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.

蓝藻是普遍存在的生物体，对所有栖息地的初级生产都有相关贡献​​。蓝藻因其在世界范围内发生水华的过程中所起的作用而闻名，同时产生无数的天然化合物，其中一些具有潜在毒性，但另一些则具有很高的经济影响，如土臭素。我们对蓝藻土壤菌落进行了环境调查，以确定这些微生物使用的有趣的代谢途径和适应策略，并分离、测序和组装了蓝藻的基因组，该蓝藻表现出独特的土味/霉味，是土臭素的典型气味，经 GC-MS 证实培养物挥发性提取物的分析。形态学研究指出，通过系统发育分析证实了一种新的振荡土壤生态型，我们将其命名为Microcoleus asticus sp。十一月我们对细菌中土臭素基因存在的研究揭示了蓝藻、放线菌、Delta 和 Gammaproteobacteria 中的分散分布，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的古老细菌起源，可能在不同的时间范围内相继丢失。淡水和土壤菌株中蓝藻土臭素基因的高度序列相似性强化了土臭素进化史的观点，该进化史与生态位适应密切相关。