Enhanced ethanol production at commercial scale from molasses using high gravity technology by mutant S. cerevisiae

Abstract Very high gravity (VHG) technology was employed on industrial scale to produce ethanol from molasses (fermented) as well as by-products formation estimation. The effect of different Brix° (32, 36 and 40) air-flow rates (0.00, 0.20, 0.40, and 0.60 vvm) was studied on ethanol production. The maximum ethanol production was recorded to be 12.2% (v/v) at 40 Brix° with 0.2 vvm air-flow rate. At optimum level aeration and 40 Brix° VHG, the residual sugar level was recorded in the range of 12.5-18.5 g/L, whereas the viable cell count remained constant up to 50 h of fermentation and dry matter production increased with fermentation time. Both water and steam consumption reduced significantly under optimum conditions of Brix° and aeration rate with compromising the ethanol production. Results revealed VHG with continuous air flow is viable technique to reduce the ethanol production cost form molasses at commercial scale.

Enhanced ethanol production at commercial scale from molasses using high gravity technology by mutant S. cerevisiae.

Very high gravity (VHG) technology was employed on industrial scale to produce ethanol from molasses (fermented) as well as by-products formation estimation. The effect of different Brix° (32, 36 and 40) air-flow rates (0.00, 0.20, 0.40, and 0.60vvm) was studied on ethanol production. The maximum ethanol production was recorded to be 12.2% (v/v) at 40 Brix° with 0.2vvm air-flow rate. At optimum level aeration and 40 Brix° VHG, the residual sugar level was recorded in the range of 12.5-18.5g/L, whereas the viable cell count remained constant up to 50h of fermentation and dry matter production increased with fermentation time. Both water and steam consumption reduced significantly under optimum conditions of Brix° and aeration rate with compromising the ethanol production. Results revealed VHG with continuous air flow is viable technique to reduce the ethanol production cost form molasses at commercial scale.

Economical production of poly(γ-glutamic acid) using untreated cane molasses and monosodium glutamate waste liquor by Bacillus subtilis NX-2.

The production of poly(γ-glutamic acid) by Bacillus subtilis NX-2 from cane molasses and monosodium glutamate waste liquor (MGWL) was studied for the first time in this work. When batch fermentation was carried out with untreated molasses, 33.6±0.37 g L(-1) PGA was obtained with a productivity of 0.46±0.006 g L(-1) h(-1). In order to minimize the substrate inhibition, fed-batch fermentation was performed with untreated or hydrolyzed molasses in 7.5 L bioreactor, giving 50.2±0.53 and 51.1±0.51 g L(-1) of PGA at 96 h, respectively. Further studies were carried out by using MGWL as another carbon source, resulting in a PGA concentration of 52.1±0.52 g L(-1) with a productivity of 0.54±0.003 g L(-1) h(-1). These results suggest that the low-cost cane molasses and MGWL can be used for the environmental-friendly and economical production of PGA by B. subtilis NX-2.

Continuous treatment of coloured industry wastewater using immobilized Phanerochaete chrysosporium in a rotating biological contactor reactor.

Coloured industry wastewaters often contain dyes and other toxic ingredients, and, therefore, pose serious threat to the receiving environment. Among the available methods the eco-friendly biological method has gained maximum attention due to its many advantages over the traditional methods. In the present study, continuous biological treatment of coloured wastewater from a textile dyeing industry was investigated using the white rot fungus Phanerochaete chrysosporium in a rotating biological contactor (RBC) reactor. The raw wastewater was diluted with an equal volume of either distilled water or media containing glucose at varying concentrations to study its effect on the decolourization process. Results revealed that the wastewater could be decolourized to an extent of more than 64% when diluted with media containing glucose; and, a maximum decolourization efficiency of 83% was obtained with 10 g/l glucose concentration. COD removal efficiencies were also found to be consistent with the decolourization efficiencies of the wastewaters. Further, the results were correlated with the enzyme activities of manganese peroxidase (MnP) and lignin peroxidase (LiP) by the fungus, which were found to play some significant role in decolourization of the wastewater. Results of replacing the costly carbon source glucose in the decolourization media with the more cheap molasses, however, revealed very high COD removal efficiency, but low decolourization efficiency of the industry wastewater.

Production and characterization of cellulose by Acetobacter sp. V6 using a cost-effective molasses-corn steep liquor medium.

In order to reduce of the manufacturing cost of bacterial cellulose (BC), BC production by Acetobacter sp. V6 was investigated in shaking culture using molasses and corn steep liquor (CSL) as the sole carbon and nitrogen sources, respectively. The highest BC production was obtained with Ca3(PO4)2-treated molasses. Maximum BC yield (2.21+/-0.04 g/l) was obtained at 5% (w/v) total sugar in molasses. In improved medium containing molasses and CSL, BC production was observed in the medium after 1 day of incubation and increased rapidly thereafter with maximum yield (3.12+/-0.03 g/l) at 8 days. This value was approximately twofold higher than the yield in the complex medium. Physical properties of BC from the complex and molasses media were studied using Fourier-transform infrared (FT-IR) spectroscopy and X-ray diffractometer. By FT-IR, all the BC were found to be of cellulose type I, the same as typical native cellulose. The relative crystallinity of BC produced in the complex and molasses media were 83.02 and 67.27%, respectively. These results suggest that molasses and CSL can be useful low-cost substrates for BC production by Acetobacter sp. V6 without supplementation with expensive nitrogen complexes such as yeast extract and polypeptone, leading to the reduction in the production costs.

Simplified soy molasses-based medium for reduced-cost production of sophorolipids by Candida bombicola.

A simplified medium containing only soy molasses and oleic acid as ingredients was developed for the production of sophorolipids (SLs) from Candida bombicola. We achieved a product yield of 53 +/- 3 g of purified sophorolipids per liter of starting culture volume, which is 71 +/- 4% of the yield obtained with growth medium that also additionally contains the costly yeast extract and urea as nitrogen source. The large majority of the SL components existed in the lactone form (87%), and the predominant component is SL containing (omega-1)-hydroxyoleic acid as the lipid moiety. The study demonstrated for the first time the usefulness of the low-value soy molasses as a combined nitrogen- and carbon-source for SL production at a reduced cost.

Optimization of dextran production by Leuconostoc mesenteroides NRRL B-512 using cheap and local sources of carbohydrate and nitrogen.

Using pure components for the fermentation medium in dextran production imposes high costs on the industry. In the present study, the economic production of dextran using local and cheap sources of carbohydrate and nitrogen was investigated. Different concentrations of molasses and wheat-bran extract, after filtration, steam sterilization and pH adjustment, were inoculated with a fresh suspension of Leuconostoc mesenteroides. Cultures were incubated, and then diluted with an equal volume of ethanol. The bacteria were pelleted, and an aliquot of the supernatant was diluted with ethanol and dextran was precipitated. The supernatant was removed and the precipitate was dissolved in a minimal volume of water. Activated charcoal was added and the solution was boiled. The solution was filtered and protein impurities removed by 2-methylbutan-2-ol/chloroform extraction. Dextran was again precipitated with cold ethanol as described above, and the precipitate was dried in a desiccator. Optimum conditions and composition of culture media for dextran production using sugar-beet molasses and wheat bran were determined. The best results were obtained when 20% (w/v) molasses and 15% (w/v) wheat bran were used. The optimal initial pH for dextran production was 7.5.

Utilización de bloques solidificados de Melaza como suplemento alimenticio para ganado bovino durante la sequía en los trópicos / Use of solified molasses blocks as supplemental feed for cattle during dry periods

Como una posible solución al problema de la producción de carne y leche, y para disminuir la pérdida de peso del ganado bovino durante al temporada de sequía en el trópico, se ofrece el proceso tecnológico de solidificación de la melaza en forma de bloques como complemento nutricional, elaborados en base de melaza y de algunos subproductos agroindustriales como cáscara de cítricos, grano seco de cervecería, soapstock, harina de sangre, entre otros, de valioso potencial alimenticio que se encuentran en abundancia en las regiones tropicales de nuestro país