Natural and induced bactericidal activities in the hemolymph of the lobster, Homarus americanus: products of hemocyte-plasma interaction

The salient features of this study of the enhancement of bactericidal activity in the hemolymph of the American lobster were as follows: (a) increase in response to a number of non-pathogens isolated from the lobster's intestinal tract (several pseudomonads, an Achromobacter and Sarcina lutea), (b) one isolate identified as Pseudomonas perolens was used for the bulk of the studies, (c) apparent bactericidal activity of the hemolymph increased severalfold with reduction of the pH of the assay system from the physiological value of 7.6 to a value of 6.0, (d) the extent of the enhancement in vivo was roughly proportional to the concentration of the vaccine, (e) the bactericidal activity's enhancement in vivo was temperature dependent, (f) heat-stability trials indicated the probable presence of more than one bactericidin, (g) the bactericidal principle(s) exists in vivo in an inactive form until activated by material contained within the hemocytes, (h) no protection against Gaffkya homari was conferred on the lobster by prior treatment with vaccines prepared from P. perolens, G. homari, or S. lutea.