Idea Paper: Predicting culturability of microbes from population dynamics under field conditions

Isolation and cultivation of microbes from environmental samples have been fundamental and important for species identification and investigating functions and ecology of target microbes. While cultivation and isolation of microbes are not easy, the natural environment can \"culture\" any endemic microbes, and thus key information for culturing and isolating microbes may be encoded in the natural population dynamics of microbes. In this paper, I present the idea that culturability of microbes may be inferred by quantifying dynamics properties of microbes using nonlinear time series analytical tools. To briefly demonstrate the idea, I analyzed high-frequency, quantitative microbial time series obtained for artificial rice plots established at Kyoto University, Japan. I selected bacterial phyla that included sufficient numbers of microbial taxa, and analyzed 398 microbial taxa using empirical dynamic modeling. The nine phyla analyzed generally followed a similar pattern: many microbial taxa fell into the \"Simple\" dynamics category, and a small proportion of taxa were categorized in \"Simple but nonlinear\" or \"Nearly random\" dynamics categories. The present analysis suggested that many microbes in the study system might be cultivated by modifying a relatively small number of conditions. However, the present idea as well as the result is preliminary and premature, and more precise taxonomic information (i.e., species-level identification) and a culturability dataset will help to validate the idea. If the present idea was found to be valid, a priori evaluation of the culturability of microbes would become possible, which would avoid unnecessary costs (labor, time and money) of attempts to cultivate microbes.