Heavy metal and antibiotic resistance of ureolytic bacteria and their immobilization of heavy metals

Environmental pollution by toxic heavy metals is spreading worldwide along with industrial progress. The isolation and characterization of microorganisms capable of resisting elevated concentrations of heavy metals as well as multiple types of antibiotics are critical to the development of an effective bioremediation strategy for polluted sites. In this study, we first investigated the interplay between heavy metals and the antibiotic resistance of ureolytic bacteria. The antibiotic resistance patterns revealed that the heavy metal resistance of these isolates was closely associated with their resistance to antibiotics. In addition, we examined the immobilization of heavy metals by these isolates, based on microbially induced calcite precipitation (MICP). The unconfined compressive strength of a cylinder specimen injected once with the selected bacterial culture showed a 3.7-fold increase relative to an untreated specimen. In addition, it was found that the heavy metals were highly immobilized in the bacteria-treated cylinder samples.