Uji potensi isolat lokal Aspergillus flavus sebagai penghasil aflatoksin

Aflatoxin is found in food and livestock feed in Indonesia. Aflatoxin is toxigenic, mutagenic, teratogenic, carcinogenic, and immunosuppresive compound. Hazardous potential of aflatoxin demands the avaibility of aflatoxin standard for analysis. Pure 55 strains of Aspergillus flavus were screened with ELISA to evaluate the potential yield of aflatoxin. Result of screening suggested that isolate S.26 contained the highest AFB1 (1212,3 ppb). This isolate was chosen for aflatoxin production on PDB (Potato Dextrose Broth) media and GAN (glucose ammonium nitrate) media with five replications. A. flavus from JCM was also grown in the same media under the same condition as the reference isolate to produce aflatoxins. TLC analysis results suggested that both A. flavus cultures from S.26 and JCM isolates grown on GAN showed no ability to produce aflatoxin while those grown on PDB could produce aflatoxin. Aflatoxin analysis of the A. flavus culture of S.26 isolate grown on PDB by TLC suggested that the highest aflatoxin production was reached at the ninth until twelfth day with a range of aflatoxin concentrations 200-500 ppb and the average of 310 ppb (n=5). Analysis of A. flavus culture of JCM isolate on PDB by TLC suggested that the highest aflatoxin production was reached at the twelfth day with a range of aflatoxin concentrations 150-400 ppb and the average of 240 ppb. HPLC analysis of A. flavus culture of S.26 isolate had the highest amount of aflatoxin of 935,8 ppb at the ninth day while A. flavus culture of JCM isolate had the highest aflatoxin production of 847,7 ppb at the twelfth day. A. flavus of local isolate (S.26) has higher potential in producing aflatoxins on PDB media compared to A. flavus of reference isolate (JCM). Production of alfatoxin might be affected by variations in nitrate source, initial pH, medium composition, and chain of serial transfers during preparation and analysis. The aflatoxin produced by A. flavus of local isolate in PDB media could be the candidate of aflatoxin standards which are essential for the analysis of aflatoxins by means of purification on column chromatography.