| Autor: |
Khalil, A.H., Mansour, E.H. |
| Zdroj: |
Letters in Applied Microbiology; September 1997, Vol. 25 Issue: 4 p269-273, 5p |
| Abstrakt: |
Extracellular products (ECP) secreted from Aeromonas hydrophilawith haemolytic andproteolytic activity were studied with respect to temperature and time of incubation as well as thelethal toxicity on tilapia, Tilapia nilotica. The highest production of the haemolysin productwas achieved when Aer. hydrophilawas grown at 35°C for 30 h. Tilapia erythrocytewas found to be more susceptible than sheep erythrocyte for determining the haemolytic activity.The haemolytic activity against tilapia erythrocyte was completely inactivated after heating theECP at 60°C for 10 min or 55°C for 15 min. The proteolytic activity was maximized whenthe bacterium was grown at 30°C for 36 h. Complete inactivation of the protease enzyme wasperformed after heating the ECP at 80°C for 10 min or 70°C for 15 min. Aeromonashydrophilawas found to produce haemolytic and proteolytic exotoxin lethal to tilapia (LD502·1 × 104cell/fish), as well as heat stable unknown virulent factors thatwere responsible for 20% mortality. The lethality of ECP was decreased by heating andcompletely inactivated by boiling at 100°C for 10 min. |
| Databáze: |
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