Bacterial Growth Efficiency (BGE) is a key characteristic of microbial physiology and an important parameter in the evaluation of the quantitative role of bacterioplankton in the microbial food web. Changes in BGE is indicative of the responses of the microbial community to changes in environmental conditions such as temperature, pressure, and substrate availability. Using a batch culture approach, we investigate the effect of these parameters on the BGE of marine microbial communities from different marine environments. We systematically quantify the effects of temperature and pressure in combination with different dissolved organic carbon (DOC) sources on BGE, while varying only one parameter at a time. Our results show that BGE is dynamic, positively correlated to temperature and addition of labile DOC, and regulated by the C and N composition of the added organic carbon sources in both shallow and deep waters. These findings allow us to distinguish between the energy and organic nutrient requirements supporting an efficient transformation of DOC into bacterial biomass. These measurements of BGE regulation across different environmental conditions provide a comprehensive range for BGE values typically observed in marine environments, contributing to our understanding of how microbes adjust their BGE according to environmental parameters. These results in combination with in-situ measurements thus provide important insights into the bacterial carbon demand across marine ecosystems, having implications for estimation of marine carbon budgets.

Primary Presenter: Devangi Sathe, University of Southern Denmark (SDU) (devangi@biology.sdu.dk)

Authors:

Devangi Sathe, University of Southern Denmark (SDU)  (devangi@biology.sdu.dk)

John Paul Balmonte, University of Southern Denmark (SDU)  (jpbalmonte@biology.sdu.dk)

Ronnie Glud, University of Southern Denmark (SDU)  (rnglud@biology.sdu.dk)

Mathias Middelboe, University of Copenhagen  (mmiddelboe@bi.ku.dk)