A rapid method for isolation of stable niaD and crnA mutants of entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae

Generally niaD mutants of fungi are selected by spontaneous mutations on appropriate minimal medium supplemented with various concentrations of KClO3 and a nitrogen source (Daboussi et al. 1989 Curr. Genet. 15:453-456; Johnstone et al. 1990 Gene 90:181-192; Malardier et al.1989 Gene 78:147-156; Unkles et al.1989 Gene 78:157-166). But in case of entomopathogenic fungi it has been observed that niaDmutants isolated simply by spontaneous mutation on chlorate were not stable, (Table-1). Therefore a method has been developed to isolate stable niaD mutants of these fungi by treating protoplasts with ethane methane sulfonate (EMS)

Effect of copper and manganese on free amino acid content of Neurospora crassa

Effect of copper and manganese on free amino acid content of Neurospora crass

AN ANTIFUNGAL EXTRACELLULAR ENZYMES FROM MALBRANCHEA CHRYSOSPORIOIDEA

ABSTRACT Extracellular enzymes of Malbranchea chrysosporioidea grown on prawn chitin showed chitinase, glucanase and protease activities in crude enzyme. The effect of the crude chitinolytic enzymes was studied for antifungal activity on the growth of several fungi on liquid and solid medium. Fifty percent growth inhibition was observed in liquid cultures by extracelluar enzymes at a concentration of 97-99 μg of protein for Neurospora crassa, Rhizopus chinensis and Trichoderma viridae and for Aspergillus niger at 122 μg. The growth inhibition was more pronounced at low concentration in liquid than in solid culture. These results demonstrate the utilization of crude enzymes of Malbranchea chrysosporioidea in biocontrol activity and opening new path for biotechnological applications

Cell Wall Composition of Neurospora crassa Under Conditions of Copper Toxicity

The mycelia of Neurospora crassa grown in the presence of high concentrations of copper were blue in color, but only on a medium containing inorganic nitrate and phosphate as the nitrogen and phosphate sources, respectively. The cell wall isolate of the blue mycelia contained large amounts (12%) of copper and higher amounts of chitosan, phosphate, and amino groups, with a 42% decrease in the chitin content. Although all the glucosamine of the cell wall of control cultures could be released within 6 h of hydrolysis with acid, that of the blue mycelium required prolonged hydrolysis for 24 h. On removal of copper, the cell wall of the blue mycelium could quantitatively bind again to copper as well as to zinc. Although zinc binding was fivefold greater, copper alone was preferentially bound from a mixture of the two metal ions. Supplementation of iron along with copper in the culture medium resulted in the disappearance of the blue color of the mycelium and restoration of normal growth and composition of the cell wall, probably by limiting the uptake of copper from the medium. The possibility of the cell wall being a specific site of lesion in copper toxicity in the mold is discussed