Elimination of Antibiotic Multi-Resistant Salmonella Typhimurium from Swine Wastewater by Microalgae-Induced Antibacterial Mechanisms

Abstract

The effect of microalgae-based swine waste water treatment on the removal of antibiotic multi-resistant Salmonella enterica serovar typhimurium was investigated. Photobioreactors (PBRs) containing diluted swine digestate with and without microalgae Scenedesmus spp. were inoculated with S. typhimurium (108 Colony Forming Units per milliliters - CFU mL-1). Viable cells of S. typhimurium were quantified over time by plate counts and qPCR amplification of the Salmonella invasion gene activator, hilA. In the absence of microalgae, S. typhimurium concentrations increased 1.5 log cells mL-1 in 96 h. In the presence of microalgae, S. typhimurium was completely eradicated within 48 h. In the PBRs with controlled pH (6.8 ± 0.8), concentration of S. typhimurium remained constant (2.8 ± 0.2 log CFU mL-1) throughout 96 h. Thus, natural increase in pH>10 due to photosynthesis was detrimental to the antibiotic multiresistant bacteria survival. Phycoremediation holds promises as an alternative for waste water treatment process for the elimination of the serious public health threatening antibiotic multi-resistant bacteria, thus effectively avoiding Salmonellosis outbreaks arising from animal farming activities.