Biology subjects

Paix, B.

Publications and source records attributed to Paix, B..

2 recordsLinked to original sources

bioRxiv2025

Adaptive strategies of Caribbean sponge holobionts beyond the mesophotic zone

Marine sponges and their microbiomes function together as holobionts, playing essential roles in ecosystem dynamics and exhibiting remarkable adaptability across depth gradients. This study utilized a multi-omics approach, integrating microbiome and metabolome analyses, to investigate adaptive strategies in sponge holobionts inhabiting the mesophotic (80-125 m), upper-rariphotic (125-200 m), and lower-rariphotic (200-305 m) zones of Curacao. We hypothesized that depth-related environmental factors drive distinct adaptive strategies, similar to patterns observed in fish and coral assemblages. Results revealed major differences in holometabolomes and microbial communities between Demospongiae and Hexactinellida sponges, reflecting class-specific adaptive strategies. Notably, phospholipid homeoviscous adaptation to temperature and pressure emerged as a key mechanism in phosphorus metabolism. Adaptations in nitrogen metabolism were linked to diverse ammonia oxidizing archaea (AOA) symbionts, and dissolved organic matter cycling. Hexactinellid microbiomes exhibited intra-specific heterogeneity; however, species-specific associations with AOA symbionts such as Cenarchaeum and Nitrosopumilus were observed. Additionally, the lower-rariphotic hexactinellid holometabolomes highlighted the significance of the nested ecosystem concept through the identification of secondary metabolites produced by their associated fauna (aphrocallistins by zoanthids, and xanthurenic acid by shrimp). This study highlights the ecological significance of sponge holobionts in mesophotic and rariphotic ecosystems, revealing diverse adaptations to unique physicochemical conditions and biotic interactions.

microbiology↗

bioRxiv2017

Bdellovibrio and like organisms bacterial predators are not equally distributed in peri-alpine lakes

Microbes drive a variety of ecosystem processes and services but still many of them remain largely unexplored because of our lack of knowledge on both diversity and functionality of some potentially key microbiological compartments. This is typically the case with and within the group of bacterial predators collectively known as Bdellovibrio and like organisms (BALOs). Here we report for the first time the abundance, distribution and diversity of the three main families of these natural and obligatory predators of gram negative bacteria in three peri-alpine lakes (e.g. lakes Annecy, Bourget and Geneva) at different depths (surface vs. 45 or 50 m) and along a few months (from August 2015 to January 2016). We show that, using PCR-DGGE and cloning-sequencing approaches, the diversity appeared relatively low and very specific to fresh waters or even of the lakes themselves. While the Peredibacteraceae family was represented mainly by a single species (i.e. Peredibacter starii), it could constitute up to 7% of the total bacterial cell abundances. Comparati vel y, the abundances of the two other families (referred to as Bdellovibrionaceae and Bacteriovaracaceae) were significantly lower. More interestingly, the distribution in the water column was very different between the three groups suggesting various life strategies/niches for each of them: Peredibactereacea dominated near surface while the Bdellovibrionaceae and the Bacteriovaracaceae were more abundant at depth. All in all, our results suggest that these bacterial predators are likely to play a significant role in mortality, carbon fluxes and prokaryotic community structure in lakes.

ecology↗