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Laboratory Simulation of an Iron(II)-rich Precambrian Marine Upwelling System to Explore the Growth of Photosynthetic Bacteria
Published on: July 24, 2016
Suspended particulate matter enhances light responsive superoxide generation at aquatic biofilm interfaces via
Haowen Li1, Fei Liu2, Chongsen Duan1
1Key Laboratory of Lake and Watershed Science for Water Security, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 211135, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Abstract:
Suspended particulate matter (SPM) is ubiquitous in shallow waters and frequently interact with aquatic biofilms, yet its role in regulating biofilm-derived superoxide (O2·-) generation remains unclear. Here, we demonstrate that SPM enhances light-responsive O2·- generation at submerged macrophyte biofilm interfaces via modulating electron supply, extracellular polymeric substances (EPS) photoreactivity, and EPS-mediated electron transfer. During biofilm development, the maximum interfacial O2·- production increased 2.36-fold as SPM concentration rose from 0 to 300 mg L-1, reflecting enhanced biofilm biomass accumulation and elevated mass-normalized O2·- production activity. SPM exposure intensified light-driven O2·- generation from 323.22 ± 6.15-558.24 ± 37.46 nmol mg C-1 h-1, and improved the electron-donating capacity from 2.11 ± 0.21-4.87 ± 0.49 μmol e- mg C-1 in intact biofilms. Isolated EPS exhibited a tighter correlation between electron-donating capacity and light-induced O2·- generation. Further experiments involving electron donors, inhibitors and redox mediators confirmed that SPM incorporation facilitates EPS-mediated electron transfer to molecular oxygen, with a 2.04-fold response at 300 mg L-1 SPM under sufficient electron-donor supply. Collectively, our findings reveal a biofilm-dependent mechanism for SPM enhances O2·- formation and highlight SPM as an overlooked regulator of biofilm interfacial O2·- generation in shallow aquatic ecosystems.
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