Light and Primary Production Shape Bacterial Activity and Community Composition of Aerobic Anoxygenic Phototrophic Bacteria in a Microcosm Experiment
Metadatos
Afficher la notice complèteEditorial
Katherine McMahon, Editor, University of Wisconsin, Madison
Materia
Phytoplankton-bacteria coupling Aerobic anoxygenic phototrophic bacteria Bacterial community composition AAP community composition
Date
2020-07-01Referencia bibliográfica
Piwosz, K., Vrdoljak, A., Frenken, T., González-Olalla, J. M., Šantić, D., McKay, R. M., ... & Fecskeová, L. K. (2020). Light and Primary Production Shape Bacterial Activity and Community Composition of Aerobic Anoxygenic Phototrophic Bacteria in a Microcosm Experiment. Msphere, 5(4). [https://doi.org/10.1128/mSphere.00354-20]
Résumé
Phytoplankton is a key component of aquatic microbial communities,
and metabolic coupling between phytoplankton and bacteria determines
the fate of dissolved organic carbon (DOC). Yet, the impact of primary production
on bacterial activity and community composition remains largely unknown,
as, for example, in the case of aerobic anoxygenic phototrophic (AAP) bacteria
that utilize both phytoplankton-derived DOC and light as energy sources. Here,
we studied how reduction of primary production in a natural freshwater community
affects the bacterial community composition and its activity, focusing primarily
on AAP bacteria. The bacterial respiration rate was the lowest when photosynthesis
was reduced by direct inhibition of photosystem II and the highest
in ambient light condition with no photosynthesis inhibition, suggesting that it
was limited by carbon availability. However, bacterial assimilation rates of leucine
and glucose were unaffected, indicating that increased bacterial growth efficiency
(e.g., due to photoheterotrophy) can help to maintain overall bacterial
production when low primary production limits DOC availability. Bacterial community
composition was tightly linked to light intensity, mainly due to the increased
relative abundance of light-dependent AAP bacteria. This notion shows
that changes in bacterial community composition are not necessarily reflected by
changes in bacterial production or growth and vice versa. Moreover, we demonstrated
for the first time that light can directly affect bacterial community composition,
a topic which has been neglected in studies of phytoplankton-bacteria interactions.