Biology subjects

Chaves, I. Z.

Publications and source records attributed to Chaves, I. Z..

3 recordsLinked to original sources

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↗

bioRxiv2024

The microbiota of wooden cheese ripening boards is a rich source of antimicrobial-producing bacteria against Listeria monocytogenes

Wooden boards are essential tools in cheese ripening and there are accumulating observations suggesting their antimicrobial effect against foodborne bacterial pathogens, such as Listeria monocytogenes. However, poor bacterial recovery of bacteria from wood can confound quantification of pathogen burdens. To assess L. monocytogenes survival on wooden cheese boards, we applied a disruptive grinding method and tracked native board-associated bacterial counts as controls. Our data revealed that L. monocytogenes declines on clean zones of wooden boards, but can replicate on areas where there is suitable cheese. Our microbiota analysis revealed diverse bacterial communities on wooden board surfaces, with a prominent presence of Brevibacterium, Brachybacterium, and Staphylococcus genera. We further identified seven bacterial species that inhibit L. monocytogenes, belonging to Bacillus, Staphylococcus, and Serratia phyla, as well as Lactococcus lactis. We focused on a Bacillus safensis isolate as a novel biocontrol agent candidate, and found it to potently inhibit L. monocytogenes via secreted antimicrobial factors. Our genomic, bioinformatic, and biochemical analyses indicate that those factors are likely antimicrobial peptides encoded by multiple biosynthetic gene clusters, several of which are unique to B. safensis and have not been characterized. A sub-inhibitory concentration of B. safensis supernatant induces a significant down-regulation of prophage elements and up-regulation antimicrobial stress response in L. monocytogenes. Taken together, our findings indicate that the wooden board microbiota is a rich source of antimicrobial-producing bacteria with potential applications in foodborne pathogen control strategies. IMPORTANCEDespite stringent food safety measures, L. monocytogenes foodborne outbreaks remain frequent with high hospitalization and mortality rates. Removal of L. monocytogenes from food processing environments is extremely challenging, because this pathogen is ubiquitous and encodes a wide array of stress response mechanisms that enable it to thrive under harsh conditions. Our study found that clean wooden boards used in cheese ripening inhibit L. monocytogenes, causing a noticeable decline in pathogen population following surface inoculation. Bacterial communities on wooden cheese boards are rich and diverse, and harbor many species that produce antimicrobial compounds against L. monocytogenes, with the example of a new B. safensis isolate. Therefore, wooden board microbiota is a promising source for future antimicrobial discovery efforts.

microbiology↗

bioRxiv2023

Determinants of Gastrointestinal Group B Streptococcus Carriage in Adults

BackgroundStreptococcus agalactiae (Group B Streptococcus, GBS) is a commensal Gram-positive bacterium found in the human gastrointestinal and urogenital tracts. Much of what is known about GBS relates to the diseases it causes in pregnant people and neonates. However, GBS is a common cause of disease in the general population with 90% of GBS mortality occurring in non-pregnant people. There are limited data about the predisposing factors for GBS and the reservoirs in the body. To gain an understanding of the determinants of gastrointestinal GBS carriage, we used stool samples and associated metadata to determine the prevalence and abundance of GBS in the gut microbiome of adults and find risk factors for GBS status. MethodsWe used 754 stool samples collected from adults in Wisconsin from 2016-2017 to test for the prevalence and abundance of GBS using a Taqman probe-based qPCR assay targeting two GBS-specific genes: cfp and sip. We compared the microbiome compositions of the stool samples by GBS status using 16S rRNA analysis. We compared associations with GBS status and 557 survey variables collected during sample acquisition (demographics, diet, overall health, and reproductive health) using univariate and multivariate analyses. ResultsWe found 137/754 (18%) of participants had detectable GBS in their stool samples with a median abundance of 104 copies per nanogram of starting DNA. There was no difference in GBS status or abundance based on gender. Beta-diversity, Bray-Curtis and Unweighted UniFrac, was significantly different based on carrier status of the participant. Prior to p-value correction, 59/557 (10.6%) survey variables were significantly associated with GBS carrier status and 11/547 (2.0%) variables were significantly associated with abundance (p-value<0.05). After p-value correction, 2/547 (0.4%) variables were associated with GBS abundance: an increased abundance of GBS was associated with a decreased frequency since last dental checkup (p<0.001) and last dental cleaning (p<0.001). Increased GBS abundance was significantly associated with increased frequency of iron consumption (p=0.007) after p-value correction in multivariate models. ConclusionsGBS is found in stool samples from adults in Wisconsin at similar frequencies as pregnant individuals screened with rectovaginal swabs. We did not find associations between risk factors historically associated with GBS in pregnant people, suggesting that risk factors for GBS carriage in pregnancy may differ from those in the general population. We found that frequency of iron consumption and dental hygiene are risk factors for GBS carriage in Wisconsin adults. Given that these variables were not assayed in previous GBS surveys, it is possible they also influence carriage in pregnant people. Taken together, this work serves as a foundation for future work in developing approaches to decrease GBS abundance in carriers.

microbiology↗