Differential Timing for Glucose Assimilation in Prochlorococcus and Coexistent Microbial Populations in the North Pacific Subtropical Gyre

María del Carmen Muñoz-Marín, Solange Duhamel, Karin M. Björkman, Jonathan D. Magasin, Jesús Díez, David M. Karl, José M. García-Fernández

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

The marine cyanobacterium Prochlorococcus can utilize glucose as a source of carbon. However, the relative importance of inorganic and organic carbon assimilation and the timing of glucose assimilation are still poorly understood in these numerically dominant cyanobacteria. Here, we investigated whole microbial community and groupspecific primary production and glucose assimilation using incubations with radioisotopes combined with flow cytometry cell sorting. We also studied changes in the microbial community structure in response to glucose enrichments and analyzed the transcription of Prochlorocccus genes involved in carbon metabolism and photosynthesis. Our results showed a diel variation for glucose assimilation in Prochlorococcus, with maximum assimilation at midday and minimum at midnight (;2-fold change), which was different from that of the total microbial community. This suggests that the timing in glucose assimilation in Prochlorococcus is coupled to photosynthetic light reactions producing energy, it being more convenient for Prochlorococcus to show maximum glucose uptake precisely when the rest of microbial populations have their minimum glucose uptake. Many transcriptional responses to glucose enrichment occurred after 12- and 24-h periods, but community composition did not change. High-light Prochlorococcus strains were the most impacted by glucose addition, with transcript-level increases observed for genes in pathways for glucose metabolism, such as the pentose phosphate pathway, the Entner- Doudoroff pathway, glycolysis, respiration, and glucose transport. While Prochlorococcus C assimilation from glucose represented less than 0.1% of the bacterium's photosynthetic C fixation, increased assimilation during the day and glcH gene upregulation upon glucose enrichment indicate an important role of mixotrophic C assimilation by natural populations of Prochlorococcus.

Original languageEnglish (US)
JournalMicrobiology Spectrum
Volume10
Issue number5
DOIs
StatePublished - Sep 2022
Externally publishedYes

Keywords

  • Prochlorococcus
  • assimilation
  • cyanobacteria
  • diel cycles
  • glucose assimilation
  • glucose transport
  • picocyanobacteria

ASJC Scopus subject areas

  • Physiology
  • Ecology
  • Immunology and Microbiology(all)
  • Genetics
  • Microbiology (medical)
  • Cell Biology
  • Infectious Diseases

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