Development Of A New Method For Enrichment Of E.coli In Water

The security of water was a very important social problem. Because many food-borne and water-borne diseases were caused by it and E. coli infection dosage was very low, the detection of E. coli appeared very important. In order to detect the E. coli in water accurately, people had been committed to the development of biological specificity method. But the development of technology methods had been proved difficult to detect all relevant types of virus and bacteria. At the same time, large volume of water sampling in real life could not be effectively detected. So the enrichment of water sampling had become the key technique in the process of detection.The purpose of this article discussed some commonly used means of enrichment, and committed to develop a new method to improve the efficiency of bacterial enrichment and detection.This article researched two steps of enrichment of E. coli 0157:H7 in water. The first enrichment step was ultrafiltration, enrichment efficiency up to 67.21%. The polypropylene membrane was used during the process and back-washing recycling was added to improve the recovery efficiency of E. coli in water. Magnetic beads were applied during secondary enrichment process. The package materials were non-toxic, good biocompatibility. Amino magnetic beads, carboxyl magnetic beads, and Chitosan magnetic beads were synthesized. The magnetic, XRD and IR were characterized and isoelectric point was determined. The enrichment efficiency of three kinds of magnetic beads were compared under different pH value, different amount of magnetic beads and different adsorption time. The enrichment efficiency of Amino magnetic beads could reach one hundred percent when the volume was 2.5 ml. The second step of enrichment improved the efficiency of the whole process. Through two steps, the large volume of water was concentrated to small volume, enrichment ratio could reach 500 times, and inaccuracy of sampling and measuring large volume water was reduced. The new method provided a new way for enrichment.