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MECHANISM OF MICROBIOLOGICAL CONTAMINATION OF JET FUEL AND DEVELOPMENT OF TECHNIQUES FOR DETECTION OF MICROBIOLOGICAL CONTAMINATION

Two methods for detecting microorganisms were examined in the light of the present understanding of the jet fuel microorganisms. One method was based on a color produced by the enzymes of the organism. This method was found suitable for the detection of organisms in the early part of their growth in fuel systems. However, the sensitivity of the method declined slightly with the age of the culture. Another detection method was devised, tested, and found to be highly sensitive and independent of the age of the culture. This detection method has two simple steps. The first step is the reaction of microbial cells with a specific metal ion; the second step is the reaction of bound metal ions with a colored reagent. The method promises to yield a simple visual readout system capable of field application. The production of compounds by microorganisms associated with aluminum corrosion was dependent on the presence of high concentrations of nitrate ion as well as on jet fuel components. A direct relationship was found between the onset time of respiratory decline and the appearance of corrosive pigments in microbial cultures oxidizing jet fuel. (Author).

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  • "Two methods for detecting microorganisms were examined in the light of the present understanding of the jet fuel microorganisms. One method was based on a color produced by the enzymes of the organism. This method was found suitable for the detection of organisms in the early part of their growth in fuel systems. However, the sensitivity of the method declined slightly with the age of the culture. Another detection method was devised, tested, and found to be highly sensitive and independent of the age of the culture. This detection method has two simple steps. The first step is the reaction of microbial cells with a specific metal ion; the second step is the reaction of bound metal ions with a colored reagent. The method promises to yield a simple visual readout system capable of field application. The production of compounds by microorganisms associated with aluminum corrosion was dependent on the presence of high concentrations of nitrate ion as well as on jet fuel components. A direct relationship was found between the onset time of respiratory decline and the appearance of corrosive pigments in microbial cultures oxidizing jet fuel. (Author)."@en
  • "This study is concerned with the detection of microorganisms in fuel- water environments and with the mechanisms by which these microorganisms cause problems in fuel systems of aircraft. Fuel isolates removed nitrate from growth medium containing iron and calcium, causing it to become more corrosive to aluminum alloys. Upon prolonged incubation (200 days) fuel isolates produced substances corrosive to aluminum alloys. Microbial sludge, which can cause corrosion, contained N, C, H, and O. Nitrate did not prevent corrosion caused by nitrated phenols; and nitrate does not prevent corrosion caused by media in which fuel isolates have gown for long periods of time. Emulsion-forming organisms contained considerably more lipid material than fuel isolates which were sedimentable in water. Some fuel additives were observed to support the growth of fuel isolates while most anti-icing and metal deactivators were mildly toxic. Respiratory inhibition and ability to kill fuel isolates was demonstrated for pentene, hexene, heptene, octene, and nonene but not for decene or dodecene. The saturated homologs of these compounds were either innocuous or supported growth."@en
  • "Progress was made in understanding and partially solving the problem of jet fuel contaminants, including microorganisms, surface-active materials, iron rust, water, and extraneous materials as they pertain to fuel properties, sludge formation, and their degree of participation in the corrosion and degradation of aircraft materials of construction throughout the fuel system. Several major developments in this area of research were accomplished. The first was the establishment of concepts that explain how various growth media cause the corrosion of aluminum. A study of the corrosion in simulated water bottoms revealed that ions, such as iron and calcium, cause aluminum corrosion like that caused by sodium chloride. However, other ions in the media, such as nitrate and phosphate, prevented aluminum corrosion. The mechanism of microbial corrosion appears to depend on the removal of these corrosion inhibitors by microbial growth. Aluminum corrosion was also caused by another mechanism as revealed by the corrosion produced by the growth of fuel isolates in media containing protein, peptides, and amino acids. This type of corrosion was not inhibited by nitrate. The second development was in understanding the metabolic mechanisms which operate in the production of fuel contaminants such as emulsions and sludges."@en
  • "This study is concerned with the detection of microorganisms in fuel water-environments and with the mechanisms by which these microorganisms cause problems in fuel systems of aircraft. The laboratory detection methods studied were the esterase approach, tetrazolium reduction, O2 consumption and CO2 evolution. The techniques which appear to have the greatest chance of success are the esterase approach and tetrazolium reduction. For field detection, the work is continuing on the electrophoresis-pulse polarization technique. These studies have been extremely successful in finding techniques which should be useful for rapidly detecting small numbers of viable microorganisms in fuel water bottoms. The esterase technique now can detect viable cells in about 5 minutes and it is expected that the tetrazolium technique will determine the number of organisms which can utilize fuel. All that remains to be done now is to establish the criteria, such as the length of time required for color to develop, which will indicate when the microbial contamination has reached a harmful level."@en
  • "The research was directed at developing rapid methods for detecting microorganisms in jet fuel water bottoms and at analyzing the chemical mechanisms by which microorganisms and other contaminants could cause operational difficulties in aircraft fuel systems. The mechanisms by which microorganisms produce emulsions, sludges, and fuel-soluble compounds and cause corrosion were studied. The ability of fuel isolates to produce emulsions was demonstrated, with jet fuel and pure hydrocarbons as substrates. The aldehyde and acid products of hydrocarbon oxidation, formed during the growth of the microorganisms, were believed to be responsible for some of the emulsions formed on jet fuel. Fuel oxidizing microorganisms were demonstrated to cause aluminum alloy corrosion by four different mechanisms: (1) alteration of the ionic composition of the growth medium, (2) production of corrosive compounds, (3) deposition on metal surfaces and establishing oxygen and metal concentration cells, and (4) production of electron mediators which transfer electrons from the metals to electron acceptors in the microorganisms. During the first year of study, the growth medium was found to contain corrosion inhibitors and corrosion stimulators. Microorganisms were demonstrated to cause corrosion by removal of nitrate and phosphate as inhibitors. Nitrate was then tested for its ability to inhibit corrosion."@en

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  • "MECHANISM OF MICROBIOLOGICAL CONTAMINATION OF JET FUEL AND DEVELOPMENT OF TECHNIQUES FOR DETECTION OF MICROBIOLOGICAL CONTAMINATION"@en
  • "Mechanism of microbiological contamination of jet fuel and development of techniques for detection of microbiological contamination"@en

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