Streptozotocin-induced hyperglycemia alters the cecal metabolome and exacerbates antibiotic-induced dysbiosis.

It is well established in the microbiome field that antibiotic (ATB) use and metabolic disease both impact the structure and function of the gut microbiome. But how host and microbial metabolism interacts with ATB susceptibility to affect the resulting dysbiosis remains poorly understood. In a streptozotocin-induced model of hyperglycemia (HG), we use a combined metagenomic, metatranscriptomic, and metabolomic approach to profile changes in microbiome taxonomic composition, transcriptional activity, and metabolite abundance both pre- and post-ATB challenge. We find that HG impacts both microbiome structure and metabolism, ultimately increasing susceptibility to amoxicillin. HG exacerbates drug-induced dysbiosis and increases both phosphotransferase system activity and energy catabolism compared to controls. Finally, HG and ATB co-treatment increases pathogen susceptibility and reduces survival in a Salmonella enterica infection model. Our data demonstrate that induced HG is sufficient to modify the cecal metabolite pool, worsen the severity of ATB dysbiosis, and decrease colonization resistance.

Microbial Metabolism Modulates Antibiotic Susceptibility within the Murine Gut Microbiome.

Although antibiotics disturb the structure of the gut microbiota, factors that modulate these perturbations are poorly understood. Bacterial metabolism is an important regulator of susceptibility in vitro and likely plays a large role within the host. We applied a metagenomic and metatranscriptomic approach to link antibiotic-induced taxonomic and transcriptional responses within the murine microbiome. We found that antibiotics significantly alter the expression of key metabolic pathways at the whole-community and single-species levels. Notably, Bacteroides thetaiotaomicron, which blooms in response to amoxicillin, upregulated polysaccharide utilization. In vitro, we found that the sensitivity of this bacterium to amoxicillin was elevated by glucose and reduced by polysaccharides. Accordingly, we observed that dietary composition affected the abundance and expansion of B. thetaiotaomicron, as well as the extent of microbiome disruption with amoxicillin. Our work indicates that the metabolic environment of the microbiome plays a role in the response of this community to antibiotics.

Microbial Community Analysis of Sauerkraut Fermentation Reveals a Stable and Rapidly Established Community.

Despite recent interest in microbial communities of fermented foods, there has been little inquiry into the bacterial community dynamics of sauerkraut, one of the world’s oldest and most prevalent fermented foods. In this study, we utilize 16S rRNA amplicon sequencing to profile the microbial community of naturally fermented sauerkraut throughout the fermentation process while also analyzing the bacterial communities of the starting ingredients and the production environment. Our results indicate that the sauerkraut microbiome is rapidly established after fermentation begins and that the community is stable through fermentation and packaging for commercial sale. Our high-throughput analysis is in agreement with previous studies that utilized traditional microbiological assessments but expands the identified taxonomy. Additionally, we find that the microbial communities of the starting ingredients and the production facility environment exhibit low relative abundance of the lactic acid bacteria that dominate fermented sauerkraut.

The impact of vegan production on the kimchi microbiome.

Despite previous inquiry into the fermentative bacterial community of kimchi, there has been little insight into the impacts of starting ingredients on the establishment and dynamics of the microbial community. Recently some industrial producers have begun to utilize vegan production methods that omit fermented seafood ingredients. The community-level impacts of this change are unknown. In this study, we investigated the differences in the taxonomic composition of the microbial communities of non-vegan kimchi and vegan kimchi prepared through quick fermentation at room temperature. In addition to tracking the community dynamics over the fermentation process, we looked at the impact of the constituent ingredients and the production facility environment on the microbial community of fermenting kimchi. Our results indicate that the bacterial community of the prepared vegan product closely mirrors the progression and final structure of the non-vegan final product. We also found that room temperature-fermented kimchi differs minimally from more traditional cold-fermented kimchi. Finally, we found that the bacterial community of the starting ingredients show a low relative abundance of the lactic acid bacteria in fermented kimchi, whereas the production facility is dominated by these bacteria.

The salivary microbiome is consistent between subjects and resistant to impacts of short-term hospitalization.

In recent years, a growing amount of research has begun to focus on the oral microbiome due to its links with health and systemic disease. The oral microbiome has numerous advantages that make it particularly useful for clinical studies, including non-invasive collection, temporal stability, and lower complexity relative to other niches, such as the gut. Despite recent discoveries made in this area, it is unknown how the oral microbiome responds to short-term hospitalization. Previous studies have demonstrated that the gut microbiome is extremely sensitive to short-term hospitalization and that these changes are associated with significant morbidity and mortality. Here, we present a comprehensive pipeline for reliable bedside collection, sequencing, and analysis of the human salivary microbiome. We also develop a novel oral-specific mock community for pipeline validation. Using our methodology, we analyzed the salivary microbiomes of patients before and during hospitalization or azithromycin treatment to profile impacts on this community. Our findings indicate that azithromycin alters the diversity and taxonomic composition of the salivary microbiome; however, we also found that short-term hospitalization does not impact the richness or structure of this community, suggesting that the oral cavity may be less susceptible to dysbiosis during short-term hospitalization.