Abstract:[Background] Bdellovibrio-and-like organisms (BALOs) can lyse pathogenic bacteria in aquaculture, so BALOs have enormous potential value in application. However, in practical applications, the inconsistency between BALOs’ growth conditions and the environment results in poor or even no effect. Therefore, it is critical to obtain BALOs with a broad range of adaptation. [Objective] The aim of this study was to screen out a euryhaline BALO for extensive application and increase its bdelloplast densities for better preservation. [Methods] A euryhaline BALO was isolate from a shallow bay with the host bacterium Bacillus subtilis. Molecular biological identification were carried out, and the biological characteristics as well as lysis properties of BDN-1 were studied. In addition, the factors affecting its bdelloplast densities such as monosodium glutamate, Ca2+ and Mg2+, indole were researched. [Results] A strain of euryhaline BALOs (named BDN-1) was isolated and identified. The optimal range of temperature, salinity and pH for BDN-1 were 20?30 °C, 0.5%?3.0%, 6.0?8.5. Lysis experiments on 30 tested strains showed that the lytic rate of BDN-1 was 86.7%, and for the 16 tested vibrios, the lytic rate was 87.5%. The monosodium glutamate, indole, Ca2+ and Mg2+ have effects on the bdelloplast densities of BDN-1. [Conclusion] This study provided a strain of BALOs with strong lysis ability which can be applied to sea and fresh water. Besides, the biological characteristics and factors of bdelloplast densities were identified, which laid the foundation for the efficient application of BALOs.
