Succession mechanism of microbial community with high species diversity in nutrient-deficient environments with low-dose ionizing radiation

•New hypothesis on forming and maintenance of microbial diversity in LDIR environment.•Highly valid models developed to depict microbial community succession with LDIR.•Computer-generated microbial species by Monte Carlo simulation.•Feedback regulation of populations by mutual promotion and restraint mechanisms.•Asynchronously convergent fluctuations of populations greatly reduce competitions. It remains a mystery why microbial community succession can violate the competitive exclusion principle to form high species diversity in nutrient-deficient environments (NDE) with low-dose ionizing radiation (LDIR). In this research, artificial microbial communities containing three common strains downloaded from China Tiangong-1 space station were cultivated in NDE with and without LDIR, respectively. By comparing their identities and differences in cellular phenotype, extracellular pH, intracellular triglycerides and population dynamics under the two circumstances, a new hypothesis was put forward from observed phenomena and experimental data to expound new interspecific relationships and interactions induced by LDIR to produce new dynamic mechanisms to drive microbial community succession with high species diversity. A set of highly valid kinetic models was then developed from this hypothesis, and finally, the hypothesis proposed was verified through a large number of digital simulations. The results show that induced by LDIR, specific feedback regulation of microbial populations by mutual promotion and restraint mechanisms might exist in microbial communities, which can cause asynchronous convergent fluctuations of microbial populations. These fluctuations remarkably alleviate interspecific competition and inhibit the emergence of dominant species, leading to the formation and maintenance of higher species diversity. The results can provide a theoretical basis for understanding the ecological effect of LDIR on microbial communities in NDE as well as its application for ecological engineering purposes.