Abstract
The reuse of waste water in agriculture and aquiculture was sensitive subject. Chemical and microbial contaminants in the sewage water stayed in the plant and were eaten by human in the food. The goal of this research was to study leaves of lettuce produced by seeding and watering with treated sewage water, sterilized distilled water and pipe water and lettuce from Riyadh market, Saudi Arabia. Germinated lettuce in planter and lettuce from market were grinded into pieces. Bacterial extraction buffer was added to the grinded samples, centrifuged and supernatants were smeared on nutrient agar in Petri dishes and incubated at 37 degrees C over night. Lettuce watered with treated sewage water was investigated for bacterial load. Bacterial colonies were observed, counted and compared with lettuce watered with distilled water, pipe water and lettuce from Riyadh market. The bacterial loads of lettuce produced with treated sewage water were higher than lettuce from Riyadh market and those produced with distilled and pipe water.