Study of clbB and clbN genes in E.coli isolates isolated from vegetables irrigated with surface water and urban waste

One of the factors causing colorectal cancer is infection with a specific strain of Escherichia coli (E.coli) that has a PKS genomic island with two clbB and clbN genes. One of the ways of human bacterial contamination is to consume vegetables irrigated with water contaminated with bacteria. These two genes cause the activation of the message transmission pathway and the DNA mutation and tumorigenesis by producing the toxin Bactin. The main aim of the present study is to investigate clbB and clbN genes in Escherichia coli isolated from vegetables irrigated with surface water and urban waste.

Vegetables irrigated with surface water, well and urban waste were collected from three regions of Tehran. Their E.coli bacteria were isolated and identified and confirmed. Then, PCR test was performed for clbB and clbN genes of all isolated E.coli bacteria.

The obtained microbial and biochemical results confirmed the E.coli bacteria isolated from the investigated vegetables. The molecular results showed that the highest and lowest frequencies for the samples that simultaneously contained both studied genes were related to vegetables irrigated with urban waste and vegetables irrigated with well water (P≤0.05). This result was almost the same for the vegetables of all three studied regions.

Considering the high frequency of E.coli bacteria isolated from vegetables irrigated with municipal waste and in order to prevent bacterial infection and consequently colorectal cancer, complete disinfection of vegetables and non-irrigation of vegetables in areas with waste are suggested. Keywords: E.coli, clbB, clbN, Vegetables, Urban waste, Surface water.