Molecular cloning of genes from the rumen anaerobic fungus Neocallimastix frontalis: expression during hydrolase induction

Abstract

Glycoside and polysaccharide hydrolase production by the rumen anaerobic fungus, Neocalimastix frontalis is induced by the presence of crystalline cellulose. A differential screening of a cDNA library was used to isolate DNA sequences transcribed at high levels under growth conditions which induce enzyme production. Seven clones were isolated that preferentially hybridized to the induced cDNA probe versus the non-induced cDNA probe. Southern analysis showed that a cDNA clone (118) hybridized to a DNA probe encoding part of the exo-cellobiohydrolase I (CBH I) gene of Trichoderma reesei. Northern analysis demonstrated that the cDNA 118 was transcribed to yield a 2.1 kb RNA. This transcript was induced in the presence of cellulose.