Modification of essential bacterial peptidoglycan (PG)-containing cell walls can lead to antibiotic resistance; for example, β-lactam resistance by L,D-transpeptidase activities. Predatory Bdellovibrio bacteriovorus are naturally antibacterial and combat infections by traversing, modifying and finally destroying walls of Gram-negative prey bacteria, modifying their own PG as they grow inside prey. Historically, these multi-enzymatic processes on two similar PG walls have proved challenging to elucidate. Here, with a PG-labelling approach utilizing timed pulses of multiple fluorescent D-amino acids, we illuminate dynamic changes that predator and prey walls go through during the different phases of bacteria:bacteria invasion. We show formation of a reinforced circular port-hole in the prey wall, L,D-transpeptidase_Bd-mediated D-amino acid modifications strengthening prey PG during Bdellovibrio invasion, and a zonal mode of predator elongation. This process is followed by unconventional, multi-point and synchronous septation of the intracellular Bdellovibrio, accommodating odd- and even-numbered progeny formation by non-binary division.

中文翻译：

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荧光 D-氨基酸揭示了对 Bdellovibrio bacteriovorus 捕食很重要的双细胞细胞壁修饰。

对含有必需细菌肽聚糖 (PG) 的细胞壁进行修饰可导致抗生素耐药性；例如，L,D-转肽酶活性对 β-内酰胺的抗性。掠食性 Bdellovibrio bacteriovorus 具有天然的抗菌性，并通过遍历、修改并最终破坏革兰氏阴性猎物细菌的壁，在它们在猎物体内生长时修改它们自己的 PG 来对抗感染。从历史上看，在两个相似的 PG 壁上的这些多酶过程已证明难以阐明。在这里，通过利用多个荧光 D-氨基酸的定时脉冲的 PG 标记方法，我们阐明了捕食者和猎物壁在细菌的不同阶段所经历的动态变化：细菌入侵。我们展示了在猎物壁上形成了一个加强的圆形端口孔，L,D-转肽酶_Bd介导的 D-氨基酸修饰在 Bdellovibrio 入侵期间增强了猎物 PG，以及捕食者伸长的带状模式。这个过程之后是细胞内 Bdellovibrio 的非常规、多点和同步分隔，通过非二元分裂适应奇数和偶数后代的形成。