The effect of citrate and sulfate of copper on the biomass composition of the medicinal mushroom Trametes versicolor (Polyporales, Polyporaceae)

Abstract

The aim of our research was to study the influence of citrate and sulfate of copper on the biomass composition of the mycelium of the medicinal mushroom Trametes versicolor (L.) Lloyd, (1920) cultivated in a liquid medium. The studied strain of Trametes versicolor 353 was obtained from the Culture Collection of Mushrooms (IBK) from M.G. Kholodny Institute of Botany, National Academy of Sciences of Ukraine. Copper citrate was obtained from the Institute of Nanobiotechnologies and Resource Conservation of Ukraine, Kyiv. In this study we used glucose-peptone-yeast extract medium. Cu2+ (sulfate or citrate form) was added to the medium in concentration 4 mg/L. Mycelium was grown in a submerged culture on a rotary shaker (120 rpm) at 26 °C in 250 ml Erlenmeyer flasks, containing 50 ml of liquid media. The biomass was harvested after 9 days of cultivation in the liquid medium, filtered, washed, dried to a constant weight at 105 °C and weighed. Total nitrogen content (Ntotal) in the mycelium determined by the Kjeldahl method, crude protein content was determined as Ntotal x 6.25. The ash was obtained by the standard method. Total lipids were extracted from undried mycelium by a modified method of Bligh and Dyer. Amino acid composition was analyzed by high-performance liquid chromatography Agilent 1200 (Agilent technologies, USA). The methyl ethers of fatty acids were determined by gas chromatography-mass spectrometry (GC/MS) Agilent 6890N/5973 inert. The results of our research demonstrated that sulfates and citrates of copper increased the amount of crude protein on the mycelium of T. versicolor 353. Also both form of copper increased the amount of ash by a third relative to the control medium. At the same time, both forms of copper reduced the amount of total carbohydrates on mycelial biomass. But copper sulfate reduced the amount of total lipids relative to the control medium and medium with copper citrate. It should be noted, that given the significant growth of biomass in both cases, the yield of the same biomass compounds (gram per liter of medium) was raised relative to the control medium. So the yield of total carbohydrates was increased by 72% (on the medium with copper citrate) and 43% (on the medium with copper sulfate) relative to the control medium. The yield of crude protein was raised by 94% (on the medium with copper citrate) and 63% (on the medium with copper sulfate) relative to the control medium. Assay of amino acid composition showed that the quality of crude protein didn’t change. Thus the yield of essential amino acids was increased in conjunction with the yield of crude protein. The yield of total lipids increased only on the medium with copper citrate (by 57%) and in this case the content of fatty acids was unchanged significantly relative to the control medium. But sulfate of copper decreased the amount of cis-linoleic acids by 7%, in return the amount of oleic acid was increased relative to the control medium without copper.

Keywords

• lipids
• crude protein
• amino acids
• fatty acids