Effect Of Pomegranate Peel Extract On Allelopathic Anti-algal

In this paper,Pomegranate peel was used as raw material to study the inhibitory effect of its extract on Microcystis aeruginosa.The inhibitory effect of Pomegranate peel added directly on Microcystis aeruginosa was investigated firstly in the experiment.Based on the extracts of Pomegranate peel prepared by different extraction methods,the inhibitory effect of Pomegranate peel extract on Microcystis aeruginosa was explored under different conditions.Then,the effects of the extract of Pomegranate peel on the physiology and biochemistry of Microcystis aeruginosa were studied.Finally,the crude extract of Pomegranate peel was preliminarily isolated and identified to explore the main inhibitory composition of pomegranate peel extract.The main conclusions of the study are as follows:(1)The direct addition of Pomegranate peel powder can inhibit the growth of Microcystis aeruginosa,and the dosage of 2g/L can reduce the algae density from 5×105cells/ml to 1.77×105cells/ml.Moreover,the growth of algae can be inhibited completely when the dosage was greater than the 6g/L.Pomegranate peel extract can be obtained by different extraction methods.The results showed that ultrasonic extraction and oscillation extraction had little effect on extracting yield.However,methanol,acetone and petroleum ether extract had different effects on the yield.Among 6 extracts for Microcystis aeruginosa inhibition,the extract yields with methanol were 54.28% and 55.79% respectively,the extract yields with acetone were 3.63% and 3.64%,the extract yields with petroleum ether were 1.17% and 1.29%.The subsequent experiment exhibited that the relative inhibition rate of petroleum ether extract obtained from the oscillationcondition was between 9% and 36% while the relative inhibition rate of the other5 extracts to Microcystis aeruginosa was above 99% during 8 days.(2)The Pomegranate peel extract had inhibitory effect on Microcystis aeruginosa under different p H conditions,and the inhibition effect was negatively correlated with pH.Under the conditions of pH=7.5 and pH=8,their algae inhibitory effect was comparable.The relative algal inhibitory rates under dosage of 10mg/L,20mg/L and 30mg/L extracts were maintained at 17%,67% and 76% over time,respectively.Under the conditions of pH=8.5 and pH=9,the relative inhibitory rates of different concentrations of extracts to Microcystis aeruginosa were 7%,67% and 71% at the end of the experiment,respectively.Under the conditions of 5 different nutrient levels(total nitrogen >1mg/L,total phosphorus >0.03mg/L),the extracts can effectively inhibit the growth of Microcystis aeruginosa.It was observed that the relative inhibition rate of Microcystis aeruginosa was almost 50% when the concentration of extract was greater than 20mg/L.Meanwhile,the extract had different inhibitory effects on different algae species.The relative inhibition rate can reach more than 90% for Microcystis aeruginosa while only 64.68% for Scenedesmus quadricauda when the concentration of extract was greater than 30mg/L.(3)The extract concentration range of 5~30mg/L had a certain inhibitory effect on the concentration of chlorophyll a(Chla)in algal cells.On the second day of the experiment,the concentration of Chla in the control group was 1.07,1.28,1.10,1.15,1.01 and 1.18 times of that of the inhibitory group.On the 8th day of the experiment,the concentration of Chla in the control group was 1.26,1.29,1.70,1.70,1.46,1.24 times of that of the inhibitory group.It also showed that the activity of the living algae cells expressed with the dehydrogenase-converting TF(1,3,5-triphenyl methanine)was inhibited by the extract of Pomegranate peel when the 25mg/L extract was used,which was only 0.75,0.15,0.07 and 0.26 times of the control group.The TF concentration of the inhibitory group was only 0.72,0.14,0.06 and 0.1 times of the control group when the 30mg/L extract was used.So The extract dosage of 25 mg / L and 30 mg / L had strong stress on the antioxidant system of Microcystis aeruginosa,and the content of MDA in algal cells reached 3.94 and 5.90 times,respectively.The activity of SOD(superoxide dismutase)was 3.25 and 4.34 times higher than that of the control group.(4)The anti-algal compounds in Pomegranate peel were isolated and identified by column chromatography and algae activity test.The glycosides of two polyphenolic compounds were preliminarily speculated through LC-MS analysis and the anti-algal compounds may be hexylglycine and ellagic acid hexaglycans.