<![CDATA[This research aimed to know the toxicity of extracellular products (ECP) of Streptococcus agalactiae was tastedin cultured Nile tilapia (Oreochromis niloticus). Streptococcus agalactiae had two haemolytic types: β-haemolyticand non-haemolytic type. Toxicity test of ECP to know the virulancy factor of S. agalactiae was still limited. It wasfound that after tested on 15 fish weighing 15 g through intraperitoneal injection 0,1 ml/fish, both bacteria causedchanges in swimming pattern, palatability, external and internal anatomy macroscopically and microscopically.Extracellular products of S. agalactiae non-haemolytic type (BHIA and BHI 24 h) and β-haemolytic type (BHI 72 h)caused mortality 12 hours after injection and the mortality continued till day 7 th of culture. Whirling happened 96hours after injection with ECP S. agalactiae β-haemolytic type (BHIA 72 h incubation) whereas injection with ECP(BHI 24 h) on 72 h after injection and continued untill day 7 th. Behavior disease signs caused by S. agalactiaeoccured on eyes. There were opacity, purulens, eye shrink, lateral and bilateral exopthalmia and haemorrhage oninfected-fish. Silver staining of sodium dodecyl sulphate-polyacrylamide gels to S. agalactiae revealed thatpredominant 51.8-69.6 kDa bands were present in BHIA ECP fraction. The 69.6 kDa was absent from the BHI ECP.Total protein on non-haemolytic S. agalactiae ECP are 28.18 ppm on BHIA medium and 13.64 ppm on BHI medium.Whereas β-haemolytic S. agalactiae ECP are 2.73 ppm on BHIA medium and 8.18 ppm on BHI medium. Concentrationof protein in ECP was one of factor that caused non-haemolytic S. agalactiae more virulent than β-haemolytic type.The conclusion from the research that ECP was virulent factor on β-haemolytic and non-haemolytic S. agalactiaein fish which caused changes in behavior disease signs.]]>
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