Effects of microbial colonisation of porous media on resistance to potentially inhibitory chemical challenges

Microbial resistance to inhibitory or toxic substances and their concentrat ions in soil and porous media are often ascribed to adsorption effects of b oth chemicals and microorganisms. In this study, the effects of pore coloni sation on microbial resistance to, and recovery from, inimical chemical cha llenges were investigated. Three experimental porous media were used. One c ontained particles with intra-particle pores, one had no such pores, while a third was a mixture of the two. The microbial colonisation of the intra-p article pores by a phenol-catabolising microbial association effected resis tance to inhibitory concentrations of cadmium cations and acetonitrile in c omparison with homogeneous (i.e. absence of porous media) cultures. Recover y, following removal of bacteriostatic concentrations, was more rapid in th e presence of porous media. Breakthrough curves of retained (cadmium) and n on-retained (phenol) compounds were significantly influenced by microbial g rowth within the porous media. The curves identified different stages of bi ofilm development and may be used to predict porosity reduction due to micr obial growth.