摘要
      微生物生物膜可以保护细菌免受抗生素等环境压力的影响。微塑料为微生物在水生系统中形成生物膜提供了附着位点；然而，在陆地系统中，研究仍然缺乏，尤其是在施肥和抗生素暴露的农田中。本研究通过检测生物膜的形成规律和施肥过程中MP附着菌株带来的风险，揭示了不同浓度的多西环素（DOX）对土壤塑性层的影响。结果表明，DOX暴露可促进土壤MP生物膜的形成，尤其是在60天以上的低DOX浓度组，低DOX暴露组MP生物膜形成基因（BFG）的表达水平更强。DOX暴露增加了MP上大多数tet基因的丰度，并且在DOX暴露组中intl1丰度高度增加（增加到1.07×108–8.37×107拷贝/g）。DOX暴露增加了MP上潜在抗生素抗性基因（ARG）宿主和生物膜产生菌株的细菌多样性，低DOX暴露增强了MP上可能病原体的丰度。DOX暴露促进了土壤MPs上生物膜、ARGs和DOX之间的相关性。进一步的实验还证明，MP和DOX的存在都增强了菌株的生物膜产生能力，并且附着在MP上的菌株的生物薄膜产生能力强于浮游细胞。这项研究表明，DOX暴露，通常是低浓度的DOX，可以通过生物膜的产生和施肥过程中的相关保护，增加ARG的转移和MP上残留病原体的丰度。
Abstract
Microbial biofilms can protect bacteria against environmental stresses, such as antibiotics. Microplastics (MPs) provide attachment sites for microbes to form biofilms in aquatic systems; however, in terrestrial systems, research is still lacking, especially in croplands under fertilization and antibiotic exposure. The present study revealed the effects of different doxycycline (DOX) concentrations on the soil plastisphere by examining biofilm formation regularity and the risk posed by MP-attached strains during manuring. The results showed that soil MP biofilm formation could be enhanced by DOX exposure, especially in low-DOX-concentration group over 60 days, and the biofilm formation gene (BFG) expression level on MPs was stronger in low-DOX-exposure group. DOX exposure increased the abundance of most tet genes on the MPs, and the intl1 abundance was highly increased in the DOX exposure groups (enhanced to 1.07 × 108–8.37 × 107 copies/g). DOX exposure increased the diversity of bacteria that were both potential antibiotic resistance gene (ARG) hosts and biofilm-producing strains on MPs, and low DOX exposure enhanced the abundance of potential pathogens on MPs. The correlations among biofilms, ARGs and DOX on soil MPs were promoted by DOX exposure. Further experiments also proved that both MPs and DOX existing enhanced the biofilm production ability of the strains, and the biofilm production ability of the strains attached to the MPs was stronger than that of planktonic cells. This study revealed that DOX exposure, typically low concentrations of DOX, could increase ARG transfer and the abundance of residual pathogens on MPs through biofilm production and the associated protection during manuring.

https://www.sciencedirect.com/science/article/abs/pii/S1385894722060107