Isolation Of Lipase-Producing Psychrotrophs And Optimization Of Conditions For Adsorption Of Oil Degradation

With the development of society,the pollution problem of oily sewage is increasing.The main pollutant of oily sewage is animal and vegetable oil.In the announcement of the second national pollution source census published in 2020,the national animal and vegetable oil pollutant emissions amounted to 309,700 tons,second only to the total phosphorus emissions.Most of my country's winter is in a low temperature state,and the northern region also has a low temperature in summer,which leads to a drop in the temperature of sewage water,which makes the biological treatment effect of grease and sewage under low temperature conditions poor.Psychrotrophs can perform normal growth and metabolic activities in environments with low temperatures and large temperature fluctuations.The lipase secreted by them still has a good effect of degrading oil at low temperatures.Therefore,the separation of cold-resistant bacteria with the ability to efficiently remove oil is the solution.The key to the puzzle.In addition,some hydrophobic microorganisms have a strong biosorption of oil.In this paper,a strain of psychrotrophs that produces high-efficiency lipase was screened from the soil: LTW-1.After sequencing the 26 S r DNA D1/D2 region sequence of the bacteria and performing Blast comparison to construct a phylogenetic tree,LTW-1can be determined the fungus belongs to the genus Saccharomyces.The optimum temperature range of this bacterium is 15-25?.The lipase enzyme activity measured at15? is 108.9U/m L,which is higher than many known low-temperature yeasts.Optimized by the response surface experiment of lipase enzyme activity,the best enzymeproducing culture conditions are: fermentation time 61 h,fermentation temperature 22?,PH 8,beef extract powder 12g/L,filling liquid volume 50 m L/250 m L,inoculation volume3%,calcium sulfate 1g/L,soybean oil 20g/L(emulsified with polyvinyl alcohol),the enzyme activity measured after optimization was 245.3U/m L,more than twice that before optimization.The LTW-1 strain has a strong adsorption effect on the suspended and dispersed oils when ingesting oils and fats,and will form a cell-oil complex,which can be removed by direct filtration,and the oil removal rate can reach 95%.The factors influencing the biological adsorption capacity of LTW-1 strain were preliminarily explored.The results showed that when the strain was cultured at 24 h,the adsorption time was at 36 h,the loading liquid volume was 100 m L/250 m L,and the initial inoculation volume was 12%,the cells were formed.The dry weight of the grease compound is the largest.