Biofilm streamer growth dynamics in various microfluidic channels

Biofilms are microbial colonies that are encapsulated in extracellular polymers secreted by cells through their proliferation and differentiation. Biofilms exist on solid surfaces, liquid surfaces, or in liquid media, where the growth of the bacterial biofilm is closely related to the velocity of the secondary flow, main flow, and geometry of the channel, which are difficult to measure in a natural fluid environment, making the study of the biofilm streamer growth process difficult. In this study, we used microfluidic channels made of polydimethylsiloxane to study the growth dynamics of Bacillus subtilis biofilm streamers. We observed that the biofilm streamer growth undergoes three stages with different growth characteristics. First, we found that the initial growth of the streamer is located at the position with the maximum value of P = secondary flow velocity × main flow velocity. Second, the biofilm underwent floating growth around the microcolumn obstacle. After the transition stage, the last growth stage includes two types because of the different attachment strengths and mechanical properties of the biofilm. Our research provides new insights into the formation and shedding of biofilm streamers in natural and industrial environments and helps us to better understand biofilm growth in fluid flow.