Se-enriched Submerged Fermentation Of Tricholoma Matsutake And The Biological Activities Of Its Mycelium Polysaccharide

ObjectiveThe bioactivity of polysaccharides from selenium-rich matsutake mycelium was investigated by extracting polysaccharides from selenium-rich matsutake mycelium.Methods Selenium tolerance concentration of matsutake mushroom was determined by plate method;Using the dry weight of matsutake mycelium as index,the nitrogen source,carbon source and vitamin of the deep fermentation medium of matsutake mycelium were determined by single factor experiment combined with orthogonal experiment,and on this basis,the ratio of nitrogen source,carbon source and vitamin was optimized through uniform design experiment;By measuring the dry weight and organic selenium content of Matsutake mycelium,the optimal selenium concentration for liquid fermentation of matsutake mycelium was determined,and the fermentation tank was expanded;With polysaccharide yield as index,extraction time,extraction times,temperature and solid-liquid ratio were selected to optimize the extraction process of polysaccharides from matsutake mycelium in water bath based on orthogonal experiments;Ultrasonic frequency,solid-liquid ratio,ultrasonic power and ultrasonic time were selected to optimize the ultrasonic-assisted extraction of polysaccharides from matsutake mycelium by orthogonal experiment on the basis of single factor experiment;Using Vc or EDTA-2Na as positive control,DPPH radical,ABTS radical,hydroxyl radical,total reducing power,FRAP and ferrous chelating ability of polysaccharides from selenium-rich matsutake mycelium were detected to determine the antioxidant activity of polysaccharides from selenium-rich matsutake mycelium;The hypoglycemic and anti-inflammatory effects of selenium-rich matsutake mycelium polysaccharide on healthy mice were studied by oral glucose tolerance test and ear swelling test induced by xylene.Results The matsutake mushroom strains preserved on the plate containing Na?Se O?50μg/m L could maintain good growth;Theoptimal medium for deep fermentation was 3.9%（g/m L）soybean powder,2.1%（g/m L）corn starch,0.004%（g/m L）VB₆,and the dry weight of matsutake mycelium reached 0.84 g/100 m L;The optimal concentration of Se in liquid fermentation was 30μg/m L,and the dry weight of matsutake mycelium under this condition reached 1.04±0.04（g/100 m L）,which was significantly higher than that under other Se concentrations（P<0.05）,The total selenium content in mycelium was 336.4 mg/kg,the organic selenium content was 304.7mg/kg,the total selenium content in fermentation broth was 8.244 mg/L and the organic selenium content was 0.681 mg/L;In the optimized hot water extraction process,when the extraction time of matsutake mycelium was 3 h,the water bath was 90℃,the ratio of solid to liquid was 1:10（g/m L）and the extraction time was 2 times,the polysaccharide yield of matsutake mycelium was the highest,reaching（1.93±0.03）%;The optimal extraction conditions were as follows:solid-liquid ratio of 1:15（g/m L）,ultrasonic power of 200 W,ultrasonic time of 10 min,temperature of 90℃,extraction time of 2 h,two times,the yield of polysaccharide reached（2.69±0.10）%,The selenium content and organic selenium content of 2 mg/m L selenium-rich matsutake mycelium polysaccharide solution were 0.347 mg/L and0.314 mg/L respectively。The scavenging abilities of DPPH radical,ABTS radical and hydroxyl radical of selenium-rich mycelium polysaccharide were（21.77±0.25）μmol V_Cequivalent/mg,（76.09±0.90）μmol V_Cequivalent/mg,and（1.66±0.10）mmol V_Cequivalent/mg,respectively.The FRAP was（25.85±2.08）μmol V_Cequivalent/mg,the chelating force of ferrous ions was（111.46±2.04）μmol EDTA-2Na equivalent/mg,and the total reducing power was（78.94±1.67）μmol Vc equivalent/mg;In vivo experiment,selenium-rich matsutake mycelium polysaccharide can accelerate glucose metabolism in healthy mice,and significantly reduce the ear swelling rate of mice induced by xylene（P<0.05）.Conclusion Matsutake has good selenium resistance,low concentration of selenium can significantly promote the growth of matsutake mycelium,and selenium-rich matsutake mycelium polysaccharide shows better antioxidant activity compared with Matsutake mycelium polysaccharide,both of which showed improved oral glucose tolerance and anti-inflammatory activity.This study lays an experimental foundation for further development and utilization of matsutake.