| Auricularia heimuer is the second largest artificially cultivated edible fungus in China,with important edible and medicinal value.In recent years,with the continuous rise of Auricularia heimuer production,coupled with the country’s restrictions on the use of wood,the shortage of wood chips resources has become a major problem in the black fungus industry.The search for new cultivation substrates with abundant sources has become a hot spot in the development of the Auricularia heimuer industry.As a large agricultural country,corn cob resources are abundant and rich in a large number of nutrients,so the formula screening and extracellular enzyme activity research of Auricularia heimuer in corn cob cultivation can not only effectively reduce the cultivation cost,but also provide the utilization value and efficiency of agricultural waste,improve the agricultural ecological environment,and promote farmers’ income increase is of great significance.By monitoring the agronomic traits,nutrients,quality characteristics,C/N changes in the matrix,extracellular enzyme activity and lignocellulose degradation in each growth period,the most suitable corn cob cultivation formula was screened,and the extracellular enzyme activity and nutrient utilization of Auricularia heimuer in the growth and development of Auricularia heimuer were monitored.The specific results of the study are as follows:1.In this study,the Auricularia heimuer produced by corn cob formula was systematically and comprehensively described and evaluated.Overall,the more suitable corn cob content did not exceed 60%,and the optimal carbon-nitrogen ratio ranged from 74.85% to 87.18%.When the corn cob content was 60%-70%,the growth rate and full bag time were the shortest,0.78mm/d and 26 d,respectively,which were better than the pure wood chips T0 group.In terms of yield traits(first ear yield,second ear yield,total yield,biological efficiency),when the cob content of maize was 60%,the yield(363.40 g)and biological efficiency(69.03%)were better than those of other formulas.In terms of fruiting body traits,when the cob content of maize cob was 70%,the size of fruiting body was significantly better than that of other formulas by 37.56 mm and 44.61 mm,respectively,and the fruiting body thickness produced by T0 formula was better than that of other formulas,which was 0.74 mm,and the T6 formula performed best in terms of fruiting body dry-wet ratio and rehydration rate.Through the sensory evaluation score and principal component analysis,T6(corn cob 60%,wheatbran 10%,wood chips 28%,2%soybean flour,1% lime,1% gypsum)was finally screened as the most suitable formula for Auricularia heimuer cultivation of corn cob.2.Change the ratio of wood chips and corn cob in the formula to affect the agronomic traits and quality of Auricularia heimuer.The increase of corn cob content promoted the growth of mycelium,shortened the number of days full of bacterial bags,the dietary fiber and total sugar content in the fruiting body increased,the length,width,dry-wet ratio,rehydration rate,viscosity and cohesion of the ear pieces were also significantly improved,the content of protein and crude fat decreased,the thickness,weight,hardness and cohesion of the ear pieces were weakened,and the carbohydrate and amino acid content did not change significantly.In terms of yield statistics,it was found that with the addition of corn cobs,except for T9,there was no significant difference in the yield of one ear in each formula.The yield of T7-T9 was significantly lower than CK,and the yield of T1-T6 was not significantly different from CK.The difference in yield was mainly due to the decrease in the yield of two ears under the high cob content formula.3.The entire growth and development of Auricularia heimuer is accompanied by the degradation of lignocellulose and starch,and the activity changes of laccase,lignin peroxidase,cellulase,hemicellulase,and amylase also run through the growth and development of black fungus.The results of extracellular enzyme activity showed that the degradation of lignocellulose and starch was related to the initial content in the matrix and the corresponding extracellular enzyme activity.In addition to cellulase,other extracellular enzymes have reached their highest peak in the mycelial growth stage,specifically laccase,hemicellulase,and amylase reach their peak at the half-bag stage,and lignin peroxidase reaches their peak in the full-bag stage.Cellulase activity increases during the fruiting body growth phase and peaks at one harvest.The increase of corn cob content changed the initial lignocellulose and starch contents of the bacterial pack,and also affected the synthesis of related extracellular enzymes,resulting in a decrease in the activity of laccase and lignin peroxidase,an increase in the activity of amylase and hemicellulase,and a decrease in the cellulase activity in the fruiting body growth stage.4.There was a positive correlation between carbon content and fruiting body yield traits,nitrogen content was negatively correlated with fruiting body traits,and the fruiting body size was smaller and thicker in high-carbon formula;The fruiting body in the high-nitrogen formula is larger in size and thinner in texture.The use of a formula with a high carbon and nitrogen ratio will promote the accumulation of hyphae,inhibit the size of the ear pieces,and increase the thickness;Formulations with a low carbon and nitrogen ratio promote the growth and extension of the ear pieces and inhibit the accumulation of hyphae in the matrix.5.The difference in the initial content of lignocellulose and starch in the matrix affects the synthesis and agronomic traits of related extracellular enzymes.Laccase,lignin peroxidase and lignin degradation are positively correlated,which has a promoting effect on fruiting body yield,the strength of amylase and hemicellulase activity determines the growth rate of mycelium and the time of hyphae full bag,cellulase activity has a significant promoting effect on the hyphae growth rate and fruiting body yield of Auricularia heimuer,but because cellulase shows strong activity in the fruiting body harvest stage,its influence on fruiting body yield is relatively large. |
