Journal of Applied Biosciences (J. Appl. Biosci.) [ISSN 1997 - 5902]
Volume 9(1): 378 - 384. Published September 2008.
Partial purification and biochemical characterization of extracellular pectinase from Aspergillus niger isolated from groundnut seeds
Rashmi R.* ^, Siddalinga Murthy K. R.**, Sneha G.*, Shabana S.*, Syama A.* and Radhika V. S.*
*Dept. of Biochemistry, Center for Post-graduate Studies, Sri Bhagawan Mahaveer Jain College, 18/3, 9th Main, 3rd Block, Jayanagar, Bangalore-560 011; 2DOS in Chemistry, Central College Campus, Bangalore University, Bangalore, India
^Corresponding author email: rashmikrishna1@yahoo.co.in; Phone: 91-098450 76500
ABSTRACT
Objectives: To produce and partially purify pectinases from Aspergillus niger isolateJGIm2, characterize the enzymes for potential industrial applications in clarifying fruit juices.
Methodology and results: Isolates of Aspergillus niger were screened for ability to produce pectinases by the enzymatic index method. All the 34 isolates screened were producers with isolates JGIm2, JGIm3 and JGIm5 being the best. Optimum enzyme production was found with medium containing 1.5% pectin after 48 h of fermentation. Partial purification of the enzyme was carried out by ethanol precipitation to give two fold purification and 56% yield. The enzyme had pH & temperature optima of 4.0 and 45°C, Km and Vmax values of 0.178 g/dl & 11.62 IU/mg protein, respectively. Clarification of banana and pineapple juice using the partially purified enzyme resulted in 38 and 41% reduction in viscosity as determined spectroscopically.
Conclusions and potential application of findings: The results illustrate that a naturally secreted pectinase, produced by A. niger which is a ‘generally regarded as a safe’ organism has good potential for industrial application in that it’s enzyme activity is in the acidic range which is suitable for fruit juices. Low Km, appreciable Vmax and good yield values also enhance its capacity to clarify fruit juices. Pectinases are widely used in industrial processes that need solubilization of the cell wall of plants, wood, fruit or paper. The pectinase identified in this study has potential applications in processing of fruits and vegetables, agricultural and agro-industrial waste, coffee and tea fermentations, and in textile and paper making industry.
Key words: pectinase, partial purification, Aspergillus niger, juice clarification
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