Microbial competition among anammox bacteria in nitrite-limited bioreactors

Abstract

Phylogenetically diverse anammox bacteria have been detected in most of anoxic natural and engineered ecosystems and thus regarded as key players in the global nitrogen cycle. However, ecological niche differentiation of anammox bacteria remains unresolved despite its ecological and practical importance. In this study, the microbial competitions for a common substrate (nitrite) among three anammox species (i.e. "Candidatus Brocadia sinica", "Candidatus Jettenia caeni" and "Candidatus Kuenenia stuttgartiensis") were systematically investigated in nitrite-limited gel-immobilized column reactors (GICR) and membrane bioreactors (MBRs) under different nitrogen loading rates (NLRs). 16 S rRNA gene-based population dynamics revealed that "Ca. J. caeni" could proliferate only at low NLRs, whereas "Ca. B. sinica" outcompeted other two species at higher NLRs in both types of reactors. Furthermore, FISH analysis revealed that "Ca. J. caeni" was mainly present as spherical microclusters at the inner part (low NO environment), whereas "Ca. B. sinica" was present throughout the gel beads and granules. This spatial distribution supports the outcomes of the competition experiments. However, the successful competition of "Ca. J. caeni" at low NLR could not be explained with the Monod model probably due to inaccuracy of kinetic parameters such as half saturation constant (K) for nitrite and a difference in the maintenance rate (m). In addition, the growth of "Ca. K. stuttgartiensis" could not be observed in any experimental conditions, suggesting possible unknown factor(s) is missing. Taken together, NLR was one of factors determining ecological niche differentiation of "Ca. B. sinica" and "Ca. J. caeni".

Aggregation ability of three phylogenetically distant anammox bacterial species

“…Anammoxoglobus propionicus" (Kartal et al, 2007)). Population dynamics of anammox bacterial species were systematically investigated in nitrite-limited bioreactors recently (Zhang et al, 2017a). A population shift from "Ca.…”

Partial denitrification coupled with immobilization of anammox in a continuous upflow reactor

“…Recently, the anaerobic ammonium oxidation technique (ANAMMOX) has increasingly attracted interest and environmentalists recognize it as the most sustainable wastewater denitrication technique. [1][2][3] However, its independent use is limited since it requires nitrite nitrogen as an electron acceptor. At present, partial nitrication is the main route to obtain NO 2 À -N; however, it has high control requirements, is easily destroyed, 4,5 and is difficult to recover once destroyed.…”

Temperature modulates stress response in anammox reactors

“…The most abundant species of the AMX consortia presumably have adaptations that allow them to thrive under these unstable conditions 72 . The low abundant AMX MAGs on the other hand are generally stressed due to constant competition for available resources with the abundant AMX fractions 73 . Thus, additional stress might have imposed the elevated stress responses of these MAGs.…”