Identification of Inhibitory Compounds in Medicinal Mushrooms against L. monocytogenes and Z. bailii
Extracts from medicinal mushrooms were prepared and tested for anti-microbial activity against food pathogens and food spoilage microorganisms. The inhibitory activity was measured using a disk diffusion assay and with optical density (OD). For OD, 7 fractions were collected using HPLC for 4 (A. blazei Murrill, G. lucidum, G. frondosa, I. obiquus) medicinal mushrooms and 6 fractions from L. edodes and 8 fractions from P. linteus.
The results from disk diffusion assay showed that most mushrooms displayed significant inhibition compared to the ethanol. The exceptions were: A. blazei Murrill, I. obliquus, and L. edodes against E. coli O157:H7; I. obliquus against L. monocytogenes V7; I. obliquus against S. cerevisiae Y99; L. edodes against Z. bailii Y03; and I. obliquus against Z. bailii/bisporus Y108. Inhibition was more effective in yeasts than bacteria. The result from Bioscreen C showed that against L. monocytogenes V7, fraction 7 in A. blazei Murrill; fraction 1, 4 and 5 in G. lucidum; fraction 4 in G. frondosa; and fraction 4 and 5 in I. obliquus significantly inhibited the growth compared to ethanol. Against Z. bailii Y03, fraction 7 in A. blazei Murrill; all fractions from G. lucidum, G. frondosa, and P. linteus; fraction 1, 2, 3, and 6 from I. obliquus; and fraction 4 and 6 from L. edodes significantly inhibited growth compare to ethanol. The results indicated that there is significant antimicrobial activity against food pathogens and spoilage organisms in the medicinal mushrooms studied.