Abstract
The type VI secretion system (T6SS) has been considered as a crucial factor in bacterial competition and virulence. The hemolysin co-regulated protein (Hcp) is the hallmark of T6SS. The secretion of Hcp in Aeromonas hydrophila Chinese epidemic strain NJ-35 indicated a functional T6SS. In this study, three copies of the hcp gene were identified in the genome of strain NJ-35. We targeted these Hcp family proteins for generating deletion mutants. These mutants showed varying levels in Hcp production, the interaction with other bacteria or eukaryotic cells, and bacterial virulence. Hcp1 was necessary for T6SS assembly and played a predominant role in the bacterial competition; Hcp2 negatively functioned in the biofilm formation and bacterial adhesion and was more involved in the A. hydrophila virulence in zebrafish and survival against the predation of Tetrahymena, and Hcp3 positively influenced the biofilm formation and bacterial adhesion. These findings illustrate that the T6SS of A. hydrophila NJ-35 is active, and the three Hcp family proteins take part in different processes in environmental adaptation and virulence of this bacterium. This study will provide valuable insights into our understanding of microbial interactions and thus contribute to a broader effort to manipulate these interactions for therapeutic or environmental benefit.
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Funding
This work was supported by the National Natural Science Foundation of China (31372454), Independent Innovation Fund of Agricultural Science and Technology in Jiangsu Province (CX(17)2027), the Three New Aquatic Projects in Jiangsu Province (D2015-13), Qing Lan Project of Jiangsu Province, and Priority Academic Program Development of Jiangsu Higher Education Institutions.
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All animal experiments were performed according to animal welfare standards and were approved for the experimental protocols from the Ethical Committee for Animal Experiments of Nanjing Agricultural University, China.
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Wang, N., Liu, J., Pang, M. et al. Diverse roles of Hcp family proteins in the environmental fitness and pathogenicity of Aeromonas hydrophila Chinese epidemic strain NJ-35. Appl Microbiol Biotechnol 102, 7083–7095 (2018). https://doi.org/10.1007/s00253-018-9116-0
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DOI: https://doi.org/10.1007/s00253-018-9116-0