Disturbance opens recruitment sites for bacterial colonization in activated sludge

Abstract

Little is known about the role of immigration in shaping bacterial communities or the factors that may dictate success or failure of colonization by bacteria from regional species pools. To address these knowledge gaps, the influence of bacterial colonization into an ecosystem (activated sludge bioreactor) was measured through a disturbance gradient (successive decreases in the parameter solids retention time) relative to stable operational conditions. Through a DNA sequencing approach, we show that the most abundant bacteria within the immigrant community have a greater probability of colonizing the receiving ecosystem, but mostly as low abundance community members. Only during the disturbance do some of these bacterial populations significantly increase in abundance beyond background levels and in few cases become dominant community members post-disturbance. Two mechanisms facilitate the enhanced enrichment of immigrant populations during disturbance: (i) the availability of resources left unconsumed by established species and (ii) the increased availability of niche space for colonizers to establish and displace resident populations. Thus, as a disturbance decreases local diversity, recruitment sites become available to promote colonization. This work advances our understanding of microbial resource management and diversity maintenance in complex ecosystems.

Species‐sorting and mass‐transfer paradigms control managed natural metacommunities

“…All localities showed a positive correlation up to a cutoff‐level of 50% of the initial SCs assembly and even at a cutoff‐level of 65% the correlation coefficients were still high (Table , S5). The results suggest that the α‐diversity is based mainly on the upper 50% of the most abundant SCs and that rare SCs do not contribute much to these values, a result that was also found elsewhere (cutoff‐level 50%, Vuono et al ., ). The fluctuations in community structure occurring both in and between localities are visualized by nonmetric multidimensional scaling (nMDS‐Plot, Fig.…”

“…A WWTP receives a source community (Shanks et al, 2013) coming from the inflow which will disperse foreign individuals. Many of them will become extinct due to competitive exclusion (Louca and Doebeli, 2015), while some may be able to use niche opportunities (Shade et al, 2012;Vuono et al, 2016). Others may serve as a seed bank for the successive localities and their constant immigration may prevent extinction within local communities (i.e.…”

Lifestyles of rarity: understanding heterotrophic strategies to inform the ecology of the microbial rare biosphere

“…There is evidence that rare taxa are or can become active in their communities (Hunt et al 2013, Wilhelm et al 2014, Aanderud et al 2015, sometimes providing key functions (Pester et al 2010, Sauret et al 2014. Additionally, some rare taxa are sensitive to disturbances (Sjöstedt et al 2012, Coveley et al 2015, Vuono et al 2016, notably after the recent Deepwater Horizon oil spill (Newton et al 2013). Rare soil taxa that were below detection not only responded to pulses of precipitation by blooming but also contributed to increased carbon dioxide and methane production, demonstrating that rare taxa collectively can contribute to ecosystem function (Aanderud et al 2015).…”

Functional and Compositional Stability of Bacterial Metacommunities in Response to Salinity Changes

“…The response of bacterial communities to disturbances may also be influenced by dispersal (e.g., Shade et al, 2012; Vuono et al, 2016). For example, dispersal can introduce new species to local communities that are specialized to the disturbance conditions or enable the re-colonization by taxa that became locally extinct in response to a disturbance, thereby enhancing community resilience.…”