Microplastics were reported to adsorb antibiotics and may modify their effects on soil systems. But there has been little research investigating how microplastics may affect the toxicities of antibiotics to microbes under future climate conditions. Here, we used a free-air CO₂ enrichment system to investigate the responses of soil microbes to sulfamethazine (SMZ, 1 mg kg⁻¹) in the presence of polystyrene microplastics (PS, 5 mg kg⁻¹) at different CO₂ concentrations (ambient at 380 ppm and elevated at 580 ppm). SMZ alone decreased bacterial diversity, negatively affected the bacterial structure and inter-relationships, and enriched the sulfonamide-resistance genes (sul1 and sul2) and class 1 integron (intl1). PS, at both CO₂ conditions, showed little effect on soil bacteria but markedly alleviated SMZ’s adverse effects on bacterial diversity, composition and structure, and inhibited sul1 transmission by decreasing the intl1 abundance. Elevated CO₂ had limited modification in SMZ’s disadvantages to microbial communities but markedly decreased the sul1 and sul2 abundance. Results indicated that increasing CO₂ concentration or the presence of PS affected the responses of soil microbes to SMZ, providing new insights into the risk prediction of antibiotics under future climate conditions.

据报道，微塑料可吸附抗生素，并可能改变其对土壤系统的影响。但是，很少有研究调查在未来的气候条件下微塑料如何影响抗生素对微生物的毒性。在这里，我们使用了自由空气CO ₂富集系统，研究了在不同CO ₂浓度下存在聚苯乙烯微塑料（PS，5 mg kg ^-1）的情况下土壤微生物对磺胺二甲嘧啶（SMZ，1 mg kg ^-1）的响应。（环境温度为380 ppm，升高为580 ppm）。单独的SMZ会降低细菌多样性，对细菌的结构和相互关系产生负面影响，并丰富了耐磺酰胺性的基因（sul1和sul2）和1类整型（intl1）。在两种CO ₂条件下，PS对土壤细菌几乎没有影响，但显着减轻了SMZ对细菌多样性，组成和结构的不利影响，并通过降低intl1丰度来抑制sul1传播。升高的CO ₂对SMZ对微生物群落的不利影响有限，但明显降低了sul1和sul2的丰度。结果表明，增加的CO ₂浓度或PS的存在会影响土壤微生物对SMZ的反应，从而为未来气候条件下抗生素的风险预测提供新的见解。