AEROBIC BIODEGRADATION OF SELECTED MONOTERPENES

Batch experiments were conducted to assess the biotransformation poten tial of four hydrocarbon monoterpenes (d-limonene, alpha-pinene, gamma -terpinene, and terpinolene) and four alcohols (arbanol, linalool, pli nol, and alpha-terpineol) under aerobic conditions at 23 degrees C. Bo th forest-soil extract and enriched cultures were used as inocula for the biodegradation experiments conducted first without, then with prio r microbial acclimation to the monoterpenes tested. All four hydrocarb ons and two alcohols were readily degraded. The increase in biomass an d headspace CO2 concentrations paralleled the depletion of monoterpene s, thus confirming that terpene disappearance was the result of biodeg radation accompanied by microbial growth and mineralization. Plinol re sisted degradation in assays using inocula from diverse sources, while arbanol degraded very slowly. A significant fraction of d-limonene-de rived carbon was accounted for as non-extractable, dissolved organic c arbon, whereas terpineol exhibited a much higher degree of utilization . The rate and extent of monoterpene biodegradation were not significa ntly affected by the presence of dissolved natural organic matter.