Studies on Thermophilic Cellulolytic Fungi

Abstract

Three thermophilic cellulolytic fungi, Chaetomium thermophile var. coprophile, Sporotrichum thermophile, and Thermoascus aurantiacus were studied to determine the conditions for a high rate of cellulose degradation. The range of temperature over which good growth occurred was determined first in a temperature gradient incubator; the optimum temperature was then established in shake flask cultures. T. aurantiacus had the highest optimum growth temperature range (46 to 51 C), whereas S. thermophile had the broadest range over which good growth occurred (36 to 43 C). Optimum temperatures for the three organisms, T. aurantiacus, S. Thermophile, and C. thermophile were 48, 40, and 40 C, respectively. It was found that the addition of an organic carbon and nitrogen source to a cellulose mineral solution medium markedly increased the rate of cellulose degradation. The surfactant, Tween 80, which has been reported to be of value in the production and recovery of the enzyme, cellulase, was shown to be detrimental to the degradation of cellulose in culture. In the medium used, S. thermophile gave the highest rate of substrate utilization; 56% of the cellulose was hydrolyzed in 72 h. The average degree of polymerization of cellulose decreased from 745 to 575.

Factors influencing the production of cellulases by Sporotrichum thermophile

“…Recently, Romanelli et al reported that Sporotrichum thermophile gave a higher rate of cellulose utilization than Chaetomium thermophile var. coprophile and Thermoascus aurantiacus (16). In a previous study of cellulolytic fungi, we obtained similar results in comparisons of S. thermophile, C. thermophile, and Humicola insolens (R. E. Smith and A. D. Coutts, unpublished data).…”

Sporotrichum thermophile Growth, Cellulose Degradation, and Cellulase Activity

“…Tansey (27) found that the cellulolytic rates of some thermophilic fungi (Chaetomium thermophile, Sporotrichum thermophile, and Thermoascus aurantiacus) were two or three times that of Trichoderma viride, one of the most cellulolytic mesophilic fungi (15). Romanelli et al (20) reported that, of the three thermophilic fungi, S. thermophile degraded cellulose fastest in liquid shake cultures. Mandels (12) also noted that thermophilic fungi, including S. thermophile, degraded cellulose rapidly, but she found that the cellulase activity of their culture filtrates was low.…”

Purification and properties of the cellulases from the thermophilic fungus Thermoascus aurantiacus

“…The cellulases from thermophiles with the ability to operate at temperatures of 550C and higher offer the advantages of an increased rate of reaction and a stable enzyme system (Bellamy, 1977;Rosenberg, 1975). Further, the high operating temperature and acid pH required by the cellulases from thermophilic fungi restrict the growth of contaminating organisms (Eriksen & Goks6yr, 1976;Romanelli et al, 1975;Rosenberg, 1975). The production of cellulases by thermophilic fungi is well documented (Fergus, 1969;Romanelli et al, 1975;Seal & Eggins, 1976), although there are conflicting reports on the ability of Thermoascus aurantiacus to produce cellulases (Fergus, 1969;Tansey, 1971).…”

“…Further, the high operating temperature and acid pH required by the cellulases from thermophilic fungi restrict the growth of contaminating organisms (Eriksen & Goks6yr, 1976;Romanelli et al, 1975;Rosenberg, 1975). The production of cellulases by thermophilic fungi is well documented (Fergus, 1969;Romanelli et al, 1975;Seal & Eggins, 1976), although there are conflicting reports on the ability of Thermoascus aurantiacus to produce cellulases (Fergus, 1969;Tansey, 1971). We have examined the optimal growth conditions for cellulase production by T. aurantiacus and the general properties of three cellulases (C. C. Tong, A. L. Cole & M. G. Shepherd, unpublished work).…”