An improved test for the evaluation of hydrocarbon degradation capacities of diesel-contaminating microorganisms. (April 2018) - Martin-Sanchez, Pedro M.
Abstract: The development of a test to evaluate the degradation of semi-volatile fuels as diesel by microorganisms is presented. This method is based on the principles described in the CEC-L-103 standard procedure that is exclusively meant for testing the biodegradability of non-volatile lubricants. Therefore, significant modifications involve aseptic conditions for testing specific microorganisms and conducting the test in closed vessels avoiding evaporation losses, while fuel quantification using gas chromatography-flame ionization detection (GC-FID) is retained. It is suggested that the modified procedure should enable routine application for semi-volatile hydrocarbon-based fuels. GC-FID provides additionally valuable information on the alteration of fuel component patterns during biodegradation. The procedure was successfully tested using two bacteria ( Pseudomonas aeruginosa and Sphingomonas sp.) and two yeasts ( Moesziomyces sp. and Candida sp.) isolated from real diesel contamination cases. All tested microorganisms caused a significant degradation of diesel fuel achieving hydrocarbon degradation percentages ranging from 23% to 35%. Specific aspects on the test modification and prospects for further modification regarding targeted investigations in the field of fuel contamination by microorganisms are briefly discussed. Highlights: A diesel degradation test procedure for isolated microorganisms was developed. Microorganisms isolated from contaminated tanks significantly degraded diesel. The procedure can provide isolate-specific fuel degradation fingerprints. The procedure may help to select reference organisms for deterioration studies.