Biology subjects

Pinto-Tomas, A. A.

Publications and source records attributed to Pinto-Tomas, A. A..

4 recordsLinked to original sources

bioRxiv2026

Good parenting of oil-collecting bees: microbial defense in nests of Centris bees?

Microbial symbionts are increasingly recognized as key contributors to bee health, yet their roles in solitary bee brood cells remain largely unexplored. Here, we characterize the bacterial and fungal communities associated with brood cell compartments (cocoon, meconium, and prepupa) of the oil-collecting bee Centris aethyctera, and compare them with gut microbiota from adult Centris species. Using 16S rRNA and ITS amplicon sequencing, we show that microbiota are strongly compartmentalized, with distinct diversity patterns, taxonomic compositions, and inferred functional profiles across brood cell components. Contrary to our initial hypothesis, antibiotic-producing bacteria, particularly Actinomycetia, are most diverse and abundant in the meconium rather than the cocoon. Cocoons are enriched in hydrocarbon-degrading and nitrogen-cycling bacteria, while pre-pupae harbor distinct bacterial and fungal taxa, including genera with potential antimicrobial and symbiotic functions. Fungal communities are likewise structured, with taxa such as Aspergillus and Lecanicillium suggesting possible roles in pathogen defense. Core gut microbiota of adult Centris include acetic acid bacteria shared across species, with partial overlap with brood cell taxa, indicating potential transmission pathways. Together, our results reveal that Centris brood cells form a highly structured, antimicrobial-rich microenvironment likely shaped by maternal provisioning and environmental acquisition. These findings provide the first comprehensive description of microbiota across brood cell compartments in a solitary bee and identify ground-nesting bee systems as promising reservoirs for novel antimicrobial discovery.

ecology↗

bioRxiv2025

The gut microbiome of the Passalid beetle has high cellulolytic potential and constitutes an unrecognized system for production of greenhouse gasses in neotropical forests

Herbivores, and their associated microbiomes, play a major role in the global carbon cycle. Recalcitrant cellulose molecules are broken down by microorganisms that colonize the herbivore gut, releasing greenhouse gasses in the process. Passalid beetles are tropical herbivores that feed only on decaying wood and present subsocial behavior that may lead to the acquisition and sharing of microbial symbionts for efficient biomass and energy production. We collected five groups of Veturius sp. Passalid beetles from different logs in the Costa Rican rainforest and analyzed the microbial communities of larval and adult guts, as well as the substrate material in which they resided (partially chewed wood material mixed with feces that covers their tunnels). Adults, larvae, and substrate harbor different microbial communities, with substrate showing the highest diversity and richness, and larvae gut comprising a high abundance of methanogenic archaea. Reconstructed metagenome assembled genomes (MAGs) revealed that larvae and adults are enriched in genomes encoding a myriad of glycosyl hydrolases. Methanogenic taxa were enriched within the larval MAGs and bins, suggesting that larval microbiota participate in the final steps of cellulose decomposition in the system. Finally, we assessed methane production rates by Passalid beetles and compared them with termites. Our results show that Passalid larvae and adults produce methane at rates comparable to termites. Passalid and other beetle larvae are potentially underappreciated contributors to the carbon cycle and the biotic production of the greenhouse gas methane.

microbiology↗

bioRxiv2021

Burkholderia from fungus gardens of fungus-growing ants produce antifungals that inhibit the specialized parasite Escovopsis

Within animal associated microbiomes, the functional roles of specific microbial taxa are often uncharacterized. Here, we use the fungus-growing ant system, a model for microbial symbiosis, to determine the potential defensive roles of key bacterial taxa present in the ants fungus gardens. Fungus gardens serve as an external digestive system for the ants, with mutualistic fungi in the genus Leucoagaricus spp. converting plant substrate into energy for the ants. The fungus garden is host to specialized parasitic fungi in the genus Escovopsis. Here, we examine the potential role of Burkholderia spp. that occur within ant fungus gardens in inhibiting Escovopsis. We isolated members of the bacterial genera Burkholderia spp. and Paraburkholderia spp. from 50% of the 52 colonies sampled, indicating that the family Burkholderiaceae are common fungus garden inhabitants of a diverse range of fungus-growing ant genera. Using antimicrobial inhibition bioassays, we found that 28 out of 32 isolates inhibited at least one Escovopsis strain with a zone of inhibition greater than 1 cm. Genomic assessment of Burkholderiaceae isolates indicated that isolates with strong inhibition all belonged to the genus Burkholderia and contained biosynthetic gene clusters that encoded the production of two antifungals: burkholdine1213 and pyrrolnitrin. Organic extracts of cultured isolates confirmed these compounds as responsible for antifungal activity that inhibit Escovopsis but, at low concentrations, not Leucoagaricus spp. Overall, these new findings, combined with previous evidence, suggest that members of the fungus garden microbiome play an important role in maintaining the health and function of the fungus-farming ant colony. IMPORTANCEMany organisms partner with microbes to defend themselves against parasites and pathogens. Fungus-growing ants must protect Leucoagaricus spp., the fungal mutualist that provides sustenance for the ants, from a specialized fungal parasite, Escovopsis spp. The ants take multiple approaches, including weeding their fungus gardens to remove Escovopsis spores, as well as harboring Pseudonocardia that produce antifungals that inhibit Escovopsis. In addition, a genus of bacteria commonly found in fungus gardens, Burkholderia spp., is known to produce secondary metabolites that inhibit Escovopsis spp. In this study, we isolated Burkholderia spp. from fungus-growing ants, assessed the isolates ability to inhibit Escovopsis spp., and identified two compounds responsible for inhibition. Our findings suggest that Burkholderia spp. are often found in fungus gardens, adding another possible mechanism within the fungus-growing ant system to suppress the growth of the specialized parasite Escovopsis.

microbiology↗

bioRxiv2019

Bacteria contribute to plant secondary compound degradation in a generalist herbivore system

Herbivores must overcome a variety of plant defenses, including coping with plant secondary compounds (PSCs). To help detoxify these defensive chemicals, several insect herbivores are known to harbor gut microbiota with the metabolic capacity to degrade PSCs. Leaf-cutter ants are generalist herbivores, obtaining sustenance from specialized fungus gardens that act as external digestive systems, degrading the diverse collection of plants foraged by the ants. There is in vitro evidence that certain PSCs harm Leucoagaricus gongylophorus, the fungal cultivar of leaf-cutter ants, suggesting a role for the Proteobacteria-dominant bacterial community present within fungus gardens. Here, we investigate the ability of symbiotic bacteria present within fungus gardens of leaf-cutter ants to degrade PSCs. We cultured fungus garden bacteria, sequenced the genomes of 42 isolates, and identified genes involved in PSC degradation, including genes encoding cytochrome p450s and genes in geraniol, cumate, cinnamate, and -pinene/limonene degradation pathways. Using metatranscriptomic analysis, we show that some of these degradation genes are expressed in situ. Most of the bacterial isolates grew unhindered in the presence of PSCs and, using GC-MS, we determined that isolates from the genera Bacillus, Burkholderia, Enterobacter, Klebsiella, and Pseudomonas degrade -pinene, {beta}-caryophyllene, or linalool. Using a headspace sampler, we show that sub-colonies of fungus gardens reduced -pinene and linalool over a 36-hour period, while L. gongylophorus strains alone only reduced linalool. Overall, our results reveal that the bacterial community in fungus gardens play a pivotal role in alleviating the effect of PSCs on the leaf-cutter ant system. ImportanceLeaf-cutter ants are dominant neotropical herbivores capable of deriving energy from a wide range of plant substrates. The success of leaf-cutter ants is largely due to their external gut composed of key microbial symbionts, specifically, the fungal mutualist L. gongylophorus and a consistent bacterial community. Both symbionts are known to have critical roles in extracting energy from plant material, yet comparatively little is known about their role in the detoxification of plant secondary compounds. Here, we assess if the bacterial community associated with leaf-cutter ant fungus gardens can degrade harmful plant chemicals. We identify plant secondary compound detoxification in leaf-cutter ant gardens as a process that depends on the degradative potential of both the bacterial community and L. gongylophorus. Our findings suggest the fungus garden and its associated microbial community influences the generalist foraging abilities of the ants, underscoring the importance of microbial symbionts in plant substrate suitability for herbivores.

ecology↗