Isolation and indentification of fungi associated with date fruits (Phoenix dactylifera, Linn) sold at Bayero University, Kano, Nigeria

Abstract

Mycological investigation on spoilage fungi in 30 apparently infected date fruits (Phoenix dactylifera, Linn.), sampled from both new and old campuses of Bayero University, Kano, Nigeria was carried out between August and September 2008. The samples were cut into 3 mm pieces on a clean and sterilized tile with the aid of sterilized razor blade, surface-sterilized in 1% hypochlorite for 2 minutes, placed on Potato Dextrose Agar and incubated at room temperature for 5 days. Pure cultures of the resulting fungi were obtained from subcultures of the primary plates. These were identified morphologically and microscopically in accordance with standard procedures. The investigation showed that the most dominant isolated fungi were Rhizopus sp. (100%) and Mucor sp. (100%), followed by Torula sp. (40%),Penicillium sp. (30%), Aspergillus sp. (16.67%) and Alternaria sp. (13.33%) respectively. Of all the samples, soft dates were the most heavily contaminated probably owing to the artificial increase in moisture content and improper storage facilities associated with it. Aspergillus species appeared to be the most toxigenic fungi recovered from the dates. It was recommended that soft dates should be stored in a cold environment while dry dates should be stored under dry condition so that they will not increase in moisture and avoid constant exposure to air at sales time, hence the use of paper wraps should be encouraged. Similarly, contaminated dates should be sorted and eliminated to avoid re-infection while washing the dates with clean water prior to consumption should be strongly encouraged by appropriate authorities with the view to checking the spread of these fungi.

Key words: Phoenix dactylifera, fungi, contamination, spoilage, Kano