AUTHOR=Lai Li-Yin , Lin Tzu-Lung , Chen Yi-Yin , Hsieh Pei-Fang , Wang Jin-Town 

TITLE=Role of the Mycobacterium marinum ESX-1 Secretion System in Sliding Motility and Biofilm Formation

JOURNAL=Frontiers in Microbiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.01160

DOI=10.3389/fmicb.2018.01160

ISSN=1664-302X

ABSTRACT=<p><italic>Mycobacterium marinum</italic> is a close relative of <italic>Mycobacterium tuberculosis</italic> that can cause systemic tuberculosis-like infections in ectotherms and skin infections in humans. Sliding motility correlates with biofilm formation and virulence in most bacteria. In this study, we used a sliding motility assay to screen 2,304 transposon mutants of <italic>M. marinum</italic> NTUH-M6885 and identified five transposon mutants with decreased sliding motility. Transposons that interrupted the type VII secretion system (T7SS) ESX-1-related genes, <italic>espE</italic> (<italic>mmar_5439</italic>), <italic>espF</italic> (<italic>mmar_5440</italic>), and <italic>eccA1</italic> (<italic>mmar_5443</italic>), were present in 3 mutants. We performed reverse-transcription polymerase chain reaction to verify genes from <italic>mmar_5438</italic> to <italic>mmar_5450</italic>, which were found to belong to a single transcriptional unit. Deletion mutants of <italic>espE</italic>, <italic>espF</italic>, <italic>espG</italic> (<italic>mmar_5441</italic>), and <italic>espH</italic> (<italic>mmar_5442</italic>) displayed significant attenuation regarding sliding motility and biofilm formation. <italic>M. marinum</italic> NTUH-M6885 possesses a functional ESX-1 secretion system. However, deletion of <italic>espG</italic> or <italic>espH</italic> resulted in slightly decreased secretion of EsxB (which is also known as CFP-10). Thus, the <italic>M. marinum</italic> ESX-1 secretion system mediates sliding motility and is crucial for biofilm formation. These data provide new insight into <italic>M. marinum</italic> biofilm formation.</p>