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Gut Microbes, 2024 Dec 11, 16 (1) | https://doi.org/10.1080/19490976.2024.2438465 Unexpected vulnerability of Enterococcus faecium to polymyxin B under anaerobic condition

Yongjun Son ^a,b*, Bitnara Kim ^a*, Pureun Kim ^a*, Jihyeon Min a, Yerim Park a, Jihye Yang a,Wonjae Kim a,b, Masanori Toyofuku c, and Woojun Park a

^aLaboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul, Republic of Korea;
^bInstitute of Life Science and Natural Resources, Korea University, Seoul, Republic of Korea;
^cDepartment of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Japan

^*These authors contributed equally to this work.
CONTACT: Woojun Park

Abstract

Gram-positive Enterococcus faecium exhibited higher susceptibility (>4-fold) to polymyxin B (PMB), the canonical antimicrobial peptide against Gram-negative bacteria, under anaerobic condition than aerobic condition. Anaerobically grown E. faecium exhibited high vulnerability to PMB, leading to alteration of cell surface and morphology, as observed based on their high dansyl-PMB affinity (>2.9-fold), a proportion (>8.5-fold) of propidium iodide-stained cells, and observation of scanning electron microscopy results. Interestingly, our transcriptomic and chemical analyses revealed that enterocin B, produced anaerobically, imposes a burden on the cellular envelope when cells are exposed to PMB. This scenario was also supported by PMB susceptibility tests and killing curves, which showed that ΔentB knockout mutant cells were more resistant to PMB (32 µg/mL) compared to wild-type cells (4 µg/mL) under anaerobic condition. Fluorescent D-amino acid and BOCILLIN™-fluorescent profiling of transpeptidase activities in ΔentB mutant cells under anaerobic condition revealed similar levels of activity to those observed in WT cells under aerobic condition. The high level of secreted bacteriocins in WT under anaerobic condition likely led to significant membrane depolarization and loosening of the peptidoglycan layer, making the cells more permeable to PMB. Overall, our findings suggest that anaerobically produced bacteriocins, in conjunction with PMB, contribute to the killing of E. faecium by destabilizing its cell envelope.

논문정보

형식Research article
게재일2024년 12월 (BRIC 등록일 2024-12-12)
연구진국내(교신)+국외 연구진
분야 생명과학 > 분류/생태/환경생물학

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