Influence of rate of salinity increase on nitrifying biofilms

Navada, Sharada; Vadstein, Ôlav; Tveten, Ann-Kristin; Verstege, Gerhardus C.; Terjesen, Bendik Fyhn; Mota, Vasco C.; Venkataraman, Vishwesh; Gaumet, Frédéric; Mikkelsen, Øyvind; Kamstra, A.

doi:10.1016/j.jclepro.2019.117835

Cited by 38 publications

(22 citation statements)

References 37 publications

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“…During the batch tests, AOR max or NPR max were calculated from the slopes of the regression lines between the parameter (ammonia or nitrate) and time. These rates were compared using analysis of covariance (ANCOVA) 22,23 . Normality of the residuals was checked by Shapiro-Wilk tests.…”

Section: Data Analysis Physicochemical Analysismentioning

confidence: 99%

Nitrifying biofilms deprived of organic carbon show higher functional resilience to increases in carbon supply

Navada

Knutsen

Bakke

et al. 2020

Sci Rep

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In nitrifying biofilms, the organic carbon to ammonia nitrogen (C/N) supply ratio can influence resource competition between heterotrophic and nitrifying bacteria for oxygen and space. We investigated the impact of acute and chronic changes in carbon supply on inter-guild competition in two moving bed biofilm reactors (MBBR), operated with (R1) and without (R0) external organic carbon supply. The microbial and nitrifying community composition of the reactors differed significantly. Interestingly, acute increases in the dissolved organic carbon inhibited nitrification in R1 ten times more than in R0. A sustained increase in the carbon supply decreased nitrification efficiency and increased denitrification activity to a greater extent in R1, and also increased the proportion of potential denitrifiers in both bioreactors. The findings suggest that autotrophic biofilms subjected to increases in carbon supply show higher nitrification and lower denitrification activity than carbon-fed biofilms. This has significant implications for the design of nitrifying bioreactors. Specifically, efficient removal of organic matter before the nitrification unit can improve the robustness of the bioreactor to varying influent quality. Thus, maintaining a low C/N ratio is important in nitrifying biofilters when acute carbon stress is expected or when anoxic activity (e.g. denitrification or H 2 S production) is undesirable, such as in recirculating aquaculture systems (RAS).

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Section: Data Analysis Physicochemical Analysismentioning

confidence: 99%

Nitrifying biofilms deprived of organic carbon show higher functional resilience to increases in carbon supply

Navada

Knutsen

Bakke

et al. 2020

Sci Rep

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“…Another potential cause for the increased rate similarity could be that in the long term the fluxes in this A B C D poorly mixed system are strongly constrained by boundary conditions and physical transport properties (Louca et al, 2019). A negative effect of salinity on metabolic rates has been observed previously, especially when microorganisms were originally taken from a less saline environment (as in our case) (Wilson et al, 2013;Rath and Rousk, 2015;Peng et al, 2017;Navada et al, 2019;Rath et al, 2019). The effects of salinity are at least partly physiological in nature, with salinity imposing a stress to cells (Rath and Rousk, 2015) that might lead to lower microbial population sizes and generally lower bulk metabolic rates.…”

Section: Metabolic Activitymentioning

confidence: 51%

“…As NaCl is not itself a metabolic substrate, we hypothesized that it may select for alternative taxa without directly selecting for or against specific metabolic groups, thus potentially permitting an investigation of how taxonomic variation in and of itself (i.e., regardless of variation in functional composition) affects function. The effects of salinity on microbial activity are also of environmental and industrial interest (Duan et al, 2018;Navada et al, 2019). We used 16S rRNA amplicon sequencing and gene-centric metagenomic sequencing to assess the taxonomic and metabolic composition of the microbial (bacterial and archaeal) communities respectively, at various time points and at two different depth intervals (henceforth 'top' and 'bottom' segments).…”

Section: Introductionmentioning

confidence: 99%

Effects of forced taxonomic transitions on metabolic composition and function in microbial microcosms

Louca

Rubin

Madilao

et al. 2020

Environ Microbiol Rep

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Summary Surveys of microbial systems indicate that in many situations taxonomy and function may constitute largely independent (‘decoupled’) axes of variation. However, this decoupling is rarely explicitly tested experimentally, partly because it is hard to directly induce taxonomic variation without affecting functional composition. Here we experimentally evaluate this paradigm using microcosms resembling lake sediments and subjected to two different levels of salinity (0 and 19) and otherwise similar environmental conditions. We used DNA sequencing for taxonomic and functional profiling of bacteria and archaea and physicochemical measurements to monitor metabolic function, over 13 months. We found that the taxonomic composition of the saline systems gradually but strongly diverged from the fresh systems. In contrast, the metabolic composition (in terms of proportions of various genes) remained nearly identical across treatments and over time. Oxygen consumption rates and methane concentrations were substantially lower in the saline treatment, however, their similarity either increased (for oxygen) or did not change significantly (for methane) between the first and last sampling time, indicating that the lower metabolic activity in the saline treatments was directly and immediately caused by salinity rather than the gradual taxonomic divergence. Our experiment demonstrates that strong taxonomic shifts need not directly affect metabolic rates.

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“…A global trend in the land-based aquaculture industry is the change from flow-through to recirculating aquaculture systems (RAS). During the production of Atlantic salmon ( Salmo salar ), freshwater is used during the young life stages (from hatching to smolt), and seawater is normally used during later life stages (post-smolt)—also for land-based production in RAS 8 , 9 . As brackish and saltwater RAS develop very rapidly, there is an urgent need for more research to improve our understanding and to optimizing biofiltration at different salinities 10 and after abrupt salinity changes.…”

Section: Introductionmentioning

confidence: 99%

“…Variable salinity leads to osmotic stress, and the consequence can be loss of metabolic enzyme activity and inhibition of the growth of microorganisms 11 . To reduce the salt stress on bacterial metabolism during shift-up, different acclimatization strategies of freshwater nitrifiers to high salinity 9 , 12 as well as utilization of halophilic nitrifying microbial consortia 7 have been reported. However, studies on the structure and function relationships of nitrifying biofilms exposed to fast (shift-up or down) salinity change in long-term are scarce in the literature.…”

Section: Introductionmentioning

confidence: 99%

Understanding structure/function relationships in nitrifying microbial communities after cross-transfer between freshwater and seawater

Gonzalez-Silva

Jonassen

Bakke

et al. 2021

Sci Rep

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In this study, nitrification before and after abrupt cross-transfer in salinity was investigated in two moving bed biofilm reactors inoculated with nitrifying cultures that had adaptation to freshwater (FR) and seawater salinities (SR). FR and SR MBRRs were exposed to short and long term cross-transfer in salinity, and the functional capacity of nitrifying microbial communities was quantified by the estimation of ammonia and nitrite oxidation rates. Salinity induced successions were evaluated before and after salinity change by deep sequencing of 16S rRNA gene amplicons and statistical analysis. The bacterial community structure was characterized and Venn diagrams were included. The results indicated that after salinity cross-transfer, the FR was not significantly recovered at seawater salinity whereas SR showed high resistance to stress caused by low-salt. Succession and physiological plasticity were the main mechanisms of the long-term adaption of the nitrifying communities exposed to abrupt salinity changes. Independently of salinity, some nitrifiers presented high physiological plasticity towards salinity and were very successful at both zero and full seawater salinity. SR culture is robust and suitable inoculum for ammonium removal from recirculating aquaculture systems and industrial wastewaters with variable and fast salinity changes. Our findings contradict the current perspective of the significance of salinity on the structure of nitrifying communities.

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Influence of rate of salinity increase on nitrifying biofilms

Cited by 38 publications

References 37 publications

Nitrifying biofilms deprived of organic carbon show higher functional resilience to increases in carbon supply

Nitrifying biofilms deprived of organic carbon show higher functional resilience to increases in carbon supply

Effects of forced taxonomic transitions on metabolic composition and function in microbial microcosms

Understanding structure/function relationships in nitrifying microbial communities after cross-transfer between freshwater and seawater

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