Corrinoids as model nutrients to probe microbial interactions in a soil ecosystem
- Univ. of California, Berkeley, CA (United States)
Soil not only represents the physical surface of the earth, but is also a habitat for thousands of species of microorganisms. Numerous species of bacteria and other microbes collectively form communities that benefit their survival. As communities, microbes have outsized impacts: soil microbial communities are major drivers of the cycling of carbon, nitrogen, and other elements of life. Soil is also a major site of carbon storage for the planet, and patterns of carbon sequestration and release are being altered by climate change. For all of these reasons, generating a more complete understanding of how the microbes in soil communities act together to impact earth’s processes is critical. Yet studying soil microbial communities is challenging because they contain many diverse species, and the heterogeneity and particulate nature of soil makes it difficult to work with compared to other systems. At the heart of microbial community function is the invisible exchange of millions of different types of molecules produced and chemically altered by the resident microbes. These metabolic exchanges are critical because microbes rely on each other to fulfill their nutritional needs. An example of a nutrient that is produced by a subset of microbes and required by others is vitamin B12. Like humans, many microbes require vitamin B12 for life and must acquire it from external sources. In microbial ecosystems, molecules related to B12 – collectively called corrinoids – also exist, and different forms are required by different microbes. This research focuses on corrinoids as a way to study how microbes in soil interact by sharing nutrients and how soil microbial communities respond to nutritional interventions. We discovered that soil from a California grassland field site contains a surprisingly high amount of corrinoids, with B12 representing over 95% of the corrinoids present, in contrast to other environments, which have a larger number of different corrinoids but often in lower abundance. We found that the corrinoids in soil are strongly adhered to the soil particles, and thus it is not yet clear how much corrinoid is accessible to the microbes in soil. We found that adding different corrinoids to soil samples and to laboratory communities derived from soil significantly changes the bacterial composition of the community, but the effect is transient, indicating the community has the ability to recover from a substantial perturbation. Additionally, to investigate how corrinoids are produced and shared among soil community members, we cultured individual bacteria taken from soil and measured the amount of corrinoid produced or required. We found that a small fraction of the bacteria produces large amounts of corrinoid at levels sufficient to support the growth of many other community members when cultured in the laboratory. Together, this research has established that studying corrinoids in soil microbial communities can reveal important insights into soil microbial ecology. The characterization of corrinoid production and dependence in isolated soil bacteria identifies specific ecological functions for key members of the complex soil microbiome. Further, our finding that corrinoids can alter community structure suggest that treatment with a biological small molecule such as corrinoids could be developed to alter microbial communities for desired applications.
- Research Organization:
- Univ. of California, Oakland, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Biological and Environmental Research (BER)
- DOE Contract Number:
- SC0020155
- OSTI ID:
- 2281020
- Report Number(s):
- DE-SC0020155
- Country of Publication:
- United States
- Language:
- English
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