Comparative studies on the in vitro response of bacteria to invertebrate body fluids: II. Aplysia california (sea hare) and Ciona intestinalis (tunicate)

Abstract

Five species of gram-negative, obligately marine bacteria, one facultatively marine gram-positive micrococcus, and a strain of the gram-negative terrestrial Serratia marcescens were used in the tests. They were incubated in vitro in cell-free and whole coelomic fluid of the sea hare Aplysia californica and the tunicate Ciona intestinalis. Both fluids of Aplysia showed little or no effect on the bacteria. Both fluids of Ciona killed two of the obligately marine species and depressed numbers of two of the remaining three, but did not affect either the gram-positive micrococcus or the gram-negative terrestrial rod. There is a discussion of the possibility that the antibacterial substances in the coelomic fluids of marine invertebrates would be more likely to affect the common gram-negative, obligately marine bacteria than the rarely encountered gram-positive and terrestrial gram-negative forms.