Journal of Advances in Microbiology

The effect of Aloe vera gel on microorganisms associated with the deterioration of sweet orange (Citrus sinensis) fruits was investigated. Sweet orange fruit was obtained from selected markets and farm in Akure, Nigeria. Microorganisms associated with the deterioration were identified using microbiological techniques. A total of nine fungi and six bacteria were isolated from the orange fruits. Fungal isolates include Aspergillus flavus, A. niger, Fusarium oxysporium, Penicillum digitatum, Rhizopus stolonifer, Penicillium italicum, Mucormucedo, Saccharomyces cerevisiae and Geotrichium candidum, while the bacterial isolates were Staphylococcus aureus, Escherichia coli, Bacillus cereus, B. substilis, Serratia marcesens and Pseudomonas aeruginosa. The average fungal counts ranged from 2.4 × 10³ cfu/g to 5.3 × 10³ sfu/g and bacterial count ranged from 1.4 × 10⁵ cfu/g to 3.6 × 10⁵ cfu/g. Pathogenicity test revealed that Rhizopus stolonifer, Penicillum digitatum, Penicillum italicum, Aspergillus flavus, Fusariun oxysporium were able to induce spoilage in apparently healthy orange fruits. At 100% concentration of Aloe vera gel, E. coli and Saccharomyces cerevisiae demonstrated the highest susceptibility among bacterial and fungal isolates respectively. This study revealed that Aloe vera gel was partially effective in controlling the growth of bacterial and fungal isolates associated with the deterioration of sweet orange. Good agricultural practices, adequate storage facilities and good handling practices must be put in place to reduce the incidence of microbial spoilage of sweet oranges to increase agricultural output, profits and maintain food security.