Pelagibacterales Bacteria Vulnerable to Ocean Change

A new study published in Nature Microbiology by scientists from the University of Southern California Dornsife, including lead author Chuankai Cheng and corresponding author Cameron Thrash, reveals that Pelagibacterales bacteria, the most abundant organisms in surface seawater, are more vulnerable to environmental changes than previously thought. Despite their evolutionary success through genome streamlining in stable, low-nutrient environments, Pelagibacterales cells lack crucial genes for cell cycle control. Under stress, their DNA replication and cell division become uncoupled, leading to abnormal cells with extra chromosomes that eventually die, slowing population growth. This finding challenges assumptions about microbial growth and explains why Pelagibacterales populations decline during phytoplankton blooms. The study has significant implications for understanding climate change and marine ecosystems, as Pelagibacterales plays a major role in ocean carbon cycling, and their sensitivity to warming and nutrient pulses could reshape microbial communities.