Bioconversion Of Food Waste By Probiotic Bacteria In Collaboration With Black Soldier Fly Larvae

With the improvement of economic level,the catering industry has been developed rapidly,but at the same time,a large amount of food waste has been generated.Food waste is characterized by high organic content,high salt content and high water content.Traditional treatment methods have limitations such as high treatment cost,complex process and long treatment cycle,and also cause waste of resources.As a resource-based insect,black soldier fly has the characteristics of large feeding capacity,wide feeding habit,short growth cycle and easy management,while the insect body is rich in nutrients.Using black soldier fly to treat food waste can not only solve environmental problems,but also obtain a resource-based insect that can be used as raw materials for animal feed,extraction of antimicrobial peptides,chitin and other high-value products.Therefore,in practical application,it is of practical significance how to improve the yield of black soldier fly and the conversion efficiency of food waste.In this paper,we use probiotic bacteria in collaboration with black soldier fly to bioconvert the food waste in three main aspects.Firstly,we studied the growth status of black soldier fly and the conversion efficiency of food waste during the bio-conversion of food waste,and the larvae with the highest growth status and conversion efficiency were identified as gut microorganisms.The results showed that the crude protein content of black soldier fly was positively correlated with the larval age,while the crude fat content decreased with increasing larval age,the survival rate of black soldier fly in the larval stage was decreasing and increased in the pre-pupal stage,the crude fat content of20-day-old larvae was high,and the crude fat,crude protein and dry matter content of 15-dayold larvae were higher.10-day-old black soldier fly grew the fastest,and the rate of weight gain(14.07%)and material production rate(18.74 mg/g),and dry matter content(37.9%)were the largest,and the bioconversion rate of food waste reached 26.11%.At this time,the dominant species at the phylum level were Firmicutes(52.05%),Proteobacteria(26.15%),and Actinobacteria(10.84%),and the dominant species at the genus level were Enterococcus(63.38%),Pediococcus(14.48%),Vagococcus(7.62%),and Morganella(5.69%).The experiments on the bioconversion of food waste by different probiotic bacteria showed that the addition of probiotic bacteria was beneficial to the survival and growth of black soldier fly and significantly improved the utilization of food waste by black soldier fly.The effect of the three bacterial agents on the nutrient uptake by the black soldier fly was Bacillus subtilis(M1)> Bacillus amyloliquefaciens(M2)> Lactobacillus acidophilus(M3).Compared with the control group,the addition of the bacterium promoted the increase of p H and temperature of the pile,which also led to higher crude protein and crude fat content of black soldier fly,improved the survival rate and pupation rate of black soldier fly,reduced the larval calendar period of black soldier fly,and also improved the reduction rate and bioconversion rate of black soldier fly to food waste,with the most obvious effect of Bacillus subtilis,which increased the reduction rate by 11.3% and the bioconversion rate by The effect of Bacillus subtilis was most obvious,with 11.3% increase in reduction rate and 7.15% increase in bioconversion rate.According to the experimental results of different probiotic bacteria to biotransform food waste,Bacillus subtilis had the best effect.A single-factor experiment was conducted on Bacillus subtilis to biotransform food waste with black soldier fly,and the optimum conditions for the growth and development of black soldier fly were determined as follows: the amount of bacterial agent added was 0.7%,the ambient temperature was 27℃,and the water content of the substrate was 70%.Under these conditions,the average insect length and weight of black soldier fly were the highest,and the utilization efficiency of food waste was the highest,which promoted the larvae of black soldier fly to accumulate more nutrients.The results of the orthogonal experiments showed that the effects on the bioconversion rate of food waste were,from largest to smallest,ambient temperature,amount of bacterium added and water content.The best conditions for synergistic transformation were 0.7% of bacterial agent addition,27℃of ambient temperature and 70% of water content of substrate,which had the highest yield of black soldier fly and the highest bioconversion rate of 19.48% of food waste,and also facilitated the separation of larvae.In summary,the addition of bacterium can strengthen the conversion efficiency of black soldier fly to kitchen waste,significantly improve the production of black soldier fly,reduce the mortality of black soldier fly,and shorten the growth cycle of black soldier fly,and this study has some guiding significance for the industrialization of black soldier fly to treat kitchen waste and the large-scale breeding of black soldier fly.