Aspergillus species and aflatoxin contamination of tobacco snuff samples sold in some parts of southeastern Nigeria

Abstract

Several commodities have been frequently reported to be contaminated by aflatoxins, but little is known about aflatoxin accumulation in tobacco snuff frequently consumed globally, especially in Nigeria. Ascertaining their aflatoxin content and by extension, the health implications on those who use these tobacco products are necessary. Snuff samples from 30 vendors in six randomly selected markets were screened for Aspergillus spp. DNA sequencing was used for molecular identification of isolated Aspergillus flavus by amplifying the ITS region of ribosomal DNA using ITS1 and ITS4 primers. The isolates were screened for aflatoxin biosynthesis genes such as ver-1, nor-1 and omt-1 genes. Aflatoxin production potentials of the isolates were analyzed using maize kernels and quantified using thin layer chromatography (TLC) technique. The tobacco snuff samples were also analyzed to detect aflatoxins and their accumulation. Forty-two Aspergillus species were recovered and identified. Aspergillus niger (24) was the most common species with an occurrence rate of 57%, followed by Aspergillus fumigatus (13), at 31% occurrence, while only five (12%) Aspergillus flavus were recovered. Out of the three selected genes screened, nor-1 gene was confirmed to be present in the five isolates, whereas ver-1 and omt-1 genes were absent. Aflatoxin B₁ (AFB₁) and aflatoxin B₂ (AFB₂) were detected in both snuff and maize samples, while aflatoxin G₁ (AFG₁) and aflatoxin G₂ (AFG₂) were absent in all samples. This study confirms that most snuff sold in markets are contaminated with toxigenic fungi. Proper production procedure and enhancement in the sanitary standards of markets and vendors will help reduce contaminations.

Keywords: Aflatoxin; Agriculture, Southeast Nigeria; Aspergillus; Contamination; Tobacco Snuff.