Abstract：
Antibiotics often coexist with other pollutants (e.g., nitrate) in an aquatic environment, and their simultaneous biological removal has attracted widespread interest. We have found that sulfamethoxazole (SMX) and nitrate can be efficiently removed by the coculture of a model denitrifier (Paracoccus denitrificans, Pd) and Shewanella oneidensis MR-1 (So), and SMX degradation is affected by NADH production and electron transfer. In this paper, the mechanism of a coculture promoting NADH production and electron transfer was investigated by proteomic analysis and intermediate experiments. The results showed that glutamine and lactate produced by Pd were captured by So to synthesize thiamine and heme, and the released thiamine was taken up by Pd as a cofactor of pyruvate and ketoglutarate dehydrogenase, which were related to NADH generation. Additionally, Pd acquired heme, which facilitated electron transfer as heme, was the important composition of complex III and cytochrome c and the iron source of iron sulfur clusters, the key component of complex I in the electron transfer chain. Further investigation revealed that lactate and glutamine generated by Pd prompted So chemotactic moving toward Pd, which helped the two bacteria effectively obtain their required substances. Obviously, metabolite cross-feeding promoted NADH production and electron transfer, resulting in efficient SMX biodegradation by Pd and So in the presence of nitrate. Its feasibility was finally verified by the coculture of an activated sludge denitrifier and So.
摘要：
抗生素通常与其他污染物共存(例如，硝酸盐)在水生环境中，它们的同时生物去除引起了广泛的兴趣。我们已经发现，磺胺甲恶唑（SMX）和硝酸盐可以通过模型反硝化菌的共培养来有效去除（反硝化副球菌，Pd)和希瓦氏菌MR-1(So)，SMX降解受NADH产生和电子转移的影响。在本文中,通过蛋白质组学分析和中间实验研究了共培养促进NADH产生和电子转移的机制。结果表明，Pd生成的谷氨酰胺和乳酸被So捕获，合成硫胺素和血红素，释放的硫胺素被Pd作为丙酮酸和酮戊二酸脱氢酶的辅因子吸收，与NADH的产生有关。此外,Pd获得血红素，像血红素一样促进电子转移，是配合物III和细胞色素C的重要组成和铁硫簇的铁源，电子转移链中配合物I的关键成分。进一步的研究表明，Pd产生的乳酸和谷氨酰胺促使So趋化性向Pd移动，这有助于这两种细菌有效地获得它们所需的物质。显然,代谢物交叉饲喂促进了NADH的产生和电子转移，在硝酸盐存在下，Pd和So可有效地生物降解SMX。最终通过活性污泥反硝化菌与So的共培养验证了其可行性。
