Abstract: This invention relates to novel microorganisms separated from natural environments and purified and genetically modified, process for immobilizing these microorganisms by affixing then to substrates, the biocatalytic compositions formed by these microorganisms affixed to substrates, and the use of the biocatalytic compositions for the detoxification of toxin-polluted streams. The microorganisms are (1) Pseudomonas fluorescens (ATCC SD 904); (2) Pseudomonas fluorescens (ATCC SD 903); (3) Pseudomonas cepacia (ATCC SD 905); (4) Methylobacter rhodinum (ATCC 113-X); and (5) Methylobacter species (ATCC 16 138-X).