Bacterial flora from echinoderm guts and associated sediment in the abyssal Vema Fault

Individuals of the asteroid Solaster sp. and the holothurian Pseudostichopus villosus (Theel) were collected from deep-sea bottom of the Vema fault in the mid-Atlantic ridge during the BIOVEMA cruise (November, 1977) of the R.V. Jean Charcot. Heterotrophic aerobic bacteria of the guts were isolated, identified and compared with bacterial isolates from surface sediment of the same area. Bacterial population structures displayed a predominance of Gram-negative rods in the echinoderm guts and a predominance of Gram-positive bacteria (particularly cocci) in the surface sediment. Investigation of the metabolic potentialities of the isolates suggested that the microflora of echinoderms, and in particular of the Asteroidea, have more specialized orientations in the catabolism of organic compounds. Single-linkage cluster analysis of all the isolates (130 strains) based on 139 phenotypic features revealed that out of 15 identified clusters, only one included both enteric and sediment isolates. The bacteria in this cluster were similar to the genus Micrococcus.