The Envirostat – a new bioreactor concept

Abstract

One major goal of biology is to provide a quantitative description of cellular physiology. This task is complicated by population effects, which perturb culture conditions and mask the behavior of the individual cell. To overcome these limitations, the construction and operation of a microfluidic bioreactor is presented. The new reactor concept guarantees constant environmental conditions and single cell resolution, thus it was named Envirostat (environment, constant). In the Envirostat, cells are contactless trapped by negative dielectrophoresis (nDEP) and cultivated in a constant medium flow. To control chip temperature, a Peltier device was constructed. Joule heating by nDEP was quantified with Rhodamine B in dependence of applied voltage, field mode, medium conductivity, and flow velocity. The integration of the Joule heating effect in the temperature control allowed setting and maintaining the cultivation temperature. For single cell cultivation of Saccharomyces cerevisiae, medium composition changes below 0.001% were estimated by computational fluid dynamic simulation. These changes were considered not to influence cell physiology. Finally, single S. cerevisiae cells were cultivated for more than four generations in the Envirostat, thus showing the applicability of the new reactor concept. The Envirostat facilitates single cell research and might simplify the investigation of hitherto difficult to access biological phenomena such as the true regulatory and physiological response to genetic and environmental perturbations.

A disposable picolitre bioreactor for cultivation and investigation of industrially relevant bacteria on the single cell level

“…27 Kortmann et al used elaborate dielectrophoretic (DEP) trapping to determine growth rates of single yeast cells and bacteria cells. 21 Walden et al developed parallel trapping regions for bacteria cultivation of up to 300 cells in a monolayer. 28 The latter allows for population heterogeneity analysis of larger bacterial microcolonies.…”

“…19 Secondly, microfluidic devices for biotechnological single cell studies including, e.g., phenotypic population heterogeneity 20 and single cell growth. 20,21 Our intention is a combination of both approaches, to be specific, a microfluidic device allowing environmental reactor control at a defined culture volume and continuous single cell observation simultaneously.…”

Fabrication of Microstructures Embedding Controllable Particles inside Dielectrophoretic Microfluidic Devices

“… represents n-DEP response and the particle moves towards the part of the electric field with lower intensity [27].…”

Magnetophoretic circuits for digital control of single particles and cells

“…The desired capabilities of single-cell arrays bear strong resemblance to random access memory (RAM) computer chips, including the ability to introduce and retrieve single cells from precise locations of the chip (writing data), and query the biological state of specified cells at future time points (reading data). Existing particle handling tools based on hydrodynamic 8-11 , optic 12-18 , electric [19][20][21][22] and magnetic [23][24][25][26][27][28][29][30][31][32][33][34][35][36] trapping forces can achieve parts of this desired functionality; however, no single technique to our knowledge encompasses the scalability, flexibility and automation that allows single-cell chips to perform with the level of integration of computer circuits.Our approach has significant similarities with magnetic bubble memory technology 37 , which was originally developed to store memory and implement logic through the precise manipulation of 'magnetization bubbles' in iron garnet films. Previous works demonstrated that magnetization bubbles could be moved along specific tracks and into desired storage locations by controlling the electrical and magnetic circuitry patterned on top of the garnet films.…”

“…The desired capabilities of single-cell arrays bear strong resemblance to random access memory (RAM) computer chips, including the ability to introduce and retrieve single cells from precise locations of the chip (writing data), and query the biological state of specified cells at future time points (reading data). Existing particle handling tools based on hydrodynamic [8][9][10][11] , optic [12][13][14][15][16][17][18] , electric [19][20][21][22] and magnetic [23][24][25][26][27][28][29][30][31][32][33][34][35][36] trapping forces can achieve parts of this desired functionality; however, no single technique to our knowledge encompasses the scalability, flexibility and automation that allows single-cell chips to perform with the level of integration of computer circuits.…”