The Study On Treatment Of Auricularia Auricula And Lentinula Edodes Spent Mushroom Substrate By Protaetia Brevitarsis Larvae

Edible mushrooms have been widely cultivated as a healthy and nutritious food with a low fat and low cholesterol content.The edible mushroom industry produces massive amounts of spent mushroom substrate(SMS).However,there is no efficient and environmental way for the treatment of SMS,resulting in serious environmental pollution and resources waste.Thus,there is an urgent need for high value utilization technology to process the SMS.In the ecosystem,soil-dwelling insects play an important role in the conversion of organic matters such as plant residues.Protaetia brevitarsis,also known as the white-spotted flower chafer,is an important soil-dwelling insect which belongs to Coleoptera.Its larvae can feed on large amounts of organic matter including crushed straw,decaying leaf and fermented wood chip,and are commercially raised to produce high quality organic fertilizer.Therefore,it has a great potential for reusing SMSs as resources.In this study,we used P.brevitarsis larva(PBL)as an experimental object to investigate the application of PBL to process SMS from Auricularia auricula(SMS-AA)and Lentinula edodes(SMS-LE)and produce larval frass as organic fertilizers.The conversion mechanism of the SMS in PBL was also analyzed.The specific research contents and conclusions are as follows:(1)The feeding experiments indicated that PBL could digest the SMS-AA and SMS-LE.SMS showed no effect on the hatching rate of P.brevitarsis eggs.Some factors,such as the composition of SMS or the ratio of insect to feed,would affect the feeding effects.(2)The germination index of frass was more than 50%,indicating that the frass has less plant toxicity than SMS.Elemental analysis showed that the maturity of frass was higher and the aromatic degree of organic matter in frass was lower.The results of nutrient element analysis revealed that the contents of nitrogen,phosphorus,and potassium were increased during the conversion process.The total nutrient of the frass produced by PBL feeding on SMS-LE increased to 6.25%,which exceeds the indicator(5%)in People's Republic of China Agricultural Industry Standard NY 525-2012.These results indicate that PBL can be used to produce larval frass as organic fertilizers.(3)Organic carbon analysis showed that the amount of total organic carbon and fulvic acid organic carbon decreased significantly during the conversion process,whereas the content of humic acid organic carbon barely changed.Further attribution analysis of the organic carbon showed that PBL could make use of both hydroxyl carbon and aromatic carbon.In addition,the contents of humic acid remained unchanged throughout the conversion process.These results revealed that the consumption of aromatic carbon and the formation of humic acid were simultaneous during the conversion of SMS.(4)Intestinal bacteria were extracted from PBL,and 16 S r DNA of the bacterial communities was sequenced.It was found that the composition of midgut and hindgut bacteria was the same at the level of dominant portal,but the abundance was different.The dominant genus showed significant differences between midgut and hindgut.? diversity analysis revealed that the bacterial communities in the hindgut were more abundant than those in the midgut.? diversity analysis showed that there were significant differences in the bacterial communities of midgut and hindgut,indicating that they may have different functions.Feeding on different SMS affected the bacterial communities in the gut,but it has little effect on the bacterial communities in the hindgut,suggesting that the hindgut has more stable bacterial communities than those in the midgut.Functional analysis showed that the lignin degradation pathway appeared in high abundance in the midgut,whereas the glycosidases involved in the degradation of cellulose and hemicellulose were more abundant in the hindgut.These results revealed that different components of SMS were degraded in different locations of gut.In summary,this study confirmed that PBL could effectively convert SMS to frass as organic fertilizers,providing an efficient method to reuse SMSs as resources.We also explored the mechanism for the conversion process of PBL.These results offer a new technology to solve the problems of SMS,and are of great significance to the sustainable development of edible mushroom industry.