Nitrification at different salinities: Biofilm community composition and physiological plasticity
Blanca M Gonzalez-Silva1, Kjell Rune Jonassen1, Ingrid Bakke1
1Department of Biotechnology, Faculty of Natural Sciences and Technology, NTNU Norwegian University of Science and Technology, Sem Saelands v. 6/8, N-7491 Trondheim, Norway.
Water Research
|March 18, 2016
Summary
Microbial communities in moving bed biofilm reactors adapt differently to salinity. Freshwater nitrifying bacteria showed high sensitivity to salt, while seawater cultures thrived in higher salinity environments.
Area of Science:
- Environmental microbiology
- Wastewater treatment technologies
- Biogeochemistry
Background:
- Moving Bed Biofilm Reactors (MBBR) are crucial for nitrification in wastewater treatment.
- Understanding microbial community adaptation to varying salinity is vital for optimizing MBBR performance.
- Nitrifying cultures from diverse salinity environments (freshwater, brackish, seawater) were studied.
Purpose of the Study:
- To investigate the impact of salinity on microbial community structure in MBBRs.
- To compare the nitrification efficiency and microbial diversity across different salinity levels.
- To assess the salt tolerance of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB).
Main Methods:
- Experimental setup using three MBBRs with distinct salinity inocula.
- 16S rRNA gene pyrosequencing for microbial community profiling.
- Statistical analyses including NMDS, PERMANOVA, and SIMPER for community structure comparison.
- Assessment of ammonium and nitrite oxidation rates under varying salt stress.
Main Results:
- Significantly different microbial community structures were observed across the three salinity reactors.
- The brackish water reactor exhibited lower microbial diversity compared to freshwater and seawater reactors.
- A small number of dominant operational taxonomic units (OTUs) explained most community differences.
- Freshwater nitrifying activity was highly inhibited by salt, while seawater cultures showed enhanced activity at higher salinities.
Conclusions:
- Salinity significantly shapes the microbial community structure and function in MBBRs.
- Nitrifying bacteria exhibit distinct adaptations and sensitivities to salt stress.
- MBBR performance and microbial community composition are strongly influenced by the salinity of the source environment.
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