Antimicrobial Activity of the Desert Truffles "Tirmania pinoyi" and "Terfezia claveryi" Against Human Pathogens

Abstract

The development of novel antimicrobials in the struggle against pathogens and antibiotic resistance is one of the most important global challenges of our time. Medicinal mushrooms represent an unlimited source of polysaccharides with nutritional, antitumoral, antibacterial and immune stimulating properties1. In recent years the traditional studies on epigeous higher Basidiomycetes have been joined by those on hypogeous fungi and in particular on the so-named “desert truffles”. Ali2 demonstrated that organic extraction of truffles of genus Tirmania and Terfezia possess antimicrobial activity with broad-spectrum effects against Gram positive, Gram negative, aerobic and anaerobic bacteria as well as Saccharomyces. The antibacterial activity was also demonstrated for Micrococcus flavus, Listeria monocytogenes, Enterobacter cloacae, Escherichia coli, Salmonella enteritidis and Salmonella typhimurium3. With the aim to obtain novel agents against pathogenic bacteria, we focused on edible desert truffles mushrooms Tirmania pinoyi and Terfezia claveryi as source of new anti-infective agents. In vitro antimicrobial activity of acid-soluble protein extracts (aqueous extracts) and organic extracts of the two species of desert truffles T. pinoyi and T. claveryi was investigated against Gram positive human pathogenic reference strains Staphylococcus aureus ATCC 29213, L. monocytogenes ATCC 7644 and Gram negative Pseudomonas aeruginosa ATCC 15442 and E. coli ATCC 10536. The acid-soluble protein extract of T. pinoyi showed minimum inhibitory concentrations ranging between 57 and 114 µg/ml against all tested pathogens; the organic extracts in hexane and acetone of both mushrooms T. pinoyi and T. claveryi resulted active in inhibiting the growth of P. aeruginosa at screening concentration of 5 mg/ml. We believe such preliminary results promising and worthy of further investigations.