Ecology, Phylogeny, and Potential Nutritional and Medicinal Value of a Rare White Maitake Collected in a Mediterranean Forest

AlbinoGrifola frondosa(Dicks.) Gray maitake mushrooms (described asG. albicansImazeki and then placed in synonymy withG. frondosa) are particularly rare, and the few pertinent records are not treated in scientific publications. A field investigation carried out in Sicily (Italy) led to the collection of an unusual whiteGrifolaspecimen at the base of a living tree ofQuercus pubescensWilld. s.l. The outcome of sequencing the internal transcribed spacer (ITS) region of nuclear ribosomal DNA (nrDNA) indicated that it belongs toG. frondosaand provided an insight to the phylogenetic relationships within the genus. The results of nutritional composition analysis showed that the albino basidioma possesses relatively high contents of Ca, Fe, K, and Cu and is rather low in Na when compared with literature data on edible mushrooms. Vitamin (B-1, B-2, B-3, B-5, B-9, and D-2) contents ranged from 0.15 to 3.89 mg per 100 g of mushroom dry weight. The cold-water extract of this specimen was effective at inhibiting the growth ofStaphylococcus epidermidisATCC 12228 andPseudomonas aeruginosaATCC 15442 at the maximum screening concentration of 50%v/v. In addition, the extract slowed down the ability ofStaphylococcus aureusATCC 43300 to form biofilms. According to data hereby reported, the albinoG. frondosais a culinary-medicinal mushroom with a promising exploitation potential.