| Title |
A Study on Effect of Repeated Freeze-Thaw Perturbation on Acclimation of Anammox Bacteria in Low-temperature |
| Authors |
김수빈(Subin Kim) ; 김상균(Sangkyun Kim) ; 박면호(Myeonho Park) ; 김성아(Seunga Kim) ; 이민주(Minjoo Lee) ; 박준홍(Joonhong Park) |
| DOI |
https://doi.org/10.15681/KSWE.2025.41.4.245 |
| Keywords |
Anammox bacteria; Freeze-thaw cycle; Low-temperature acclimation; Specific anammox activity; Nitrogen removal; Water quality |
| Abstract |
In our previous study, we found that Freeze-Thaw Cycle (FTC) pre-treatment under substrate-free conditions (with ammonia and nitrite absent) effectively enriched Anammox bacteria for low-temperature environments. However, it remains unclear whether FTC-treated Anammox bacteria can acclimate during low-temperature reactivation when substrates are added. This study investigated the survival and functional recovery of Anammox bacteria subjected to repeated FTC pre-treatment during low-temperature reactivation. The results indicated that specific Anammox activity (SAA) increased with the number of FTC cycles compared to the control (30°C) and No Freeze-Thaw (NFT) conditions (15°C without FTC). However, this increase was primarily driven by nitrite removal efficiency (NRE), while ammonia removal efficiency (ARE) remained low. Subsequent qPCR analysis revealed a decline in RNA/DNA ratios, suggesting reduced transcriptional activity and survival of Anammox bacteria. This indicates that repeated FTC perturbations hindered their acclimation and recovery during reactivation. Additionally, our previous NGS-based study demonstrated that repetitive FTC significantly enriched Pseudomonas within the same inoculum. Consequently, the increased NRE observed in this study is likely facilitated by cold-adaptive denitrifiers such as Pseudomonas. These selectively grown Pseudomonas can utilize nitrite effectively even in low temperatures, potentially outcompeting Anammox bacteria for nitrite and playing a critical role in overall nitrogen removal.These findings suggest that while FTC pre-treatment selectively enriches cold-adaptive Anammox bacteria, successful reactivation of these FTC-pretreated Anammox bacteria at low temperatures is not guaranteed. This highlights gaps in our understanding of bacterial population dynamics during the low-temperature reactivation of FTC-pretreated Anammox bacteria |