Studies have revealed new mechanisms by which diatoms adapt to nitrate contamination

Nitrate pollution from human activities such as household life, animal husbandry and fertilizer application is threatening marine ecosystems and net primary productivity. As a major component of primary productivity, diatoms are able to adapt to high nitrate environments, but their mechanisms are unclear. Recently, the latest research by Hu Xiangang’s team in the School of Environmental Science and Engineering of Nankai University found that the reason why diatoms can adapt to nitrate pollution is because marine colloids promote the pollution adaptation of diatoms through directional electron transfer. The results were published online on April 18 in Environmental Science and Technology.

The study found that under visible light irradiation, electron transfer from marine colloids to diatoms enhanced nitrogen absorption and assimilation, providing a new way for diatoms to adapt to high nitrate environments. Under radiation, marine colloids exhibit semiconductor properties and can trigger the production of free electrons and single-line oxygen. They also exhibit electron receptor and donor properties, the former stronger than the latter, reacting with polysaccharides in extracellular polymers (EPSs) under high nitrogen stress, enhancing the elasticity and permeability of cells, and promoting nitrogen assimilation and electron transfer to marine diatom EPSs.

Further studies have found that electron transfer promotes extracellular to intracellular nitrate transport through upregulation membrane nitrate transporters and nitrate reductase. Upregulation of anion transporter genes and unsaturated fatty acids also contributes to nitrogen assimilation. The team estimates that colloids can increase the nitrate absorption efficiency of marine diatoms by 10.5–82.2%.

Electron transfer enhances the nitrogen absorption capacity of diatoms Picture from the paper

The team said the discovery reveals the mechanism by which diatoms adapt to nitrate pollution and provides direction for low-cost control of marine pollution. (Source: China Science Daily Zheng Jinwu)

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