Study On Screening And Identification Of Oil Degradated Strains And The Property Of The Lipase

Oily food waste and oily wastewater are large and extensive sources of pollution.With the rapid economic development during the transition period and the increase of oily pollution,how to deal with oily pollution economically and quickly is the top priority of solving environmental problems.At present,the usually used treatment methods mainly include physical and chemical methods,but none of them can eliminate oily pollution,and the treatment method is likely to cause the secondary pollution.The use of biological methods to treat oily waste is a relatively safe,effective,and fast method.The final product of this method H₂O and CO₂,which will not cause secondary pollution to the environment.Therefore,biological treatment of oily pollution has attracted more and more attention from scientists.In this study,samples were taken from the vegetable market near the school.After using an effective screening system,4 strains with high oil degradation ability were successfully isolated.The 4 strains were preliminarily judged to be Asinibacterium lactis through molecular biological identification.At the same time,it is the first time that Asinibacterium lactis strains have been used as oil treatment.Studies on the oil degradation performance of 4 strains show that the degradation rate of each strain can reach more than 80%at 72 hours;the degradation rate can reach more than 96%at 28°C;the degradation rate of each strain is relatively maximum when p H=7 The degradation rates of BB3,BB4,and BB5 at 5%salt concentration are as high as 98.47%,96.5%,and 96.17%;the degradation rates of BB2 and BB3 at 5%oil concentration are as high as 97.26%and 97.48%.To further enhance its degradation level in various environments,4 strains were subjected to a mixed degreasing experiment.The non-inhibition between strains provides a basis for mixing.Orthogonal experiments of strain ratios have determined the preliminary mixing ratio.The result is:BB2:BB3:BB4:BB5=3:1:2:1.The results of the compound bacterial agent in the fat degradation experiment have been further improved.Lipase plays a vital role in the oil degradation by microorganisms.The fermentation of the mixed bacterial culture was uesd as crude enzyme solution,and the lipase was purifed by a series of steps.And its specific activity was 4191.77 U/mg protein,the purification factor was 19.43 fold,and the yield was 62.32%.After SDS-PAGE electrophoresis inspection,the contrast protein marker calculated the molecular weight of the natural microbial lipase to be 34 k Da.The properties of the purified lipase from Asinibacterium lactis strains were studied,and the results showed that the optimum temperature of the lipase is 50?,and the optimum p H=7.It is an Mn²⁺dependent metalloenzyme,and it is resistant to many organic solvents(except chloroform),detergents,and inhibitors.It also shows a certain degree of tolerance and has good hydrolysis to olive oil,rapeseed oil,and rice oil.The results above showed that the selected strains and the lipase separated from bacterial consortium had good ability in oil degradation,which provided a certain theoretical basis for the oil dispose in the future.