Biodegradation of 2-methylisoborneol by enzyme separated from Pseudomonas mandelii

As a kind of odorous substance, 2-methylisoborneol (2-MIB) is difficult to be degraded naturally. Some isolated strains of bacteria can degrade 2-MIB effectively. In this study, a strain of bacteria which can remove 2-MIB from drinking water efficiently was obtained from activated carbon in a filter, and was identified to be Pseudomonas mandelii based on 16S rRNA gene sequence analysis. Pseudomonas mandelii was not sensitive to the initial concentration of 2-MIB, and could tolerate a rather high concentration of 2-MIB. The best growth conditions for this degrader were 25-35 degrees C and initial pH of 7. The concentration of 2-MIB in mineral salt medium was reduced from 2 mg/L to 471.9 mu g/L by Pseudomonas mandelii in 20 d after incubation. Nineteen bands of degrading enzyme were isolated from Pseudomonas mandelii, one of which was identified as a NAD-dependent dehydratase. It was found that 2-methyl-2-bornene was the metabolite in the presence of both the Pseudomonas mandelii and the isolated enzymes, indicating that NAD-dependent dehydratase might be involved in the biodegradation process or cooperate with other enzymes in the metabolic process to complete the dehydration process of 2-MIB.