Both carveol and carvone were effective in dispersing Rhodococcus erythropolis cells that were being stimulated to aggregate by the presence of organic solvents. The two terpenes influenced the fatty acid composition of the cell membrane, decreasing the percentage of fatty acids with more than 16 carbon atoms, and thus cell hydrophobicity, and also the degree of saturation of the fatty acids. In the presence of 250 μmol of terpene, the volume of biofilm was reduced by one third in comparison with biofilms in the absence of terpenes. The percentage of aggregated cells was also found to depend on carvone concentration during the bioconversion of carveol to carvone, in a membrane reactor. The extent of cell aggregation decreased from 90% to 10% when carvone concentration reached ca. 48 mM in the organic phase.