Inhibitory Effect And Mechanism Of Plant-source N-caprylic Acid On Algae

With the rapid development of the global industry,the environmental pollution is increasing outstanding.Among which,the water pollution is a severe threat to human's life.The earth is already in a state of lack available water resource,and the eutrophication comes from the industrial development and human activity has produced hidden danger on water resource,which making the problem worse.With the discovery of allelopathy,the utilization of allelochemicals to inhibit the growth and breeding of algae has become a research hotspot.There are manly kinds of allelochemicals.Allelochemicals have selectivity and specificity on different algal,generally speaking,one kind of allelochemical only has inhibition on one or a same category of algae.In addition,the amount of allelochemicals generated by plants is extremely low,which is far from the quantity demand of controlling algae blooms.While the allelochemicals produced in chemical industry are often degradation-resistant,and will bring about secondary pollution when it is applied to governance of eutrophication.Compared with the n-caprylic acid produced by chemical industry,the coconut oil n-caprylic acid extracted from the natural plant oil of coconut oil not only has the natural scent of the coconut oil,but also always used in cosmetic industry,pharmaceutical industry and food industry,which indicates the application security of the coconut oil extractive.Through systematic study about the inhibitory effect and its mechanism of coconut oil n-caprylic acid on algae,we have obtained the following results preliminary:1.Research on the coconut oil n-caprylic acid inhibitory effect.The experimental result of coconut oil n-caprylic acid on only M.aeruginosa shows that coconut oil n-caprylic acid has an obvious inhibiting on M.aeruginosa and exerts a certain dose-effect relationship.When the coconut oil n-caprylic acid concentration was 12.5?L/L and treatment time was 96 h,the inhibition ratio on M.aeruginosa exceeded 95%.When the concentration was 100?L/L and treatment time was 24 h,the inhibition ratio reached about 70%.And when the treatment was prolonged to 96 h,the inhibition ratio approached 100%.The experimental result of coconut oil n-caprylic acid on only S.obliquus indicates that coconut oil n-caprylic acid also has a certain inhibitory on S.obliquus and there is dose-effect relationship.When coconut oil n-caprylic acid density was 50?L/L,it shows a better inhibitory on S.obliquus when the treatment time scratched 120 h(P<0.01),and the inhibition ratio is 13.73%.When the concentration increased to 250?L/L,the inhibitory ratio more than 80% while the duration extended to 96 h.2.Study on algae inhibiting mechanism of natural coconut oil n-caprylic acid.Using coconut oil n-caprylic acid to inhibit the growth of M.aeruginosa,and the result revealed that the conductivity,nucleic acids and nucleotides content,and soluble protein content all showed increasing trend.And this trend presented positive correlation with concentration of coconut oil n-caprylic acid.The content of superoxide anion radical (?) increased firstly and then decreased,and the content of superoxide dismutase(SOD)activity presented a tendency of rise when the coconut oil n-caprylic acid density was within 25?L/L,while the density exceeded 25?L/L,the SOD activity tended to reduce.The content of malondialdehyde(MDA)increased with the increasing of coconut oil n-caprylic acid concentration.The experiment results of scanning electron microscope show that the coconut oil n-caprylic acid can destroy the cell membrane structure and inner cell's ultrastructure of M.aeruginosa,and the damage extent increases with the increasing of n-caprylic acid concentration.3.Study on effect of coconut oil n-caprylic acid to intracellular and extracellular polysaccharides and microcystins content of M.aeruginosa.The result shows that when the M.aeruginosa cells were under the stress of coconut oil n-caprylic acid,both polysaccharides and microcystins increased markedly.When the coconut oil n-caprylic acid concentration was 12.5?L/L,compared with control groups,the content of polysaccharides increased significantly(P <0.05),and the content of microcystins increased highly significantly(P<0.01).This suggests that coconut oil n-caprylic acid has a significant inhibitory effect on algae,but it needs to consider of the influence of microcystins on the environment in specific application.