Isolation Of Bacteriophages Against Enteric Pathogens From Sewage
Poor sanitation contributes to 1.5 million child deaths globally from diarrhoea alone caused by enteric pathogens each year. Solving the sanitation challenge in the developing world will require radically new innovations that are deployable on a large scale. Hence, we aimed to reduce the bacterial load of waste water by developing bacteriophages from sewage against the enteric pathogens. Bacteriophages are the viruses which infect bacteria and kill them. They are very specific to the target bacteria and hence can safely be used to kill the bacterial pathogens without affecting the human host or any non-target organisms in waste water. Thus they can be used to treat human waste and waste water safely. We developed broad spectrum phages by simply filtering the sewage water from different regions of the Amritapuri campus through 0.22μm filter, enrich the filtrated virus stock against all the waste water microbes by culturing them in different enrichment media recommended for different classes of bacteria such as Vibrio, Shigella, sulphur reducers, coliforms and nutrient broth media. We successfully could reduce the bacterial count from 20 to 90% (colony counts) by 1hr treatment of the waste water with the different enriched virus filtrates. Most successful were the enrichment of phages against E. coli, which could reduce the growth of waste water flora by 90% (colony counts method). We isolated specific plaques from different bacterial colonies isolated from the waste water cultured on different enrichment media. Few phages against E. coli were given to another group to test their binding capability to human extracellular matrix proteins such as fibronectin, heparin and gelatine (denatured collagen).
We also attempted to develop novel phage enrichment media from waste food and leaf materials so that the phages can be produced in cost-effective and convenient way. We tried rice water supplemented with chicken waste, the fruit extract of badam tree (Terminaliacatappa) and leaf extract of money-plant (Epipremnumaureum) and compared the growth of sewage water flora with nutrient broth (NB). The positive and negative attributes of the respective media were studied and compared.