A Preliminary Study on Microbial Contamination of Leafy Vegetables in Sokoto Metropolis, Nigeria

Abstract

-Five leafy vegetables commonly consumed in Sokoto metropolis were evaluated for microbiological quality using standard procedures involving standard plate count (SPC). The vegetables investigated included Lactuaca sativa (Lettuce), Amaranthus hybridus (Spinach), Vernonia amagdalina (Bitter leaf), Brassica oleracea (Cabbage) and Moringa oleifera Lam (Horse radish). Ten fungal species which include Alternaria alternata, Absidia corymbifera, Aspergillus niger, A. flavus, Cladosporium herbarum, Fusarium oxysporium, Geotrichum candidum, Mucor racemoses, Rhizopus stolonifer and Trichoderma harzianum and four species of bacteria: Bacillus cereus, Escherichia coli, Listeria monocystogens and Staphyllococus aureus were isolated from the leafy vegetables. The total colony counts of fungi ranged from 1.8 x 10 6 -6.28 x 10 5 (cfu/g) of the vegetables while that of bacteria ranged from 1.0 x 10 6 to 2.94 x 10 6 cfu/g of the vegetables. The highest counts of microbial organisms were found on A. hybridus while M. oleifera and B. olerarea had the lowest fungal and bacterial counts respectively. There is a need to reduce the levels of microbial contamination on leafy vegetables through appropriate production practices, careful handling by the vendors and appropriate processing with a view to minimize the risk of human exposure to fungal and bacterial pathogens associated with the vegetables.

Quality and labeling information of Moringa oleifera products marketed for HIV-infected people in Zimbabwe

“…This is a common finding in similar studies. 13 , 14 In our case, since Moringa is a cultivated species in Zimbabwe, the herbal products may have been contaminated by microbes carried over from the soil or animal manure and waste used as fertilizers. Given that the herb was mainly supplied by local farmers who may not be trained in hygienic processing of herbs and operating from an open market, the contamination could also have been transferred from personnel during harvesting and processing of the plant material.…”

Diseases of Major Bulbous Vegetable Crops and Their Management

“…The fungi that cause neck rot survive in winter on previously infected onion debris in the soil, in cull piles and refuse dumps. Water may be source of pathogen; and could be transferred from water to the vegetables [9,10]. Initial symptoms include water soaked areas on the outer surface of scales.…”