Sulphur-oxidising bacteria and haemoglobin in gills of the bivalve mollusc Myrtea spinifera
Dando, P.R. and Southward, A.J. and Southward, E.C. and Terwilliger, N.B. and Terwilliger, R.C. (1985) Sulphur-oxidising bacteria and haemoglobin in gills of the bivalve mollusc Myrtea spinifera. Marine Ecology Progress Series, 23. pp. 85-98. ISSN 0171-8630
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Official URL: http://www.int-res.com/abstracts/meps/v23/
ABSTRACT: The gills of Myrtea spinifera carry large numbers of Gram-negative bacteria within the epithelia1 cells of the subfilamentar region and contain elemental sulphur. Haemoglobin which has a high affinity for oxygen is present in the gill tissue. Homogenates of gill tissue fix carbon dioxide vJa ribulosebisphosphate carboxylase and contain 3 enzymes concerned in the oxidation of sulphur, adenylylsulphate reductase, sulphate adenylyltransferase and sulphate adenylyltransferase (ADP). Fixation of carbon dioxlde by whole gills is enhanced by free sulphide. Whole gills accumulate labelled sulphur when supplied with Na235S, and a major proportion of the labelled sulphur is metabolized to non-volatile compounds or is bound to the tissues. The bacteria are evidently chemoautotrophs and presumably obtain energy for fixation of carbon dioxide by oxidation of reduced sulphur compounds. The haemoglobin is not apparently involved in transport of sulphide but may control oxygen tension close to the bacteria. The sediment in which the bivalves live is low in sulphide compared with some coastal muds and the hydrothermal vents. The interstitial water contains less than 1 pM of dissolved sulphide and the sediment releases less than 700 pmoles dm-3 of dissolved sulphide when treated with dilute acid. Habitats with similar low concentrations of dissolved sulphide are widespread in nature. An ability to exploit such low levels of reduced sulphur must be nlutually advantageous to host and bacteria, though as yet we have no direct evidence for transfer of organic matter from bacteria to host. To obtain sufficient energy for growth and maintenance of the association,the bacteria must have access to the sediment-bound sulphide.
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