title: Productive chemical interaction between a bacterial microcolony couple is enhanced by periodic relocation.
abstract: This paper describes a system to study how small physical perturbations can affect bacterial community behavior in unexpected ways through modulation of diffusion and convective transport of chemical communication molecules and resources. A culture environment that mimics the chemically open characteristic of natural bacterial habitats but with user-defined spatiotemporal control of bacteria microcolonies is realized through use of an aqueous two phase system (ATPS). The ATPS is formulated with nontoxic dextran (DEX) and poly(ethylene glycol) (PEG) dissolved in cell culture media. DEX-phase droplets formed within a bulk PEG-phase stably confine the bacteria within it while small molecules diffuse relatively freely. Bacteria-containing DEX droplets can also be magnetically relocated, without loss of its bacterial content, when DEX-conjugated magnetic particles are included. We found that decreasing the distance between quorum-sensing (QS)-coupled microcolonies increased green fluorescent protein (GFP) expression due to increased inter-colony chemical communication but with upper limits. Periodic relocation of the chemical signal receiver colony, however, increased GFP expression beyond these typical bounds predicted by quorum sensing concepts alone by maintaining inter-colony chemical communication while also relieving the colony of short-range resource depletion effects. Computer simulations suggest that such increased productive output in response to periodic nonlethal physical perturbations is a common feature of chemically activated interactive cell systems where there is also a short-range inhibitory effect. In addition to providing insights on the effect of bacteria relocation, the magnetic ATPS droplet manipulation capability should be broadly useful for bioanalyses applications where selective partitioning at the microscale in fully aqueous conditions is needed.
authors: School of Nano-Bioscience and Chemical Engineering, Ulsan National Institute of Science and Technology, Republic of Korea.
authors: Chang Kyu
authors: CK
authors: Byun
authors: Hyundoo
authors: H
authors: Hwang
authors: Woon Sun
authors: WS
authors: Choi
authors: Toshiyuki
authors: T
authors: Yaguchi
authors: Jiwoon
authors: J
authors: Park
authors: Dasol
authors: D
authors: Kim
authors: Robert J
authors: RJ
authors: Mitchell
authors: Taesung
authors: T
authors: Kim
authors: Yoon-Kyoung
authors: YK
authors: Cho
authors: Shuichi
authors: S
authors: Takayama
mesh_terms: D001431:Bacteriological Techniques; D003911:Dextrans / Q000737:chemistry; D004926:Escherichia coli / Q000166:cytology* / Q000254:growth & development / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000096:biosynthesis / Q000737:chemistry; D056004:Molecular Dynamics Simulation; D011092:Polyethylene Glycols / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D003911:Dextrans; D014867:Water; D049452:Green Fluorescent Proteins; D011092:Polyethylene Glycols