Galès Grégoire, Libert Marie-Françoise, Sellier Régine, Cournac Laurent, Chapon Virginie, Heulin Thierry
DTN/SMTM/LMTE, CEA Cadarache, F-13108 Saint-Paul-lez-Durance, France.
FEMS Microbiol Lett. 2004 Nov 15;240(2):155-62. doi: 10.1016/j.femsle.2004.09.025.
Although being deionized, filtered and therefore normally deeply oligotrophic, the water from a basin containing irradiating waste presented relatively high bacterial concentrations (ca 10(5) cfu ml(-1)) and biofilm development at its surface and on the walls. This water was characterized by a high concentration of molecular H2 due to water radiolysis, while its electrochemical potential was around +400 mV due the presence of dissolved O2 and active oxygen compounds. This combination of H2 availability and of an oxidant environment is completely original and not described in nature. From surface and wall biofilms, we enumerated the autotrophic populations ( approximately 10(5) bacteria ml(-1)) able to grow in presence of H2 as energy source and CO2 as carbon source, and we isolated the most abundant ones among cultivable bacteria. They efficiently grew on a mineral medium, in the presence of H2, O2 and CO2, the presence of the three gases being indispensable. Two strains were selected and identified using their rrs gene sequence as Ralstonia sp. GGLH002 and Burkholderia sp. GGLH005. In pure culture and using isotope exchange between hydrogen and deuterium, we demonstrated that these strains are able to oxidize hydrogen as energy source, using oxygen as an electron acceptor, and to use carbon dioxide as carbon source. These chemoautotroph hydrogen-oxidizing bacteria probably represent the pioneer bacterial populations in this basin and could be primary producers in the bacterial community.
尽管经过去离子、过滤处理，因此通常处于深度贫营养状态，但来自含有放射性废物的水池中的水呈现出相对较高的细菌浓度（约10⁵ cfu ml⁻¹），并且在其表面和池壁上有生物膜形成。由于水的辐射分解，这种水的特点是分子态H₂浓度很高，而由于溶解的O₂和活性氧化合物的存在，其电化学电位约为 +400 mV。H₂可利用性与氧化环境的这种组合是完全独特的，在自然界中未曾有过描述。我们从表面和池壁生物膜中，列举了能够以H₂作为能源、CO₂作为碳源生长的自养菌群（约10⁵ 个细菌 ml⁻¹），并从可培养细菌中分离出了最丰富的菌群。它们在含有H₂、O₂和CO₂的矿物培养基上能高效生长，这三种气体的存在不可或缺。通过其rrs基因序列，选择并鉴定出两株菌株，分别为罗尔斯通氏菌属GGLH002和伯克霍尔德氏菌属GGLH005。在纯培养中，并利用氢与氘之间的同位素交换，我们证明这些菌株能够以氧作为电子受体氧化氢作为能源，并利用二氧化碳作为碳源。这些化能自养型氢氧化细菌可能是该水池中的先锋细菌种群，并且可能是细菌群落中的初级生产者。
