Screening And Making Of Compound Microbial Agents And Degradation Of Kitchen Waste

Taking the food waste as the source of bacteria,screening the strains with strong degradation ability of the main ingredients in the food waste,which aims to prepare a solid composite microbial agent that has a good degradation effect on the food waste.The microbial agent was used to study the reduction rate,deodorization effect and maturity of food waste,which provided a certain theoretical basis for the utilization of food waste.A total of 46 strains were isolated and screened,including 30 strains of bacteria and 16strains of fungi.Among them,strains with better degradation effects on starch,protein,fat and cellulose were recorded as HJ-15,XR-2,XJ-9 and HX-8 respectively.and the enzyme activities were:31.32 U/mL,54.13 U/mL,41.36 U/mL,and 42.66U/mL respectively.By morphological and molecular biological identification,the four strains were identified as Bacillus velezensis XJ-9,Bacillus velezensis XJ-15,Bacillus subtilis XR-2.and Meyerozyma HX-8.The Plackett-Burman method was used to screen the seven factors which was carbon source,nitrogen source,p H,culture temperature,culture time,oxygen supply conditions and inoculum size.The culture temperature,culture time and oxygen supply conditions had significant effects on the viable count.The culture temperature,oxygen supply conditions and culture time were selected as the main factors.The culture conditions were optimized by Box-Behnken response surface optimization method.The optimal culture conditions were:culture temperature 34.74°C,oxygen supply condition 0.69,reaction time 130.27 h,The predicted viable count under the condition was 21.05×10⁷ cfu/mL.The confirmatory experiment showed that the viable count of the composite microorganism was 20.06×10⁷cfu/mL,which was basically consistent with the predicted value.Under optimal culture conditions,the fermentation broth is centrifuged and freeze-dried to become a solid fungus,and the appropriate carrier is selected at a mass ratio to crush the peanut shell:bran:shavings:solid fungicide:fish bone powder=8:3:3:3:3 is mixed to prepare a solid composite microbial agent,which is designated as"XH".Using the gravimetric method as the evaluation index of the reduction rate,the reduction rate of the food waste by the"XH"was 63.21%,so the reduction effect was obvious.Taking the olfactory threshold as the evaluation index,the bactericidal threshold of the"XH"microbial agent to the food waste is 420,which effect is superior to the commercially available"EM"microbial agent.The immediate volatilization concentrations of NH₃ and H₂S were 8.30 ppm and 0.70 ppm respectively,which were lower than the"EM"microbial agent.E₄/E₆ was used as the evaluation index of maturity.The"XH"microbial agent was on the 12th day,E₄/E₆ was 1.59,so the maturity effect was better.The maximum amylase activity was145.32 U/mL,the proteinase was 54.98 U/mL,the lipase was 43.46 U/mL,and the cellulase was 57.22 U/mL.