Some factors affecting cellulase production and activity by a thermotolerant aspergillus terreus R -4 from filter mud

The growth and cellulase production by the thermotolerant Aspergillus terreus R-4 grown on filter mud [FM] waste, as the sole carbon source, were optimal when the culture medium was composed of [g/I]: FM, 25; casein, 4; KH[2]PO[4], 2; MgSO[4]. 7H[2]O, 0.5; NaCl, 2. The effect of adding various substrates in presence of FM was examined. The supplementation of glucose [5 g/I] to the fermentation medium stimulated maximal cellulase activity, but higher concentrations of glucose repressed production of cellulases. The optimal conditions for CMCase, FPase and cellobiase were at pH 4.8 and 60°C. The cellulolytic enzymes produced by A-terreus R-4 were stable over a wide range of pH values. Enzyme activity was assayed after exposure to elevated temperatures for 15 min and its thermal stability was determined

Production and properties of cellobiases from immobilized cultures of aspergillus terreus R-4

Cultures of Aspergillus terreus R-4 were immobilized using different supports. The highest cellobiase activity [22.4 U/mg protein] was obtained in alginate entrapped cultures. Optimum alginate concentration and size of bead inoculum were 3% and 10 ml beads/50 ml culture, respectively. Addition of wheat bran or corn steep liquor stimulated the biosynthesis of the enzyme. Alginate beads retained 64% of their activity after 4 reuses. Purification of cellobiase [s] from free [FMC] and immobilized [IMC] cultures was fulfilled by ammonium sulphate precipitation followed by gel filtration on Sephadex G-150 and ion exchange chromatography on CM-Sephadex C50. Two cellobiases were obtained CB[im] II[b][MW 54.3-F:D] from immobilized cultures and CB[f]Ia [MW 72.1 KD] from free cultures. CB[imII][b]and CB[fIa]showed optimum temperature of 65 and 60°C and optimum pH values of 5.2 and 4.8, r-espectively. CB[im] II[b]was more thermostable than CB[f]Ia and both enzymes differed in their amino acid composition. Ca[2], Ba[2+], Na[+]and K[+]ions slightly activated or stabilized both cellobiases. CB[im] I[b]was highly activated by Mn[+]2 and strongly inhibited by Hg[2+]and pdraehioromercuribenzoate, while CBI, was only partially inhibited parachloromercurilbenzoate

Optimization of cellulase production by a thermotolerant aspergillus terreus R4 from filter mud

Seven strains of thermotolerant Aspergillus species were screened for cellulolytic activities. Aspergillus terreus R-4 was selected as the most potent cellulase producer on filter mud [FM], as a new substrate, produced as a by-product in cane sugar industry. CMCase, FPase and cellobiase production were optimal when 10% inoculum was used. The optimum fermentation conditions consist of medium composed of [g11]: FM, 25, NH[4]CI, 2, HKH[2]PO[4]; MgSO[4-], 7H[2]O, 0.5; NaCI, 0.5 at pH 7.0 and incubation period for 7 days under shaking conditions