The Secretion Of Pyochelin And Its Effects On Alkanes Degradation By Pseudomonas Aeruginosa NY3

Pseudomonas aeruginosa could secrete abundant extracellular active substances,such as rhamnolipid and vario us protease.Except the effect of rhamnolipid had sufficient study,other extracellular active substances' effect had little study on the degradation of alkanes.PCH was a siderophore secreted by Pseudomonas aeruginosa,and was important for bacterial to achieve iron element.As we known,iron was the active center of most enzymes which was important to alkanes degradation and iron was important to initiate these enzymes.Iron efficiency could affect the degradation of hydrocarbons by NY3.So based on the promoting effect of extracellular active substances secreted by NY3 on the degradation of alkanes and the important role of PCH on the growth of NY3 bacterial,we started our research.And these research had great significance in the degradation of petroleum hydrocarbons pollutants.In this paper,the characteristics of PCH secreted by Pseudomonas aeruginosa NY3 were studied,and the conditions of PCH secretion were optimized.And the effects and mechanism of PCH on the degradation of hexadecane by NY3 and the mechanism of action of FePCH on hexadecane were studied.(1)NY3 could secrete PCH,and the was a mixture of chiral enantiomers.The aqueous solution of the purified mixture had a strong ultraviolet absorption peak at 215 nm,252 nm and 360 nm.M9 medium could secreted more PCH,and optimized basic M9 medium could improve the secretion of PCH.When the concentration of FeCl3 was 0.02 mmol/L,the concentration of NH4 C l was 5 g/L,and the sodium pyruvate was the source of carbon,the secretion of PCH up to 240.240 mg/L.(2)The secretion of PCH by NY3 was a "double-edged sword" on the degration of hydrocarbons.PC H could increase the growth of bacteria,improve the degradation of hydrocarbon activity,and degraded some alkanes through the free rad ical pathway.However,excessive secretion of PCH could make the cell death.(3)The extracellular fluid of Pseudomonas aeruginosa NY3 which had high concentration of PCH had the hexadecane degradation ability.However,the PCH extracted from extracellular fluid had lower degradation ability of hexadecane.When FeCl3 or FeC l3 and H2O2 cooperated with PC H,he degradation efficiency of hydrocarbons was improved,and the highest hexadecane degradation rate could up to 13.81 % at 8 h.The degradation mechnism was the oxidation reaction which initiated by hydroxyl radicals produced by its chelating process.And the free radical strength in the reaction system was positively correlated with the degradation efficiency of hexadecane.(4)The 7 kinds of conversion products identified in the system of C H with FeCl3 or with H2O2 or with FeC l3 and H2O2 by GC-MS,and the conversion products included n-butanol,4,5-dihydroxy-2-pentene,1-methyl-3-hydroxypentyl alcohol,1-hydroxyhexanoic acid,1-methyl-2-hydroxyhexanol,adipic acid and palmitic acid.Three transformants of pyrene was identified,included 1-methyl-2-propenoic acid benzene,1,2-dihydroxy naphthalene,4-alcohol hydroxy phenanthrene.