Advances in Biological Chemistry, 2013, 3, 141-145 ABC http://dx.doi.org/10.4236/abc.2013.31017 Published Online February 2013 (http://www.scirp.org/journal/abc/) Bio-chemical characterization of bacterial flora associated with spoilt vegetables in Kaduna markets Northern Nigeria F. M. Mahamud1*, D. B. Dangora2, S. Mu’azu2, A. U. Khan2, S. Nura3, Z. A. Gaiya4 1Department of Applied Science, Kaduna Polytechnic, Kaduna, Nigeria 2Department of Biological Sciences, Ahmadu Bello University, Zaria, Nigeria 3School of Basic and Remedial Studies, Ahmadu Bello University, Funtua, Nigeria 4Department of Microbiology, Ahmadu Bello University, Zaria, Nigeria Email: *[email protected] Received 14 November 2012; revised 16 December 2012; accepted 27 December 2012 ABSTRACT Keywords: Bacterial Flora; Characterization; Kawo Market; Kaduna Market; Vegetables Some vegetables such as Capsicum annum (Pepper), Lycopersicon esculentum (Tomato), Allium cepa (On- ion), Cucumis sativus (Cucumber), Solanum tubero- 1. INTRODUCTION sum (Potato) and Daucus carrota (Carrot) which are Vegetables are the edible product of an herbaceous plant consumed more frequently in the area were obtained from Kaduna central market and Kawo market with that are mostly valuable sources of vitamins, minerals the aim of isolating and characterizing the different and fiber and are low in fat and calories [1,2]. Vegetables bacterial flora associated with their spoilage. Four are vital sources of nutrient to human beings. They give bacteriological media: Mannitol Salt Agar (MSA), the body the necessary vitamins, fats, minerals and oil in MacConkey Agar (MA), Salmonella Shigella Agar the right proportion for human growth and development (SSA) and Blood Agar (BA) were used for the isola- [3]. The nutritional content of vegetables varies consid- tion of the bacterial populations. The results obtained erably, though generally they contain little protein or fat from Kaduna central market indicated the presence [4,5] and varying proportions of vitamins, provitamins, of two Gram positive bacteria viz: Staphylococcus and dietary minerals, fiber and carbohydrates. Vegetables Streptococcus strains as well as three Gram negative contain a great variety of other phytochemicals, some of bacteria including Escherichia coli, Citrobacter and which have been claimed to have antioxidant, antibacte- Klebsiella spp. Staphylococcus aureus is the most rial, antifungal, antiviral and anticarcinogenic properties abundant (with 80% relative occurrence) with Strep- [6]. This quality makes the vegetables to be suitable en- tococcus spp being the least abundant (with 10% rela- vironment for bacterial and other microbial growth and tive occurrence). Furthermore, among the Gram neg- development. ative isolates, Escherichia coli, Citrobacter and Kleb- The occurrence of bacterial populations on vegetables siella spp had the highest occurrence of 30% each, is recognized as a source of potential health hazard to while Enterobacter spp had the least. Similar results man and his animals. This is due to their production of were obtained of the isolates from Kawo market ex- bacteriotoxins compounds which are capable of inducing cept that among the Gram negatives, Edwardsiella spp several critical clinical symptoms in man following in- was found in Kawo market but E. coli is absent. More gestion or inhalation; even though they differ in their so, S. aureus and K. spp has the highest percentage of degree and manner of toxicity. The contamination of 605 each in Kawo market. The result showed that the fruits and vegetables by bacteria could also be as a result people consuming these vegetables are at higher risk of poor handling practices in food supply chain, storage of boils, carbuncles, impetigo, infections of wounds conditions, distribution, marketing practices and trans- and burns, breast abscesses, whitlow, osteomyelitis, portation [7]. Several varieties of vegetables were sold in bronchopneumonia, septicemia, bacteremia, acute Kaduna central market and Kawo market within Kaduna endocarditis, food poisoning and scalded skin syn- metropolis, Northern Nigeria. These vegetables includes drome due to these bacterial populations. roots such as carrot, a tuber or storage stem such as po- tato and sweet potato, a leaf such as cabbage, lettuce and *Corresponding author. spinach and immature flower such as watermelon and OPEN ACCESS 142 F. M. Mahamud et al. / Advances in Biological Chemistry 3 (2013) 141-145 pumpkin as well as some fruits that are used as vegeta- isms on the agar plates (MA, MSA, SSA and BA). The bles such as cowpea, cucumber, garden egg, okra, pepper, pulverized sample was transferred to the edge of an agar tomato, and bulbs such as onion. The sources of these plates with a sterilized wire loop, and then a parallel, vegetables are the irrigated farms within Kaduna me- non-overlapping streaks were made on the surface of the tropolis and the neighboring states like Kano state and already solidified agar plates and incubated in the incu- Niger state. They are transported to these markets in Lor- bator for 24 hours at 37˚C. ries and buses packed in sacks and baskets. Human ac- tivities contribute greatly to post harvest contamination 2.3. Isolation and Characterization of Bacterial either through mishandling such as improper harvest Colonies handling or lack of proper storage measures and personal With the aid of a sterilized inoculating needle, a small hygiene as those adopted in the two markets under study. portion of bacterial colony was transferred into the glass The subsequent effect of which is the production of high slide and teased properly with two sterilized inoculating microbial load, being passed on to the final consumer needles as described by the method of Dashwood et al. with the imminent risk of infection and illness. In order [8]. The prepared slide was observed under low and high to find solution to this problem awareness has to be made power resolution objectives of a compound microscope. of the health hazard this negligence poses to the larger Individual colonies were chosen and the top of an indi- society. This study therefore aimed at investigating the prevalence and occurrence of different bacterial species vidual colony each was touch lightly with a sterile loop on the vegetables sold in Kaduna central market and or needle and streak on a fresh agar plate The various Kawo market from Kaduna state, Northern Nigeria; with colonies observed in the plates were distinguished on the the view of identifying the different species of bacteria basis of their cultural characteristics such as colony size, and their prevalence. The results of this research is also shape, color, consistency and haemolytic characteristics intended to be used in suggesting possible ways of mini- as described by Fawole and Oso [10]. Bacterial growth mizing or avoiding possible health problem associated was sub-cultured on NA and was preserved in NA slants. with these bacterial species. The bacterial representative cultures distinguished on the basis of their cultural characteristics were smeared thinly 2. MATERIALS AND METHOD on grease free microscopic slide. The smears were al- lowed to air dry and heat-fixed by passing the slide The samples were collected from both the whole sellers through the Bunsen flame. The heat-fixed smear was and retailers in Kaduna Central market and Kawo market, allowed to cool; and were Gram stained. The stained Kaduna state, Nigeria (lat 10˚31"06.29'N and long smears were then examined microscopically under the oil 7˚25"36.57'E). The vegetables used include: Pepper immersion lens. The organism recovered from the dete- (Capsicum annum), Tomato (Lycopersicon esculentum), riorated vegetables were grouped on the basis of their Carrot (Daucus carota), Cucumber (Cucumis sativus), Gram reaction, cell morphology and cell arrangement. Onion (Allium cepa), and Potato (Solanum tuberosum). The isolates were further characterized using biochemi- The samples were collected twice monthly from the cal test described by Faiers et al. [11] and Wreghitt and market, put into a clean polythene bag and labeled re- Morgan [12]. spectively. The samples were kept in the refrigerator at 4˚C for later use. 2.4. Data Analysis The data collected was analyzed statistically using per- 2.1. Bacterial Isolation from Deteriorated 2 Vegetables centages with Chi (X ) Square (P < 0.05) to test whether there is association between symptoms and occurrence of For isolation of bacterial flora, the method of Dashwood, the isolates. et al. [8] and Balali, et al. [9] was used. The surface of the vegetables that showed spoilage symptomatology 3. RESULTS were sterilized with 0.1% Mercury chloride (HgCl) for 2 The result of the biochemical characterization of Gram minutes then rinsed three times with distilled water. A positive bacterial isolates on the vegetables in Central sterile blade and forceps was use to cut small section of Market Kaduna was presented in Table 1. The result the tissue containing both the healthy and the rotten por- revealed the presence of Staphylococcus aureus and tion. The cut potions were pounded with pistil and mortar Streptococcus spp. as the Gram positive bacteria associ- to make paste. ated with the vegetables. 2.2. Inoculation and Incubation However, the result obtained in vegetables from Kawo market have shown that, S. aureus is the only Gram posi- Streaking method was used for inoculation of the organ- tive bacterial isolate (Table 2). Copyright © 2013 SciRes. OPEN ACCESS F. M. Mahamud et