Biology subjects

Sbardellati, D. L.

Publications and source records attributed to Sbardellati, D. L..

3 recordsLinked to original sources

bioRxiv2026

Temperate Phage Shape Honey Bee Gut Microbiome Structure and Response to Antibiotic Treatment

Bacteriophage (phage) are hypothesized to play a significant role in modulating gut microbiomes. Yet, in vivo research examining the role of phage in gut ecosystems remains sparse, largely due to a lack of tractable model systems. Here, we use the honey bee (Apis mellifera) gut as a model to test the hypotheses that phage-bacteria interactions in the gut are temporally variable and that stress, in the form of antibiotics, can enhance phage killing of their bacterial hosts. First, we isolated and characterized a novel temperate phage which infects a bee-specific strain of Bifidobacterium. We then mono-colonized adult honey bees with this Bifidobacterium strain and tested how phage treatment impacts bacterial abundance over time. Next, using a series of in vitro and in vivo experiments, we examined how phage-bacteria interactions change in response to treatment with tetracycline, an antibiotic commonly used in commercial beekeeping. Finally, to probe the biological mechanisms underlying different phage-antibiotic synergies, we assayed how different classes of antibiotics impacted bacterial growth with and without phage infection. Our results indicate that a single temperate phage can both promote the ability of its Bifidobacterium host to colonize the gut, while also increasing host sensitivity to antibiotic treatment. Together, these findings demonstrate that environmental stressors can shift phage-bacteria interactions from mutualism to antagonism, highlighting the significance of phage in shaping how gut microbiomes respond to antibiotic or xenobiotic perturbation.

microbiology↗

bioRxiv2025

Bee Microbiomes Harbor Diverse Antimicrobial Resistance Genes on Plasmids

Antimicrobial resistance (AMR) is an emerging public health threat. In North America, tetracycline and macrolide antibiotics are often used to prevent or treat bacterial infections in honey bees. Previous research has shown that this practice has led to widespread drug resistance in honey bee gut microbiomes. However, where bee-associated bacteria encode AMR, genomically or on mobile genetic elements, is less well understood. Moreover, how the abundance, diversity, and mechanism of AMR differs between managed honey bees and other bees remains largely unexplored. Here we use existing metagenomic data from two previous studies to profile the AMR genes associated with managed honey bees, commercially produced bumble bees, and wild bumble bees. Our results suggest that honey bee associated bacteria house a greater diversity of AMR genes, specifically on plasmids, compared to bumble bees. In addition, we show that honey and bumble bee bacteria likely develop resistance to tetracyclines via different mechanisms. Overall, this study showcases how agricultural management has shaped the AMR genes associated with bees, and offers insights into the ecological context of differential AMR evolution within host-associated systems.

microbiology↗

bioRxiv2024

Targeted Viromes and Total Metagenomes Capture Distinct Components of Bee Gut Phage Communities

Despite being among the most abundant biological entities on earth, bacteriophage (phage) remain an understudied component of host-associated systems. One limitation to studying host-associated phage is the lack of consensus on methods for sampling phage communities. Here, we compare paired total metagenomes and viral size fraction metagenomes (viromes) as methods for investigating the dsDNA viral communities associated with the GI tract of two bee species: the European honey bee Apis mellifera and the eastern bumble bee Bombus impatiens. We find that viromes successfully enriched for phage, thereby increasing phage recovery, but only in honey bees. In contrast, for bumble bees, total metagenomes recovered greater phage diversity. Across both bee species, viromes better sampled low abundance and low occupancy phage, while total metagenomes were biased towards sampling temperate phage and the most prominent phage. Additionally, many of the phage captured by total metagenomes were absent altogether from viromes. Comparing between bees, we show that phage communities in commercially reared bumble bees are significantly reduced in diversity compared to honey bees, likely reflecting differences in bacterial titer and diversity. In a broader context, these results highlight the complementary nature of total metagenomes and targeted viromes, especially when applied to host-associated environments. Overall, we suggest that studies interested in assessing total communities of host-associated phage should consider using both approaches. However, given the constraints of virome sampling, total metagenomes may serve to sample phage communities with the understanding that they will preferentially sample dominant and temperate phage.

microbiology↗