A sustainable process for co-production of xylooligosaccharides and ethanol from alkali treated sugarcane bagasse: A strategy towards waste management.

Present study aims at sustainable utilization of sugarcane bagasse (SCB) for production of valuable prebiotic xylooligosaccharides (XOS) along with second generation ethanol. Fractionation of SCB into hemicellulose rich liquid fraction and cellulose rich solid residue was achieved using alkaline treatment. Carbohydrate rich precipitate obtained from liquid fraction was utilized for XOS production using inhouse produced endoxylanase. XOS production from SCB xylan was optimized by employing response surface methodology. Under optimized conditions, maximum XOS yield was 227.72 mg/g of carbohydrate rich precipitates. The solid residue obtained after alkaline pretreatment was used for ethanol fermentation by prehydrolysis and simultaneous saccharification and fermentation (P-SSF) process using cellulolytic enzyme cocktail and Saccharomyces cerevisiae SM1. Maximum ethanol concentration, productivity and yield were 79.76 ± 0.16 g/L, 0.83 g/L/h and 69.38%, respectively by employing P-SSF process. Based on the experimental data it can be predicted that bioconversion of 100 g raw SCB can yield 6.26 g of XOS (DP 2-DP 5), 15.95 g ethanol and 1.44 g of xylitol. Present investigation reports an integrated process for effective bioconversion of SCB into value added products by maximum utilization of cellulosic and hemicellulosic fractions simultaneously using indigenously produced fungal enzymes.

Fomitopsis meliae CFA 2, a novel brown rot for endoglucanase: emphasis towards enhanced endoglucanase production by statistical approach.

Brown rot basidiomycetes are a principal group of wood-decaying fungi which degrade wood cellulose and hemicellulose by the combination of carbohydrate active enzymes and non-enzymatic oxidation reactions. Very scant information is available on carbohydrate active enzymes of brown rot fungi. In this context, present study focused on the production of cellulolytic-hemicellulolytic enzymes from newly isolated brown rot Fomitopsis meliae CFA 2. Under solid-state fermentation using wheat bran as the substrate Fomitopsis meliae CFA 2 was able to produce a maximum of 1391.12 ± 21.13 U/g of endoglucanase along with other cellulolytic and hemicellulolytic enzymes. Various fermentation parameters were optimised for enhanced production of endoglucanase by employing Plackett-Burman design followed by Box-Behnken design. A well-fitted regression equation with R2 value of 98.91% was attained for endoglucanase. The yield of endoglucanase was enhanced by 1.83-fold after executing statistical optimisation of various fermentative parameters. The newly isolated Fomitopsis meliae CFA 2 was found to be a potential producer of endoglucanase. Enzymatic saccharification of alkali-treated wheat straw and rice straw resulted in release of 190.8 and 318.8 mg/g of reducing sugars, respectively.

Degradation and Toxicity Analysis of a Reactive Textile Diazo Dye-Direct Red 81 by Newly Isolated Bacillus sp. DMS2.

An efficient diazo dye degrading bacterial strain, Bacillus sp. DMS2 was isolated from a long-term textile dye polluted environment. The strain was assessed for its innate ability to completely degrade and detoxify Direct Red 81 (DR81) textile dye under microaerophilic conditions. The degradation ability of strain showed significant results on optimizing the nutritional and environmental parameters. Based on statistical models, maximum efficiency of decolorization achieved within 24 h for 100 mg/l of dye supplemented with glucose (0.02%), MgSO4 (0.002%) and urea (0.5%) at 30°C and pH (7.0). Moreover, a significant catabolic induction of a laccase and azoreductase suggested its vital role in degrading DR81 into three distinct metabolites (intermediates) as by-products. Further, toxicity analysis of intermediates were performed using seeds of common edible plants, aquatic plant (phytotoxicity) and the nematode model (animal toxicity), which confirmed the non-toxic nature of intermediates. Thus, the inclusive study of DMS2 showed promising efficiency in bioremediation approach for treating industrial effluents.

Optimal and/or efficient three treatment crossover designs for five carryover models.

The additional benefits in the analysis of crossover designs with two active treatments and a placebo motivated us to study these kinds of designs. These designs have been studied through a computer search algorithm, called 5M balanced algorithm, in two to four periods for different number of units, which resulted in optimal and/or efficient crossover designs. The new two periods crossover designs having two active treatments and a placebo, enables the estimation of treatment contrasts, unlike the classic two treatments two periods crossover which fails to estimate the treatment contrasts under self and mixed carryover model. The crossover designs having three or four periods in two active treatments and a placebo, estimate treatment contrasts more efficiently under self and mixed carryover model than the usual two treatments crossover designs. An exhaustive list of optimal and/or efficient crossover designs has been provided for designs in two periods having 6-21 subjects, three periods having 3-20 subjects and four periods having 3-14 subjects. In this list, 35 new designs are optimal for one of the established carryover models and 26 new designs are optimal and/or efficient to all four plausible carryover models.

Optimal and/or Efficient Two treatment Crossover Designs for Five Carryover Models.

Crossover designs robust to changes in carryover models are useful in clinical trials where the nature of carryover effects is not known in advance. The designs have been characterized for being optimal and efficient under no carryover-, traditional-, and, self and mixed carryover- models, however, ignoring the number of subjects, which has significant impact on both optimality and administrative convenience. In this article, adding two more practical models, the traditional, and, self and mixed carryover models having carryover effect only for the new or test treatment, a 5M algorithm is presented. The 5M algorithm based computer code searches all possible two treatment crossover designs under the five carryover models and list those which are optimal and /or efficient to all the five carryover models. The resultant exhaustive list consists of optimal and/or efficient crossover designs in two, three, and four periods, having 4 to 20 subjects of which 24 designs are new optimal for one of the established carryover models, and 34 designs are optimal for newly added models.

Biocatalytic synthesis of flavor ester "pentyl valerate" using Candida rugosa lipase immobilized in microemulsion based organogels: effect of parameters and reusability.

Pentyl valerate was synthesized biocatalytically using Candida rugosa lipase (CRL) immobilized in microemulsion based organogels (MBGs). The optimum conditions were found to be pH 7.0, temperature of 37 °C, ratio of concentration of water to surfactant (Wo) of 60, and the surfactant sodium bis-2-(ethylhexyl)sulfosuccinate (AOT) for MBG preparation. Although kinetic studies revealed that the enzyme in free form had high affinity towards substrates (K(m) = 23.2 mM for pentanol and 76.92 mM for valeric acid) whereas, after immobilization, the K(m) values increased considerably (74.07 mM for pentanol and 83.3 mM for valeric acid) resulting in a slower reaction rate, the maximum conversion was much higher in case of immobilized enzyme (~99%) as compared to free enzyme (~19%). Simultaneous effects of important parameters were studied using response surface methodology (RSM) conjugated with Box-Behnken design (BBD) with five variables (process parameters), namely, enzyme concentration, initial water content (Wo), solvent used for MBG preparation, substrate ratio and time, and response as the final product formation, that is, pentyl valerate (%). The MBGs were reused for 10 consecutive cycles for ester synthesis. Efficacy of AOT/isooctane as dehydrating agent for extracting excess water from MBGs was found to exert a positive effect on the esterification reaction.

Production of cellulases by solid state fermentation with Aspergillus terreus and enzymatic hydrolysis of mild alkali-treated rice straw.

Rice straw was used as substrate for cellulase production by solid state fermentation with Aspergillus terreus. Substrate concentration, moisture ratio, inoculum size and initial pH were optimized using response surface methodology involving Box-Behnken design. The predicted filter paper activity under optimized parameters was 9.73 U/g and the validated filter paper activity was 10.96 U/g. Hydrolysis of the biomass pretreated with 0.125% to 1% NaOH for 24h at room temperature was performed using crude cellulase preparation. Treatment with 0.5% NaOH at room temperature for 24h was the most efficient treatment method for saccharification. Under the optimized conditions, rice straw yielded 676 mg reducing sugars per gram of substrate at a cellulase loading of 9 FPU g(-1) substrate. The present study establishes the possibility of using mild alkali pretreated rice straw for the production of fermentable sugars with 74.19% efficiency which can be further utilized for the production of ethanol.

Optimization of inulinase production by a newly isolated Aspergillus tubingensis CR16 using low cost substrates.

Production of an extracellular, thermostable inulinase was carried out by a newly isolated strain of Aspergillus tubingensis CR16 using wheat bran and corn steep liquor (CSL) under solid state fermentation (SSF). Response surface methodology (RSM) involving Box Behnken design (BBD) was employed for the optimization of process parameters viz. time period of fermentation, % moisture content, inoculum size and pH of the medium. Maximum yield of inulinase was 257±11.4 U/g, obtained by inoculating 5 g of wheat bran with 10(9) spores/ml, at initial 71.2% moisture content and pH 6.1 after 103 h of fermentation along with 1358.6±0.8 U/g of invertase activity. Crude inulinase showed maximum activity at 60 °C and pH 5.0. The enzyme was found to be thermostable retaining about 90% of its activity for 4.5 h at 60 °C. Fructose was produced as an end product of inulin hydrolysis proving that the enzyme produced was exoinulinase.

Utilization of anaerobically treated distillery spent wash for production of cellulases under solid-state fermentation.

Pollution caused by distillery spent wash on one hand has stimulated the need to develop new technologies to treat the waste and on the other, forced us to reevaluate the efficient utilization of its nutritive potential for production of various high value compounds. In this study, anaerobically treated distillery spent wash was used for the production of cellulases by Aspergillus ellipticus under solid-state fermentation using wheat straw as a substrate. The interactions between distillery effluent concentration, initial pH, moisture content and inoculum size were investigated and modeled using response surface methodology (RSM) involving Box-Behnken design (BBD). Under optimized conditions, filter paper activity, beta-glucosidase and endo-beta-1,4-glucanase activities were found to be 13.38, 26.68 and 130.92 U/g of substrate respectively. Characterization of endo-beta-1,4-glucanase and beta-glucosidase was done after partial purification by ammonium sulfate fractionation followed by desalting. The partially purified endo-beta-1,4-glucanase and beta-glucosidase showed maximum activity at 60 degrees C. Saccharification studies performed with different lignocellulosic substrates showed that wheat bran was most susceptible to enzymatic hydrolysis. The study suggests that anaerobically treated distillery spent wash can be used as a viable nutrient source for cellulase production under solid-state fermentation by A. ellipticus.

Xylanase production by Burkholderia sp. DMAX strain under solid state fermentation using distillery spent wash.

Xylanase production by a newly isolated strain of Burkholderia sp. was studied under solid state fermentation using anaerobically treated distillery spent wash. Response surface methodology (RSM) involving Box-Behnken design was employed for optimizing xylanase production. The interactions between distillery effluent concentration, initial pH, moisture ratio and inoculum size were investigated and modeled. Under optimized conditions, xylanase production was found to be in the range of 5200-5600 U/g. The partially purified enzyme recovered after ammonium sulphate fractionation showed maximum activity at 50 degrees C and pH 8.6. Kinetic parameters like Km and Vmax for xylan were found to be 12.75 mg/ml and 165 micromol/mg/min. In the presence of metal ions such as Ca2+, Co2+, Mn2+, Ba2+, Mg2+ and protein disulphide reducing agents such as beta-mercaptoethanol and dithiotheritol (DTT) the activity of enzyme increased, where as strong inhibition of enzyme activity was observed in the presence of Cu2+, Ag+, Fe2+ and SDS. The crude enzyme hydrolysed lignocellulosic substrate, wheat bran as well as industrial pulp.

Response surface methodology for optimization of medium for decolorization of textile dye Direct Black 22 by a novel bacterial consortium.

Decolorization and degradation of polyazo dye Direct Black 22 was carried out by distillery spent wash degrading mixed bacterial consortium, DMC. Response surface methodology (RSM) involving a central composite design (CCD) in four factors was successfully employed for the study and optimization of decolorization process. The hyper activities and interactions between glucose concentration, yeast extract concentration, dye concentration and inoculum size on dye decolorization were investigated and modeled. Under optimized conditions the bacterial consortium was able to decolorize the dye almost completely (>91%) within 12h. Bacterial consortium was able to decolorize 10 different azo dyes. The optimum combination of the four variables predicted through RSM was confirmed through confirmatory experiments and hence this bacterial consortium holds potential for the treatment of industrial waste water. Dye degradation products obtained during the course of decolorization were analyzed by HPTLC.