Chemical Pretreatments and Anaerobic Digestion Shape the Virome and Functional Microbiome in Fecal Sludge

Abstract

The decomposition and pathogen inactivation of fecal sludge (FS) are vitally important for safely managing onsite sanitation and protecting public and environmental health. However, the microbiome and virome assemblages in FS after chemical and biological treatments remain unclear. Here, we reported the differences in the solid reduction and microbiomes of FS subjected to potassium ferrate (PF), alkali (ALK), and sodium hypochlorite (NaClO) pretreatments and anaerobic digestion (AD). The PF and NaClO pretreatments enhanced FS hydrolysis and pathogen suppression, respectively; AD suppressed Grampositive bacteria. Most of the viromes were those of bacteriophages, which were also shaped by chemical pretreatments and AD. Metatranscriptome analysis revealed distinct gene expression patterns between the PF-and ALK-pretreated FS and the subsequent AD. Differentially expressed gene profiles indicated that genes related to biological processes, molecular functions, and transcriptional regulators were upregulated in ALK-AD and PF-AD samples. These findings suggested that the effect of different treatment technologies on the viral diversity, pathogen abundance, and metabolic function of the core microbiome extends beyond FS decomposition and that the use of combined processes would provide possible alternatives for FS management in pandemic emergencies.

Temporal Dynamics and Contribution of Phage Community to the Prevalence of Antibiotic Resistance Genes in a Full-Scale Sludge Anaerobic Digestion Plant

“…Viral metagenomic sequencing is a rising technique recovering bioinformation on viruses from environmental samples. There have been some studies on lab-scale AD reactors revealing the characteristics of viral community in AD habitat, but the report of the diversity and dominant species of viruses in a full-scale AD plant through long-term monitoring is still lacking. , The virus identification thresholds used in the AD studies were divergent, making the results less comparable and reliable. Some methods concerning the host linkages of phages have indicated that the combination of viral and prokaryotic metagenomic data could provide more reliable results but have not been applied in the AD process. , The current research status is calling for consistent experimental procedures and full-scale reports of AD virome studies.…”