College of Food Science, Southwest University, 2 Tiansheng Rd, Beibei, Chongqing 400715, China; Chongqing Key Laboratory of Speciality Food Co-Built by Sichuan and Chongqing, 400715, China.
Division of Animal and Nutritional Sciences, West Virginia University, Morgantown, WV 26506, USA.
J Food Prot. 2023 Mar;86(3):100050. doi: 10.1016/j.jfp.2023.100050. Epub 2023 Jan 24.
The combination of levulinic acid (LVA) and sodium dodecyl sulfate (SDS) in recent years has shown a considerable potential to use as an antimicrobial intervention. The objectives of this study were to evaluate the antimicrobial efficacy of the combination against Staphylococcus aureus in both planktonic and biofilm states and to investigate the transcriptional changes in S. aureus biofilms coincubated with sublethal concentrations of LVA and/or SDS. The minimum inhibitory concentrations (MICs) of LVA and SDS determined by the microdilution method were 3.125 and 0.039 mg/mL, respectively. An additive bacteriostatic interaction (fractional inhibitory concentration index = 1) between the two compounds was observed by the checkerboard assay, whereas a synergistic bactericidal activity was displayed by the time-kill assay. The biomass and viable cells in the biofilms were reduced by both antimicrobials either alone or in combination in a dose-dependent manner. Transcriptomics indicated that more differentially expressed (DE) genes were observed in the biofilm treated with SDS (103 up- and 205 downregulated DE genes) and LVA + SDS (187 up and 162 down) than that coincubated with LVA (34 up and 32 down). The SDS and LVA + SDS treatments mainly affected the expression of genes responsible for cell surface proteins, virulence factors, adhesins, and capsular polysaccharides. Both the antibiofilm assay and the transcriptomics indicated that SDS, not LVA, was the major chemical contributing to the antibacterial efficacy of the combination. This study reveals the behavioral responses and protective mechanisms of S. aureus to LVA and SDS applied individually or in combination.
近年来，乙酰丙酸（LVA）和十二烷基硫酸钠（SDS）的组合已显示出相当大的潜力，可作为一种抗菌干预手段。本研究的目的是评估该组合对浮游和生物膜状态下金黄色葡萄球菌的抗菌功效，并研究与亚致死浓度的 LVA 和/或 SDS 共孵育的金黄色葡萄球菌生物膜中的转录变化。通过微量稀释法确定 LVA 和 SDS 的最小抑菌浓度（MIC）分别为 3.125 和 0.039 mg/mL。棋盘试验观察到两种化合物之间存在相加的抑菌相互作用（部分抑菌浓度指数 = 1），而时间杀伤试验显示出协同杀菌活性。无论是单独使用还是联合使用，这两种抗菌剂都以剂量依赖性方式减少生物膜中的生物量和活细胞。转录组学表明，用 SDS（103 个上调和 205 个下调的差异表达基因）和 LVA+SDS（187 个上调和 162 个下调）处理的生物膜中观察到更多差异表达（DE）基因，而与 LVA 共孵育的生物膜中观察到 34 个上调和 32 个下调的 DE 基因。SDS 和 LVA+SDS 处理主要影响负责细胞表面蛋白、毒力因子、黏附素和荚膜多糖的基因表达。抗生物膜试验和转录组学均表明，SDS 而非 LVA 是该组合抗菌功效的主要化学物质。本研究揭示了金黄色葡萄球菌对单独或联合应用 LVA 和 SDS 的行为反应和保护机制。
