Dual thermal ecotypes coexist within a nearly genetically identical population of the unicellular marine cyanobacterium Synechococcus
Dual thermal ecotypes coexist within a nearly genetically identical population of the unicellular marine cyanobacterium Synechococcus
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DOI：
10.1073/pnas.2315701120
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发表时间：
2023-11-21
影响因子：
11.1
通讯作者：
Hutchins，David A.
中科院分区：
文献类型：
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作者：
Kling，Joshua D.;Lee，Michael D.;Hutchins，David A.
海洋微生物种群内种内功能多样性的程度和生态意义仍然知之甚少，并且尚不清楚这种菌株水平的微多样性是否会影响快速变化的海洋环境中的适应性和持久性。在这项研究中，我们培养了从纳拉甘西特湾 (RI) 浮游植物群落热选择实验中分离出来的 11 种普遍存在的海洋微微蓝细菌聚球藻的同域菌株。热性能曲线显示，冷温和暖温下的选择已将初始群体细分为最大生长温度存在显着差异的热型。奇怪的是，所有 11 个分离株的基因组几乎相同（平均核苷酸同一性 >99.99%，基因组比对 >99%），并且基因内容或单核苷酸变异没有差异与低温或高温表型相关。尽管基因组相似性非常高，但两个菌株的表观基因组测序显示与光合作用相关的基因甲基化存在差异。这些与光生理学中测量到的差异相对应，表明未来热微多样性机制研究的潜在途径。我们的研究表明，当今的海洋微生物种群可以隐藏神秘但与环境相关的热型，这可能会增强它们对未来气温上升的适应能力。
The extent and ecological significance of intraspecific functional diversity within marine microbial populations is still poorly understood, and it remains unclear if such strain-level microdiversity will affect fitness and persistence in a rapidly changing ocean environment. In this study, we cultured 11 sympatric strains of the ubiquitous marine picocyanobacteriumSynechococcusisolated from a Narragansett Bay (RI) phytoplankton community thermal selection experiment. Thermal performance curves revealed selection at cool and warm temperatures had subdivided the initial population into thermotypes with pronounced differences in maximum growth temperatures. Curiously, the genomes of all 11 isolates were almost identical (average nucleotide identities of >99.99%, with >99% of the genome aligning) and no differences in gene content or single nucleotide variants were associated with either cool or warm temperature phenotypes. Despite a very high level of genomic similarity, sequenced epigenomes for two strains showed differences in methylation on genes associated with photosynthesis. These corresponded to measured differences in photophysiology, suggesting a potential pathway for future mechanistic research into thermal microdiversity. Our study demonstrates that present-day marine microbial populations can harbor cryptic but environmentally relevant thermotypes which may increase their resilience to future rising temperatures.