PRODUCTION OF POLYGALACTURONASE FROM THERMOSTABLE MOLD ASPERGILLUS NIGER 1- ISOLATION AND SCREENING THE ENZYME PRODUCER THERMOSTABLE MOLDS AND IDENTIFYING THE PRODUCER ONE

Abstract

A total of 147 isolates of pectin hydrolysis enzymes producer molds were isolated from various sources(soil and decayed vegetables and fruit) using Czapek Dox Agar using 3% pectin as the sole carbon source by adding of 1M Hcl at PH5 and submitted to primary and secondary screening at 40 CO to select the best isolate that produces the highest level of polygalacturonase. It was found that 7 isolates were good producer but the isolate which designated TP4 was the highest producer one. The source of this isolate was deteriorated orange and identified as Aspergillus niger according to morphological, biochemical and molecular analysis which was achieved using PCR (Polymerase Chain Reactions) technique. This isolate was nominated as Aspergillus niger TP4 for distinguishing it from any other isolates used for production the same enzyme. This part of study was aimed to investigate the optimal condition of production the enzyme Polygalacturonase from Aspergillus niger TP4 by solid state fermentation using different wastes available locally. It was found that the higher level of production could be achieved on wheat bran and sunflower head extract moistened with water at a ratio 3:1 with an initial pH 5 inoculated with 107 spores/gm during an incubation time of 4 days at 4 C0.the polygalacturonase activity was assay by measuring reducing groups The productivity under these conditions was 325.45 unit/gm using wheat bran and 242.28 unit/gm using sunflower head with an increase estimated about 124.7% and 120.8% respectively in relationship with productivity before of the optimization.