Biotransformation Of Selenium By Pleurotus Osteratus And Its Differential Proteomics

Selenium-enriched Pleurotus ostreatus was cultivated by adding selenoarginine to substrate. Effect of selenoarginine on mycelium growth, mushroom yields and mushroom quality was observed. The method of total protein extraction of mushroom was optimized and the different expressed proteins between Se-enriched mushroom and non-Se-enriched mushroom were evaluated. These researches have laid theoretical foundation for further study on selenoarginine applied in Se-enriched Pleurotus ostreatus.Influence of selenoarginine on mycelium and mushroom which were grown in substrate with various concentrations of selenoarginine was investigated. In substrates with Se concentrations lower than 22.13 mg/kg, selenoarginine had a promoting effect on mycelium growth than in that without selenoarginine. However, the promoting effect was disappeared when Se concentrations was increased to 44.26 mg/kg in substrates. Selenoarginine accelerated formation of button, shorten growth cycle and significantly increased biological efficiency and yields, therefore selenoarginine promoted mushroom formation. However, Selenoarginine affected the shape of the Se-enriched mushrooms which tend to be more decentralized with smaller lid and coarsen stipe.Quality of first flush of selenium-enriched mushrooms was analyzed. Selenium content in mushrooms and its protein and polysaccharide was measured by atomic fluorescence spectrophotometer (AFS). The results showed that selenium concentration in samples increased significantly and it had a significant positive relationship with selenium concentration in the cultivation material. A large amount of selenium accumulated in the protein rather than in the polysaccharide. The Gas Chromatograph-Mass Spectrometer (GC-MS) analysis indicated that mushroom’s volatile substance was mainly alcohols and relative content of 1-Octen-3-ol of Se-enriched mushrooms was higher than control. However, there had no significant changes in protein content and glutathione peroxidase activity.Total protein extraction of mushroom by different methods was compared. Trichloroacetic acid (TCA) showed a good effect on removal of water-soluble impurities, clearer background, less longitudinal and transverse stripes, clear protein points, uniform shape, better contrast, smooth point edge which was suitable for total protein extraction of mushroom. Two-dimensional electrophoresis combining with mass spectrometry technology was applied to identify proteins that are differentially expressed in mushroom grown in the substrates with 44.26 mg/kg of Se. From 2D maps,51 differentially expressed proteins were detected,17 of those were up-expressed, and 34 of those were down-expressed.8 up-expressed proteins were analyzed by MALDI-TOF-MS/MS:3 proteins were identified, one was hypothetical protein (gi|270056453), and the other two proteins are respectively NAD-dependent formate dehydrogenase (gi| 164564766) and Aldo keto reductase (gi|628847367). These two proteins are mainly involved in substance and energy metabolism in the cell.