Laser induced isolation and cultivation of single microbial cells

Single cell isolation and cultivation play an important role in studying physiology, gene expression and functions of microorganisms. Laser Induced Forward Transfer Technique (LIFT) has been applied to isolate single cells but the cell viability after sorting is unclear. We demonstrate that a three-layer LIFT system could be applied to isolate single cells of Gram-negative (E. coli), Gram-positive (Lactobacillus rhamnosus GG, LGG), and eukaryotic microorganisms (Saccharomyces cerevisiae) and the sorted single cells were able to be cultured. The experiment results showed that the average cultivation recovery rate of the ejected single cells were 58% for Saccharomyces cerevisiae, 22% for E. coli, and 74% for Lactobacillus rhamnosus GG (LGG). The identities of the cultured cells from single cell sorting were confirmed by using colony PCR with 16S-rRNA for bacteria and large unit rRNA for yeast and subsequent sequencing. This precise sorting and cultivation technique of live single microbial cells can be coupled with other microscopic approaches (e.g. fluorescent and Raman microscopy) to culture single microorganisms with specific functions, revealing their roles in the natural community.