PATHOLOGICAL ACTIVITIES OF YERSINIA-RUCKERI, THE ENTERIC REDMOUTH (ERM) BACTERIUM

The adherence and invasive capacities as well as the pathobiological a ctivities exhibited by Yersinia ruckeri were examined. Although adhesi ve ability was dependent on the cell-line employed, all the strains sh owed moderate adhesion and invasiveness in the salmon cell-line CHSE-2 14. With regard to the extracellular products (ECP) all of them were s trongly toxic for fish with LD50 ranging from 2 to 9.12 mug protein pe r g fish. In addition, all the ECP samples showed caseinase, gelatinas e, amylase, lipase and phospholipase activities, hydrolysed esculin an d displayed hemolytic activities for trout, salmon, sheep and human er ythrocytes. Heat treatment (100-degrees-C for 10 min) caused the loss of all these biological activities except the hydrolysis of gelatin. O n the other hand, SDS-PAGE analysis of the LPS and protein components of the ECP revealed variations among strains depending on the serotype . The lack of lethal effects of the LPS present in the ECP was also de monstrated.