Use of sheep myeloid antimicrobial peptide (SMAP-18) and siderophore Pyochelin for mitigation of aerospace fuel-degrading microbes

Abstract

Sustainment of aviation fuel infrastructure is expensive and requires frequent testing for hydrocarbon-degrading microbes to assure safeguarding of fuel quality and engineering systems. Microbial contaminants in Jet fuel, including Gram-positive and Gram-negative bacteria, yeast, and filamentous fungi, necessitate early action to prevent biofouling and biocorrosion. Recent studies have identified two novel antimicrobial agents, the sheep myeloid antimicrobial peptide SMAP-18 and the iron chelating siderophore, Pyochelin with potential suitable antimicrobial properties for jet fuel sustainment. This study evaluates the antimicrobial activity of SMAP-18 and Pyochelin in specialized antimicrobial assays including liquid and fuel-culture minimum inhibitory concentration (MIC) testing, small-scale (25 mL) and large-scale (1 L) Jet A fuel microbial consortium cultures. The results show that repetitive dosing of combined SMAP-18 and Pyochelin is bactericidal and able to control bio-contaminant progression of Gram-positive Gordonia sp., and Gram-negative Pseudomonas putida bacteria in jet fuel. Moreover, the synergy observed between SMAP-18 and Pyochelin highlights their complementary mechanisms of action against microbial targets resulting in complete elimination of bacterial growth with a −7.9 log fold reduction through day 24.