Studies on the effect of pH, temperature and metal ions on the production of pectinase from tamarind kernel powder by submerged fermentation using Aspergillus foetidus (NCIM 505)
ABSTRACT Filamentous fungi Aspergillus foetidus NCIM 505 was studied for its capacity to produce exo-pectinase in submerged fermentation (SMF) from a new substrate of tamarind kernel powder (TKP). The process was further studied to optimize the initial operating variables like pH, time and temperature. Maximum pectinolytic activity was reached at 72 h of growth and the best fungal strain was found to be A. foetidus NCIM 505. Further, to increase the production rate of pectinase, the effects of metal ions were studied. Metal ions like Cu++, Mg++, Fe++, Co++ and Zn++ at different concentrations were used. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
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ABSTRACT: In the present study, the molecular and basic biochemical characterization of endopolygalacturonase E, the fourth Aspergillus niger N400 endopolygalacturonase, is reported. The entire endopolygalacturonase E gene consists of 1293 bp interrupted by three short introns (50, 50, and 59 bp, respectively) as concluded from the cDNA sequence. The deduced amino acid sequence comprises 378 residues that include 39 N-terminal amino acids of the prepropeptide. The calculated Mr and pI of the mature protein are 35 584 and 3.6, respectively.Compared with other endopolygalacturonases from A. niger N400, the mature protein endopolygalacturonase E has the highest sequence identity with endopolygalacturonase C (77.6 %) followed by endopolygalacturonase I (57.6 %) and endopolygalacturonase II (54.3 %).For overproduction of endopolygalacturonase E, an A. niger multicopy strain was used that was transformed with a promoter gene fusion construct that directs expression from the glycolytic A. niger pyruvate kinase promoter. The enzyme was purified and characterized as an endopolygalacturonase based on product analysis after polygalacturonate hydrolysis and on bond cleavage frequencies of oligogalacturonates of different degree of polymerisation (n = 2−7). The pH optimum was 3.8. The Km and Vmax for polygalacturonate hydrolysis were 2.5 ± 0.4 mg ml−1 and 1.3 ± 0.2 μkat mg−1, respectively. A subsite map was calculated by the combination of the methods of Suganuma et al. [Suganuma, T., Matsuno, R., Ohnishi, M. & Hiromi, K. (1978) J. Biochem. (Tokyo) 84, 293−316] and Nitta et al. [Nitta, Y., Mizushima, M., Hiromi, K. & Ono, S. (1971) J. Biochem. (Tokyo) 69, 567−576]. This indicated that the enzyme was composed of at least five subsites.European Journal of Biochemistry. 12/1997; 251(1‐2):72 - 80.
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ABSTRACT: The effects of various metal ions on the simultaneous production of glucose oxidase and catalase by Aspergillus niger were investigated. Calcium carbonate induced synthesis of both enzymes. The induction of calcium carbonate was accompanied by a metabolic shift from the glycolytic pathway (EMP, Embden-Meyerhof-Parnas) to direct oxidation of glucose by glucose oxidase. The time course of the biosynthesis of both enzymes is reported. The logistic model was in good agreement with the experimental growth results. The production of both enzymes was growth-associated. Finally, a model of growth and product formation was also proposed.Letters in Applied Microbiology 02/2001; 32(1):16-9. · 1.75 Impact Factor
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ABSTRACT: Xylanases are hydrolytic enzymes which randomly cleave the β-1, 4 backbone of the complex plant cell wall polysaccharide xylan. Diverse forms of these enzymes exist, displaying varying folds, mechanisms of action, substrate specificities, hydrolytic activities, and physicochemical characteristics. This article focuses on the fermentative production of xylanase from Arthrobacter sp. and the factors affecting the production. The batch-submerged fermentation was carried out in a 250-ml Erlenmeyer flask. The inoculum size of 5% v/v, initial pH of 7.0, and shaking speed of 150 rpm at 32 °C were maintained for the optimization of medium components. The cell growth, xylanase activity, cellulase activity, protein, and pH were determined at regular time intervals. Plackett–Burman statistical methodology was adopted to study the effect of media components on xylanase production. The effect of temperature and pH was studied using optimized medium composition determined by Plackett–Burman experimental design. The maximum xylanase activity of 4.0 U ml−1 at 84 h at the optimum temperature of 35 °C and pH of 7.0 was obtained. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.Asia-Pacific Journal of Chemical Engineering 07/2008; 3(3):347 - 353. · 0.80 Impact Factor