1. Academic Validation
  2. Single and combined effects of amino polystyrene and perfluorooctane sulfonate on hydrogen-producing thermophilic bacteria and the interaction mechanisms

Single and combined effects of amino polystyrene and perfluorooctane sulfonate on hydrogen-producing thermophilic bacteria and the interaction mechanisms

  • Sci Total Environ. 2020 Feb 10;703:135015. doi: 10.1016/j.scitotenv.2019.135015.
Wanying Chen 1 Dong Yuan 2 Min Shan 1 Zhongbao Yang 3 Chunguang Liu 4
Affiliations

Affiliations

  • 1 School of Environmental Science and Engineering, China-America CRC for Environment & Health of Shandong Province, Shandong University, 72# Jimo Binhai Road, Qingdao, Shandong 266237, PR China.
  • 2 Department of Chemistry and Chemical Engineering, Qilu Normal University, Shandong Province, 36# Lishan Road, Jinan 250013, PR China.
  • 3 School of Life Science, Shandong University, 72# Jimo Binhai Road, Qingdao, Shandong 266237, PR China.
  • 4 School of Environmental Science and Engineering, China-America CRC for Environment & Health of Shandong Province, Shandong University, 72# Jimo Binhai Road, Qingdao, Shandong 266237, PR China; Guangzhou Key Laboratory of Environmental Exposure and Health, School of Environment, Jinan University, PR China. Electronic address: chunguangliu2013@sdu.edu.cn.
Abstract

As a carrier of perfluorooctane sulfonate, nano-plastics are ubiquitous and finally enriched in the sludge, which is widely used as a raw material for the production of bioenergy (hydrogen or methane) by anaerobic digestion. However, there are still many unknowns about their metabolic toxicity to functional microbes (e.g. hydrogen-producing thermophilic bacteria). Therefore, single and combined effects of amino polystyrene (NPS: 70 nm; 0.2 mg/L) and perfluorooctane sulfonate (PFOS: 0.1, 1 and 5 mg/L) on hydrogen-producing thermophilic bacteria were investigated after exposure for 7 days at 55 °C and pH = 5.7. Single NPS exhibited obvious interference to the metabolism of thermophilic bacteria, resulting in a 53.9% reduction in hydrogen production. However, the combined NPS + PFOS produced an antagonistic effect, leading to a 31.6% reduction in hydrogen production. Nonetheless, the single and combined exposure did not alter the type of hydrogen production (acetic acid-type hydrogen fermentation). Moreover, single NPS and combined NPS + PFOS not only induced the changes of the composition of extracellular Polymers (EPSs) and π bond structure of the protein in EPSs, but also decreased the activity of hydrolase in EPSs and surface charge of EPSs. Compared to single NPS exposure, NPS + PFOS-exposed thermophilic bacteria was less permeable to a semi-membrane permeable dye and produced less Reactive Oxygen Species, but were still significantly higher than control group. In short, the main mechanisms of single NPS and combined NPS + PFOS were both to increase cell permeability and to induce oxidative stress. The addition of PFOS alleviated the toxic effect of NPS, but did not change its mechanism of toxicity.

Keywords

Antagonistic effect; Extracellular polymers; Hydrogen fermentation; Nano-plastics; Nano-toxicity; Perfluorinated compounds.

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