Antimicrobial activity of polysaccharides extracted from medicinal mushrooms on Campylobacter jejuni and Staphylococcus aureus

Modern consumers demand for fresh and minimally treated food products is dictating a trend of reducing the use of man-made chemical preservatives, although this could increase health risk, caused by foodborne pathogens and spoilage. Therefore the interest in finding new natural antimicrobials and antioxidants is increasing. We investigated antimicrobial activity of hot water and hot alkali extracted polysaccharides from selected medicinal mushrooms, which are known for their broad spectrum of health promoting activities. The most effective against Staphylococcus aureus and Campylobacter jejuni were crude hot water extracts of Phellinus linteus and Ganoderma lucidum, composed of a mixture of polysaccharides and phenolic compounds and partially purified extract of G. lucidum. MIC (minimal inhibitory concentration) of P. linteus and G. lucidum crude extracts were 5 mg/ml and >10 mg/ml on S. aureus, and 10 mg/ml on C. jejuni, respectively. These extracts showed considerable bacteriostatic effect against gram-negative C. jejuni already in concentration of 0.25 MIC. Lower antimicrobial effect was observed on S. aureus.