Biology subjects

PEREZ-PASCUAL, D.

Publications and source records attributed to PEREZ-PASCUAL, D..

4 recordsLinked to original sources

bioRxiv2025

A Chryseobacterium massiliae pore-forming MACPF domain protein mediates intra and interspecies competition against Bacteroides

Microbiota play crucial roles in host health, including protection against pathogens through competitive interactions between commensal and pathogenic bacteria that are mediated by direct contact or secreted factors. We previously demonstrated that Chryseobacterium massiliae, a zebrafish commensal, protects larvae against infection by Flavobacterium covae (formerly F. columnare). Here, we investigated whether interference interactions contribute to this protective effect. We found that C. massiliae culture supernatant inhibits F. covae growth and a transposon mutagenesis screen identified mutants lacking this activity. All identified mutants carried insertions in a gene encoding a protein homologous to Bacteroidales BSAP pore-forming toxins, characterized by a Membrane Attack Complex/Perforin (MACPF) domain. We showed that this protein, which we named CSAP-1 (for Chryseobacterium Secreted Antimicrobial Protein) displays bactericidal, pore-forming activity that lyses F. covae cells. Unlike BSAP proteins from Bacteroides spp., CSAP-1 displays broader antagonistic activity, targeting multiple species across the Flavobacterium and Chryseobacterium genera - thus mediating interspecies and intergenus inhibition within Bacteroidetes. Although CSAP-1 is not essential for the in vivo protective effect of C. massiliae, administration of purified CSAP-1 alone confers significant protection to zebrafish larvae against sensitive F. covae infection. This study therefore identifies CSAP-1 as the first MACPF protein from C. massiliae with broad-spectrum inhibitory activity against members of the order Flavobacteriales. These findings highlight CSAP-1 as a promising candidate for the development of novel antimicrobial strategies and warrant further mechanistic investigation.

microbiology↗

bioRxiv2023

Anti-diarrheal drug loperamide induces dysbiosis in zebrafish microbiota via bacterial inhibition

BackgroundPerturbations of animal-associated microbiomes from chemical stress can affect host physiology and health. While dysbiosis induced by antibiotic treatments and disease are well known, chemical, non-antibiotic drugs have recently been shown to induce changes in microbiome composition, warranting further exploration. Loperamide is an opioid-receptor agonist drug widely prescribed drug for treating acute diarrhea in humans. Loperamide is also used as a tool to study the impact of bowel dysfunction in animal models by inducing constipation, but its effect on host-associated microbiota is poorly characterized. ResultsWe used conventional and gnotobiotic larval zebrafish models to show that in addition to host-specific effects, loperamide also has anti-bacterial activities that directly induce changes in microbiota diversity. This dysbiosis is due to changes in bacterial colonization, since germ-free zebrafish mono-reconventionalized with bacterial strains sensitive to loperamide are colonized up to 100-fold lower when treated with loperamide. Consistently, the bacterial diversity of gnotobiotic zebrafish colonized by a mix of representative bacterial strains is affected by loperamide treatment. ConclusionOur results demonstrate that loperamide, in addition to host effects, also induces dysbiosis in a vertebrate model, highlighting that established treatments can have underlooked secondary effects on microbiota structure and function. This study further provides a insights for future studies exploring how common medications directly induce changes in host-associated microbiota. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=103 SRC="FIGDIR/small/537295v1_ufig1.gif" ALT="Figure 1"> View larger version (21K): org.highwire.dtl.DTLVardef@11c5492org.highwire.dtl.DTLVardef@f44f40org.highwire.dtl.DTLVardef@17eff8corg.highwire.dtl.DTLVardef@bb691a_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2020

Gnotobiotic rainbow trout (Oncorhynchus mykiss) model reveals endogenous bacteria that protect against Flavobacterium columnare infection

The health and environmental risks associated with antibiotic use in aquaculture have promoted bacterial probiotics as an alternative approach to control fish infections in vulnerable larval and juvenile stages. However, evidence-based identification of probiotics is often hindered by the complexity of bacteria-host interactions and host variability in microbiologically uncontrolled conditions. While these difficulties can be partially resolved using gnotobiotic models harboring no or reduced microbiota, most host-microbe interaction studies are carried out in animal models with little relevance for fish farming. Here we studied host-microbiota-pathogen interactions in a germ-free and gnotobiotic model of rainbow trout (Oncorhynchus mykiss), one of the most widely cultured salmonids. We demonstrated that germ-free larvae raised in sterile conditions displayed no significant difference in growth after 35 days compared to conventionally-raised larvae, but were extremely sensitive to infection by Flavobacterium columnare, a common freshwater fish pathogen causing major economic losses worldwide. Furthermore, re-conventionalization with 11 culturable species from the conventional trout microbiota conferred resistance to F. columnare infection. Using mono-re-conventionalized germ-free trout, we identified that this protection is determined by a commensal Flavobacterium strain displaying antibacterial activity against F. columnare. Finally, we demonstrated that use of gnotobiotic trout is a suitable approach for the systematic identification of both endogenous and exogenous probiotic bacterial strains that may protect teleostean hosts against F. columnare and other pathogens. This study establishes a novel and ecologically-relevant gnotobiotic model that will improve the sustainability and health of aquaculture.

microbiology↗

bioRxiv2020

Mining zebrafish microbiota reveals key community-level resistance against fish pathogen infection

The long-known resistance to pathogens provided by host-associated microbiota fostered the notion that adding protective bacteria could prevent or attenuate infection. However, the identification of endogenous or exogenous bacteria conferring such protection is often hindered by the complexity of host microbial communities. Here, we used zebrafish and the fish pathogen Flavobacterium columnare as a model system to study the determinants of microbiota-associated colonization resistance. We compared infection susceptibility in germ-free, conventional and re-conventionalized larvae and showed that a consortium of 10 culturable bacterial species are sufficient to protect zebrafish. Whereas survival to F. columnare infection does not rely on host innate immunity, we used antibiotic dysbiosis to alter zebrafish microbiota composition, leading to the identification of two different protection strategies. We first identified that the bacterium Chryseobacterium massiliae individually protects both larvae and adult zebrafish. We also showed that an assembly of 9 endogenous zebrafish species that do not otherwise protect individually confer a community-level resistance to infection. Our study therefore provides a rational approach to identify key endogenous protecting bacteria and promising candidates to engineer resilient microbial communities. It also shows how direct experimental analysis of colonization resistance in low-complexity in vivo models can reveal unsuspected ecological strategies at play in microbiota-based protection against pathogens.

microbiology↗