Preliminary Study On Physiological Response Of Navicula Gregaria Donkin To Three Antibiotic Stresses

Antibiotics are becoming more and more widely used in people’s lives.However,due to the increasing misuse and abuse of antibiotics,a large number of antibiotics have flowed into the water through animal feces and patients’ urine,which caused the antibiotic content in the water exceed the water quality assess standards and broke the balance of aquatic ecosystem.As the primary producer of aquatic ecosystems,algae is an important food for aquatic organisms.The entry of antibiotics into the water environment has a serious impact on the growth,physiological activity,and storage of algae.With the algae entering the food chain,it also causes serious problems to water ecosystems and human health.In this study,the freshwater benthic diatom Navicula gregaria Donkin was obtained through purification and culture.Three commonly used antibiotics(ampicillin,streptomycin sulfate,and kanamycin sulfate)were perform a single acute stress experiment to determine the clumps of cell density,chlorophyll a content,soluble protein content,MDA content,SOD activity,lipid content and composition,antibiotic residues and morphological changes after stress.the result shows:1.under the stress of antibiotics ampicillin,streptomycin sulfate and kanamycin sulfate,the cell density of N.gregaria showed a trend of low concentration increase and high concentration decrease during each stress time.2.under the stress of antibiotics ampicillin,streptomycin sulfate and kanamycin sulfate,the chlorophyll a content of N.gregaria and soluble protein content both showed an "up-down" trend,which may be affected by high concentration antibiotic stress.The physiological,biochemical,and metabolic processes of algae destroy its chloroplast structure,hinder its protein synthesis,cause both chlorophyll and soluble protein content decreased.3.under the shrot-term stress of antibiotics ampicillin,streptomycin sulfate,and kanamycin sulfate,SOD enzyme activity basically increased,and under long-term stress,SOD enzyme activity first increased,then decreased.The trend of low concentration of MDA basically showed a tendency to inhibit high concentration.4.under the stress of antibiotics ampicillin,streptomycin sulfate,and kanamycin sulfate,the oil content of N.gregaria present an "increasing-decreasing" trend;for the composition of oil,by the increasing of the stress content,saturated fatty acids(TSFA)appeared first decline and then increase,the unsaturated fatty acid increased first,then decreased;the lipase activity showed increase to decrease trend also.5.under the stress of antibiotics ampicillin,and kanamycin sulfate,as the stress concentration increases,both the residual amount and recovery rate within N.gregaria was smaller.After 96 h stress by ampicillin,no ampicillin residue was detected.6.under the stress of antibiotics ampicillin,streptomycin sulfate,and kanamycin sulfate,the morphology of N.gregaria were distorted,swelled in the middle,narrower at both ends,asymmetrical along the transpical axis and bent to one side of the valve.The results of this study showed that antibiotic treatment can effect many morphological and physiological features of N.gregaria,based on our data the cell density,chlorophyll a,soluble protein,antioxidant enzyme activity,oil content and composition,cell morphology,and residue detection all have great changes After the stress by anitibotic.