Bacteria-host relationships in the bivalve mollusc Loripes lucinalis

Loripes lucinalis, a lucinid species found in reduced sediments, contains endosymbiotic bacteria within specialized gill cells which contribute to the bivalve's nutrition. An additional bivalve-bacteria association can be seen in the digestive gland where large inclusion bodies filled with rickettsia- or chlamydia-like organisms are observed in the duct and tubule cells. Despite indications of a possible energy parasitism on the part of these endocellular digestive gland bacteria, the digestive epithelium of the host is not significantly damaged by the infection suggesting that this is a generalized and normal bivalve-bacteria association in adults of this species.