Winner: Oona Snoeyenbos-West, Ph.D. Research Scientist, University of Arizona (Carini Lab) (Photo credit: Deanna Sanchez (BIO5 Institute)

Co-Culture Champion

Defying Arsenic: Insights into Gut Microbiome Resilience

Oona will examine the effects of arsenic exposure on the mouse gut microbiome and its impact on host health. By leveraging Cerillo’s Co-Culture System, Dr. Snoeyenbos-West aims to identify key microbial interactions and develop insights into potential shifts in microbial functions under arsenic-induced stress. This research holds promise for mitigating the health effects of arsenic exposure on the host.

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How she will use Cerillo's Co-Culture Research Platform

Does the Dose make the Poison? Understanding Arsenic tolerance and biotransformation in the mouse gut microbiome via a co-culture approach.

Arsenic (As) poses serious human health risks and ingestion from environmental sources such as legacy mine tailings is associated with diabetes, cancer, and heart disease. The gut microbiome is a first point of contact for ingested As and influences the host toxicity through biotransformation to arsenicals of varying toxicity. However, we don’t know what biotransformation’s individual gut taxa are responsible for nor how specific bacterial strains respond to As at different concentrations and at different valences; data that are key for understanding the mammalian gut microbiome’s capacity to either buffer or exacerbate As toxicity. Our primary objective is to understand how the gut microbiome may impact As toxicity for potential development of probiotics to reduce the impact of ingested As on host health. We are quantifying the As tolerance for strains in the mouse intestinal bacterial collection (MiBC (Lagkouvardos et al., Nat Microbiol 1, 16131 (2016))) to increasing doses of arsenite (AsO3) or arsenate (AsO4). We have developed a high-throughput anaerobic growth analysis workflow, that allows us to generate automated growth curves for aerobic and anaerobic gut bacteria from mice, challenged with various doses of As. We are now able to conduct a comprehensive assessment of As tolerance and biotransformation for the full suite of bacteria that comprise the murine gut microbiome. MiBC isolates exhibit a range of responses to As exposure, from complete As tolerance at doses as high as 270 ppm AsO3 (e.g., Bacillus licheniformis, Proteus mirabilis, Pasteurella caecimuris) to a linear dose inhibition response with growth inhibition followed by death at 10 ppm AsO3, in for example Escherichia coli and Staphylococcus xylosus. To date, our data indicate widely variable tolerance of As in the gut microbiome, spanning the gamut of aerobes, microaerophiles and anaerobes. This points to the likely existence of different bacterial guilds that respond to ingested As in novel and dynamic ways, and that warrant further exploration by construction of synthetic co-culture communities and testing of such communities for enhanced As biotransformation.

The key metrics we use to assess the outcomes of our single culture and co-culture experiments are growth curve analyses which are then combined with genomic, transcriptomic and metabolomic data for various statistical analyses, e.g., network analysis. Typically, we culture our microbes for 1-4 days, depending on the strains under investigation. Two co-culture plates will typically be needed to complete one set of experiments, but we anticipate future scale up.

We know that our experiments will benefit from Cerillo’s new co-culture system as it will allow us to set up many simultaneous co-culture experiments in a small footprint area inside an anaerobic chamber thus allowing collection of phenotypic co-culture data in a high-throughput manner. Furthermore, the unique design of the co-culture duet system affords us with the ability to sample growth media directly for metabolite identification and to also harvest cells in real time for time-series gene expression profiling of microbes growing together in different co-culture combinations, versus those growing alone.

Expected Outcomes:
1. Identification of key microbial interactions influenced by distinct arsenic concentrations.
2. Insights into potential shifts in microbial functions due to As-induced stress.
3. Understanding of how pure isolates of mouse gut bacteria adapt and respond to As exposure in various co-culture combinations for development of an As ameliorating probiotic.

This research holds significance for deepening our understanding of how arsenic exposure impacts the interactions among mouse gut bacteria. This knowledge is key for understanding the potential impact on host health, as alterations in gut microbiota composition and function can have far-reaching effects on various physiological processes of the host.