Linking bacterial colony growth dynamics to indoor environments

Bacteria are widely distributed in indoor environments, yet their growth behavior and ecological differentiation remain insufficiently understood. As a pilot study, how nutritional richness influences the colony growth dynamics of indoor culturable bacteria was quantitatively analyzed. Whether microbial growth characteristics can serve as ecological indicators for classifying indoor environments was also explored. Samples were collected from a variety of indoor object surfaces representing different types and functional areas, and cultured on agar media with a variety of concentrations of LB to simulate nutrient gradients. The growth of culturable bacteria was quantitatively evaluated using multiple parameters, followed by clustering analyses based on nutrient-response profiles and growth dynamics. Distinct grouping patterns of bacterial growth behavior were observed, suggesting that variations in environmental conditions, surface materials, and possibly human-associated factors shape microbial growth strategies across indoor surfaces. Although the overall trends were stable across nutrient levels, the differentiation among clusters implied varying adaptive capacities of bacterial populations under nutrient limitation or enrichment. These findings highlight that microbial growth dynamics can reflect underlying ecological and physicochemical conditions of the indoor environment. This study provides a preliminary but quantitative framework for linking microbial growth to environmental characteristics. It indicates that bacterial proliferation potential may serve as an indicator for assessing indoor ecological states, surface susceptibility to contamination, and overall microbial resilience within human-occupied environments.