Biological interactions with Prochlorococcus: implications for the marine carbon cycle

• Published in: Trends in microbiology (Regular ed.) 2024-03, Vol.32 (3), p.280-291
• Main Authors: Cai, Lanlan, Li, Haofu, Deng, Junwei, Zhou, Ruiqian, Zeng, Qinglu
• Format: Article
• Language: English
• Subjects: Bacteria; biological interactions; Carbon; Carbon Cycle; Carbon Dioxide; carbon fixation; marine carbon cycle; photosynthesis; Prochlorococcus; Prochlorococcus - physiology; Seawater - microbiology
• ISSN: 0966-842X; 1878-4380
• DOI: 10.1016/j.tim.2023.08.011

Prochlorococcus is the smallest and most abundant photoautotroph on Earth, contributing significantly to global CO2 fixation. Under climate change, ocean warming and reduced nutrients are expected to benefit Prochlorococcus, increasing its distribution and global abundance.The presence of helper heterotrophic bacteria facilitates the growth and environmental adaptability of Prochlorococcus, which in turn provide organic carbon and nutrients to heterotrophic bacteria, forming mutualistic interactions that drive marine carbon cycling.The fate of Prochlorococcus is mainly controlled by two top-down drivers, including viral lysis and protist grazing. Viruses primarily recycle Prochlorococcus-fixed carbon within the microbial loop via the viral shunt, and predatory protists transfer Prochlorococcus biomass to higher trophic levels through the grazing food chain.Prochlorococcus phages inhibit carbon fixation of the infected host cells while maintaining the light reactions of photosynthesis and the pentose phosphate pathway to maximize energy and materials for nucleotide biosynthesis which is a bottleneck in phage replication. The unicellular picocyanobacterium Prochlorococcus is the most abundant photoautotroph and contributes substantially to global CO2 fixation. In the vast euphotic zones of the open ocean, Prochlorococcus converts CO2 into organic compounds and supports diverse organisms, forming an intricate network of interactions that regulate the magnitude of carbon cycling and storage in the ocean. An understanding of the biological interactions with Prochlorococcus is critical for accurately estimating the contributions of Prochlorococcus and interacting organisms to the marine carbon cycle. This review synthesizes the primary production contributed by Prochlorococcus in the global ocean. We outline recent progress on the interactions of Prochlorococcus with heterotrophic bacteria, phages, and grazers that multifacetedly determine Prochlorococcus carbon production and fate. We discuss that climate change might affect the biological interactions with Prochlorococcus and thus the marine carbon cycle. The unicellular picocyanobacterium Prochlorococcus is the most abundant photoautotroph and contributes substantially to global CO2 fixation. In the vast euphotic zones of the open ocean, Prochlorococcus converts CO2 into organic compounds and supports diverse organisms, forming an intricate network of interactions that regulate the magnitude of carbon cycling