Jogia, W. | bioRxiv Science

bioRxiv2025

Sugar ABC transporter repertoires predict ecological dynamics in gut microbiome communities

The gut microbiome plays a central role in human health, but modern diets and lifestyles alter its composition. The microbial genomic traits that drive these ecological shifts, particularly in response to dietary sugars, remain poorly characterized. Here, we integrate a large dataset of longitudinal human diet-microbiome records and comparative genomics of human and murine gut isolates with in vitro and in vivo experiments to identify sugar ABC (ATP-binding cassette) transporters as key predictors of bacterial fitness and microbial community responses to dietary sugars. Strains encoding these transporters exhibit enhanced growth and consistently outcompete others in both monocultures and complex consortia across contexts. In gnotobiotic mice, dietary sugar supplementation selectively increases the expansion of sugar ABC transporter-positive bacteria, including the model gut pathobiont Escherichia coli. Systematic deletion of sugar transporter genes in E. coli revealed that a specific sugar ABC transporter gene was required to invade a model gut consortium, highlighting its importance in microbial competition. Together, these findings establish sugar ABC transporters as genomic predictors of microbial community dynamics in response to dietary sugars.

microbiology↗

bioRxiv2022

3D-printed capillaric ELISA-on-a-chip with aliquoting

Sandwich immunoassays such as the enzyme-linked immunosorbent assay (ELISA) have been miniaturized and performed in a lab-on-a-chip format, but the execution of the multiple assay steps typically requires a computer or complex peripherals. Recently, an ELISA for detecting antibodies was encoded structurally in a chip thanks to the microfluidic chain reaction but the need for precise pipetting and intolerance to commonly used surfactant concentrations limited the potential for broader adoption. Here, we introduce the ELISA-on-a-chip with aliquoting functionality that obviates the need for precise pipetting, accommodates higher surfactant concentrations, includes barrier channels that delay the contact between solutions and prevent undesired mixing, and that executed a quantitative, high sensitivity assay for the SARS-CoV-2 nucleocapsid protein in 4x-diluted saliva. Upon loading the chip using disposable pipettes, capillary flow draws each reagent and the sample into a separate volumetric measuring reservoir for detection antibody (70 {micro}L), enzyme conjugate (50 {micro}L), substrate (80 {micro}L), and sample (210 {micro}L), and splits washing buffer into 4 different reservoirs of 40, 40, 60, and 20 {micro}L. The excess volume is autonomously drained via a structurally encoded capillaric aliquoting circuit, creating aliquots with an accuracy of >93%. Next, the user click-connects the assay module, comprising a nitrocellulose membrane with immobilized capture antibodies and a capillary pump, to the chip which triggers the step-by-step, timed flow of all aliquoted solutions. A colored precipitate forming a line on a nitrocellulose strip serves as an assay readout, and upon digitization, yielded a binding curve with a limit of detection of 54 and 91 pg/mL for buffer and diluted saliva respectively, vastly outperforming rapid tests. The ELISA chip is 3D-printed, modular, adaptable to other targets and assays, and could be used to automate ELISA in the lab; or as a diagnostic test at the point of care with the convenience and form factor of rapid tests while preserving the protocol and performance of central laboratory ELISA.

bioengineering↗