Correlation between catalase activity and aflatoxin synthesis in Aspergillus flavus

Cilj ovog rada bio je utvrditi da li postoji korelacija aktivnosti katalaze Aspergillus flavusa uzgojenog na podlogama koje potiču ili suprimiraju sintezu aflatoksina. Istraživanje je provedeno na podlozi GMS koja sadrži glukozu i podlozi PMS s peptonom u podlozi. Koncentracija aflatoksina je nakon uzgoja plijesni, ekstrakcije i prečišćavanja određena HPLC-om. Na osnovi rezultata istraživanja utvrđen je viši stupanj konverzije glukoze u biomasu plijesni u odnosu na pepton. Kod PMS podloge utvrdeno je ukupno najviše 23 ppb aflatoksina, dok je na GMS podlozi koncentracija dosegla i 333 ppb. Pepton u hranjivoj podlozi predstavlja izvor dušika, pa je PMS podloga pogodnija za sintezu proteina što bi moglo objasniti nižu aktivnost katalaze na GMS podlozi. Aktivnost katalaze i količina aflatoksina ponašaju se obrnuto proporcionalno. Na GMS podlozi koeficijent korelacije iznosi -0,91, sličan koeficijentu korelacije na PMS podlozi koji iznosi -0,94. Veliki pad aktivnosti katalaze je možda uzrokovao oksidativni stres u stanici plijesni koja na to odgovara pojačanom sintezom aflatoksina.The aim of this study was to determine whether there is a correlation between catalase activity of Aspergillus flavus, grown on substrates which either promote or inhibit the synthesis of aflatoxins. The GMS medium was used which contains glucose as well as the PMS medium with peptone. The concentration of aflatoxins was determined by HPLC following cultivation of mold, extraction, and purification. Based on the results, glucose has a higher degree of conversion to mold biomass than peptone. A total of 23 ppb aflatoxin was detected in the PMS medium, while the GMS had a significantly higher amount of up to 333 ppb. Pepton is a source of nitrogen in beef broth and which made the PMS medium more suitable for protein synthesis. Consequently, catalase activity in the GMS medium is less compared to the PMS. Catalase activity and the amount of aflatoxins were inversely proportional. Correlation coefficient in the GMS medium was -0.91, similar to the correlation coefficient in the PMS medium (-0.94). Major decline of catalase activity may have brought about cellular oxidative stress prompting molds to aflatoxin synthesis