We present a miniaturized, free-floating monitoring system which makes use of electron transfer in Shewanella oneidensis sequestered behind a permeable membrane while maintaining diffusive contact with the environment, allowing for sensing environmental conditions. The system makes use of a commercial off-the-shelf (COTS) integrated circuit (IC) which sets a potential between a working electrode and a Ag/AgCl reference electrode while recording the resulting current from the electroactive cells. We successfully sensed both pyruvate and the environmental presence of E. coli via changes in the currents sensed. This work will enable the development of mobile aquatic sensing systems which make use of bacterial electron transfer as a transduction method. Further miniaturization of the recording mote, electrodes, packaging, and system is discussed.