Profiling And Enhancement Of The Decomposition Of Methicillin Resistant Staphylococcus Aureus And Its Genes During Waste Treatment By Black Soldier Fly Larvae

The treatment of food waste by black soldier fly is a fast-developing organic solid waste treatment method in recent years.However,during the treatment of black soldier fly,whether the pathogenic bacteria can be quickly inactivated,the key factors affecting the pathogenic bacteria and gene removal.In this study,penicillin-resistant Staphylococcus aureus(MRSA)was selected as the model pathogenic strain.In the process of black soldier fly's treatment of food waste,the law of inactivation of MRSA was studied.The specific research results are as follows:(1)The effect of p H conditions on the removal efficiency of MRSA.The initial p H of the kitchen waste is p H5.3,adjust the p H to p H6,p H8,p H10 and p H12,inoculate twice with MRSA with an amount of about 10~7CFU/g on the 0th and 6th days,and treat them with black soldier fly larvae.For 18 days,the decreasing law of MRSA and the efficiency of garbage disposal during this process were tested.It was found that adjusting the initial p H value of food waste has no significant effect on enhancing the inactivation of MRSA.Within the range of the initial p H value of 5.3-10,the amount of MRSA drops by the order of 10~4CFU/g within 3-6 days.The antimicrobial peptide activity was the highest under p H8,and it was antibacterial.The rate reaches 96.0%;p H value of 6-10 is beneficial to increase the yield of black water fly insects to 14.0-16.3%and the biotransformation rate to 16.7-21.4%(p=0.002).(2)Screening of strains with enhanced ability to remove MRSA.From the 11 strains in the laboratory,according to the efficiency of strains inhibiting MRSA under the background of food waste,the ability of strains in the culture solution to inhibit MRSA,the antibacterial efficiency of bacterial metabolites,and the ability of black soldier fly to produce antimicrobial peptides under the induction of strains.As a result,two strains,L4(Enterobacter sp.)and L102(Enterococcus faecalis),which may enhance the ability of black soldier fly to remove MRSA,were screened.(3)The influence of C/N and microbial conditions on the law of MRSA inactivation and gene degradation.The initial C/N of kitchen waste is 20:1.By adding urea,it is adjusted to 18:1,16:1,14:1,and 12:1.After inoculation with MRSA,use black soldier fly and Two conditions for the treatment of food waste without black soldier fly,and the use of 16:1 C/N conditions at the same time,under the premise of black soldier fly,single and multiple inoculation of L4,L102,and RS54(Lactobacillus rhamnosus)and RS72(Lactobacillus plantarum),to study the inactivation of MRSA resistance gene mec and constitutive gene nuc.It was found that in the absence of black soldier fly,in the group with black soldier fly,The copy number of mec and nuc genes continued to decrease,approaching 10~4-10~6genome/g at the end of the treatment.In the C/N condition,20:1-16:1 is the dominant condition for mec and nuc genes to go out.The number of mec and nuc genes is equal to the yield of the black soldier fly.The values are significantly positively correlated,suggesting that the growth and metabolism of black soldier fly is the main factor in the degradation of resistance genes.Based on the above research results,it can be seen that the p H value of 6-10 and C/N20:1-16:1 are the advantageous conditions for black soldier fly to treat food waste.When the environmental conditions are within these ranges,black soldier fly transforms into food waste.The degradation rate of MRSA and its resistance genes is not affected by the activity of the antimicrobial peptides of black soldier fly.The rate becomes a significant positive correlation,indicating that the metabolism of black soldier fly is the main factor in the degradation of MRSA and its related genes.