Thermochemolysis–GC-MS as a tool for chemotaxonomy and predation monitoring of a predatory actinobacteria against a multidrug resistant bacteria

Abstract

Thermochemolysis-GC-MS was used to characterize Methicillin resistant Staphylococcus aureus (MRSA) and a predatory actinobacteria isolated from Moroccan marine water through their membrane fatty acids released as methyl esters (FAMEs).FAMEs from MRSA were dominated by branched iso and anteiso C15, straight C18 and C20 whereas the predatory actinobacteria was dominated by branched C14, iso and anteiso C15, and straight C16. The iso to anteiso C15 ratio was 0.44 for MRSA and 0.9 for the actinomycete. A co-culture of actinomycetes and bacteria was conducted during 15 days. An increase in the iso to anteiso ratio, a decrease in C18 and C20 FAMEs and an increase in branched C14 and C16 FAMEs demonstrated the predation of MRSA by the actinomycete.The total amount of FAMEs which was significantly higher in the studied actinobacteria (83 mg/g) compared to MRSA (17 mg/g) increased during the co-culture demonstrating the predation.Principal Component (PCA) and Hierarchical Cluster Analysis (HCA) were used to correlate fatty acids (FA) distributions with the strains. HCA allowed to discriminate between MRSA and the actinobacteria. With PCA, long chained (>C18) FAMEs correlated with MRSA whereas short branched-chained FAMEs correlated with the actinobacteria and T15. Consequently, a clear distinction in the chemotaxonomy of MRSA and actinobacteria was established by PCA. Additionally, PCA highlighted the predation of MRSA by the actinobacteria through dissimilarity between MRSA and T15 and similarity between actinobacteria and T15.