Study On The Effect Of Ultrasonic Inactivation Of Limnoperna Fortunei And Its Influencing Factors

The bivalve mussel species Limnoperna fortunei is one of the most destructive invasive species in freshwater ecosystems worldwide.After the invasion,the L.fortunei quickly proliferated and caused biofouling,which led to clogging pipes,reducing water delivery efficiency,seriously threatening the normal operation of structures and the mutations in freshwater ecosystems.However,the biofouling phenomenon still lacks effective antifouling strategies,especially in drinking water treatment systems that cannot use many existing strategiesBased on the biological damage problems of water conservancy projects in southern China,this paper summarizes the existing L.fortunei prevention means at home and abroad Utilizing the penetrability and lethality of ultrasonic waves,a L.fortunei killing method was selected to establish an ultrasonic reaction device for ultrasonic testing,and the single-factor analysis and response surface method were used to determine the best conditions for L fortuneis mortality;By comparing the response of tissue such as closed-shell-muscle and gills of the L.fortunei before and after ultrasonic treatment,and combining with molecular biology techniques,the tissue damage was quantified by combining PMAxxTM with fluorescence quantitative PCR.The differences of SEM,EDS,XRD,compressive strength and FT-IR between the adult and the juvenile L.fortunei were compared,In order to investigate the effect of ultrasonic killing on the L.fortunei and the influencing factorsThe result showed that:(1)The effects of ultrasonic power,ultrasonic time and action distance on the mortality of L.fortunei were studied by the single factor method and response surface method.The optimal technological conditions were optimized,when the operating distance was 8.5cm,the ultrasonic power reached 600w,and the ultrasonic time was 68min,the mortality rate of the adult L.fortunei could reach 100%,and that of the juvenile L.fortunei could reach 100%(2)The relative quantitative relationship between the copy number of mitochondrial COI gene and CT value was established.The established standard curve is y=-3.25x+35.67 The determination coefficient(R2)is 0.9965 and the E value is 102%,which can realize rapid relative quantification of the gene copy number of tissue samples(3)A technique was developed to quantitatively detect the number of COI mitochondrial gene inactivated cells in L.fortunei by PMAxxTM-qPCR,which could remove the interference of membrane damaged cells on the detection of living tissue cells and reduce the possibility of false-positive detection results.and realize accurate and rapid quantification of inactivated cells in samples.Combined with the observation of pathological tissue sections,using PMAxxTM-qPCR method to study the damage of L.fortunei tissue under different ultrasonic killing conditions can be more clearly shown.At the ultrasonic power of 600W and the ultrasonic time of 30min,adult L.fortunei has the greatest damage to the gill and muscle tissue.The difference in logio gene copy number between tissue samples treated with PMAxxTM and those not treated with PMAxxTM was 2.19 and 2.13,respectively(4)After the ultrasonic test,It was found that under the same ultrasonic conditions,it takes a long time for the death of adult L.fortunei.Through exploring the SEM,EDS,XRD,FT-IR and compressive strength tests of the shell,and found that the adult shell has smaller particle size,smaller porosity,more orderly molecular,stronger crystallinity,and penetration ability is poorer,organic matter content is much more,the toughness is stronger,so it is also relatively strong in resisting the external environment compared to the shell of the juvenile L fortunei.This explains why it takes longer for the death of adult L.fortunei than for a juvenileIn this paper,the effects and influencing factors of ultrasonic inactivation of L.fortunei are studied.While killing the adult L.fortunei,the mortality of the juvenile and larva can reach 100%,which provides an important scientific basis for controlling the invasion and reproduction of the L.fortunei,and has certain reference value for the control of the biofouling.