Production of cutinolytic esterase by filamentous bacteria

Thirty-eight strains of filamentous bacteria, many of which are thermophili c or thermotolerant and commonly found in composts and mouldy fodders, were examined for their ability to produce cutinolytic esterase (cutinase) in c ulture media supplemented with cutin, suberin or cutin-containing agricultu ral by-products. Initially, the ability of culture supernatants to hydrolys e the artificial substrate p-nitrophenyl butyrate was determined by spectro photometric assays. Only one bacterium, Thermoactinomyces vulgaris NRRL B-1 6117, exhibited cutinolytic esterase production. The enzyme was highly indu cible, was repressed by the presence of glucose in the medium and hydrolyse d both apple and tomato cutins. Inducers included apple cutin, apple pomace , tomato peel, potato suberin and commercial cork. Unlike similar fungal en zymes, the T. vulgaris cutinolytic esterase was not inducible by cutin hydr olysate. The cutinolytic esterase exhibited a half-life of over 60 min at 7 0 degrees C and a pH optimum of greater than or equal to 11.0. This study i ndicates that thermophylic filamentous bacteria may be excellent commercial sources of heat-stable cutin-degrading enzymes that can be produced by fer mentation of low cost feedstocks.