Screening Of Biodegradation Bacteria For Kitchen Waste And Study On New Methods Of Microbial-enzyme Combined Degradation

The use of microorganisms to degrade kitchen waste is a green and environmentally friendly method.At present,there have been reports of the use of microbial agents in the degradation of kitchen waste in China.However,most bacterial agents are obtained from imports,and the degradation effect is not obvious.In this study,new microorganisms capable of degrading kitchen waste were screened out from nature,and their species were preliminarily identified.On the other hand,it is explored to further improve the degradation efficiency of kitchen waste by adopting a combination of enzyme preparations and microbial agents.At the same time,the degradation conditions are optimized,and a new microorganism-enzyme combination degradation method that can efficiently degrade kitchen waste was established.The first part of the thesis is to enrich and cultivate microorganisms in soil samples collected from nature,and use screening media to screen out microorganisms that can efficiently degrade kitchen waste.Firstly,33 strains were isolated purely from the enriched and cultivated microorganisms according to the different colony morphology.According to the main components of kitchen waste,the separated microorganisms were cultured with a screening medium with starch,protein,cellulose,and fat as the main components,and 20strains that can grow well on various screening media were obtained.Furthermore,15 strains with relatively high activity were screened out by considering the transparent circle formed by the hydrolyzed substrate on the plate and the size of extracellular enzyme activity.Finally,using 16s r DNA to identify the screened microorganisms,it was found that most of the 15strains belonged to the genus of Bacillus,including 8 strains of Bacillus licheniformis,2strains of Bacillus paralicheniformis,1 strain of Paenibacillus cookii,and 3 strains of Brevibacillus borstelensis And 1 strain of Actinomycete.The second part of the thesis is to use 15 of selected strains to produce complex microbial inoculants for the degradation of kitchen waste.And the method of combining microorganisms and enzyme preparations to degrade kitchen waste as well as establishing an efficient kitchen waste degradation process was also studied.The conditions for the degradation of kitchen waste are 50~oC for 24 h.By using microbial agents,76.87 g of kitchen waste with a 98.0%degradation ratio was obtained.When the enzyme preparation is added during the preparation of the microbial inoculants for the degradation of kitchen waste,the degraded weight increases to 79.67 g with a degradation ratio reaches 99.8%.Adding enzymes will facilitate the degradation of kitchen waste.When the degradation starts,adding enzyme preparations and microbial inoculum degraded 151.58 g of kitchen waste with 98.7%of degradation ratio.When the microbial inoculum was instead by microbial fermentation broth,the degradation amount and degradation ratio was changed to 157.9 g and 99.7%,respectively.By using enzyme preparation combined with microbial inoculum,3.33 g of chicken bones was degraded 5.23 g of chicken bones after 24 h,corresponds a degradation ratio of 63.7%.This thesis screened out microorganisms that efficiently degrade kitchen waste and established a new and efficient method of degrading kitchen waste by microorganism-enzyme combination,which has potential application value.