Biology subjects

Yuda, L.

Publications and source records attributed to Yuda, L..

3 recordsLinked to original sources

bioRxiv2025

Algal Betaine Triggers Bacterial Hydrogen Peroxide Production that Promotes Algal Demise

Hydrogen peroxide (H2O2) plays various roles in the ocean, acting as a signaling molecule at low concentrations and causing oxidative stress when accumulated. While many marine microbes produce H2O2, its role in microbial interactions remains unclear. Here, we used transcriptomics, genetics, and metabolomics to study H2O2 dynamics in the interaction between Emiliania huxleyi algae and Phaeobacter inhibens bacteria. We found that H2O2 levels rise during algal death and that bacterial H2O2 production triggers this demise. Manipulating H2O2 levels shifted the outcome of the interaction. We also uncovered a link between H2O2 and betaine metabolism: aging algae release betaine, which promotes bacterial H2O2 production and, in turn, accelerates algal death. Genes involved in H2O2 and betaine metabolism were upregulated in environmental samples from an algal bloom. Together, our findings identify H2O2 and betaine as key molecules that modulate algal-bacterial interactions, potentially impacting microbial dynamics in marine ecosystems.

microbiology↗

bioRxiv2023

Algal Exudates Promote Conjugation in Marine Roseobacters

Horizontal gene transfer (HGT) is a pivotal mechanism driving bacterial evolution, conferring adaptability within dynamic marine ecosystems. Among HGT mechanisms, conjugation mediated by type IV secretion systems (T4SSs) plays a central role in the ecological success of marine bacteria. However, the conditions promoting conjugation events in the marine environment are not well understood. Roseobacters, abundant marine bacteria commonly associated with algae, possess a multitude of T4SSs. Many Roseobacters are heterotrophic bacteria that rely on algal secreted compounds to support their growth. These compounds attract bacteria, facilitating colonization and attachment to algal cells. Algae and their metabolites bring bacteria into close proximity, potentially promoting bacterial HGT. Investigation across various Roseobacters revealed that algal exudates indeed enhance plasmid transfer through conjugation. While algal exudates do not influence the transcription of bacterial conjugative machinery genes, they promote bacterial attachment, potentially stabilizing proximity and facilitating HGT. Notably, under conditions where attachment is less advantageous, the impact of algal exudates on conjugation is reduced. These findings suggest that algae enhance bacterial conjugation primarily by fostering attachment and highlight the importance of studying bacterial HGT within the context of algal-bacterial interactions.

microbiology↗

bioRxiv2023

Bacterial lag phase shortening is triggered by methyl groups

The bacterial lag phase is a key period for resuming growth. Despite its significance, the lag phase remains underexplored, particularly in environmental bacteria. Here, we explore the lag phase of the model marine bacterium Phaeobacter inhibens when it transitions from starvation to growth with a microalgal partner. Utilizing transcriptomics and 13C-labeled metabolomics, our study reveals that methylated compounds, which are abundantly produced by microalgae, shorten the bacterial lag phase. Our findings underscore the significance of methyl groups as a limiting factor during the lag phase and demonstrate that methyl groups can be harvested from algal compounds and assimilated through the methionine cycle. Furthermore, we show that methylated compounds, characteristic of photosynthetic organisms, induce variable reductions in lag times among bacteria associated with algae and plants. These findings highlight the adjustability of the bacterial lag phase and emphasize the importance of studying bacteria in an environmental context. One-Sentence SummaryBacteria use algal compounds as a metabolic shortcut to transition from starvation to growth.

microbiology↗