Cyanobacteria are common in symbiotic relationships with diverse multicellular organisms (animals, plants, fungi) in terrestrial environments and with single-celled heterotrophic, mixotrophic, and autotrophic protists in aquatic environments. In the sunlit zones of aquatic environments, diverse cyanobacterial symbioses exist with autotrophic taxa in phytoplankton, including dinoflagellates, diatoms, and haptophytes (prymnesiophytes). Phototrophic unicellular cyanobacteria related to Synechococcus and Prochlorococcus are associated with a number of groups. N2-fixing cyanobacteria are symbiotic with diatoms and haptophytes. Extensive genome reduction is involved in the N2-fixing endosymbionts, most dramatically in the unicellular cyanobacteria associated with haptophytes, which have lost most of the photosynthetic apparatus, the ability to fix C, and the tricarboxylic acid cycle. The mechanisms involved in N2-fixing symbioses may involve more interactions beyond simple exchange of fixed C for N. N2-fixing cyanobacterial symbioses are widespread in the oceans, even more widely distributed than the best-known free-living N2-fixing cyanobacteria, suggesting they may be equally or more important in the global ocean biogeochemical cycle of N.Despite their ubiquitous nature and significance in biogeochemical cycles, cyanobacterium-phytoplankton symbioses remain understudied and poorly understood.

中文翻译：

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浮游植物-蓝藻单细胞共生协会的多样性，基因组学和分布。

蓝细菌与陆地环境中的多种多细胞生物（动物，植物，真菌）共生关系中常见，而在水生环境中与单细胞异养，混合营养性和自养性原生生物共生。在水生环境的阳光照射区，浮游植物中存在多种带有自养生物分类群的蓝细菌共生体，包括鞭毛藻，硅藻和触藻。与Synechococcus和Prochlorococcus相关的光养单细胞蓝细菌与许多组相关。固定N2的蓝细菌与硅藻和附生植物共生。固定N2的内共生菌涉及广泛的基因组还原，最显着的是与触附植物相关的单细胞蓝细菌，这些细菌失去了大多数光合作用，固定C的能力，和三羧酸循环。N2固定共生酶所涉及的机制可能涉及更多的相互作用，而不仅仅是固定碳简单地交换为N。N2固定氰生共生菌在海洋中分布广泛，甚至比最著名的自由活动的N2固定蓝藻分布更广。尽管它们在生物地球化学循环中无处不在的性质和重要性，但它们在北大西洋的全球海洋生物地球化学循环中可能同等或更重要。