ISOLATION AND CHARACTERIZATION OF MICROBES ASSOCIATED WITH THE DETERIORATION OF BANANA FRUITS

Abstract

Banana fruits are staple food source for millions of people worldwide which has led to an increased global demand for the fruit. However, they are susceptible to various forms of deterioration which is often attributed to the activity of microorganisms, including bacteria, fungi and yeasts, which can cause various types of spoilage, such as discoloration, texture changes, off flavors, etc and can lead to post-harvest losses. This study was carried out to isolate and identify microorganism associated with the deterioration of bananas fruits. A total of 4 samples were examined for fungal and bacteria species by serial dilution, inoculation and cultured on Nutrient agar and Sabouraud Dextrose Agar respectively. Both cultured plates were incubated at 37⁰c for 24 hours and at 28 ±1°C for five days, and sub cultured respectively. Macroscopic and microscopic examination of the fungal species was conducted, and morphological features were studied and used for fungal identification by comparison with a standard fungal identification guide. Morphological examination, Gram staining and biochemical test were also conducted to identify bacteria species. The bacteria count ranged from 4.5 x 105 to 1.21 x 106 CFU/ml indicating higher amounts of bacteria population in the spoilt samples. Fusarium spp, Rhizopus spp and Candida spp were the most isolated fungi from fresh banana fruits with an occurrence of (2)25% while Aspergillus flavus and Candida spp were the least isolated with an occurrence of (1)12.5%. Aspergillus fumigatus, Rhizopus spp, Mucor spp and Candida spp were the most isolated fungi from spoilt banana fruits with an occurrence of (2)20% while Fusarium spp and Aspergillus flavus was the least isolated with an occurrence of (1)10%. Staphylococcus aureus and Streptococcus pyogenes were the least isolated bacteria from fresh banana fruits with an occurrence of (1) 25% while Escherichia coli was the most isolated with an occurrence of (2) 50%. Staphylococcus aureus and Streptococcus pyogenes were the least isolated bacteria from spoilt banana fruits with an occurrence of (1) 25% while Escherichia coli was the most isolated with an occurrence of (2) 50%. The presence of the isolates may be due to the careless handling and storage conditions of banana fruits which would have bruised or cut the banana peel. Another factor that could lead to the its spoilage was improper hygienic practices from the point of harvesting, transportation and storage by handlers. The high moisture content of banana fruit makes it highly perishable and contributes to its low shelf life, as it supports the growth of microbes.