Bacterial Diversity in Some Selected Agricultural Food Products

A total of 27 bacterial strains were isolated from apple, potato, turnip, onion, cucumber, zinger, lemon, spinach, radish and mint marketted in Labore, Pakistan. Highest frequency of occurrence (4%) was recorded for each of Enterobacter aggglomerans, Ensifer adhaerens and Bordetella pertussis, Brassica rapa and Kurthia gibsonii showed 30% frequency of occurrence. Frequency of all other bacterial strain ranged from 10 20%. Highest number (7) of bacterial speices were recorded from lemon and potato while the minimum number (4) was represented by each of apple, onion, ginger, spinach and radish. Bacteria enter plant tissue primarily through the root zone; however, aerial portions of plants, such as flowers, stems, and cotyledons, may also be used for entry. Specifically, the bacteria enter tissues via germinating radicles, secondary root, stomata, or as a result of foliar damage. Bacteria inside a plant may either become localized at the point of entry or spread throughout the plant. These microorganisms can reside within cells, in the intercellular spaces, or in the vascular system (Zinniel et al. 2002). The aim of the present study was to isolate and identify the bacterial species found in different agronomic crops for their diversity. Ten infected agricultural products viz: apple (Malus domestica L. Borkh.), potato (Solanum tuberosum L.), turnip (Brassica rapa L.), onion (Allium cepa L.), cucumber (Cucumis sativus L., ginger (Zingiber officinale L.), lemon (Citrus limon L. Burm. f.), spinach (Spinacia oleracea L.), radish (Raphanus sativus L.) and mint (Mentha sativa L.) were collected from markets of Lahore, Pakistan, during September to December 2012. The collected materials were stored in sterilized polythylene bags for further investigation. Surface sterilization of samples was done by stepwise washing in 70% ethanol for 5 min, sodium hypochlorite solution for 5 min, and 70% ethanol for 30 sec, followed by three rinses in sterile distilled water (Ishaq and Khan 2011). Different types of media viz: Luria Bertani agar (LBA), nutrient agar (NA), trypton agar (TA) and yeast extract agar (YEA) were used for isolation and identification (Ali and Naseem 2011, 2012). The surface of infected samples was removed with a sterilized razor blade, and the inner infected tissue was cut into pieces 4 to 6 mm long and were placed on media plates. Incubation was carried out at 37°C for 24 hrs to allow growth of endophytic bacteria. Moreover, fragments of diseased samples were homogenized in 5 ml of sterile saline solution with a blender. The serial dilutions (1 ml of 10) were spread with sterilized spreader onto media (Ishaq and Khan 2011) incubated at 37°C for 24 hrs. After incubation, distinct individual colonies were selected and sub-cultured by streaking on an agar plate for purification and preservation. Identification of bacterial species was done by following morphological, microscopic characteristics and biochemical tests and consulting the pertinent literature (Holt et al. 2000, Koneman et al. 1997, Benson 1996). After the identification of bacterial species, following values were determined: (i) percentage of each bacterial isolate in *Author for correspondence: .