ORIGINAL RESEARCH article
Front. Mar. Sci.
Sec. Microbial Symbioses
Volume 12 - 2025 | doi: 10.3389/fmars.2025.1587729
This article is part of the Research TopicMarine Ecology: Functional Symbioses in Marine HolobiontsView all articles
Life at Oxygen Minimum Zone: bacterial symbiosis in the gills of the bivalve Kelliella miliaris
Provisionally accepted
- 1University of Malaga, Málaga, Spain
- 2Oceanographic Center of Málaga, Spanish Institute of Oceanography (IEO), Málaga, Andalusia, Spain
- 3Muséum National d'Histoire Naturelle, Paris, France
- 4Instituto de Investigación Biomédica de Málaga y Plataforma en Nanomedicina-IBIMA Plataforma BIONAND, Malaga, Spain
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Kelliella miliaris (Philippi, 1844) is a minute bivalve, living on the surface of soft sediments, from the continental shelf to bathyal depths, commonly in the oxygen minimum zones (OMZ) and/or in reducing habitats. The scarcity of data on the biology of Kelliella prompted us to investigate, at ultrastructural level, specimens found in southern Spain. Kelliella miliaris shows several morphological characteristics that would be adaptive for living in the OMZ: (1) presence of numerous muscular fibres in the mantle, mantle edge and gills-visceral mass connection; all of which would allow to actively move the gills and/or enable a better control of the ventral opening in relation to vertical movements of the animal; (2) high number (in relation to body size) and large size of gill filaments, mainly in the large inner demibranch; and (3) long cilia which would provide a large surface for capture of oxygen and a highly effective uptake of oxygen from water.We have observed in all the specimens examined the presence of numerous rod shaped bacteria among the gill cilia. These bacteria show the typical double membrane of Gram-negative bacteria.The analysis of the bacterial DNA revealed that Gammaproteobacteria is the most abundant class, with 53.69% of total reads. The latter, together with the peak of oxygen and the presence of sulphur inside the electron dense granules from the bacteria, determined by TEM-EDX analysis, point to the
Keywords: Kelliella miliaris, Oxygen minimum layer, Chemosymbiosis, Gammaproteobacteria, internal fertilization, planctotrophic protoconch
Received: 04 Mar 2025; Accepted: 30 May 2025.
Copyright: © 2025 Utrilla, Mínguez, Gofas, Marina, Félix López and Salas. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Carmen Salas, University of Malaga, Málaga, Spain
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