Temperature modulates stress response in mainstream anammox reactors

Abstract

Autotrophic nitrogen removal by anaerobic ammonium oxidizing (anammox) bacteria is an energy-efficient nitrogen removal process in wastewater treatment. However, full-scale deployment under mainstream conditions remains challenging for practitioners due to the high stress susceptibility of anammox bacteria towards fluctuations in dissolved oxygen (DO) and temperature. Here, we investigated the response of microbial biofilms with verified anammox activity to DO shocks under 20 °C and 14 °C. While pulse disturbances of 0.3 mg L−1 DO prompted only moderate declines in the NH4+ removal rates, 1.0 mg L−1 DO led to complete but reversible inhibition of the NH4+ removal activity in all reactors. Genome-centric metagenomics and metatranscriptomics were used to investigate the stress response on various biological levels. We show that temperature regime and strength of DO perturbations induced divergent responses from the process level down to the transcriptional profile of individual taxa. Community-wide gene expression differed significantly depending on the temperature regime in all reactors, and we found a noticeable impact of DO disturbances on genes involved in transcription, translation, replication and posttranslational modification at 20 °C but not 14 °C. Genome-centric analysis revealed that different anammox species and other key biofilm taxa differed in their transcriptional responses to distinct temperature regimes and DO disturbances.

Response and resilience of anammox consortia to nutrient starvation

“…In particular, divergent responses of the hzs complex and hdh gene to other shocks or disturbances have been discovered. In contrast to our observations in this study, decreased transcriptional activities of the hzs complex and upregulation or downregulation of hdh gene expression were observed when the anammox bacteria were subjected to a lower temperature regime (20 °C to 14 °C) or DO exposure [ 24 , 25 ]. These effective regulation strategies are able to alleviate the negative impacts of stress conditions on the anammox bacteria.…”

“…Understanding the transcriptional responses of anammox consortia during disturbances as well as the synergetic interactions between microorganisms is crucial for understanding the capacity of anammox consortia in response to stress and system stability. The integrated strategy has been used to investigate the stress (e.g., DO, temperature, or nutrient limitation) responses of anammox bacteria at various biological levels and the subsequent recovery process [ 24 – 27 ]. However, few studies have revealed the effect of starvation caused by short-term nutrient deprivation (e.g., caused by system failures) on the anammox system, especially using multi-omics strategies.…”

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

“…Microbiome and virome analyses showed that the chemical pretreatments and AD substantially influenced the assemblages of bacterial and viral communities in FS. Similarly, previous studies also indicated that the changes in microbial co-occurrence networks and community assemblages enhanced microbiome resilience of sewage sludge to oxygen and temperature fluctuations. − Spore-forming Romboutsia and Clostridium could tolerate the ALK and NaClO pretreatments (Figure e), but both genera were suppressed after AD. In contrast to the findings for non-spore-forming bacteria, Escherichia and Shigella abundance was decreased by ALK-P and NaClO-P pretreatments but not by AD (Figures e and S10).…”

Start‐up and operation of anammox biofilter in treating low‐strength ammonia wastewater prepared by tail water from a municipal wastewater treatment plant

“…Meanwhile, ΔNO 2 − ‐N/ΔNH 4 + ‐N was 1.66 ± 0.42, 1.29 ± 0.12, 1.46 ± 0.28 and 1.45 ± 1.45, and ΔNO 3 − ‐N/ΔNH 4 + ‐N was 0.03 ± 0.33, 0.08 ± 0.13, 0.24 ± 0.19 and 0.50 ± 0.22, respectively. These findings could be attributed to the challenge of NOB reproduction 22,23 . In fact, at lower substrate concentrations, the higher proportions of NO 2 − ‐N will be consumed by NOB using the equivalent amount of DO in influent, thus reducing the available NO 2 − ‐N for AnAOB and ultimately leading to lower TNRE under the lower substrate conditions.…”

“…These findings could be attributed to the challenge of NOB reproduction. 22,23 In fact, at lower substrate concentrations, the higher proportions of NO 2 − -N will be consumed by NOB using the equivalent amount of DO in influent, thus reducing the available NO 2 − -N for AnAOB and ultimately leading to lower TNRE under the lower substrate conditions. -N consumed by NOB was prior to AnAOB, which was influenced by the EBCT decrease resulting in substrate competition between AnAOB and NOB escalating.…”