[Objective] To identify and develop a phage-derived lyase that can be heterologously expressed with high activity and stability and determine its optimal working conditions. [Methods] We employed the turbidity reduction assay to evaluate the bacteriolytic activity and identify the optimal parameters. [Results] Genome annotation and protein prediction of the Vibrio alginolyticus phage phiV208 showed that ORF30 encoded a lyase, named lysV208. This enzyme demonstrated soluble expression in Escherichia coli BL21(DE3), reaching a purified concentration of 204 μg/mL after 16 h induction with 0.25 mmol/L IPTG. Its bacteriolytic activity (turbidity reduction rate) increased from 24.2% to 68.0% in the presence of 0.5 mmol/L EDTA. Enzymatic characterization revealed that lysV208 exhibited the maximum bacteriolytic activity (75.6%) at 45 ℃ while maintaining high activity (52.8%-71.9%) within the temperature range of 25-37 ℃, which is typical for bacterial disease outbreaks in aquatic and terrestrial animals. The enzyme showed the maximum activity at pH 7.0 and retained substantial bacteriolytic activity (44.0%-63.2%) under alkalescence conditions (pH 7.0-9.0), demonstrating adaptability to marine and freshwater aquaculture environments. Divalent metal ions including Zn2+, Mg2+, Mn2+, and Fe2+ at 0.1-1.0 mmol/L moderately enhanced the bacteriolytic activity of lysV208, whereas those at 10.0 mmol/L reduced the activity (P<0.01). In addition, lysV208 displayed broad-spectrum lytic effects, showing the bacteriolytic activity of 59.7% against V. alginolyticus V039, 68.9% against Vibrio vulnificus H1, 65.8% against Vibrio parahaemolyticus GH32, and 38.0% and 65.6% against Vibrio harveyi TY13 and G1, respectively. [Conclusion] The recombinant lyase lysV208 demonstrates robust and stable in vitro bacteriolytic activity and a broader spectrum than its source phage. These findings highlight its potential for the control of bacterial infections and the development of phage-lyase synergistic agents.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |