Extracellular mannanases and galactanases from selected fungi

Abstract

Eight thermophilic fungi were tested for production of mannanases and galactanases. Highest mannanase activities were produced by Talaromyces byssochlamydoides and Talaromyces emersonii. Mannanases from all strains tested were induced by locust bean gum except in the case of Thermoascus aurantiacus, where mannose had a greater inducing effect. Locust bean gum was also the best inducer of β-mannosidase and galactanase except in the case of T. emersonii where galactose was a better inducer of both these enzymes. Highest mannanase activity was produced by Talaromyces species when peptone was used as nitrogen source whereas sodium nitrate promoted maximum production of this enzyme by Thielavia terrestris and T. aurantiacus. The pH optima of mannanases from the thermophilic fungi were in the range 5.0-6.6 and contrasted with the low pH optimum (3.2) of the enzyme from Aspergillus niger. Galactanases had pH optima in the range 4.3-5.8. The mannanase from T. emersonii and the galactanase from T. terrestris were most thermostable, each retaining 100% activity for 3 h at 60°C. © 1990 Society for Industrial Microbiology.