Abstract
In this study, we demonstrated the label-free continuous separation and enrichment of Bacillus subtilis populations based on length using viscoelastic microfluidics. B. subtilis, a gram-positive, rod-shaped bacterium, has been widely used as a model organism and an industrial workhorse. B. subtilis can be arranged in different morphological forms, such as single rods, chains, and clumps, which reflect differences in cell types, phases of growth, genetic variation, and changing environmental factors. The ability to prepare B. subtilis populations with a uniform length is important for basic biological studies and efficient industrial applications. Here, we systematically investigated how flow rate ratio, poly(ethylene oxide) (PEO) concentration, and channel length affected the length-based separation of B. subtilis cells. The lateral positions of B. subtilis cells with varying morphologies in a straight rectangular microchannel were found to be dependent on cell length under the co-flow of viscoelastic and Newtonian fluids. Finally, we evaluated the ability of the viscoelastic microfluidic device to separate the two groups of B. subtilis cells by length (i.e., 1–5 μm and >5 μm) in terms of extraction purity (EP), extraction yield (EY), and enrichment factor (EF) and confirmed that the device could separate heterogeneous populations of bacteria using elasto-inertial effects.
Highlights
Bacillus subtilis is a model gram-positive, rod-shaped bacterium commonly found in soil and the gastrointestinal (GI) tract of ruminants and humans
The viscoelastic microfluidic device for the length-based separation of B. subtilis cells used in our experiment has four main elements: two inlets, a straight rectangular microchannel, an expansion region, and seven outlets
Longer B. subtilis cells penetrated the interface and migrated to the channel center faster than the shorter B. subtilis cells that were intercepted by the interface, resulting in different lateral positions of B. subtilis cells that were dependent on cell length
Summary
Bacillus subtilis is a model gram-positive, rod-shaped bacterium commonly found in soil and the gastrointestinal (GI) tract of ruminants and humans It is generally recognized as safe (GRAS) by the US Food and Drug Administration (FDA) and widely used as a cell factory for the industrial production of heterologous proteins, pharmaceuticals, and functional biomaterials due to its propensity for genetic manipulation and ease of culture[1]. B. subtilis populations typically exhibit numerous cellular arrangements, such as single rods, chains of varying length connected by uncleaved septal wall material, sporulating cells, and biofilms comprised of matrixproducing cells These heterogeneous cell states depend on various factors, such as the individual cell properties, the phase of growth, genetic variations, and environmental stressors[4,5,6].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
