Ritu Mahajan

Application of cellulase-free xylano-pectinolytic enzymes from the same bacterial isolate in biobleaching of kraft pulp.

A synergistic action of xylano-pectinolytic enzymes from the same bacterial isolate Bacillus pumilus was evaluated for the prebleaching of kraft pulp. The enzymatic prebleaching of kraft pulp resulted in 8.5% reduction in kappa number of the pulp, showing remarkable delignification with the enzyme treatment. This approach resulted in 25% reduction in active chlorine consumption in subsequent bleaching stages without any decrease in brightness. Increase in Burst factor (9%), Tear factor (4.6%), Breaking length (4.4%), Double fold number (12.5%), Gurley porosity (4%) and Viscosity (11.8%) of enzyme treated pulp reflected the significant improvement in pulp properties. This is the first report describing the use of xylanase and pectinase produced simultaneously in the same production medium from the same bacterial isolate for effective biobleaching of kraft pulp. Use of this xylano-pectinolytic synergism in paper and pulp industry will ultimately help in making the process not only economically feasible but also eco-friendly.

Characterization of statistically produced xylanase for enrichment of fruit juice clarification process

Critical factors for xylanase production of Bacillus stearothermophilus under batch fermentation and for clarification of citrus fruit juice using this xylanase were optimized through central composite design of response surface methodology. Statistical approach resulted in an increase of 1.19-fold in xylanase yield over conventional method. Model equation for juice clarification included independent variables viz. temperature, incubation time and enzyme dose to study the dependent variables such as yield, acidic neutrality and filterability etc. Coefficient of determination, R(2) for enzyme production model and for different juice properties were in accordance with the linearity of the model. On the basis of the contour plots the optimum enzyme dose was 12.5 IU/g of xylanase. Enzymatic treatment has resulted in the improvement of twofold in the release of reducing sugars and 52.97% in juice yield, whereas 35.34% reduction in turbidity was observed.

An ecofriendly cost effective enzymatic methodology for deinking of school waste paper.

Efficiency of xylano-pectinolytic enzymes in deinking of school waste paper for its reuse has been investigated in the present study. Enzymatic deinked pulp decreased the requirement of chemicals to nearly 50% and gave same optical properties of pulp as obtained by conventional deinking process. This biodeinking plus chemical deinking approach resulted in a decrease of 20.15% and 22.64% in BOD and COD values of effluents and a gain of 10.71% in viscosity, 7.49% in breaking length, 10.52% in burst factor and 6.25% in tear factor as compared to conventional chemical deinking. This is the first report mentioning the use of xylanase and pectinase produced from a cellulase free alkalo-thermotolerant bacterial strain in the same cost effective agricultural residues based production medium for deinking and will help in making the process ecofriendly with 50% reduction in chemicals, commercially viable with better paper quality.

Bleach-boosting effect of crude xylanase from Bacillus stearothermophilus SDX on wheat straw pulp

Pretreatment of wheat straw pulp using cellulase-free xylanase produced from Bacillus stearothermophilus SDX at 60°C for 120min resulted in 4.75% and 22.31% increase in brightness and whiteness, respectively. Enzyme dose of 10U/g of oven dried pulp at pH 9 decreased the kappa number and permanganate number by 7.14% and 5.31%, respectively. Further chlorine dioxide and alkaline bleaching sequences (CDED(1)D(2)) resulted in 1.76% and 3.63% increase in brightness and whiteness, respectively. Enzymatic prebleaching of pulp decreased 20% of chlorine consumption without any decrease in brightness. Improvement in various pulp properties like viscosity, burst factor, burstness, breaking length, double fold, gurley porosity, tear factor, and tearness were also observed after bleaching of xylanase treated wheat straw pulp.

Microbial pectinases: an ecofriendly tool of nature for industries

Pectinases are the growing enzymes of biotechnological sector, showing gradual increase in their market. They hold a leading position among the commercially produced industrial enzymes. These enzymes are ecofriendly tool of nature that are being used extensively in various industries like wine industry; food industry; paper industry for bleaching of pulp and waste paper recycling; in the processing of fruit–vegetables, tea–coffee, animal feed; extraction of vegetable oil and scouring of plant fibres. Moreover, enzymatic catalysis is preferred over other chemical methods, since it is more specific, less aggressive and saves energy. This is the review which covers the information available on the applicability potential of this group of enzymes in various sectors.

Comparison and suitability of gel matrix for entrapping higher content of enzymes for commercial applications

To check the suitability of enzyme entrapped beads for use in pharmaceutical industry, amylase enzyme was entrapped in agar/agarose, polyacrylamide gels and calcium alginate beads. Sodium alginate of 1% concentration was found to be best with respect to immobilization efficiency and calcium alginate beads so obtained were not much susceptible to breakage. When sodium alginate- amylase mixture was added from a height of about 20-30 cm. into CaCl2 solution, size of beads was large at higher alginate concentration due to the increase in the size of droplet formation before entering into CaCl2 solution. Enzyme entrapped polyacrylamide and agar/agarose gels were fragile and could not withstand repeated use whereas enzyme entrapped in large calcium alginate beads was used successfully for 50 cycles for the conversion of starch into product without much damage to the beads under stirring conditions. Amylase preparation was also mixed with urease, lysozyme and coimmobilized in large sized calcium alginate beads. These beads were used for 10 repeated cycles to check the conversion of substrates into their products by their respective enzymes and we concluded that an enzyme or mixture of two or three enzymes can be immobilized in the same large sized calcium alginate beads. This will save the additional cost of bioreactor, manpower, maintenance conditions required for the conversion of one drug into another using enzyme/s entrapped in large sized beads.

Xylanase production using agro-residue in solid-state fermentation from Bacillus pumilus ASH for biodelignification of wheat straw pulp

Two stage statistical design was used to optimize xylanase production from Bacillus pumilus ASH under solid-state fermentation. Initially, Plackett–Burman designing (PB) was used for the selection of crucial production parameters. Peptone, yeast extract, incubation time, moisture level and pH were found to be the crucial factors for the xylanase production. Crucial variables were further processed through central composite designing (CCD) of response surface methodology (RSM) to maximize the xylanase yield. Each significant factor was investigated at five different levels to study their influence on enzyme production. Statistical approach resulted in 2.19-fold increase in xylanase yield over conventional strategy. The determination coefficient (R2) as shown by analysis of variance (ANOVA) was 0.9992, which shows the adequate credibility of the model. Potential of cellulase-free xylanase was further investigated for biobleaching of wheat straw pulp. Xylanase aided bleaching through XCDED1D2 sequence resulted in 20 and 17% reduction in chlorine and chlorine dioxide consumption as compared to control. Significant increase in pulp brightness (%ISO), whiteness and improvement in various pulp properties was also observed.

BIOREACTIVE COMPOUNDS AND ANTIOXIDANT PROPERTIES OF METHANOLIC EXTRACT OF FENNEL (FOENICULUM VULGARE MILLER)

Methanolic extract of dried Fennel ( Foeniculum vulgare Miller) seeds was analyzed for the presence of bioreactive compounds: ascorbate, riboflavin, tocopherol and polyphenols with potential antioxidant properties. The extract had low ascorbate (197.12 + 1.82 µg), riboflavin (11.97 + 0.35 µ g ) and tocopherol (280.33 + 5.67 µg/g dry seeds) content. Howeve r the extract had high polyphenol content ( 16.506 + 0.32 mg/g dry seeds ) . Antioxidant activity of the extract was determined by various mechanisms including DPPH free radical scavenging, metal induced protein and lipid oxidation inhibition and protection of D NA against H 2 O 2 induced damage. Fennel had excellent free radical scavenging activity with IC 50 2.1 mg dry seed weight . IC 5 0 observed for protection of proteins and lipids against met al ion induced oxidation is 2.1 and 2.5mg dry seed weight respectively . E x tract equivalent to 0 .5µg seeds is enough to protect DNA against H 2 O 2 induced oxidation. The results suggest that polyphenols are the principal components responsible for high antioxidant potential of methanolic extract of fennel .

ANTIMICROBIAL PROPERTIES OF METHANOLIC EXTRACT OF CUMIN ( CUMINUM CYMINUM ) SEEDS

Antimicrobial properties of methanolic extract of cumin ( Cuminum cyminum ) seeds on f our enteropathogenic and food - spoiler bacterial strains have been investig ated. The cumin extract has been fo und to be effective against both gram positive and gram negative bacteria. Increase in absorb ance between 260 - 280 nm indicates that incubation of bacterial cultures with cumin extract causes damage to the ir cell membranes and release of intracellular nucle otides and proteinaceous materials from the cells . The g rowth inhibition zone s observed b y agar well diffusion method we re 10.7 to 14.0 mm in diameter in presence of cumin extract. Minimum concentration s of cumin extract effective against E,coli , P.aerugin osa, S.aureus and B. pumilus we re found to be 12.5, 6.25, 25.0 and 6.25 mg dry weight per ml respectively.

An efficient and improved methodology for the screening of industrially valuable xylano-pectino-cellulolytic microbes.

Xylano-pectino-cellulolytic enzymes are valuable enzymes of the industrial sector. In our earlier study, we have reported a novel and cost effective methodology for the qualitative screening of cellulase-free xylano-pectinolytic microorganisms by replacing the commercial, highly expensive substrates with agricultural residues, but the microorganisms with xylanolytic, pectinolytic, cellulolytic, xylano-pectinolytic, xylano-cellulolytic, pectino-cellulolytic, and xylano-pectino-cellulolytic potential were obtained. The probability of getting the desired combination was low, so efforts were made to further improve this cost effective methodology for obtaining the high yield of the microbes capable of producing desired combination of enzymes. By inclusion of multiple enrichment steps in sequence, using only practically low cost substrates and without any nutrient media till primary screening stage, this improved novel protocol for screening gave only the desired microorganisms with xylano-pectino-cellulolytic activity. Using this rapid, efficient, cost effective, and improved methodology, microbes with required combination of enzymes can be obtained and the probability of getting the desired microorganisms is cent percent. This is the first report presenting the methodology for the isolation of xylano-pectino-cellulolytic positive microorganisms at low cost and consuming less time.