Grain-borne mycoflora and fumonisin B1 from fresh-harvested and stored rice in Northern Iran

Abstract

Background: Fumonisins B1 (FB1) is the main member of the family of fumonisins produced by several Fusarium species in cereals, especially rice. Objectives: The purpose of this study was to analyze mycofora and FB1 contamination of fresh and stored rice grains. Materials and Methods: One-hundred and fifty different fresh and stored rice samples were collected from 30 different zones of the Mazandaran province, Iran between August 2010 and November 2011. After sterilization, the grains were cultured on potato dextrose agar (PDA) containing chloramphenicol (100 mg/L) at 27°C for 7-10 days. All Fusarium isolates were sub-cultured on PDA, SpeziellerNährstofarmer agar (SNA) and carnation leaf agar (CLA). FB1 was extracted with acetonitrile: water (50: 50, v/v) solution and detected by high-performance liquid chromatography (HPLC) analysis using a fuorescence detector (excitation: 229 nm; emission: 442 nm).Results: Mycofora profles of fresh and stored rice grains showed that Aspergillus species (37.3%, 40.7%) were the predominant fungal agents, followed by Fusarium (21.6%, 16.2%), Mucor (19.6%, 16.7%) and Rhizopus (9.8%, 11.1%), respectively. In HPLC analysis, most of the rice samples (96.7%) collected were found to be positive for FB1 with mean levels ranging from not detected to 56.2 mg/kg for fresh samples and from 4.3 to 42.8 mg/kg for stored ones. FB1 levels varied from one zone to another and throughout the storage time, showing a decreasing trend in most zones. Conclusions: Rice samples with a high prevalence of diverse species of toxigenic fungi, in particular Aspergillus and Fusarium species, and high levels of FB1 in many samples indicate the need for proper surveillance and monitoring exclusively for the prevention of fungi and FB1 in rice produced in Mazandaran province before it reaches the consumer. © 2013, Ahvaz Jundishapur University of Medical Sciences; Licensee Kowsar Ltd.