Time Series Genome-Centric Analysis Unveils Bacterial Response to Operational Disturbance in Activated Sludge

PÉREZ, MARÍA VICTORIA; GUERRERO, LEANDRO D.; ORELLANA, ESTEBAN; FIGUEROLA, EVA L.; ERIJMAN, LEONARDO

mSystems

American Society for Microbiology

Lugar: Washington DC; Año: 2019 vol. 4

Understanding ecosystem response to disturbances and identifying themost critical traits for the maintenance of ecosystem functioning are important goalsfor microbial community ecology. In this study, we used 16S rRNA amplicon se-quencing and metagenomics to investigate the assembly of bacterial populations ina full-scale municipal activated sludge wastewater treatment plant over a period of3 years, including a 9-month period of disturbance characterized by short-term plantshutdowns. Following the reconstruction of 173 metagenome-assembled genomes,we assessed the functional potential, the number of rRNA gene operons, and the insitu growth rate of microorganisms present throughout the time series. Operationaldisturbances caused a significant decrease in bacteria with a single copy of the rRNA(rrn) operon. Despite moderate differences in resource availability, replication rateswere distributed uniformly throughout time, with no differences between disturbedand stable periods. We suggest that the length of the growth lag phase, rather thanthe growth rate, is the primary driver of selection under disturbed conditions. Thus,the system could maintain its function in the face of disturbance by recruiting bac-teria with the capacity to rapidly resume growth under unsteady operating condi-tions.