Microbial persistence beneath temporal restructuring in university wastewater metagenomes

Abstract

Temporal changes in wastewater microbiomes can reflect shifts in microbial abundance, detectable membership, and genome recovery. We paired genome-resolved and read-based metagenomics to distinguish these signals in 25 spatially pooled university wastewater samples collected during wet and dry periods. The workflow recovered 203 wet-period and 230 dry-period metagenome-assembled genomes (MAGs). Community composition differed between periods in both MAG-derived presence/absence profiles (Jaccard PERMANOVA, R2 = 0.548, p = 0.001) and read-based relative-abundance profiles (BrayCurtis PERMANOVA, R2 = 0.167, p = 0.001). Greater dry-period read-based richness persisted after rarefaction but disappeared under more stringent abundance thresholds, indicating a substantial contribution from low-abundance detections. Of 57 period-associated core species in the MAG-derived profiles, 14 had exact species-level matches in the read-based dataset. All 14 remained detectable at >=90% prevalence in the opposite period, and 13 had higher relative abundance in the period corresponding to their MAG-based association. Continued species detection therefore accompanied changes in community composition and MAG-based representation. Perfect/Strict CARD/RGI resistance-associated annotations occurred in 94.1% of wet-period and 92.2% of dry-period MAGs and were distributed across shared-core and period-associated taxa. These findings reveal repeated detection of a matched subset of microbial taxa beneath temporal community restructuring, together with widespread resistance-associated genetic potential among recovered genomes. Combining read-based and genome-resolved profiles helps distinguish changes in detectable membership from changes in the genomic characterization available for wastewater surveillance.