Combined application of bacterial predation and carbon dioxide aerosols to effectively remove biofilms

This study evaluated predation with Bdellovibrio bacteriovorous and CO2 aerosol spraying to remove fluorescent Escherichia coli biofilms from silicon chips. Initial tests found that 7.5 x 10(5) viable E. coli cells were dispersed into the surrounding environment during aerosol treatment. The total number dispersed per test decreased to only 16 for predated biofilms. This is nearly 50,000-fold lower compared to untreated chips and 1000-fold lower compared to chips soaked in HEPES buffer only. Both scanning electron microscopy (SEM) and fluorescent microscopy analyses confirmed that predation alone did not completely eradicate the biofilm population. When used in conjunction with CO2 aerosols, however, no fluorescent signals remained and the SEM pictures showed a pristine surface devoid of bacteria. Consequently, this study demonstrates these two methods can be used with each other to significantly remove biofilms from surfaces while also significantly reducing the likelihood of human exposure to potential pathogens during their removal.