Quorum Sensing Signaling Alters Virulence Potential and Population Dynamics in Complex Microbiome-Host Interactomes.

Marine environments host a vast array of microbial life, yet the role of quorum sensing (QS) in these systems remains poorly understood. While QS has been well-characterized in terrestrial and freshwater ecosystems, its prevalence and function in marine settings are still unclear. The marine sponge Stelletta normani and BD1268 provide a unique model for studying microbial interactions in complex host-microbiome systems. Prior research has shown that QS systems influence microbial communication and behavior. However, the diversity of QS systems in marine sponges and their impact on microbial dynamics has not been fully explored. This gap motivated the current investigation into QS activity within sponge-associated bacterial isolates. The study aimed to determine the abundance and nature of QS systems in these isolates. Understanding QS in marine sponges could reveal how these systems shape microbial population structures and host interactions. The findings may contribute to broader insights into microbial signaling in marine ecosystems.

This study aimed to investigate the presence and diversity of N-acyl homoserine lactone (AHL)-based quorum sensing (QS) systems in marine sponge-associated bacterial isolates. The researchers focused on the marine sponge Stelletta normani and BD1268 as model systems for microbial-host interactions. By identifying QS-active genera and isolates, the study sought to explore how QS systems might influence microbial population dynamics in these environments. The researchers also aimed to determine whether QS signaling affects microbial growth and biofilm formation in co-culture experiments. A key objective was to assess the impact of QS signaling on intermicrobial interactions within the sponge microbiome. The study further aimed to evaluate the limitations of current culture methods in capturing the full diversity of QS-active bacteria. By combining microbiome profiling and biosensor screening, the researchers hoped to uncover new insights into QS systems in marine sponges. The ultimate goal was to contribute to a better understanding of QS signaling in complex marine microbial ecosystems.

The researchers conducted microbiome profiling of Stelletta normani and BD1268 sponge samples to identify potential QS-active bacterial genera. They then used biosensor-based screening to test a library of 650 marine sponge bacterial isolates for QS activity. Ten isolates were selected for further validation using Ultra-High Performance Liquid Chromatography Mass Spectrometry. This method confirmed the presence of AHLs in eight of the ten isolates. The researchers performed co-culture experiments with QS-active isolates and S. normani sponge samples to observe microbial interactions. They tested the effect of AHL addition on the growth and biofilm formation of selected isolates. Supernatants from QS-active strains were also tested for their impact on biofilm formation in Bacillus sp. CH8a. Genome sequencing and phylogenetic analysis were conducted on a QS-positive Psychrobacter isolate to identify QS-associated systems. The study combined culture-based and molecular approaches to assess the diversity and function of QS systems in marine sponges.

Microbiome profiling revealed several potential QS-active genera in Stelletta normani and BD1268 sponge samples. Biosensor screening identified ten isolates that activated at least one of three AHL biosensor strains. Mass spectrometry confirmed AHLs in eight of these isolates. Co-culture experiments with QS-active isolates led to the isolation of Pseudomonas and Paenibacillus, which were previously low abundance in the sponge microbiome. However, adding AHLs to isolates from co-cultures did not affect their growth or biofilm formation. Supernatants from QS-active strains significantly impacted the biofilm formation of Bacillus sp. CH8a. Genome sequencing of a Psychrobacter isolate revealed multiple QS-associated systems but no classical QS synthase gene. The study found a stark contrast between the sponge microbiome's biodiversity and the limited diversity observed on culture media. These results suggest that QS systems may influence microbe-microbe interactions in marine sponges. The findings highlight the challenges in culturing QS-active bacteria from complex marine environments.

The study suggests that QS systems may play a role in shaping microbial interactions within marine sponge microbiomes. The researchers observed that QS-active isolates could influence the abundance of certain bacterial genera in co-culture experiments. However, the addition of AHLs did not significantly affect the growth or biofilm formation of isolates from co-cultures. The impact of QS-active supernatants on Bacillus sp. CH8a biofilm formation supports a potential role for QS in microbe-microbe interactions. The absence of a classical QS synthase gene in a Psychrobacter isolate indicates the presence of alternative QS mechanisms. The study highlights the limited success of culture-based methods in capturing the full diversity of QS-active bacteria. The findings underscore the need for improved techniques to isolate and study QS systems in marine environments. The results contribute to a better understanding of QS signaling in complex marine microbial ecosystems.