---
title: "Bacterial secreted products selectively inhibit non-symbiotic fungi in stingless bee larval diet"
id: "biorxiv-9-bacterial-secreted-products-selectively-inhibit-non-symbiotic-fungi-in-bees"
canonical_url: "https://medichelpline.com/clinical-feed/biorxiv-9-bacterial-secreted-products-selectively-inhibit-non-symbiotic-fungi-in-bees"
content_type: "clinical_feed_article"
specialty: "General"
source_name: "bioRxiv (Biomedical Preprints)"
source_url: "https://www.biorxiv.org/content/10.64898/2026.09.16.752052v1?rss=1"
published_at: "2026-09-20T12:00:00.000Z"
evidence_level: "Verified Feed"
license: "CC-BY-NC-4.0 / Informational Use"
---
# Bacterial secreted products selectively inhibit non-symbiotic fungi in stingless bee larval diet
## Provenance & Clinical Metadata
- **Canonical URL:** https://medichelpline.com/clinical-feed/biorxiv-9-bacterial-secreted-products-selectively-inhibit-non-symbiotic-fungi-in-bees
- **Specialty:** [General](https://medichelpline.com/clinical-feed/general.md)
- **Primary Source:** bioRxiv (Biomedical Preprints)
- **Source URL:** [Original Journal Publication](https://www.biorxiv.org/content/10.64898/2026.09.16.752052v1?rss=1)
- **Published At:** 2026-09-20T12:00:00.000Z
- **Evidence Rating:** Verified Feed
## Executive GIST (TL;DR)
- Microbial interactions influence microbiome assembly in pollinators, including stingless bees, by limiting invasion of harmful organisms and protecting host-associated benefits. - In Scaptotrigona depilis, bacteria associated with the larval diet can inhibit potentially pathogenic **filamentous fungi** while allowing beneficial yeast symbionts to persist. - The study used conditioned media (cell-free supernatant) assays combined with genomic and metabolomic analyses to test whether **bacterial secreted products** mediate selective effects on fungi. - Secreted products from prevalent bacterial taxa, notably **Apilactobacillus kunkeei**, strongly affected fungal growth in vitro. - Filamentous fungi, including the pathogen **Aspergillus**, were consistently inhibited by bacterial conditioned media. - Part of the inhibitory effect on filamentous fungi was attributable to substrate acidification driven by **organic acids**, but additional acidity-independent factors also contributed. - Yeast responses were heterogeneous: a non-symbiotic **Zygosaccharomyces** strain was inhibited by bacterial metabolites under near-neutral pH, while the symbiotic Zygosaccharomyces required for larval development was maintained or promoted under acid-conditioned media. - Genomic analyses detected limited canonical antifungal biosynthetic gene clusters in the most prevalent bacteria from the larval diet, suggesting classic antifungal pathways are scarce in these strains. - Metabolomic profiling identified extracellular peptide-like compounds across bacterial strains, indicating **non-canonical secreted products** may play a role in selective fungal inhibition. - Overall, data support that bacterial secreted products are key mediators shaping fungal community composition in the stingless bee larval diet, providing mechanistic hints for how microbial interactions structure this ecosystem.
## Clinical Analysis & Structured Key Points
Bacterial secreted products selectively inhibit non-symbiotic fungi in bees | bioRxiv Skip to main content New Results Bacterial secreted products selectively inhibit non-symbiotic fungi in bees View ORCID Profile Lílian Caesar , Amadeus Wagner , Gabriela Toninato de Paula , View ORCID Profile Monica T. Pupo , View ORCID Profile Irene L. G. Newton doi: https://doi.org/10.64898/2026.09.16.752052 Lílian Caesar 1 The University of Oklahoma; Find this author on Google Scholar Find this author on PubMed Search for this author on this site ORCID record for Lílian Caesar For correspondence: caesarl{at}ou.edu Amadeus Wagner 2 Indiana University Bloomington; Find this author on Google Scholar Find this author on PubMed Search for this author on this site Gabriela Toninato de Paula 3 University of São Paulo; Find this author on Google Scholar Find this author on PubMed Search for this author on this site Monica T. Pupo 4 Universidade de Sao Paulo Campus de Ribeirao Preto; Find this author on Google Scholar Find this author on PubMed Search for this author on this site ORCID record for Monica T. Pupo Irene L. G. Newton 5 Indiana University, Bloomington Find this author on Google Scholar Find this author on PubMed Search for this author on this site ORCID record for Irene L. G. Newton Abstract Info/History Metrics Preview PDF Abstract Microbial interactions play an important role in shaping microbiome assembly, such as by limiting invasion by harmful organisms that can directly affect the host or disrupt microbiome-associated benefits. Such interactions have been observed across systems, including in the microbiomes of key pollinators such as stingless bees. In Scaptotrigona depilis , bacteria associated with the larval diet inhibit potentially pathogenic filamentous fungi while allowing beneficial yeast symbionts to persist. The mechanisms underlying these effects, however, remain unclear. Here, we combined conditioned media (cell-free supernatant) assays with genomic and metabolomic analyses to investigate whether bacterial secreted products mediate these effects in the bee microbiome. Our results show that bacterial secreted products, particularly from prevalent bacterial taxa such as Apilactobacillus kunkeei , strongly affect fungal growth. Filamentous fungi, including the pathogen Aspergillus , were consistently inhibited, partly through substrate acidification driven by organic acids, but also through additional acidity-independent factors. In contrast, yeast responses were more variable: a non-symbiotic Zygosaccharomyces was inhibited by bacterial metabolites under near-neutral pH, whereas the symbiotic Zygosaccharomyces required for larval development was maintained or promoted under acid-conditioned media. Genomic analyses revealed limited canonical antifungal biosynthetic clusters in the most prevalent bacteria in the larval diet, while metabolomics identified extracellular peptide-like compounds across strains, suggesting a role for non-canonical secreted products. Together, these results show that bacterial secreted products play a key role in selectively shaping fungal communities in the stingless bee larval diet, providing first hints on a mechanistic basis for how microbial interactions structure this ecosystem. Copyright The copyright holder for this preprint is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY 4.0 International license . Back to top Previous Posted September 20, 2026. Download PDF Email Thank you for your interest in spreading the word about bioRxiv. NOTE: Your email address is requested solely to identify you as the sender of this article. Your Email * Your Name * Send To * Enter multiple addresses on separate lines or separate them with commas. You are going to email the following Bacterial secreted products selectively inhibit non-symbiotic fungi in bees Message Subject (Your Name) has forwarded a page to you from bioRxiv Message Body (Your Name) thought you would like to see this page from the bioRxiv website. Your Personal Message CAPTCHA This question is for testing whether or not you are a human visitor and to prevent automated spam submissions. Share Bacterial secreted products selectively inhibit non-symbiotic fungi in bees Lílian Caesar , Amadeus Wagner , Gabriela Toninato de Paula , Monica T. Pupo , Irene L. G. Newton bioRxiv 2026.09.16.752052; doi: https://doi.org/10.64898/2026.09.16.752052 Share This Article: Copy Citation Tools Bacterial secreted products selectively inhibit non-symbiotic fungi in bees Lílian Caesar , Amadeus Wagner , Gabriela Toninato de Paula , Monica T. Pupo , Irene L. G. 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