The aceE involves in mycolic acid synthesis and biofilm formation in Mycobacterium smegmatis

BMC Microbiology

article

Chen, Suting¹  Teng, Tianlu¹  Wen, Shuan¹  Zhang, Tingting¹  Huang, Hairong¹ 

[1] National Clinical Laboratory on Tuberculosis, Beijing Key laboratory for Drug Resistant Tuberculosis Research, Beijing Chest Hospital, Capital Medical University, Beijing Tuberculosis and Thoracic Tumor Institute

关键词: Mycobacterium smegmatis;    aceE;    Biofilm;    Mycolic acid;    Cell wall;   

DOI  :  10.1186/s12866-020-01940-2

学科分类：放射科、核医学、医学影像

来源: BioMed Central

【 摘 要 】

The integrity of cell wall structure is highly significant for the in vivo survival of mycobacteria. We hypothesized that changes in morphology may indicate changes in cell wall metabolism and identified an aceE gene mutant (aceE-mut) which presented a deficient colony morphology on 7H10 agar by screening transposon mutagenesis in Mycolicibacterium smegmatis, basonym Mycobacterium smegmatis (M. smegmatis). This study aimed to identify the functional role of aceE gene in cell wall biosynthesis in M. smegmatis. We observed that the colony morphology of aceE-mut was quite different, smaller and smoother on the solid culture medium than the wild-type (WT) strain during the transposon library screening of M. smegmatis. Notably, in contrast with the WT, which aggregates and forms biofilm, the aceE-mut lost its ability of growing aggregately and biofilm formation, which are two very important features of mycobacteria. The morphological changes in the aceE-mut strain were further confirmed by electron microscopy which indicated smoother and thinner cell envelope images in contrast with the rough morphology of WT strains. Additionally, the aceE-mut was more fragile to acidic stress and exhibited a pronounced defects in entering the macrophages as compared to the WT. The analysis of mycolic acid (MA) using LC-MS indicated deficiency of alpha-MA and epoxy-MA in aceE-mut strain whereas complementation of the aceE-mut with a wild-type aceE gene restored the composition of MA. Over all, this study indicates that aceE gene plays a significant role in the mycolic acid synthesis and affects the colony morphology, biofilm formation of M. smegmatis and bacteria invasion of macrophage.

【 授权许可】

CC BY|CC0