Occurrence of aflatoxin contamination in maize kernels and molecular characterization of the producing organism, Aspergillus

Abstract

Aflatoxins are toxic metabolites produced mainly by Aspergillus flavus and Aspergillus parasiticus. Aflatoxin B1 (AFB1) is a potent carcinogen, teratogen and mutagen. 660 pre-and post-harvest maize samples were collected from major maize growing areas in Tamil Nadu, India. A flatoxin contamination was observed in 40.22% of the samples tested of which, 22.97% of pre-harvest and 53.93% post-harvest maize samples were found to be infected with AFB1 and 12.05% of the total samples exceeded WHO permissible limit of 20 μg/kg. AFB1 contamination ranged from 0 to 149.32 µg/kg. 28 A. flavus isolates were isolated and grouped into three sets based on aflatoxin producing potential viz., highly aflatoxin producing isolates, medium producing isolates and no aflatoxin producer or traces of aflatoxin producing isolates. The genetic coefficient matrix analysis using random amplified polymorphic DNA (RAPD) with ten random primers revealed minimum and maximum percent similarities among the tested A. flavus strains ranging from 35 to 89%. Cluster analysis separated the three sets of isolates into two groups (groups I and II) with each two subgroup confirming the genetic diversity among the A. flavus isolates from maize.

Aspergillus species and Aflatoxin Contamination of Pre and Post- Harvest Maize Grain in West Gojam, Ethiopia

“…The current prevalence of AFB1 (66.7%) in pre-harvest and (87.7%) in post-harvest was consistent to results previously reported in India which was 79.7% in pre-harvest maize [4] and in Iran which was 77% of post-harvest samples [24] but higher than reported by Muthusamy et al, [21] which was 22.97% of pre-harvest maize and 53.93% post-harvest maize by Ayyathurai et al, [4] which was 22.97% of pre-harvest and 53.93% post-harvest maize. This variation may be due to number of factors such as temperature, humidity, insect injury, handling during pre-harvest, harvest and storage [4,21].…”

“…These results were also higher than reported in Kenya which was 22.97% of total aflatoxin contamination in pre-harvest maize [21]. The high total aflatoxin contamination in pre-harvest may be due to delayed harvesting (high likelihood of kernel damage by pests, insect injury), differences in temperature, humidity, using crop resistance variety, crop rotation system and maintaining adequate irrigation schedule [18].…”

“…Which means total aflatoxin level was significantly increase from pre-harvest to post-harvest pre-harvest maize. The reasons for high increment of aflatoxin level in post-harvest may be poor harvest and post-harvest practices of the maize [18,21] and once the crop becomes infected under field conditions, the fungal growth continues with increasing at post-harvest and storage conditions [23].…”

“…This variation may be due to number of factors such as temperature, humidity, insect injury, handling during pre-harvest, harvest and storage [4,21].…”

“…It is also well known that growth of Aspergillus spp. and subsequent production of aflatoxins in maize is dependent on a number of factors such as temperature, humidity, insect injury, handling during pre-harvest, harvest and storage [4,21].…”