Pleurotus eryngii var. thapsiae a new potential culinary-medicinal mushroom from Sicily with antibiofilm potentiality

Introduction: Mushroom extracts are a rich source of natural compounds with antimicrobial properties. In recent years, there has been an increased interest in natural antimicrobials, especially those obtained from medicinal and culinary mushrooms. The genus Pleurotus (Fr.) P. Kumm. includes economically important mushrooms, cultivated around the world, widely used in human nutrition and recognized as medicinal mushrooms. Within this genus, the P. eryngii species-complex is undoubtedly worth mentioning. Among the members of the P. eryngii species-complex, our attention focused on P. eryngii (DC.) Quél.var. thapsiae Venturella, Zervakis & Saitta, this mushroom has been reported so far only in Sicily (Italy), where it has a rather limited geographical distribution, at altitude ranging from 0 to 1500 m. The aim of this study was to investigate the potential of extracts from P. eryngii var. thapsiae, against ATCC Gram-positive and Gram-negative strains. Materials and Methods: The cultivation was carried out on two different substrates, one based on wheat straw and another consisting of a mix of wheat straw and Aegilops geniculata Roth., a wheat weed. P. eryngii var. thapsiae exhibited good production performance, with yields above 15% on both substrates. Besides, the collected basidiomes were subjected to drying, then reduced to powder and a chemical analysis was then performed on this powder. One share of the mushroom powder was used to obtain aqueous extracts using two different techniques, traditional and ultrasound-assisted extraction, in order to evaluate and compare their activity against ATCC Gram-positive (S.aureus, E faecalis), and Gram-negative (K pneumoniae, E. coli and P.aeruginosa) strains. Crystal violet assay (CVA) was executed to quantify biofilm formation by all ATCC isolates Results: The best activity was obtained against S. aureus, with a reduction of about 60% of biofilm biomass, by means of both ultrasonic extracts. Conclusions: Extract of mushroom or their purified antimicrobial constituents are alternative biocides that have recently gained attention as possible cleansing agents, because the chances of resistance development in bacterial cells could be minimal. This study, therefore, highlights the potential application of this mushroom for large-scale cultivation, aimed at the marketing of a local, quality product with high nutritional and organoleptic properties.