Recently a Bacillus sp. strain FW 1 was isolated from biogas digestate and shown to have novel resistance to meropenem (MEM), of critical importance in human medicine. MEM-resistance has so far only been described for one species within the genus Bacillus, that is, Bacillus cereus. Bacillus is an abundant representative of the microbial community in biogas digesters and consequently, the finding indicates a risk of spreading such resistance when using the digestate as fertiliser. In this study, the Bacillus strain was characterised and classified as Heyndrickxia oleronia (previous Bacillus oleronius), previously not described to harbour MEM-resistance. The mechanism of resistance was explored by metallo-β-lactamase (MBL) production, mapping of carbapenemase genes and genome analysis. The transferability of MEM-resistance in strain FW 1 was investigated by plasmid transformation/conjugation, combined with genome analysis. The results confirmed MBL production for both strain FW 1 and the type strain H. oleronia DSM 9356^T. However, elevated MEM resistance was found for strain FW 1, which was suggested to be caused by the production of unclassified carbapenemase, or overexpression of MBL. Moreover, the results suggest that the MEM-resistance of strain FW 1 is not transferable, thus representing a limited risk of MEM-resistance spread to the environment when using digestate on arable land.

中文翻译：

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耐美罗培南芽孢杆菌的特征。从沼气沼渣中分离出 FW 1

最近发现了芽孢杆菌。菌株 FW 1 从沼气沼渣中分离出来，并显示出对美罗培南 (MEM) 具有新的耐药性，这在人类医学中至关重要。迄今为止，仅描述了芽孢杆菌属内的一种物种，即蜡状芽孢杆菌的MEM抗性。芽孢杆菌是沼气池中微生物群落的丰富代表，因此，这一发现表明，当使用沼渣作为肥料时，存在传播这种耐药性的风险。在这项研究中，芽孢杆菌菌株被表征并分类为Heyndrickxia oleronius（以前的 Bacillus oleronius），之前没有被描述为具有 MEM 抗性。通过金属-β-内酰胺酶（MBL）的产生、碳青霉烯酶基因图谱和基因组分析来探索耐药机制。通过质粒转化/接合并结合基因组分析研究了菌株 FW 1 中 MEM 抗性的可转移性。结果证实菌株 FW 1 和模式菌株H. oleronia DSM 9356 ^T均产生 MBL 。然而，发现菌株 FW 1 的 MEM 抗性升高，这被认为是由未分类的碳青霉烯酶的产生或 MBL 的过度表达引起的。此外，结果表明菌株 FW 1 的 MEM 抗性不可转移，因此在耕地上使用沼渣时，MEM 抗性传播到环境的风险有限。