Bio-processing of agro-industrial waste orange peel for induced production of pectinase by Trichoderma viridi; its purification and characterization

Objective: Agro-industrial residues are primarily composed of complex polysaccharides that strengthen microbial growth for the production of industrially important enzymes. For industrial use, pectinases can be produced from several agricultural pectin-containing wastes like orange peel. The selection of cheap source benefits the production of industrial important enzymes in term to costs-effective production. Methods: The indigenously produced pectinase was purified to homogeneity level using a combination of ammonium sulphate precipitation and Sephadex G-100 gel filtration chromatography. The molecular weight and properties of the purified enzyme were studied following the standard procedures. Results: Under optimized solid state fermentation conditions Trichoderma viridi exhibited superior enzymatic production. On optimization, the culture showed the maximum enzyme yield (325 U/mL) at 30 °C in an orange peel medium having a pH of 5.5 and a substrate concentration of 4% on the 4th day of fermentation of orange peel based medium that was additionally supplemented with glucose and ammonium chloride as an inexpensive carbon and nitrogen supplements in a ratio of 20:1, respectively. A purification fold of 5.59 with specific activity and percent recovery of 97.2 U/mg and 12.96% was achieved respectively. The molecular weight of purified pectinase from T. viridi was 30 kDa evidenced by PAGE analysis. After 6 h incubation the pectinase activity profile showed that the purified enzyme was optimally active and stable at a pH of 5 and at 60°C. Conclusions: The present study concluded that the indigenous strain T. viridi showed incredible potential for pectinase synthesis. The maximum production of pectinase in the presence of a cheaper substrate at low concentrations makes the enzyme useful in industrial sectors, especially for the textile and juice industries.