ISOLATION OF BACTERIA AND FUNGI ASSOCIATED WITH SPOILAGE OF SOME YOGHURT BRANDS SOLD IN AZARE TOWN

Abstract Diary foods provide an ideal food system for the delivery of beneficial bacteria to the human gut. Given the suitable environment that milk and certain dairy products including yoghurt and cheese) provided, it promotes growth and support viability of these cultures. Some yoghurt have been found to loose their taste and produce uncharacteristic odour before their expiry date which may be as a result of contamination through the processing line, packaging and or poor handling. Bacterial infestation has been reported among consumers of yoghurt leading to vomiting, diarrhea, stomach upset and flatulence. Youghurt production is very expensive and most of its methods are tedious. This research work is aimed to isolate bacteria and fungi associated with spoilage of some yoghurt brands solds in Azare town.Seven samples of yoghurt were purchased and processed for culturing on nutrient agar and potato dextrose agar. The plates of nutrient agar were subsequently incubated at 37 ̊C for 24 hours and the bacterial load was determined, similarly, the plates of potato dextrose agar were incubated at 37 ̊C for 5 days and the fungal load was determined on the basis of their growth. The bacterial colonies were subjected to Gram staining techniques and other biochemical tests such as catalase, citrate, coagulase, urease, methyl red, and Voges Proskauer test to identify the bacterial isolates. The fungal colonies were subjected to lactophenol blue stain or identification also. The yoghurt labelled F shows the highest count while the yoghurt labelled J shoes the lowest count. All the samples shows a remarkable fungal count with yoghurt B having the highest count of (1.7 × 104) and yoghurt A having the lowest count (1.0× 104). The bacteria isolated are Escherichia coli, Staphylococcus, Streptococcus, and Shigella. While the fungi isolated are Mucor, Cladosporium, Rhizopus and Aspergillus fumigamate.