Department of Plant Pathology, College of Plant Protection, China Agricultural University; Beijing Key Laboratory of Seed Disease Testing and Control, Beijing 100193, P.R. China.
Key Laboratory of Environmental and Applied Microbiology, CAS, Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, P.R. China.
Phytopathology. 2021 Aug;111(8):1301-1312. doi: 10.1094/PHYTO-08-20-0326-R. Epub 2021 Sep 11.
Previous research has shown that penicillin-binding proteins (PBPs), enzymes involved in peptidoglycan (PG) assembly, could play an important role during the induction of the viable but nonculturable (VBNC) state, which allows non-spore-forming bacteria to survive adverse environmental conditions. The current study found that has seven PBPs. Mutant analysis indicated that deletion of either of the class B PBPs was lethal and that the class A PBPs had an important role in PG synthesis, with the Δ mutant having an altered cellular morphology that resulted in longer cells that were swollen at one end and had thinner cell walls. The mutant was also found to produce mucoid colonies in solid culture and a lower final cell titer in liquid medium, as well as having high sensitivity to osmotic stress and lysozyme treatment and surprisingly high pathogenicity. The double mutant, , also had a slightly altered phenotype, resulting in longer cells. Further analysis revealed that both mutants had high sensitivity to copper, which resulted in quicker induction into the VBNC state. However, only the mutant had significantly reduced survivorship in the VBNC state. The study also confirmed that the VBNC state significantly improved the survivorship of wild-type cells in response to environmental stresses and systemically demonstrated the protective role of the VBNC state in , which is an important finding regarding its epidemiology and has serious implications for disease management.
先前的研究表明，参与肽聚糖（PG）组装的青霉素结合蛋白（PBP）在诱导活但非可培养（VBNC）状态中可能发挥重要作用，这种状态使非孢子形成细菌能够在不利的环境条件下存活。本研究发现 有七个 PBP。突变分析表明，缺失任何一种 B 类 PBP 都是致命的，而 A 类 PBP 在 PG 合成中具有重要作用，Δ 突变体具有改变的细胞形态，导致细胞变长，一端肿胀，细胞壁变薄。还发现 突变体在固体培养中产生粘液状菌落，在液体培养基中的最终细胞滴度较低，对渗透压应激和溶菌酶处理的敏感性较高，令人惊讶的是其致病性也较高。双突变体 ，也表现出轻微改变的表型，导致细胞变长。进一步分析表明，两种突变体对铜都高度敏感，这导致更快地诱导进入 VBNC 状态。然而，只有 突变体在 VBNC 状态下的存活率显著降低。该研究还证实，VBNC 状态显著提高了野生型 细胞在应对环境压力时的存活率，并系统地证明了 VBNC 状态在 中的保护作用，这是关于其流行病学的一个重要发现，对疾病管理具有严重影响。
