Antibacterial activity, optimal culture conditions and cultivation of the medicinal Ganoderma australe, new to Thailand

Abstract

Ganoderma is a well-known genus of medicinal mushrooms that belongs to the order Polyporales. Many members of this genus are extensively used in traditional Asian medicines. Herein we report a new strain of Ganoderma australe collected in Thailand and identified using macro- and micro-morphological characteristics as well as phylogenetic analysis. The optimal conditions for mycelia growth were 25-30 degrees C at pH 7-8, while sorghum and barley were found to be the best grain media for spawn production. The best medium for mycelia growth was Potato Dextrose Agar (PDA) medium. Para rubber sawdust with organic and inorganic additives is used as a standard cultivation substrate in Thailand. The mycelia were fully distributed throughout the sawdust substrate after being incubated at 30 degrees C, 60-75% relative humidity for 18 days. The first primordia were observed three days after the bags were opened. Three fruiting cycles were obtained, although the weight of mushrooms produced decreased each time (115.04 +/- 48.85 g kg(-1), 72.01 +/- 6.00 g kg(-1) and 36.47 +/- 9.04 g kg(-1), respectively). Extracts of G. australe inhibited Micrococcus luteus, Bacillus subtilis, Staphylococcus aureus and Salmonella typhimurium bacteria however, the extracts were not effective against Escherichia coli and Pseudomonas aeruginosa. This is the first report of the antimicrobial activities observed in G. australe.