1093 Marı  a M. REYNOSO 1 , Adriana M. TORRES 1 †, Marı  a L. RAMIREZ 1 , Marı  a I. RODRI  GUEZ 1 , Sofı  a N. CHULZE 1 and Naresh MAGAN 2 *  Departamento de Microbiologia e Inmunologia, Facultad de Ciencias Exactas Fisico-Quı  micas y Naturales, Universidad Nacional de Rio Cuarto, Rio Cuarto, Cordoba, Argentina.  Applied Mycology Group, Cranfield Biotechnology Centre, Cranfield University, Silsoe, Bedford MK45 4DT, UK. E-mail : n.magancranfield.ac.uk Received 7 January 2002 ; accepted 10 May 2002. The effect of single or mixtures of antioxidants on the lag phase prior to growth, growth rate, hydrolytic enzyme production (N-acetyl-β-glucosaminidase, β--glucosidase and α--galactosidase) and fumonisin production by Fusarium verticillioides and F. proliferatum was evaluated on maize-based media at 25 C, and under different water activity (a w ) conditions. An increase in the lag phase (h) was observed for both F. verticillioides and F. proliferatum especially with propyl paraben (PP)butylated hydroxyanisole (BHA) treatments at all a W levels tested. For both species PP alone or in combination with BHA, at concentrations of 05 and 1 m reduced the growth rates by 85% at the three a W levels tested (0995; 098 and 095). PPbutylated hydroxytoluene (BHT) or trihydroxybutyrophenone (THBP) were less effective in controlling growth, regardless of a W level. Combinations of PPBHA reduced the fumonisin concentrations produced by F. verticillioides and F. proliferatum at 0995 and 098 a W significantly. However, at low concentrations of antioxidants (05m) some stimulation in fumonisin production was observed with some treatments. The efficacy of the treatments was reflected in the impact on enzyme production. In the untreated control the highest total enzyme activity of three hydrolytic enzymes was observed at 0995 a W after 96 h. All the antioxidant treatments alone or combined resulted in a significant reduction (P  0001) of the total enzyme activity at the a W levels tested. Only 10 m THBP produced an increase in the total amount of N-acetyl-β--glucosidase by both F. verticillioides and F. proliferatum. For the three enzymes single factors : time, a W and antioxidant treatments, most two and all three way interactions were significant (P  0001). The use of combined mixtures of antioxidants could be a good strategy to diminish the entry of fumonisin into the animal feed and human food chains. INTRODUCTION Maize (Zea mays) is an important crop both for food and feedstuffs production in different parts of the world where this cereal is cultivated. In Argentina, the cultivated area ranges from 3–35 M ha -. About 48% of the production is used for internal consumption and the rest is exported, representing 40 % of the total cereal export in Argentina (Secretarı  a de Agricultura, Ganaderı  a, Pesca y Alimentacio  n 1997). Maize is susceptible to colonization by several fungal species including Fusarium, Aspergillus during ripening and at harvest. Among the Fusarium species, F. verticillioides and F. proliferatum are of concern due to their toxigenic * Corresponding author. † Members of the Research Career of Consejo Nacional de Investigaciones Cientı  ficas y Te  cnicas from Argentina (CONICET). potential of producing fumonisins. F. verticillioides is the most prevalent Fusarium species in freshly harvested corn in Argentina cultivated under no-till and con- ventional tillage conditions. F. proliferatum is a rela- tively minor component (Chulze et al. 1996, 2000, Gonzalez et al. 1995). Fumonisins are important because of an association with human and animal mycotoxicoses, such as leukoencephalomalacia (ELEM) in horses and pul- monary edema in swine (PPE) (Harrison et al. 1990, Ross et al. 1990) and oesophageal cancer in humans (Chu & Li 1994, Thiel et al. 1992). The International Agency for Research on Cancer (1993 : 257–263) has evaluated these toxins derived from F. verticillioides as group 2B carcinogens, i.e. possibly carcinogenic to humans. Different strategies have been examined to diminish the entry of fumonisins into the human and animal food chain. Efficient drying of maize immedi- Mycol. Res. 106 (9) : 1093–1099 (September 2002).  The British Mycological Society DOI : 10.1017S0953756202006135 Printed in the United Kingdom. Efficacy of antioxidant mixtures on growth, fumonisin production and hydrolytic enzyme production by Fusarium verticillioides and F. proliferatum in vitro on maize-based media