Effect of Complexation of Humic Acid with Iron Minerals on Microbial Degradation of Sulfamethoxazole

Chen Xueyan,Jiang Jie

doi:10.11648/j.sd.20190705.22

Abstract

Microbial Shewanella oneidensis MR-1 can degrade sulfamethoxazole (SMX) and act as a microorganism with strong electron donating properties, which can accelerate the degradation of SMX when it cooperates with electronic shuttle and disproportionated iron. By adding different TOC concentrations, different molecular weight humic acids, and magnetite and hematite suspensions, the optimal system growth conditions, ie, the temperature of 30°C, pH = 7, the TOC concentration, The effect of humic acid with different molecular weights and the addition and synergistic addition of different iron minerals on the degradation of SMX by Shewanella oneidensis MR-1. The study found that humic acid stock solution, small molecule humic acid, iron mineral and both of them will accelerate the degradation of SMX by microbial MR-1. The concentration of small molecule humic acid will degrade SMX by Shewanella oneidensis MR-1. The effect of the humic acid is greater than that of the original solution. The addition of magnetite and hematite suspension to the reactor alone promotes the degradation of SMX by Shewanella oneidensis MR-1, and the addition of humic acid will improve the degradation rate of SMX.

Highlights

which can accelerate the degradation of SMX
it cooperates with electronic shuttle
The study found that humic acid stock solution

Summary

Introduction

Microbial Shewanella oneidensis MR-1 can degrade sulfamethoxazole (SMX) and act as a microorganism with strong electron donating properties, which can accelerate the degradation of SMX when it cooperates with electronic shuttle and disproportionated iron. 摘要:微生物Shewanella oneidensis MR-1可以降解磺胺甲恶唑(SMX),并作为具有强给电子性能的微生物,与电子穿梭体、部分铁矿物协同作用时可加速对SMX的降解。文章通过添加不同TOC浓度、不同分子量大小的腐殖酸以及磁铁矿和赤铁矿悬浊液,研究了在微生物最适生长条件即温度为30°C、pH=7时不同体系包括TOC浓度、分子量大小不同的腐殖酸与不同铁矿物单独添加及协同添加的作用对Shewanella oneidensis MR-1降解SMX的影响。研究发现,腐殖酸原液、小分子腐殖酸、铁矿物以及二者同时添加皆会加速微生物MR-1对SMX的降解,小分子腐殖酸的浓度变化对 Shewanella oneidensis MR-1降解SMX的影响相比于原液腐殖酸的影响更大,铁矿物悬浊液单独添加于反应器内对 Shewanella oneidensis MR-1降解SMX的促进作用比较明显,同时加入腐殖酸则会加速对SMX的降解作用。抗生素经常被用于畜牧业以及人类医用中进行微生物生长及感染的抑制[1],世界上每日都有大量的抗生素被投入使用,据2009年的调查显示,每年将近10万-20万吨[2] 的抗生素被投入使用,而我国对世界卫生组织推荐抗生素的使用量可占据世界用量的80%,而且短时间内若无同功能替代品,抗生素的使用量只增不减。大多数抗生素的人体吸收率较低,因此人体的抗生素用量的70%—90%[3]容易被排入到环境中,大多数抗生素半衰期皆较长[4],所以抗生素经常富集于土壤、水体中,难以降解,不仅容易造成环境中微生物的抗药性,产生“超级细菌”使得目前抗生素失去其原有的效用[5],早于2018年有科学家发现对部分抗生素产生抗药性的超级细菌的感染会使人体产生较为严重的反应,甚至导致死亡。除此之外,环境中的抗生磺胺甲恶唑作为人工合成的抗生素,多用于畜牧业, 因此在粪便覆盖的过的土壤中以及农场附近的水体中皆含有大量的抗生素[6]。李彦文[7]等经调查分析发现,我国部分地区的土壤中的磺胺类抗生素的存在含量可达试剂:SBM溶液(MgSO4,KH2PO4,K2HPO4·3H2O, NaCl,(NH4)2·SO4, HEPES,C3H5O3Na)、buffer溶液 (Na2HPO4·12H2O、KH2PO4、KOH与HCl调节pH)、腐殖酸(PPHA)、磁铁矿悬浊液(Fe3O4)、赤铁矿悬浊液 (Fe2O3)、甲醇(分析纯)、乙酸(色谱纯)、乙腈(色谱纯)、超纯水等。

Results

Conclusion