This study was aimed to evaluate the pattern of cellulase biosynthesis from Aspergillus fumigatus ABK9 under submerged fermentation. Production was increased concomitantly with fungal growth up to 72 h and reached maximum (Xmax –6.72 g/l) with specific growth rate (µmax) of 0.126/h. Highest specific rate of enzyme production (qp) was found at initial medium pH of 5.0 and incubation temperature of 30°C. At the same time, in the presence of 2-deoxy-D-glucose concentration of 0.5 mg/ml, the production of cellulolytic enzymes, viz, carboxymethyl cellulase activity (CMCase), filter paper degrading activity (FPase) and β-glucosidase activity reached maximum of 132.2, 21.3 and 28.9 U/ml, respectively. Cellulase biosynthesis was induced in respect to higher volumetric production rate (Qp), specific rate of enzymes production (qp, U/g biomass/h) and enzyme/biomass yield (YE/X) when grown in carboxymethyl cellulose in comparison to other saccharides as sole carbon source. Induction ratios (IR) of cellulases were between 12.3 and 24.4 in the presence of 1.5% (w/v) CMC in the culture media. The strain was quite resistant to catabolic repression by glucose up to 0.4% (w/v). Cellulases production was greatly influenced in the presence of yeast extract and potassium dihydrogen phosphate (KH₂PO₄) as nitrogen and phosphate sources in the culture media. C/N ratio of 10.0 and C/P ratio of 4.0 proved to be the best for the production of enzyme cocktail. Along with the high production yield, the crude enzymes showed a promising cellulose hydrolyzing efficiency of rice straw, indicating the enzyme could be beneficial for its large scale industrial exploitation.
The virulent isolates of Colletotrichum capsici and Alternaria alternata produced more cellulolytic enzymes viz., C1 and Cxin vitro than the avirulent ones and the activity of these enzymes increased with the increase in age of culture. The virulent isolates of C. capsici and A. alternata produced more pectinolytic enzymes (macerating enzymes, pectin methyl esterase and endo polygalacturonase) than the avirulent ones. All the pectinolytic enzymes were highly active in 10-day-old culture and the activities decreased with the increase of culture age. Whereas the activity of enzymes produced by avirulent isolate of pathogens did not decrease and these enzyme activities increased with the increase in the age of culture. These pathogens also produced nonspecific toxic metabolites in culture filtrate which reduced seed germination, root length, shoot length and vigour index of the seedlings of chilli, rice, mungbean, maize, cotton, groundnut, okra, egg plant, cucumber and tomato. The toxins of the pathogens reduced seed germination and caused mortality of chilli seedlings in pot culture. The toxins also produced phytotoxic symptoms in the treated ripe and green chilli fruits and leaves.
Po mutagenizacji promieniowaniem UV i NTG szczepu Trichoderma reesei M-7 i selekcji na podłożu z dodatkiem żelatyny wyizolowano około 960 niskoproteazowych mutantów. Dziesięć z nich zostało przetestowanych podczas hodowli okresowych w zakresie produkcji celulaz, proteaz i beta-galaktozydazy w obecności serwatki i laktozy jako źródła węgla. Aktywności proteolityczne oznaczone po hodowlach 9 mutantów w obecności laktozy były niższe od szczepu wyjściowego. Zaobserwowano większy indukcyjny wpływ serwatki niż laktozy, na sekrecję proteaz przez wszystkie badane szczepy. Czysta laktoza okazała się bardziej efektywnym induktorem produkcji beta-galaktozydazy niż zawarta w serwatce. Plony biomasy większości mutantów po hodowlach na serwatce były tylko nieznacznie wyższe od oznaczonych po hodowlach na czystej laktozie. Było to prawdopodobnie związane z litycznym mechanizmem kompensującym proteaz, przejawiających wyższe aktywności w filtratach pochodzących z hodowli w obecności serwatki. Praca jest wstępem do dalszych badań nad zależnościami pomiędzy proteazami i innymi enzymami w filtratach pohodowlanych Trichoderma reesei.