Table_3_Unique Features of Mycobacterium abscessus Biofilms Formed in Synthetic Cystic Fibrosis Medium.XLSX

Characterizing Mycobacterium abscessus complex (MABSC) biofilms under host-relevant conditions is essential to the design of informed therapeutic strategies targeted to this persistent, drug-tolerant, population of extracellular bacilli. Using synthetic cystic fibrosis medium (SCFM) which we previously reported to closely mimic the conditions encountered by MABSC in actual cystic fibrosis (CF) sputum and a new model of biofilm formation, we show that MABSC biofilms formed under these conditions are substantially different from previously reported biofilms grown in standard laboratory media in terms of their composition, gene expression profile and stress response. Extracellular DNA (eDNA), mannose-and glucose-containing glycans and phospholipids, rather than proteins and mycolic acids, were revealed as key extracellular matrix (ECM) constituents holding clusters of bacilli together. None of the environmental cues previously reported to impact biofilm development had any significant effect on SCFM-grown biofilms, most likely reflecting the fact that SCFM is a nutrient-rich environment in which MABSC finds a variety of ways of coping with stresses. Finally, molecular determinants were identified that may represent attractive new targets for the development of adjunct therapeutics targeting MABSC biofilms in persons with CF.在宿主相关条件下表征脓肿分枝杆菌复合群（Mycobacterium abscessus complex, MABSC）的生物被膜，对于制定针对这类持续存在、耐受药物的胞外杆菌群体的精准治疗策略至关重要。本研究采用此前已报道可精准模拟脓肿分枝杆菌复合群在实际囊性纤维化（CF）痰液中所处微环境的合成囊性纤维化培养基（SCFM），结合全新的生物被膜形成模型，发现该条件下形成的MABSC生物被膜，在组成、基因表达谱及应激反应方面，均与此前在标准实验室培养基中培养的生物被膜存在显著差异。研究证实，维系杆菌集群聚集的核心细胞外基质（extracellular matrix, ECM）组分为胞外DNA（extracellular DNA, eDNA）、含甘露糖与葡萄糖的聚糖及磷脂，而非蛋白质与分枝菌酸。此前报道的所有影响生物被膜发育的环境信号，对SCFM培养的生物被膜均无显著影响，这大概率反映出SCFM为营养丰富的环境，在此环境中MABSC可通过多种途径应对应激压力。最后，本研究鉴定出的分子决定因子，或可作为针对囊性纤维化患者体内MABSC生物被膜的辅助治疗药物开发的极具潜力的全新靶点。