Influence of carbon and nitrogen sources on ochratoxin A production by two species of Penicillium isolated from poultry feeds

Abstract

Mycotoxins are natural, secondary metabolites produced by fungi on agricultural commodities in the field and during storage under a wide range of climatic conditions. The ochratoxin A (OTA) is a nephrotoxic mycotoxin produced by several species of Aspergillus and Penicillium. In this study, the influence of carbon and nitrogen sources on ochratoxigenic Penicillium species was assessed. The ochratoxigenic Penicillium species were isolated from poultry feed samples of Andhra Pradesh, India. The isolated ochratoxigenic Penicillium species were identified, screened and characterised as OTA producers by high performance thin layer chromatography (HPTLC) and confirmed by high performance liquid chromatography (HPLC). This experiment was carried out using Czapak yeast Autolysate (CYA) medium with different carbon (C) and nitrogen (N) sources at pH 6.5 and incubated at 25 ± 2°C under dark condition. Maximum OTA production was recorded in the presence of D-glucose followed by D-galactose and D-lactose as carbon sources. Similarly, the maximum amount of OTA production was observed in thiourea followed by potassium nitrate as nitrogen source. However, OTA production, final pH of the medium, and mycelial yield and OTA production of both the species of Penicillium varied with C and N present in the medium. The kinetics of the both species of Penicillium was observed for 30 days at an interval of three days. The maximum amount of OTA was detected by 12 and 15 days incubation periods for Penicillium nordicum and Penicillium verrucosum, respectively.

Keywords:

• poultry feed
• Penicillium verrucosum
• P. nordicum
• HPTLC
• carbon
• nitrogen sources
• ochratoxin A
• HPLC

Acknowledgements

This research has been financially supported by UGC.F .N.36-129/2008 (SR) MRP, New Delhi and the authors are grateful for all the facilities provided by the Head of the Department of Microbiology, Kakatiya University. The authors also thank Dr H.V. Batra (Additional Director) and Dr H.S. Murali (HOD, Microbiology), Defence Food Research Laboratory, Mysore, Karnataka, India, for their valuable support and suggestions.