Biokinetic Constants of a Mixed Microbial Culture with Model Diesel Fuel

Abstract

ABSTRACT

The objective of this investigation was to determine the aerobic biokinetic constants for a mixed culture utilizing diesel fuel as a substrate. Bacterial strains capable of degrading diesel fuel were obtained for this study by enrichment culturing. These were identififed as Pseudomonas putida, Pseudomonas alcaligenes, Pseudomonas aeruginosa and Arthrobacter crystallopoietes.

Several substrate concentrations were monitored for utilization using 500 mL gas sampling bulbs containing minimal medium. These gas tight, batch vessels were used to determine biodegradation in a closed, aqueous system. The fuel was readily degraded with a maximum utilization rate of 0.75 hours-1. The maximum growth rate was 0.55 hours-1. The half saturation constant, Ks, was determined to be 81.22 mg/L. The cell yield was found to be 0.73 mg/L biomass as suspended solids produced per mg/L substrate as COD.

Growth of each of four bacterial isolates on BTX, n-dodecane, 1-tridecene, naphthalene and anthracene in minimal medium was investigated. The least substrate specificity was shown by Arthrobacter crystallopoietes and Pseudomonas putida. Naphthalene was the most readily degraded by all isolates.