Biodegradation of 2-methoxyethanol under aerobic conditions by bacterial isolate pseudomonas sp. Strain VB

Abstract

Four bacterial isolates from four different environmental samples (agricultural soil, compost soil and sewage sludge-anaerobic and aerobic wastewaters) were screened for their ability to mineralize 2-methoxyethanol under aerobic conditions. Isolate from anaerobic sewage wastewater was most efficient with an average of 48.6mmol/day mineralisation capacity. Morphological, physiological, biochemical and molecular characterization of the isolate showed that the strain, designated VB is of the genus Pseudomonas. 16S rRNA sequence analysis showed that the organism is related to Pseudomonas putida at 99.9% and Pseudomonas plecoglossicida at 99.8% similarity level. It is related to members of the genus Pseudomomas belonging to the rRNA group 1 within the gamma (γ) Proteobacteria. The G+C content 64.5±0.8mol% is within the range characteristic of the genus Pseudomonas. In a time course experiment Pseudomonas sp. strain VB was grown in 2-methoxyethanol, ethylene glycol, glycollate, glyoxylate, oxalate and methanol. Strain VB was able to utilize all proposed intermediates except methanol. Comparable growth characteristics of Pseudomonas sp. strain VB grown in 2-methoxyethanol and proposed intermediates showed significant molar growth yields. These results indicate that ethylene glycol, glycollate, glyoxylate and oxalate might be intermediates in the degradation pathway of 2-methoxyethanol. Thus a reaction sequence: 2-methoxyethanol → ethylene glycol → glycollate → glyoxylate → oxalate is been proposed in this study.