Toward Real-Time Determination of Yield Coefficients of Early-Stage Electroactive Biofilms by Optical Microscopy

Physiological cellular parameters, such as latency times (lagt), cell production rates (CPR), doubling times (t(d)), relative growth rates (RGR), and yield coefficients (Y-Ne), are only known as endpoint measurements for electroactive microorganisms (EAM). Here we show that these can be gained non-invasively and in real-time for early-stage biofilm formation at electrodes using a microfluidic electrochemical flow-cell (EFC) allowing in vivo optical microscopy. Parameters obtained for early-stage mixed culture biofilm anodes formed at +150 mV vs. Ag/AgCl sat. KCl have lagt of 2.31-4.58 days, CPR of 0.72-1.20 x 10(5) cells h(-1), t(d) of 176.54-1838.65 min, RGR of 0.02-0.27 h(-1), and Y-Ne of 5.99-7.94 x 10(12) cells mol(e-)(-1). However, oxygen permeation into the EFC was the main problem that remained unsolved during the study that provides interesting lessons for future improvements.