The passive sampling hypothesis is one of the most important hypotheses used to explain the mechanism of species–area relationships (SAR) formation. This hypothesis has not yet been experimentally validated due to the confusion between passive sampling (a larger area may support more colonists when fully sampled) and sampling effects (more sampling effort will result in increased species richness when sampling is partial). In this study, we created an open microcosm system with homogeneous habitat, consistent total resources, and biodiversity background using Chinese paocai soup, a fermented vegetable, as a substrate. We made efforts to entirely exclude the influence of sampling effects and to exclusively obtain microorganisms from dispersal using microcosm and high‐throughput sequencing techniques. However, in this study, passive sampling based on dispersal failed to shape SAR, and community differences were predominantly caused by species replacement, with only minor contributions from richness differences. Ecological processes including extinction and competitive exclusion, as well as underlying factors like temporal scales and the small island effects, are very likely to have been involved in the studied system. To elucidate the mechanism of SAR development, future studies should design experiments to validate the involvement of dispersal independently.

High body mass index (high BMI, obesity) is a serious public health problem, and “obesity‐induced oxidative stress, inflammation, and cancer” have become modern epidemic diseases. We carried out this study to explore a functional beverage that may protect against obesity‐induced diseases. The Engleromyces goetzei Henn herbal tea is such a candidate. For this study, we carried out LC–MS analysis of E. goetzei Henn aqueous extract (EgH‐AE); then used the Caco‐2 cell line for the model cells and treated the cells with t‐BHP to form an oxidative stress system. An MTT assay was used for testing the biocompatibility and cytoprotective effects; reactive oxygen species and malondialdehyde determination was used for evaluating the antioxidative stress effect; TNF‐α and IL‐1β were used for observing the anti‐inflammatory effect, and 8‐OHdG for monitoring anticancer activity. The results of this study demonstrate that the EgH‐AE has very good biocompatibility with the Caco‐2 cell line and has good cytoprotective, antioxidant, anti‐inflammatory, and anticancer properties. It is clear that EgH‐AE, a kind of ancient herbal tea, may be used to develop a functional beverage that can be given to people with a high BMI to protect against obesity‐induced diseases.