Influence of Media and Temperature on Gliotoxin Production in Aspergillus Fumigatus Strains

Gliotoksin je sekundarni metabolit iz skupine epipolitiodioksipiperazina s biološki aktivnim internim disulfidnim mostom u molekuli, koji tvore razne plijesni i gljivica Candida albicans. Plijesan Aspergillus fumigatus vodeći je uzročnik invazivnih aspergiloza i također može tvoriti gliotoksin. Pretpostavlja se da in situ tvorba gliotoksina utječe na patogenezu aspergiloze. U ovom radu ispitali smo in vitro tvorbu gliotoksina u devet sojeva A. fumigatus vrste, izoliranih iz imunokompromitiranih pacijenata. Praćen je utjecaj medija i temperature inkubacije na tvorbu gliotoksina. Gliotoksin je ekstrahiran iz biomase i koncentracija mu je utvrđena polukvantitativno tankoslojnom kromatografijom. Tvorba gliotoksina uočena je već nakon trodnevne inkubacije u koncentracijama 4,06 mg mL-1 (u bujonu s kvaščevim ekstraktom – YES na 37 °C) i 1,07 mg mL-1 (u sintetskom Czapek-Dox bujonu – CZA na 25 °C). Tvorba gliotoksina bila je veća u YES bujonu, za razliku od sintetskog CZA bujona. Viša temperatura inkubacije (37 °C) također utječe na jaču tvorbu gliotoksina nego niža temperatura (25 °C). YES bujon s dodatkom 4 % saharoze i 2 % kvaščeva ekstrakta vrlo je bogat supstrat za in vitro tvorbu gliotoksina, kao jednog od lipofilnih sekundardnih metabolita plijesni vrste A. fumigatus.Gliotoxin is a secondary metabolite of the epipolythiodioxopiperazine family with biologically active internal disulfide bridge. It is produced by many fungal species, including Aspergillus fumigatus and A. terreus. A. fumigatus, which produces gliotoxin and more than twenty other secondary metabolites, is the leading cause of invasive aspergillosis. Gliotoxin production in situ influence the development of aspergillosis. This study investigated the in vitro production of gliotoxin in nine A. fumigatus isolates from the upper respiratory tract of immunocompromised patients. The effects of media composition and incubation temperature were studied. Gliotoxin was extracted from biomass and its concentration was semi-quantitatively analysed using thin-layer chromatography. Gliotoxin production was higher in the yeast-extract liquid medium (YES) than in the synthetic Czapek-Dox liquid medium (CZA). Incubation at 37 °C resulted in higher gliotoxin production than at 25 °C, probably because higher temperatures favour expansive growth of the mycelium. Gliotoxin could be detected after three days of incubation at concentrations 4.06 mg mL-1 (in YES at 37 °C) and 1.07 mg mL-1 (in CZA at 25 °C). YES broth as a medium containing 4 % sucrose and 2 % of yeast extract is a very rich substrate for the production of gliotoxin in vitro