Inactivation of Escherichia coli in soil amended with organo-zeolitic substrates

Abstract

Abstract This study evaluated the survival characteristics of Escherichia coli (E. coli), a fecal indicator bacterium, in soil treated with organo-zeolitic substrates with different zeolite particle sizes in micro and nanoscale. For this purpose, we added 5, and 15 grams (g) zeolite or nano-zeolite to 5 g cow manure, and then added these substrates to the different amounts of a loam soil to obtain a 100 g mixture. To examine the net effects of substrates, our experiments were conducted in unsterile and sterile conditions. After the mixture’s preparation, all mixtures were inoculated by 106 cells of a nalidixic-acid resistant E. coli (E. coli NAR) per g mixtures. Results showed that the application of organo-zeolitic substrates and sterilization significantly influenced E. coli NAR inactivation in soil. in unsterile mixtures, the presence of micro-size zeolite results in a higher td value, and in sterile mixtures, E. coli NAR survived more in mixtures containing nano-zeolite. These results clearly showed that competition and the presence of nutrient resources are the most important factors that control the inactivation of fecal bacteria in soil. These findings could have important implications for soil management and agricultural practices, as well as for the development of new soil remediation strategies.