Effects Of Petroleum Hydrocarbon On Growth, Biochemical Characteristics And The Related Gene Expressions Of Four Microalgae Species

With the development of offshore oil, marine transportation and sewage, a lot of oilhave been flowing into the ocean, and petroleum hydrocarbon toxicity has affected marineecosystem seriously. Marine microalgae is the producer of marine food chain and provideprimary productivity for marine. So research about the effects of petroleum hydrocarbonon microalgae could help to draw attention to the seriousness of oil pollution and providegood theoretical foundation for studying the mechanism of petroleum hydrocarbon toxicon microalgae.Through screening a wide range of microalgae species to choose microalgae that hasgood tolerance to petroleum hydrocarbon. To study the effects of petroleum hydrocarbonon growth and metabolites(chlorophyll a, chlorophyll b, proteins, polysaccharides, crudefat and SOD) of microalgae in laboratory simulation training and from the cellular level toexplore the impact of petroleum hydrocarbon on microalgae cell morphology and frommolecular biology level to analysis the effects of petroleum hydrocarbons on theexpression of related gene of microalgae. The main conclusions are as follows:(1) By acute toxicity tests for a large number of algae species, ultimately we selectedfour microalgae species: marine microalgae Nannochloropsis Oculata, freshwatermicroalgae Chlorella vulgaris, Phaeodactylum tricornutum Bohlin and Isochrysisgalbana.(2)96h EC50of four microalgae were: Nannochloropsis59.43mg/L, Phaeodactylum53.95mg/L, Chlorella vulgaris45.92mg/L, Isochrysis38.62mg/L. Thus, order oftolerance to petroleum hydrocarbons were Nannochloropsis> Phaeodactylum> Chlorellavulgaris> Isochrysis.(3) Effect of petroleum hydrocarbon on growth of four microalgae showed thatconcentration of petroleum hydrocarbon which can inhibit growth of Nannochloropsis,Chlorella, Phaeodactylum and Isochrysis is greater than30mg/L,10mg/L,20mg/L and10mg/L respectively. Moreover the greater the concentration was, the more obviousinhibition was. However lower doses can promote growth of microalgae. (4) A growth model with consideration of effects of petroleum hydrocarbon ongrowth of microalgae, was developed by incorporating Logistic model with Lorentz andExponential equation. Lorentz equation can describe effects of No.0petroleumhydrocarbon on growth rate of microalgae, while Exponential equation suggests that onbiomass. It was indicated that the experimental data was in conformity with growth model.(5) Impact of petroleum hydrocarbons on metabolites of one microalgae: the overallvariation of metabolites was similar to its growth" low promote high suppression". But fordifferent metabolites, the impact of petroleum hydrocarbons was not the same.(6) Impact of petroleum hydrocarbons on metabolites of four different microalgae:the impact had a certain relationship with the hydrocarbon concentration, different typesof metabolites and microalgae species.(7) By scanning electron microscopy to determine the effects of petroleumhydrocarbon on microalgae cell morphology: cells appeared irregular deformation, surfaceapparently shrinked, and even some cell had structural damage and rupture phenomenon.(8) From the level of molecular biology, petroleum hydrocarbon could influencephotosynthesis, respiration and fat metabolism etc. In addition to EST01794genes, theexpression of related gene had "low promote high inhibition" phenomenon. But theexpression of gene EST01794was increasing with the concentration of petroleumhydrocarbon rose.