Laboratório de Fitoplâncton, Departamento do Mar e Recursos Marinhos, Instituto Português do Mar e da Atmosfera, Rua Alfredo Magalhães Ramalho, 6, 1449-006, Lisboa, Portugal.
Blue Biotechnology and Ecotoxicology (BBE), CIIMAR - Centro Interdisciplinar de Investigação Marinha e Ambiental, Universidade do Porto, 4450-208, Matosinhos, Portugal.
Sci Rep. 2020 May 26;10(1):8679. doi: 10.1038/s41598-020-64774-y.
Cyanobacteria are ubiquitous organisms with a relevant contribution to primary production in all range of habitats. Cyanobacteria are well known for their part in worldwide occurrence of aquatic blooms while producing a myriad of natural compounds, some with toxic potential, but others of high economical impact, as geosmin. We performed an environmental survey of cyanobacterial soil colonies to identify interesting metabolic pathways and adaptation strategies used by these microorganisms and isolated, sequenced and assembled the genome of a cyanobacterium that displayed a distinctive earthy/musty smell, typical of geosmin, confirmed by GC-MS analysis of the culture's volatile extract. Morphological studies pointed to a new Oscillatoriales soil ecotype confirmed by phylogenetic analysis, which we named Microcoleus asticus sp. nov. Our studies of geosmin gene presence in Bacteria, revealed a scattered distribution among Cyanobacteria, Actinobacteria, Delta and Gammaproteobacteria, covering different niches. Careful analysis of the bacterial geosmin gene and gene tree suggests an ancient bacterial origin of the gene, that was probably successively lost in different time frames. The high sequence similarities in the cyanobacterial geosmin gene amidst freshwater and soil strains, reinforce the idea of an evolutionary history of geosmin, that is intimately connected to niche adaptation.
蓝藻是一种普遍存在的生物，在各种生境中对初级生产都有重要贡献。蓝藻以在全球范围内产生水生水华而闻名，同时产生了许多具有潜在毒性的天然化合物，但也有一些具有很高的经济价值，如土臭素。我们对蓝藻土壤菌落进行了环境调查，以确定这些微生物所使用的有趣代谢途径和适应策略，并分离、测序和组装了一个显示出独特泥土/发霉气味的蓝藻基因组，这气味是通过对培养物挥发性提取物的 GC-MS 分析来证实的。形态学研究表明，通过系统发育分析，该蓝藻属于一个新的 Oscillatoriales 土壤生态型，我们将其命名为 Microcoleus asticus sp. nov. 我们对细菌中土臭素基因的研究表明，它在蓝藻、放线菌、Delta 和 Gamma 变形菌中呈分散分布，涵盖了不同的生态位。对细菌土臭素基因和基因树的仔细分析表明，该基因具有古老的细菌起源，可能在不同的时间框架内相继丢失。在淡水和土壤菌株中蓝藻土臭素基因的高度序列相似性，加强了土臭素进化历史的观点，这与生态位适应密切相关。
