Production of cell wall-degrading enzymes by a pH tolerant estuarine fungal isolate Fusarium moniliforme NCIM1276 in different culture conditions

Abstract

A pH tolerant strain of Fusarium moniliforme NCIM1276 with a saprophytic mode of nutrition was isolated from a coastal estuarine environment. Under laboratory conditions, the fungus produced significant biomass between pH 3 and 9, and produced cell wall degrading enzymes such as pectinases (polygalacturonase and pectate lyase), carboxymethylcellulase, xylanase and amylase. The production of these enzymes by the isolate in liquid medium, semi-solid medium and in infected tomato and cauliflower plants tissue was investigated. In liquid medium, the production of cell wall-degrading enzymes was induced by appropriate substrates, whereas the organism secreted all enzymes constitutively on wheat bran. The production of polygalacturonase, pectate lyase, carboxymethylcellulase, xylanase and amylase was increased by 3, 2, 11, 10 and 4-fold respectively on semi-solid medium containing wheat bran and orange pulp. Moreover when the fungus was allowed to infect tomato and cauliflower plants, the fungus was localized in the cortical tissues of the plants and secreted pectinases, carboxymethylcellulase and xylanase enzymes in the infected host tissue.