Effects Of Exogenous Nitric Oxide On The Characters Of Fruiting Bodies,Enzyme Activity Andsubstrate Bacterial Community Structure Of Auricularia Cornea

This study was conducted to investigate the effects of exogenous nitric oxide(NO)addition from sodium Nitroprusside(SNP)on the fruit properties,lignin peroxidase(LiP),laccase,manganese peroxidase(MnP),and cellulase(LC)activities and bacterial diversity of Auricularia cornea High-throughput sequencing technology was used to analyze the bacterial community structure of Auricularia cornea at the hyphal,budding,elongation and mature stage,so as to explore the influence of NO on the bacterial community structure in the media and provide theoretical basis for the application of NO in the cultivation of edible fungi.The main results are as follows:(1)The thickness was significantly increased when the SNP concentration was 0.25 mmol/L~ 0.75 mmol/L,and the maximum thickness was 1.58 mm when SNP concentration was 0.75 mmol/L.When the SNP concentration was 0.75 mmol/L,the average auricular size was significantly increased.While the weight was significantly increased at the SNP concentration of 0.25 mmol/L~0.50 mmol/L,and the maximum weight(235.91 g)was found at SNP concentration of 0.50 mmol/L.When the SNP concentration was 0.25 mmol/L~0.50 mmol/L,the cluster weight was significantly increased,and the maximum reached 365 g at SNP concentration of 0.25 mmol/L.When the SNP concentration was 0~0.75 mmol/L,there was no significant difference between auricular amounts.However,when the SNP concentration was 1.00 mmol/L,the auricular amount was significantly smaller than that of the control group,indicating that high concentration of SNP may affect auricular formation.When the SNP concentration was 0.50 mmol/L,Auricularia cornea showed the best characters.(2)The activity of manganese peroxidase and lignin peroxidase was significantly increased at the concentration of 0.25 mmol/L ~1.00 mmol/L during each growth period of Auricularia cornea.The activity of manganese peroxidase was the highest at the concentration of 0.75 mmol/L,and the activity of lignin peroxidase was the highest at the concentration of 0.50 mmol/L.When the SNP was 0.50 mmol/L~1.00 mmol/L during the hyphal,budding and enlongation period,the laccase activity of mycelia was significantly increased,and the laccase activity was the highest when the SNP concentration was 0.75 mmol/L.The SNP concentration of 0.25 mmol/L significantly increased the cellulase activity at all growth stages,and the cellulase activity was the highest among all the enzyme activities.During the budding and elongation period,the cellulase activity was significantly increased when the SNP concentration was 0.50 mmol/L and 0.75 mmol/L,and the cellulase activity was inhibited when the SNP was 1.00 mmol/L.The cellulase activity of each treatment with SNP addition was higher than that of the control at the mature stage,while the cellulase activity was the highest at the SNP concentration of 1.00 mmol/L.The results showed that manganese peroxidase,lignin peroxidase,laccase and cellulase were all related to the fruit body formation of Auricularia cornea,as well as SNP addition.(3)Firmicutes had the highest abundance in Auricularia cornea.The changes of Firmicutes were not obvious in each growth period,but when the SNP concentration was 0.50 mmol/L,the abundance of Firmicutes in the budding period was significantly lower than that in other treatments.Other dominant bacteria included Bacteroidetes,Actinomycetes and Cyanobacteria.In addition,the dominant bacterial genus in the substrate was Bacillus.A total of 39 KEGG pathways were identified for bacterial function prediction,mainly involved in metabolism,environmental information processing and genetic information processing.In the process of Auricularia cornea growth,membrane transport was the most important biological pathway.With the growth of Auricularia cornea,the relative abundance of this biological pathway increased first and then decreased,and the relative abundance at SNP concentration of 0.75 mmol/L was the highest.In summary,proper addition of nitric oxide can significantly promote Auricularia cornea growth,enzyme activities that are involved in the decomposition and transformation of substrate materials,and the bacterial composition.Thus,it is recommended to control the SNP concentration between 0.25 mmol/L and 0.50 mmol/L for better growth indicators of Auricularia cornea.