Department of Microbiology and Microbial Engineering, School of Life Sciences, Fudan University, Shanghai 200433, PR China.
Institute of Advanced Materials, Nanjing University of Posts and Telecommunications, Nanjing, Jiangsu, 210046, PR China.
J Med Microbiol. 2011 Nov;60(Pt 11):1643-1650. doi: 10.1099/jmm.0.029058-0. Epub 2011 Jul 21.
Candida is an important opportunistic human fungal pathogen. Infections caused by Candida albicans are related to the formation of a biofilm. The biofilm enhances the resistance of the C. albicans defence system, increases its resistance to antifungal drugs and induces increased drug tolerance, making clinical care more challenging. The in vitro activity of cis-2-dodecenoic acid (BDSF; a diffusible signal factor from Burkholderia cenocepacia) and trans-2-dodecenoic acid (trans-BDSF) against C. albicans growth, germ-tube germination and biofilm formation was estimated by absorbance measurements and microscopic assessments. C. albicans biofilms were prepared using a static microtitre plate model. Quantitative analysis of biofilm formation was performed using a 2,3-bis(2-methoxy-4-nitro-5-sulfo-phenyl)-2H-tetrazolium-5-carboxanilide reduction assay to evaluate the effect of different concentrations of BDSF and trans-BDSF at different stages of biofilm formation. Reductions in biofilm structure and formation were visualized by inverted microscopy. Real-time RT-PCR was employed to estimate the mRNA expression levels of the hyphae-specific genes HWP1 and ALS3. It was found that 30 µM of either BDSF or trans-BDSF reduced germ-tube formation by approximately 70 % without inhibiting yeast growth. Yeast growth was strongly repressed by the exogenous addition of 300 µM BDSF and trans-BDSF at 0 and 1 h after cell attachment, with biofilm formation being reduced by approximately 90 and 60 %, respectively. BDSF and trans-BDSF were more effective against biofilm formation than farnesol and the diffusible signal factor cis-11-methyl-2-dodecenoic acid. None of the four drugs was able to destroy pre-formed biofilms. Real-time RT-PCR analysis showed that HWP1 was downregulated by approximately 90 % and ALS3 was downregulated by 70-80 % by 60 µM BDSF and trans-BDSF, implying that BDSF and trans-BDSF block C. albicans biofilm formation by interfering with the morphological switch. These results suggest that BDSF and trans-BDSF are potentially useful therapeutic agents worthy of further study.
白色念珠菌是一种重要的机会性人类真菌病原体。由白色念珠菌引起的感染与生物膜的形成有关。生物膜增强了白色念珠菌防御系统的耐药性，增加了其对抗真菌药物的耐药性，并诱导了药物耐受性的增加，这使得临床护理更加具有挑战性。通过吸光度测量和显微镜评估，估计 cis-2-十二烯酸（BDSF；来自伯克霍尔德氏菌 cenocepacia 的可扩散信号因子）和 trans-2-十二烯酸（trans-BDSF）对白色念珠菌生长、芽管发芽和生物膜形成的体外活性。使用静态微量滴定板模型制备白色念珠菌生物膜。使用 2,3-双（2-甲氧基-4-硝基-5-磺基-苯基）-2H-四唑-5-羧基苯胺还原测定法对生物膜形成进行定量分析，以评估不同浓度的 BDSF 和 trans-BDSF 在生物膜形成的不同阶段的作用。通过倒置显微镜观察生物膜结构和形成的减少。实时 RT-PCR 用于估计菌丝特异性基因 HWP1 和 ALS3 的 mRNA 表达水平。结果发现，30 µM 的 BDSF 或 trans-BDSF 可将芽管形成减少约 70%，而不抑制酵母生长。在细胞附着后 0 和 1 小时，外源添加 300 µM 的 BDSF 和 trans-BDSF 强烈抑制酵母生长，生物膜形成分别减少约 90%和 60%。BDSF 和 trans-BDSF 比法尼醇和可扩散信号因子 cis-11-甲基-2-十二烯酸更有效地抑制生物膜形成。这四种药物都无法破坏已形成的生物膜。实时 RT-PCR 分析表明，60 µM 的 BDSF 和 trans-BDSF 将 HWP1 下调约 90%，将 ALS3 下调约 70-80%，这意味着 BDSF 和 trans-BDSF 通过干扰形态转换来阻止白色念珠菌生物膜的形成。这些结果表明，BDSF 和 trans-BDSF 可能是有前途的治疗药物，值得进一步研究。
