Composted Sewage Sludge Influences the Microbiome and Persistence of Human Pathogens in Soil.

Composted sewage sludge (CSS) gained attention as a potential fertilizer in agriculture. Application of CSS increases soil microbial activity and microbial biomass, however, it can also lead to increased chemical and microbiological risks. In this study, we performed microcosm experiments to assess how CSS reshapes the microbial community of diluvial sand (DS) soil. Further, we assessed the potential of CSS to increase the persistence of human pathogens in DS soil and the colonization of Chinese cabbage (Brassica rapaL. subsp.pekinensis(Lour.) Hanelt). The results revealed that CSS substantially altered the prokaryotic community composition. Moreover, addition of CSS increased the persistence ofSalmonella entericaserovar Typhimurium strain 14028s andS.entericaserovar Senftenberg in DS soil. However, the enhanced persistence in soil had no impact on the colonization rate ofB.rapagrown on soil inoculated withSalmonella. We detectedSalmonellain leaves of 1.9% to 3.6% of plants. Addition of CSS had no impact on the plant colonization rate. The use of sewage sludge composts is an interesting option. However, safety measures should be applied in order to avoid contamination of crop plants by human pathogens.