screening of urease production by aspergillus niger strains

in this study, urease production was investigated among thirteen strains of aspergillus niger seven strains isolated from soils of semnan province in iran and six strains obtained from persian type culture collection (ptcc). the enzyme production was screened in two submerged media quantitatively. the registered ptcc 5011 and the native s31 strains showed more urease production than the other eleven strains. the maximum enzyme productions by ptcc 5011 and s31 strains were 106 and 109 u.g-1dry mass in submerged culture, respectively. also, we used two solid media for screening all of the strains for urease production semi quantitatively. due to the acceptable correlations between the two methods, the latter can be used as an ancillary method to mass screening of urease production by filamentous fungi.