Adaptation of flocculent anammox culture to low temperature by cold shock: long-term response of the microbial population

Abstract

Partial nitritation-anammox (PN/A) process will substantially reduce the costs for the removal of nitrogen in the mainstream of municipal sewage. However, one of the mainstream PN/A challenges is to reduce the time necessary for the adaptation of anammox bacteria to lower temperatures in mild climates. In this study, we exposed anammox flocculent culture to cold shocks [35°C → 5°C (8 h) → 15°C] and evaluated long-term cold shock response. Over a postshock period of 40 d at 15°C, the nitrogen removal rates in the shocked culture were significantly higher compared to control, with maximum rates up to 0.082 and 0.033 kg-N/kg-VSS/d or 0.164 and 0.076 kg-N/m 3 /d, for shocked culture and control, respectively. In the corresponding semi-batch cycles, the shocked culture was on average 136 ± 101% more active than the control, due to the negative effect of cold shock on side populations and more active anammox cells. Per FISH, Ca. Brocadia anammoxidans and Ca. Scalindua survived the shock and remained present throughout. Thus, both anammox microorganisms seem to respond favourably to cold shocks. In sum, we provide further evidence that cold shocks accelerate the adaptation of anammox to the mainstream of municipal WWTPs. Further, for the first time, we report the long-term adaptive response of anammox to cold shocks.

Physiology of anammox adaptation to low temperatures and promising biomarkers: A review

“…Another gradually adapted enrichment of "Ca. Kuenenia" maintained the level of metabolic proteins less efficiently than enrichment exposed to a more elaborate adaptation methodology (Kouba et al, 2022) which explained the increased activity of anammox bacteria as a result of this methodology in two previous studies (Kouba et al, 2018(Kouba et al, , 2021. This suggests that the downregulation of energy generation at lower temperatures could be transitory and its occurrence depends on the applied adaptive regime.…”

Effect of Mineral Carriers on Biofilm Formation and Nitrogen Removal Activity by an Indigenous Anammox Community from Cold Groundwater Ecosystem Alone and Bioaugmented with Biomass from a “Warm” Anammox Reactor

“…However, it should be taken into account that the current methods of adaptation of a “warm” anammox community to low temperatures (10–15 °C) take months or even years. Techniques such as cold shock [ 100 , 101 ] or gradual acclimation and cold shocks [ 102 ] have been shown to be promising. A feasibility study of these methods may also be the focus of future work on sustainable bioremediation of cold polluted groundwater ecosystems through bioaugmentation.…”