Raw 16S sequence reads of the active bacteriaplankton community in a microcosm study

Previous studies mainly examined how the effects of warming on OCC and BGE interacted with substrate quality (Lonborg et al. 2019; Kim et al. 2020). However, in natural scenarios, microbial history also varies among different sites (Glassman et al. 2018; Simon et al. 2020) and microbial history, temperature, and substrate quality are key factors that shape carbon cycling. Understanding their relative importance as well as the context-dependent nature of warming may help us predict dynamics of carbon cycling. In the present study, we used a three-factor factorial design to explore how OCC, BGE, DOM consumption, and active community structure respond to substrate quality, microbial community history, and temperature. We manipulated the substrate quality using different combinations of phytoplankton-derived DOM (DOMphyto) and leaf-derived DOM (DOMleaf) at consistent dissolved organic carbon (DOC) concentrations. DOMphyto and DOMleaf represent typical autochthonous and allochthonous DOM sources respectively (Attermeyer et al. 2014). We aimed to answer the following questions: (1) How important are the three factors in DOM decomposition, a microbial-mediated process? (2) How do substrate quality and community history shape the effect of warming on DOM decomposition?