Institute for Coastal Marine Environment, CNR, Spianata S.Raineri 86, 98122 Messina, Italy.
Environ Microbiol. 2013 Jun;15(6):1717-33. doi: 10.1111/1462-2920.12060. Epub 2012 Dec 18.
We used a combination of molecular and microbiological approaches to determine the activity, abundance and diversity of archaeal populations inhabiting meromictic saline Lake Faro (Messina, Italy). Analysis of archaeal 16S rRNA, amoA, accA and hbd genes and transcripts revealed that sub- and anoxic layers of Lake Faro are primarily inhabited by the organisms related to the clusters of Marine Group I.1a of Thaumarchaeota frequently recovered from oxygen-depleted marine ecosystems. These organisms dominated the metabolically active archaea down to the bottom of the lake, indicating their adaptation to recurrent changes in the levels of water column hypoxia. The upper microaerobic layer of Lake Faro redoxcline has the maximal rates of dark primary production much lower than those of other previously studied pelagic redoxclines, but comparable to the values of meso- and bathypelagic areas of Mediterranean Sea. Application of bacterial inhibitors, especially azide, significantly declined the CO2 fixation rates in the low interface and monimolimnion, whereas archaea-specific inhibitor had effect only in upper part of the redoxcline. Based on these findings, we hypothesize that dark bicarbonate fixation in suboxic zone of Lake Faro results mainly from archaeal activity which is affected by the predicted lack in oxygen in lower layers.
我们采用分子生物学和微生物学方法相结合，以确定栖息在半深盐水湖法罗湖（意大利墨西拿）中的古菌种群的活性、丰度和多样性。对古菌 16S rRNA、amoA、accA 和 hbd 基因和转录本的分析表明，法罗湖的亚缺氧层和缺氧层主要由与海洋群 I.1a 经常从缺氧海洋生态系统中回收的 Thaumarchaeota 相关的生物群组成。这些生物在湖底占据了代谢活跃的古菌优势地位，表明它们适应了水柱缺氧水平的反复变化。法罗湖氧化还原梯度的上层微需氧层的暗初级生产力比其他先前研究的水层氧化还原梯度的最大速率要低得多，但与地中海中中层和深海区的数值相当。细菌抑制剂的应用，特别是叠氮化钠，显著降低了低界面和 monimolimnion 的 CO2 固定率，而古菌特异性抑制剂仅在氧化还原梯度的上部有作用。基于这些发现，我们假设法罗湖缺氧区的暗碳酸氢盐固定主要来自古菌活动，而古菌活动受下层缺氧预测的影响。
