Genetic markers for detection of Escherichia coli K-12 harboring ampicillin-resistance plasmid from an industrial wastewater treatment effluent pond.

Abstract

Biotechnology industries that use recombinant DNA technology are potential sources for release of genetically modified organisms to the environment. Antibiotic-resistance marker genes are commonly used for recombinant bacteria selection. One example is the marker gene coding for β-lactamase (bla) in plasmids found in Escherichia coli K-12. The aim of this study was to provide an approach to develop a molecular method for genetic marker detection in E. coli K-12 harboring bla genes from an industrial wastewater treatment effluent pond (IWTEP). For the detection of bla and Achromobacter lyticus protease I (api) genes in samples from IWTEP, we employed multiplex polymerase chain reaction (PCR) using E. coli K-12 genetic marker detection primers, previously described in the literature, and primers designed in our laboratory. The microbiological screening method resulted in 22 bacterial colony-forming units isolated from three different IWTEP harvesting points. The multiplex PCR amplicons showed that five isolates were positive for the bla gene marker and negative for the E. coli K-12 and api genes. The 16S rRNA regions of positive microorganisms carrying the bla gene were genotyped by the MicroSeq®500 system. The bacteria found were Escherichia spp (3/5), Chromobacterium spp (1/5), and Aeromonas spp (1/5). None of the 22 isolated microorganisms presented the molecular pattern of E. coli K-12 harboring the bla gene. The presence of microorganisms positive for the bla gene and negative for E. coli K-12 harboring bla genes at IWTEP suggests that the ampicillin resistance found in the isolated bacteria could be from microorganisms other than the E. coli K-12 strain harboring plasmid.