What is it about?
This paper deals with the biosynthetic capacity for ochratoxin A (OTA) production by Aspergillus ochraceus E'G isolate derived from A. ochraceus CBS 108.08 strain, during 2007. Preliminary analysis of fungal potential for the production of OTA were performed according to the modified method of F i l t e n b o r g et al. (1983). Toxin production was tested in the following liquid media: (i) glucose-peptone-yeast extract broth (GPY — pH 5.6), (ii) potato-dextrose broth (PDB — pH 6.9), (iii) yeast extract-sucrose broth (YES — pH 6.5), and (iv) YES broth supplemented with 0.23 mg/l ZnSO4 x 5 H2O (YESZn — pH 6.5) after stationary and submerged cultivation. Dynamics of OTA biosynthesis was tested after the cultivation of A. ochraceus E'G on natural solid substrates, such as wet sterilized rice, corn and wheat grain. Cultivations were performed during different time periods (ranging from four days to few weeks) at different temperatures (ranging from 21°C to 30°C). The presence of OTA was determined as follows: (i) in liquid media according to the method of B a l z e r et al. (1978) modified by B o å a r o v - S t a n å i ã et al. (2003), and (ii) in the solid substrates according to the Serbian official methods for sampling and analyzing of fodder (Official Gazette of SFRY, No. 15/87). After the cultivation of A. ochraceus E'G isolate in liquid media, the highest yield of OTA (6.4 mg/l) was obtained after submerged cultivation in PDB (4 days, 128 rpm, 21—23°C). In the case of cultivation on solid substrates, the highest amount of OTA (800.0 mg/kg of dry matter) was recorded after several week long cultivation on wheat grain at 30 1°C.
Featured Image
Why is it important?
the aim of this paper was to examine the kinetics of OTA biosynthesis under laboratory conditions, and to complete the optimization of conditions for the OTA production by the newly isolated culture of A. ochraceus designated E'G.
Perspectives
Preliminary analysis of A. ochraceus E'G potential for the production of ochratoxin A showed that isolate E'G had similar toxicological profile as its parent strain CBS.108.08. At the end of the cultivation period, in different liquid media, the decrease of initial pH was recorded in all cases, although the most outstanding change occurred after the 10-day stationary cultivation in chamber (27 1°C). Aeration influenced the toxin biosynthesis much more than the temperature during the cultivation of A. ochraceus E'G in liquid media. The highest yield of OTA (6.4 mg/l) was obtained after submerged cultivation in potato-dextrose broth. Type of cereal grain used for OTA production showed a significant influence on the dynamic of the process and toxin yields. After three weeks of cultivation of A. ochraceus E'G the similar concentrations of ochratoxin A were recorded on corn kernels and rice grain (80.0 mg/kg and 96.0 mg/kg, respectively) while the highest amounts were found on wheat grain (800.0 mg/kg). Contrary to wheat substrate where the yield of OTA was increasing until the 21st day of cultivation, the corn substrate did not show any changes in the quantity of the produced toxin from the 14th day of cultivation until the end of the same process.
Research Professor Vesna Jaćević
National Poison Control Centre, Military Medical Academy & Medical Faculty, University of Defence, Belgrade, Sebia
Read the Original
This page is a summary of: Ochratoxin A 'in vitro' biosynthesis by the Aspergillus ochraceus E'G isolate, Zbornik Matice srpske za prirodne nauke, January 2009, National Library of Serbia,
DOI: 10.2298/zmspn0917069b.
You can read the full text:
Contributors
The following have contributed to this page
