Allelopathic Inhibition And Mechanism Of Spathiphyllum Kochii Root Water Extract On Pseudanabaena Sp.

Pseudanabaena sp.is a widely-existing filamentous cyanobacteria in water and has been proved to be 2-methylisoborneol(2-MIB)producer.It is common for Pseudanabaena sp.to be dominant in the lakes and reservoirs of Southern China.But research about its growth characteristics and effective control method is very limited.In recent years,algae inhition method through the allelopathic effect of plant has been widely proved to be efficiency and eco-friendly.Based on the result of previous research,a method using the Spathiphyllum Kcochii Root Water Extract(SKRE)to control the Pseudanabaena sp.was proposed.The growth characteristics of Pseudanabaena sp.,allelopathic effection characteristics and mechanism of SKRE on Pseudanabaena sp.were studied.Based on the cascade reservoirs in southern China,the spatial and temporal distribution of a Pseudanabaena sp.was studied.The results showed that Pseudanabaena sp.dominated all the year round in the reserovirs,especially from April to August.The highest cell density of Pseudanabaena sp.was 4.69 × 107 cells/L,far exceeding the standard of algal bloom.The cell density of Pseudanabaena sp.increased step by step along the water flow direction of the reservoirs and there was no significant vertical difference.Pseudanabaena sp.biomass in reservoirs was significantly correlated with the concentration of 2-MIB(p< 0.01),and Pseudanabaena sp.might be the important source of odors in the reservoirs.Therefore,it is very necessary to further study the growth characteristics and effective control measures of Pseudanabaena sp.The growth characteristics of Pseudanabaena sp.were studied by single factor simulation.Results show that compared with other species,Pseudanabaena sp.appropriate a more broad growth environment conditions with characteristics of wide suitable temperature range,low light intensity,phosphorus deficiency and disturbance tolerance.The conditions under which the Pseudanabaena sp.could grow well are: water temperature is 15～35 ℃,the light intensity is 9～216 μmol/m2 s,total nitrogen concentration is greater than 2.4 mg/L,total phosphorus concentration is greater than 0.04 mg/L,the p H value range is from 7 to 11,water velocity range is from 0 m/s to 0.10 m/s.The environment characteristics with adapt water temperature,phosphorus deficiency,vertical light intensity decline and significant hydraulic disturbance of the Southern pumped reservoirs is conduce to the dominance of Pseudanabaena sp.The allelopathic effection characteristics of SKRE on Pseudanabaena sp.was studied by experiments adding gradient SKRE.The results showed that SKRE could effectively control Pseudanabaena sp.The dosage achieving the same inhibition rate is related to the initial concentration of Pseudanabaena sp..The higher the initial concentration,the higher the dosage required.For Pseudanabaena sp.with initial concentrations of 8.3 × 107,2.8 × 108,and 6.2 × 108 cells/L,an inhibition rate over 90% needs SKRE dosage of 0.68,1.02,and 1.36 g/L,respectively.SKRE can effectively reduce the concentration of 2-MIB.When the Pseudanabaena sp.initial concentration is 2.8 × 108 cells/L,SKRE dosage is 0.68 g/L,the remove efficiency of 2-MIB could reach 81.5%.Thus,SKRE can effectively control the risk of Pseudanabaena sp.outbreak.Focused on the allelopathic mechanism of SKRE on Pseudanabaena sp.,the effects of SKRE on photosynthesis,membrane lipids of Pseudanabaena sp.were studied through allelopathic inhibition simulating experiments.Metabolomics and proteomics were used to study the influence of SKRE on the metabolism and protein of Pseudanabaena sp.The results showed that the main mechanism of SKRE on Pseudanabaena sp.is to reduce the photosynthetic efficiency by inhibiting the synthesis of photosynthetic pigments and the activity of key proteins such as oxygen-releasing complexes,ATP synthase and NADP reductase.P metabolism is inhibited through inhibiting the activities of phosphate substrate-binding enzymes,permeability enzymes and ATP-binding enzymes.The activities of four kinds of nitrogen transporters,nitrate reductase and nitrite reductase are down-regulated significantly.The N metabolism is also inhibited.The activities of glutamate dehydrogenase and glutathione synthetase increased,and the contents of glutathione and glutamine increased significantly,which indicated the destruction of cell membrane structure,cell death and even cell disintegration.The main components of SKRE were analyzed,and it was found that there were 4 kinds of alcohols,3 kinds of acids,3 kinds of esters,2 kinds of aldehydes,1 kind of amides,1 kind of ethers and 1 kind of azoline.Specifically include(S)-piperidine-2-formamide,2,6-diaminocapric acid,diethyl phthalate,tetrahydrozoline,oleoyl glycerophosphate,and so on.The research could provide a basis for the growth prediction of Pseudanabaena sp.in the typical pumped reservoirs of Sourthern China.Meanwhile,a foundation for the further study of allelopathic control technology through SKRE on Pseudanabaena sp.was established.