Water & Steam Chemistry Division, BARC Facilities, Kalpakkam; Homi Bhabha National Institute, Mumbai, India.
Indian J Med Res. 2017 Jul;146(Supplement):S1-S8. doi: 10.4103/ijmr.IJMR_410_15.
BACKGROUND & OBJECTIVES: Among cell surface proteins, biofilm-associated protein (Bap) promotes biofilm development in Staphylococcus aureus strains. The aim of this study was to investigate proteinase-mediated biofilm dispersion in different isolates of S. aureus.
Biofilm assay was done in 96-well microtitre plate to evaluate the effect of proteinase K on biofilms of bovine mastitis S. Aureus isolates. Extracellular polymeric substances were extracted and evaluated for their composition (protein, polysaccharides and extracellular DNA), before and after the proteinase K treatment.
Biofilm assay showed that 2 μg/ml proteinase K significantly inhibited biofilm development in bap-positive S. aureus V329 as well as other S. aureus isolates (SA7, SA10, SA33, SA352), but not in bap-mutant M556 and SA392 (a weak biofilm-producing strain). Proteinase K treatment on S. aureus planktonic cells showed that there was no inhibition of planktonic growth up to 32 μg/ml of proteinase K. Proteinase K treatment on 24 h old preformed biofilms showed an enhanced dispersion of bap-positive V329 and SA7, SA10, SA33 and SA352 biofilms; however, proteinase K did not affect the bap-mutant S. aureus M556 and SA392 biofilms. Biofilm compositions study before and after proteinase K treatment indicated that Bap might also be involved in eDNA retention in the biofilm matrix that aids in biofilm stability. When proteinase K was used in combination with antibiotics, a synergistic effect in antibiotic efficacy was observed against all biofilm-forming S. aureus isolates.
INTERPRETATION & CONCLUSIONS: Proteinase K inhibited biofilms growth in S. aureus bovine mastitis isolates but did not affect their planktonic growth. An enhanced dispersion of preformed S. aureus biofilms was observed on proteinase K treatment. Proteinase K treatment with antibiotics showed a synergistic effect against S. aureus biofilms. The study suggests that dispersing S. aureus by protease can be of use while devising strategies againstS. aureus biofilms.
在细胞表面蛋白中，生物膜相关蛋白（Bap）促进了金黄色葡萄球菌菌株的生物膜发育。本研究旨在探讨不同金黄色葡萄球菌分离株中蛋白酶介导的生物膜分散作用。
通过 96 孔微量滴定板进行生物膜测定，以评估蛋白酶 K 对牛乳腺炎金黄色葡萄球菌分离株生物膜的影响。在蛋白酶 K 处理前后，提取细胞外聚合物质并评估其组成（蛋白质、多糖和细胞外 DNA）。
生物膜测定显示，2 μg/ml 蛋白酶 K 可显著抑制 bap 阳性金黄色葡萄球菌 V329 以及其他金黄色葡萄球菌分离株（SA7、SA10、SA33、SA352）的生物膜发育，但不能抑制 bap 突变体 M556 和 SA392（弱生物膜产生株）的生物膜发育。蛋白酶 K 对浮游细胞的处理表明，直到 32 μg/ml 的蛋白酶 K 处理，浮游生长均未受到抑制。蛋白酶 K 对 24 小时形成的生物膜的处理显示，bap 阳性 V329 和 SA7、SA10、SA33 和 SA352 生物膜的分散性增强；然而，蛋白酶 K 对 bap 突变体金黄色葡萄球菌 M556 和 SA392 生物膜没有影响。蛋白酶 K 处理前后的生物膜组成研究表明，Bap 可能也参与了细胞外 DNA 在生物膜基质中的保留，从而有助于生物膜的稳定性。当蛋白酶 K 与抗生素联合使用时，观察到所有形成生物膜的金黄色葡萄球菌分离株对抗生素疗效均具有协同作用。
蛋白酶 K 抑制了牛乳腺炎金黄色葡萄球菌分离株的生物膜生长，但不影响其浮游生长。在蛋白酶 K 处理时观察到预先形成的金黄色葡萄球菌生物膜的分散增强。蛋白酶 K 与抗生素联合使用对金黄色葡萄球菌生物膜显示出协同作用。该研究表明，在制定针对金黄色葡萄球菌生物膜的策略时，通过蛋白酶分散金黄色葡萄球菌可能会有所帮助。
