame agro-residues performed using isoconversional techniques such as Kissinger, KAS, and OFW methods showed activation energies of 192, 120, and 123 kJ mol ^−1 , respectively. The impact of the pyrolysis temperature (550, 650, 750 °C) on the generation of biochar, bio-oil, and gas is also studied; the exergy efficiency increased from 82.7 at 550 °C to 87.3% at 750 °C with an increase in the temperature. Sesame biochar’s Van Krevalan diagram showed how its fuel-like characteristics also grew with rising temperatures. The input and output parameters showed a high agreement in the mass, energy, and exergy balance closures. However, it was shown that the overall energy efficiency was greater at 750 °C (71.2%) compared to 55.5% and 69.8% at 550 °C and 650 °C, respectively. Sustainability analysis showed that lower temperatures had a smaller impact on the environment

Levan Production in Shake Flask and Fermenter Influence of Feeding Strategy on Levan Yield and Molecular Weight Distribution

Effect of feeding strategy on levan production was studied in a shake flask and a 5 L lab scale fermenter. In a shake flask, levan specific substrate yield (YP/S) increased from 0.35 g levan/g sucrose to 0.48 g levan/g sucrose with repeated batch feeding. In a 3 L reactor, levan productivity of 7.18 g/L h was obtained with the fed-batch mode of fermentation. The gel permeation chromatography results indicate that higher initial sucrose concentration under the fed-batch mode operation resulted in the formation of low molecular weight fractions (4 and 10 kDa). Thus, fed-batch fermentation favors levan production resulting in higher yield and productivity and also affects the molecular weight distribution of the biopolymer

Biorefinery approaches for production of cellulosic ethanol fuel using recombinant engineered microorganisms

Cellulosic ethanol has been gaining high attention due to its potential to reduce the greenhouse gas emission and cut down the world dependence on fossil fuels. Biorefinery approach for cellulosic ethanol has advantages due to its non-food competing status, natural abundance and benefit to decrease the combustion of agricultural wastes after harvesting seasons. Due to the recalcitrant structure of lignocellulose biomass, pretreatment and hydrolysis are critical to determine the economic viability of the process because they influence the conversion rate of fermentable sugars and, subsequently, final product i.e. ethanol. Therefore, the design for the process to compromise fermentation and upstream process is also essential. With all constraints exist when using harsh conditions during pretreatment, the recombinant engineered microorganisms have been developed and applied as biocatalysts during fermentation. To achieve the maximum production efficiency, different strategies of recombinant engineered microbes include expression optimization to modify the metabolic pathway, modification of secretion and transportation routes, improvement of stress tolerance, and utilization of both C5 and C6 sugars. This review provides the development and current status of cellulosic ethanol production via biorefining process by genetic engineered microbes with a focus on the technological aspects. The remaining challenges, perspective, and economical feasibility of the process are also discussed