Quantitative analysis of the growth of individual Bacillus coagulans cells by microdroplet technology

Abstract

Background

Cellular physiological responses, which are often obscured by inferences from population-level data, are of great importance in cell biology. Microfluidics has emerged as an important tool for biological research on a small scale, reaching even the single-cell level.

Results

In this work, a flow-focusing microdroplet generator was developed to produce monodisperse microdroplets with high stability. Individual B. coagulans cells were encapsulated in the microdroplets and cultured offline. The specific growth rate of B. coagulans at the single-cell level was analyzed, and the growth of B. coagulans in the droplets showed good consistency with that in flasks, with a correlation coefficient of 0.98. The morphological heterogeneity and its potential relationship with the production of lactic acid by B. coagulans were evaluated using a microscopic imaging method.

Conclusion

We have demonstrated a single-cell monitoring methodology based on microdroplets. This approach has great potential for studying a range of behavioral and physiological features of bacteria at the single-cell level.

Keywords

Bacillus coagulans / Microdroplets / Morphological heterogeneity / Single cell

References

[1] Abalde-Cela S, Gould A, Liu X, Kazamia E, Smith AG, Abell C. High-throughput detection of ethanol-producing cyanobacteria in a microdroplet platform. J R Soc Interface, 2015, 12(106): 0216.

[2] Abdel-Rahman MA, Tashiro Y, Sonomoto K. Recent advances in lactic acid production by microbial fermentation processes. Biotechnol Adv, 2013, 31(6): 877-902.

[3] Falconnet D, Niemistoe A, Taylor RJ, Ricicova M, Galitski T, Shmulevich I, Hansen CL. High-throughput tracking of single yeast cells in a microfluidic imaging matrix. Lab Chip, 2011, 11(3): 466-473.

[4] Hosokawa M, Hoshino Y, Nishikawa Y, Hirose T, Yoon DH, Mori T, Sekiguchi T, Shoji S, Takeyama H. Droplet-based microfluidics for high-throughput screening of a metagenomic library for isolation of microbial enzymes. Biosens Bioelectron, 2015, 67: 379-385.

[5] Jakiela S, Kaminski TS, Cybulski O, Weibel DB, Garstecki P. Bacterial growth and adaptation in microdroplet chemostats. Angew Chem Int Ed, 2013, 52(34): 8908-8911.

[6] Kim HS, Devarenne TP, Han A. A high-throughput microfluidic single-cell screening platform capable of selective cell extraction. Lab Chip, 2015, 15(11): 2467-2475.

[7] Lim SW, Abate AR. Ultrahigh-throughput sorting of microfluidic drops with flow cytometry. Lab Chip, 2013, 13(23): 4563-4572.

[8] Maerkl SJ. Integration column: microfluidic high-throughput screening. Integr Biol, 2009, 1(1): 19-29.

[9] Shen HH, Tsai HY, Yao DJ. Single mouse oocyte encapsulated in medium-in-oil microdroplets by using a polydimethylsiloxane microfluidic device. Sensors Mater, 2014, 26(2): 85-94.

[10] Yu JQ, Chin LK, Lei L, Lin ZP, Ser W, Chen H, Ayi TC, Yap PH, Chen CH, Liu AQ. Droplet optofluidic imaging for lambda-bacteriophage detection via co-culture with host cell Escherichia coli. Lab Chip, 2014, 14(18): 3519-3524.

Funding

National Science Foundation for Young Scientists of China(31700038)

National Key Research and Development Program(2017YFB0309302)