iScienceAug 30, 2026

Bacterial stress changes diatom daily rhythms and affects ecosystem roles

Circadian Biology Weekly Brief ↗PubMed ↗DOI ↗

Updated Aug 31, 2026

Abstract

A 16.3% reduction in rhythmic genes was observed in the diatom Phaeodactylum tricornutum with prolonged culture time alongside the bacterium Aliivibrio fischeri.

Time-dependent physiological and transcriptomic changes were noted in P. tricornutum when co-cultured with A. fischeri.
Genome-scale metabolic modeling indicated a biphasic response, with biomass flux predicted to increase by 81% initially but decrease by 87% during extended co-culture.
AI-driven analysis of the transcriptome identified gene modules linked to silica transport and senescence under co-culture conditions.
Findings suggest that interactions between diatoms and bacteria may influence phytoplankton's biological rhythms and overall functioning.

Simplified

Diatoms are vital primary producers in marine ecosystems and play a key role in blue carbon sequestration. Although their circadian rhythms have been studied in isolation, how these rhythms are modulated by co-occurring bacteria remains unknown. Using a defined co-culture of the diatom Phaeodactylum tricornutum with the marine bacterium Aliivibrio fischeri, we observed time-dependent physiological and transcriptomic changes in P. tricornutum, including a 16.3% reduction in rhythmic genes with prolonged culture time. Genome-scale metabolic modeling suggested a biphasic response, with predicted biomass flux increasing by 81% at the early co-culture stage but decreasing by 87% during prolonged co-culture. Deconvolution of the transcriptome via AI-driven independent component analysis identified gene modules associated with silica transport and senescence-related responses under co-culture conditions. Together, these findings establish a systems-level framework that links interspecies interactions between diatoms and bacteria, providing mechanistic insights into how microbial associations influence phytoplankton chronobiology and rhythmic regulation.

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Bacterial stress changes diatom daily rhythms and affects ecosystem roles

Abstract

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