Evaluation on the Efficacy of Formulated Pseudomonas Cells in Degrading the Aromatic Hydrocarbon Toluene

In this study, the hydrocarbon-degrading bacterium Pseudomonas spp. isolate UTAR EPA2 was formulated with various combinations of formulative materials, comprising of clay-based carrier materials (bentonite (B) and kaolin (K)), enrichment materials (non-fat skimmed milk (N) and sucrose (S)), and a UV-protectant agent (para-aminobenzoic acid (P)). The efficacy of the formulated cells in degrading the aromatic hydrocarbon toluene (methylbenzene) and their subsequent cell viability after exposure to sunlight (natural UV irradiation) were investigated. Results indicated that degradation efficacy was slightly higher for kaolin-based formulated cells compared to bentonite-based formulations, especially after exposure to sunlight, although their percentages of degradation were not statistically different. Nevertheless, kaolin-based formulations have very low viable cell count especially in formulations with P (KP, KNP, KSP, KNSP). This suggested that aside from viable cells, the physical properties of the clays could have also contributed to the degradation of toluene. For storage purposes and applications in the field, we suggest that the bacterium is formulated with bentonite-based formulations especially using bentonite (B) clay singly, as relatively high percentage of toluene degradation and viable cell count was achieved with this formulation