Cholera outbreaks may be mitigated by monitoring drinking waters for the bacterial disease agent, Vibrio cholerae. However, present microbial methods for V. cholerae require advanced training and specialized equipment, limiting their use in low-resource settings that are most vulnerable to cholera outbreaks. We hypothesized that we could simplify sample analysis through one-step liquid culture-based quantification of V. cholerae. In this study, we evaluated selective culture media for V. cholerae that could be adapted for culture and quantification of the organism in liquid samples using a most probable number (MPN) format. We evaluated previously described and newly derived selective V. cholerae broth culture media for exclusivity against non-target organisms and for productivity in culturing representative V. cholerae strains, including O1 El Tor Ogawa, O139, and non-O1. Among previously described media, CHROMagar Vibrio and taurocholate tellurite-based media demonstrated the best balance of exclusivity and productivity in broth format, although productivity varied by V. cholerae strain. Newly proposed formulations improved exclusivity in some cases, particularly with the addition of the antibiotics fosfomycin and streptomycin. Overall, these results demonstrate the promise of selective broth media for one-step liquid-based culture of Vibrio cholerae under laboratory conditions, but further optimization is necessary prior to implementation with complex water samples and field deployment.

Background: Built environments function as hubs of microbial exchange, and kitchens serve as key sites for interaction between occupants and physical surfaces. Understanding how spatial connectivity and regional variation influence bacterial and fungal colonization on kitchen surfaces is relevant to the protection of human health and food safety. Here, we applied long-read 16S rRNA and ITS amplicon sequencing to samples collected from countertops, drain holes, and faucet spouts (n = 123) in 41 residential kitchens across two counties in North Carolina, USA to quantify variation in microbial community structure across multiple spatial scales. Results: We found lower taxonomic resolution for bacteria than for fungi, with species-level assignments representing ~ 30% of bacterial reads and ~ 88% of fungal reads. Community structure was driven primarily by kitchen identity (45% of bacterial and 37% of fungal variation), with ZIP code, surface type and county each explaining smaller, yet significant, proportions of the observed variation. Countertops exhibited the highest bacterial and fungal diversity, whereas drain holes and faucet spouts were dominated by taxa including Pseudomonas , Acinetobacter , Penicillium , and Candida . Targeted taxonomic screening identified Stenotrophomonas maltophilia , Acinetobacter junii , Aspergillus fumigatus , and Penicillium brevicompactum , indicating that sink surfaces can harbor opportunistic taxa associated with infections in immunocompromised individuals. Conclusions: Our findings demonstrate that kitchen identity signatures dominate microbial community structure, with moisture-retaining surfaces acting as key niches. This multi-scale structuring supports the framework that indoor microbiomes are seeded by outdoor inputs but structured by human occupancy.