摘要
      抗微生物耐药性（AMR）正成为全球日益关注的问题，当消化物用作肥料时，厌氧消化（AD）过程是一种潜在的传播途径。AMR污染物，如抗生素抗性细菌（ARB）和质粒介导的抗生素抗性基因（ARGs），已在不同的底物和AD系统中发现，但尚未在植物基质中进行研究。已经观察到AMR从土壤转移到蔬菜微生物群，因此作物材料可能是农业AD过程中迄今为止被忽视的AMR负荷，有助于AMR的传播。为了验证这一假设，本研究检查了三种仅使用植物基质或混合植物基质和粪肥基质的沼气厂在整个过程中的AMR情况。评估包括培养无关和依赖性方法的组合，即通过DNA阵列鉴定ARGs、质粒和致病菌，以及细菌分离株的系统发育分类及其表型抗性模式。据我们所知，这是首次对植物基质和相应沼气厂中的AMR进行研究。结果表明，从所研究的底物和AD处理设施中分离出的细菌群落主要是革兰氏阳性芽孢杆菌。无论是通过细菌培养还是DNA分型阵列，都没有发现其他革兰氏阴性菌株。相反，ARGs和质粒的存在清楚地表明在底物和AD过程中都存在革兰氏阴性致病菌。与底物相比，消化物的ARGs、质粒和可培养ARB水平较低。因此，与底物本身相比，消化物传播AMR的风险更低。总之，植物性底物与AMR相关，包括可培养的革兰氏阳性ARB和革兰氏阴性致病菌相关的ARGs和质粒。因此，在农业沼气处理中应考虑植物基质的AMR负荷。
Abstract
Antimicrobial resistance (AMR) is becoming an increasing global concern and the anaerobic digestion (AD) process represents a potential transmission route when digestates are used as fertilizing agents. AMR contaminants, e.g. antibiotic-resistant bacteria (ARB) and plasmid-mediated antibiotic resistance genes (ARGs) have been found in different substrates and AD systems, but not yet been investigated in plant-based substrates. AMR transfer from soils to vegetable microbiomes has been observed, and thus crop material potentially represents a so far neglected AMR load in agricultural AD processes, contributing to AMR spread. In order to test this hypothesis, this study examined the AMR situation throughout the process of three biogas plants using plant-based substrates only, or a mixture of plant-based and manure substrates. The evaluation included a combination of culture-independent and –dependent methods, i.e., identification of ARGs, plasmids, and pathogenic bacteria by DNA arrays, and phylogenetic classification of bacterial isolates and their phenotypic resistance pattern. To our knowledge, this is the first study on AMR in plant-based substrates and the corresponding biogas plant. The results showed that the bacterial community isolated from the investigated substrates and the AD processing facilities were mainly Gram-positive Bacillus spp. Apart from Pantoea agglomerans, no other Gram-negative species were found, either by bacteria culturing or by DNA typing array. In contrast, the presence of ARGs and plasmids clearly indicated the existence of Gram-negative pathogenic bacteria, in both substrate and AD process. Compared with substrates, digestates had lower levels of ARGs, plasmids, and culturable ARB. Thus, digestate could pose a lower risk of spreading AMR than substrates per se. In conclusion, plant-based substrates are associated with AMR, including culturable Gram-positive ARB and Gram-negative pathogenic bacteria-associated ARGs and plasmids. Thus, the AMR load from plant-based substrates should be taken into consideration in agricultural biogas processing.

https://www.sciencedirect.com/science/article/pii/S0048969722016497