The Hormesis Effect Of Three Quinolone Antibiotics In Chlorella Pyrenoidosa

The hormesis effect is a special phenomenon that is different from the traditional dose-effect relationship of toxicology.It refers to a certain benign stimulatory effect when the body is exposed to low doses of pollutants,and it exhibits an inhibitory response under high dose conditions.The presence of hormesis effect means that when the organism is stressed by low-level contaminants,its biological response may be completely different from that of traditional risk assessment studies.Quinolone antibiotics are a large group of broad-spectrum bactericides that have high antimicrobial activity and low toxic and side effect.They are used in human and veterinary medicine to treat bacterial infections,as well as in animal husbandry,which has become a most frequently used and most rapidly developed antibiotics in our country.Chlorella pyrenoidosa is one species of algal that contains abundant protein,vitamins and other nutrition.Chlorella is also a kind of edible algae which is very sensitive to pollutants,and is often used to test the toxicity of pollutant in the water.Therefore,we choose chlorella pyrenoidosa as the test recipient,under the coerce of three specific types of quinolone antibiotics including pipemidic acid,ciprofloxacin and norfloxacin,we tested the variation of growth condition,pnhysiological characteristics and antioxidant index of chlorella pyrenoidosa,in order to study the hormesis effect of quinolone antibiotics to chlorella pyrenoidosa.The research contents are as follows:(1)Linear equations of the number and absorbency of chlorella were established,which shows desired results.In this experiment,six concentration gradients include low concentration group(10-3,10-2,10-1mg/L)and high concentration group(1,10,100 mg/L)of three kinds of quinolone antibiotics were acted on chlorella for 24,48,72,96 hours respectively.Then,the growth condition of chlorella was observed.Results show that the three antibiotics in low concentration group have significant positive effect on the growth of chlorella(P<0.05).The effect climaxed when the concentration of the three antibiotics is 10-3mg/L,acting on chlorella for 96h.On the contrary,high concentration of three antibiotics restrains the growth of chlorella(P<0.05).When concentration of the tree antibiotics was 100mg/L,acting on chlorella for 96h,the restraining effect maximized.(2)The level of chlorophyll,?-carotene and soluble protein in chlorella pyenoidosa were measured.After being treated by three antibiotics in six different concentration gradients from low to high.Result shows,when the concentration of three antibiotics are 10-3,10-2mg/L,they have significant promotion to the generating of chlorophyll,?-carotene and soluble protein in chlorella pyenoidosa(P<0.05).When the coucentratio1 was 10-3mg/L,the effects were the highest.And the acting time of the antibiotics also shows significant positive effects on the chlorophyll,?-carotene and soluble protein generated in chlorella pyenoidosa(P<0.01);10-1?lmg/L concentration of antibiotics also affect chlorophyll,?-carotene and soluble protein in chlorella pyenoidosa,but the effects are insignificant(P>0.05);After treating chlorella pyenoidosa with 10,100mg/L of the three antibiotics,the contents of chlorophyll,P-carotene and soluble protein in chlorella pyenoidosa all decreased significantly(P<0.05),and when the concentration was 100mg/L,chlorophyll,?-carotene and soluble protein in chlorella pyenoidosa decreased the most(P<0.01).(3)In this experiment,the three antioxidant indexes in chlorella pyrenoidosa,including superoxide dismutase,glutathione and malondialdehyde were measured.The result shows,after 10-3mg/L of the three antibiotics acting on chlorella pyrenoidosa for 96h,superoxide dismutase activity increased significantly,while glutathione content decreased signigicantly(P<0.01).The change of malondialdehyde content was not significant(P>0.05).Perhaps the oxidative coerce caused by stimulation of low concentration of antibiotics to the chlorella pyrenoidosa did not exceed the tolerance range,therefore motivated the metabolism of the chlorella cells.10-2 and 10-1mg/L concentration of antibiotics also had effects on the chlorella pyrenoidosa's antibiotic index,but the effects were not obvious(P>0.05);After being treated by the three antibiotics with concentration of 1,10,100mg/L,the activity of superoxide dismutase and the content of malondialdehyde increased signigicantly,while the content of glutathione decreased significantly(P<0.05),There were large accumulations of active oxygen and free radical in the chlorella pyrenoidosa cells,which caused serious oxidation coerce,therefore generated Oxidative toxicity effect.Research shows:Low concentration of antibiotics stimulated the photosynthetic activity,the synthesis of nutrient vitamin A and increased the content of soluble protein.While the active oxygen and free radical the antioxidants generated are within the tolerant range of the cells,therefore stimulates the growth of the chlorella cells.High concentration of antibiotics significantly restrains the growth of chlorella;restrains chlorophyll,?-carotene and soluble protein in chlorella pyenoidosa cells,therefore restrains the physiological metabolic activity of the cells,generates oxidation toxicity,destroys the structure and function of the cells,and restrains the growth of chlorella.Three kinds of carbostyril had hormesis effect on chlorella pyrenoidosa cells.