Aflatoxin production by Aspergillus flavus isolates from green- tiger shrimps (Penaeus semisulcatus)

Backgrounds and to obtain information about aflatoxigenicity of isolated Aspergillus flavus strains from shrimps. Forty - three isolates of Aspergillus flavus from cultured green tiger shrimps of Persian Gulf were examined for their ability to produce aflatoxins. Initially two media; Aflatoxin Producing Ability medium and Coconut Agar medium were used to detect fluorescence under UV light, later the presence of aflatoxin in culture extract was confirmed and quantified by high pressure liquid chromatography. Only 2 (4.6%) isolates fluoresced on Aflatoxin Producing Ability medium and Coconut Agar medium under UV light. In sum, 9 (20.93%) isolates (including the 2 above mentioned isolates) were confirmed to be aflatoxigenic by High Performance Liquid Chromatography. Eight (18.7%) of isolates produced aflatoxin B1 ranging from 0.32 to 12.18 ppb, while 1(2.3%) of isolates produced 18.88 ppb and 0.36 ppb of aflatoxin B1 and aflatoxin B2 respectively. Aspergillus oryzae did not produce any detectable aflatoxins. Although highest level of aflatoxin B1 (18.88 ppb) was detected in an isolate from a hepato-pancreatic sample, no histopathological change was observed in that tissue. Some Aspergillus flavus strains which were isolated from shrimps showed aflatoxin producing ability without any histopathological changes in tissues of contaminated shrimps.