Preservation of Uncultivated Microbial Cells for Single Cell Genomics and Cultivation in Future

Microbes have conventionally been studied in pure culture obtained on culture media in the laboratory. With very limited media options at the disposal of a microbiologist as compared to the vast diversity of microbes that are known to exist, it is not surprising that only about 1-10% of them have been cultivated so far [1]. However, since microbes are the key components of every process on the planet, the cultivation of these as-yet-uncultivated microbes and the conservation of microbial diversity is the current research priority of the world for sustainable environment and Earth. Metagenomic studies prove beyond doubt that the vast majority of this yet-uncultivated microbial diversity inhabiting our planet has immense medical, agricultural, environmental and industrial potential. In order to utilize this hidden potential, cultivation and appropriate preservation of the source material is the only viable option. Driven by this fact, microbiologists have started seeking these yet-uncultivated microbes using high-throughput approaches of microbial cultivation giving rise to what is now known as culturomics [2]. While culturing was rampant during the infancy of microbiology, the recent rebirth of culturomics has successfully brought some previously uncultured microbes into the laboratory through innovative strategies. Many of these involved the use of different carbon sources and/or electron acceptors in the medium, extended incubation in a wide range of pH and temperature conditions, and growth in laboratory conditions that mimic the natural environment, such as in diffusion chambers or attached to carriers [3]. However, it is still a big challenge to cultivate all sorts of organisms and preserve them in culture collections for future use and study [4]. The availability of a live culture will supplement the information made available from metagenomics studies on the physiology, functionality and industrial applications of the organism. Although culturomics is time consuming and labour intensive, it has raised the hope that with careful design of culture media and cultivation conditions it is possible to bring the asyet-uncultivated microbes in culture for their study and exploitation.