Effects of Selected Strains of Microorganisms on the Composition of Fuels and Lubricants

摘要

Thirty-six jet fuels (JP-4, JP-6, thermally stable, and high temperature), one liquid rocket propellant and one lubricant were screened against 16 aerobic bacterial cultures (isolates from contaminated fuel tank bottoms) for growth supporting properties. Twenty-nine of the 35 jet fuels, the liquid rocket propellant and the lubricant were also screened against 5 fungal cultures (also isolates from contaminated jet fuel tank bottoms). A selected number of the fungal and aerobic bacterial cultures were also screened against a selected number of pure hydrocarbons (normal and branched alkanes and naphthenes). Under the same screening conditions all microorganisms showed variable growth on the jet fuels with the exception of one fuel sample (designated A-33), which did not support growth of any of the microorganisms. When screened against the pure hydrocarbons, the n-alkanes were found. to support the most growth, the 2-methyl and 2,2-dimejthyl alkanes' lesser growth, and the highly branched alkanes and naphthenes no. growth. The initially resistant fuel contained no detectable amount. of n-alkanes, which were. present in the growth-supporting .fuels Removal of all n-alkanes from a selected number of the latter sig¬nificantly reduced their growth-supporting properties, and the residual growth is attributed to secondary growth-supporting com¬ponents, one type being 2-methyl alkanes. Attempts to resolve the components of growth- and nongrowth-supporting fuels by chemical and physical methods were only partially successful. After pro¬longed incubations, two aerobic bacterial cultures were eventually adapted to grow on the initially resistant fuel sample (A-33) Partial fractionation of A-33 fuel yielded fractions (lower boiling) that supported growth of the bacterial cultures. However, fractions from a second sample of A-33 (designated A-33') or the sample itself did not support growth of the adapted cultures. Hence, it is con¬cluded that the A-33 fuel has extremely low concentrations of growth-supporting components Slight variations from batch to batch in process variables can thus greatly influence the growth supporting properties of a given fuel. A number of typical jet fuel additives were also screened at various concentrations and some found to be inhibitory to the growth of microorganisms.nThis report has been reviewed and is approved.