Production of cellulolytic and xylanolytic enzymes by a phytopathogenic Myrothecium roridum and some avirulent fungal isolates from water hyacinth

Abstract

The cellulolytic and xylanolytic activity of a pathogenic Myrothecium roridum Tode (IMI 394934) and non-pathogenic Fusarium solani and Curvularia pallescence Boedjin isolates from water hyacinth were investigated. The mycelial plugs of each isolate was grown in submerged cultures of Czapeck Dox broth containing the appropriate carbon source (carboxymethylcellulose, sawdust and homogenized dry water hyacinth leaf) at 25°C for 16 days. The enzyme activity assay was carried out on the culture filtrates obtained. This was measured as micromole sugar released per min. The result obtained showed that the enzyme activity (U/ml) for b-1,4-exoglucanase, b-1,4-endoglucanase and xylanase was maximum 3.70 ± 0.43, 0.95 ± 0.03 and 2.32 ± 0.10, respectively, in C. pallescens Boedjin grown on carboxymethylcellulose and minimum 0.12 ± 0.02, 0.13 ± 0.03 and 0.34 ± 0.01 respectively, in M. roridum grown on homogenized dry water hyacinth leaf. The b-glucosidase activity (U/ml) was highest, 1.74 ± 0.06 in M. roridum grown on sawdust and least, 0.08 ± 0.00 in C. pa llescens Boedjin grown on homogenized water hyacinth leaf broth. The maximum (324.00 ± 19.51 mg/ml) and minimum (130.00 ±5.83 mg/ml) total extracellular protein was produced in M. roridum grown on homogenized dry water hyacinth leaf and carboxymethylcellulose, respectively. This study showed that the phytopathogenic strain of M. roridum is capable of producing cellulases and xylanase enzyme in submerged cultures but to a lesser degree compared to F. solani and C. pallescence Boedjin.