A Microfluidic Oxygen Gradient Generator for the Study of Aerotropism in Hyphae of Oomycetes

This paper reports a microfluidic platform that enables the study of aerotropism in hyphal microorganisms, such as fungi and oomycetes. While oxygen concentration is likely a key factor influencing the direction of growth of these organisms, how they sense and respond to O
2
is poorly understood. Our device generates O
2
gradients in a central growth channel in which hyphae have been inoculated. The gradient is generated via diffusion of gas through gas-permeable polydimethylsiloxane from two adjacent channels running in parallel to the growth channel. The resulting O
2
gradient perpendicular to the axis of growth is monitored via an integrated fluorescent sensor film. Our results show that the device enables hyphal growth, that the directionality of growth can be characterized and that hyphae of the oomycete Achlya bisexualis tend to grow away from low O
2
.