Study On Degradation Of Lutein By Enterobacter

Lutein is an important fragrance precursor,under certain conditions can be degraded to produce a series of fragrant substances.In this experiment,a strain capable of degrading lutein and producing tobacco aroma components was screened from tobacco leaves.In this study,bacterial identification,degradation kinetics,degradation product characterization and strain degradation were studied.As follows:??The strain was identified as Enterobacter hormaechei by means of morphological observation,physiological and biochemical tests and molecular identification.The results showed that the higher the protein content(g / L)and the lower the content of lutein(%),the higher the amount of lutein was.When the A20 strain grew to 42 h,the leaf yellow The content of the basic is not changed,indicating that the degradation of lutein has basically ended.??We analysed compounds in lutein degradation products,and evaluated the effect of its cigarette flavoring.The degradation products were identified by gas chromatography-mass spectrometry and nuclear magnetic resonance(NMR),then their products were added into cigarette to proceed sensory evaluation.First,three kinds of products were obtained by GC-MS analysis,which were 8-methyl-?-ionone,3-hydroxy-?-ionone and 3-oxo-?-ionone;Through the 8-methyl-?-ionone was the final product of lutein degradation by NMR analysis.Evaluation results show that:moderate concentration of lutein degradation products can improve the overall coordination of cigarette,reduce thrill of oral cavity and nasal cavity,reduce mixed gas,make aftertaste comfortable.??In order to improve the degradation rate of lutein,optimization of the fermentation medium and culture conditions for Enterobacter hormaechei A20 strain.Firstly,the optimization of fermentation medium composition(carbon source,nitrogen source and inorganic salts source).the single factor and the Box-Behnken response surface analysis test were designed with the degradation rate of lutein as the index.As a result,the optimum fermentation medium was composed of glucose 8 g/L,mixed nitrogen sources(yeast extract: peptone = 2: 1)14 g/L and K2HPO4 0.72 g/L.Under the situation,lutein degradation rate increased from 45.7% to 70.37%,which increased by 53.98% compared with the original medium.And then the culture conditions(culture time,culture temperature,rotational speed,pH value and inoculation volume)were optimized.The optimum culture conditions of microorganisms were determined through the single factor and orthogonal experiments with the degradation rate as the index.The optimized culture conditions as follows: The culture time is 42 h;the best temperature is 25 ?;the speed is 150r/min;pH value should be 7.0;and the total inoculation volume is 1.0%.Under the situation,carotenoids degradation rate increased from 70.8% to 91.53%.??Studies on the production of aroma to lutein by resting cells of Enterobacter hormaechei A20 degradation.Based on single factor experiments,the Box-Behnken response surface design was conducted to optimize the degradation conditions of its.The optimized conditions were as follows: the reaction time 120 min,temperature31.14 ?,pH value 4.98,the concentration of resting cells 17.64%,the concentration of substrate 70 mg/L.Under these conditions,the degradation rate of lutein was up to71.37%,consistent was the software prediction value 71.54%,which indicated that the optimized scheme reached the expected effect and had good stability.The main component in fermentation broth of lutein degraded by resting cells were analyzed by GC/MS,and were identified 3-oxo-?-ionone and 8-methyl-?-ionone.In this study,the strain of this study can efficiently degrade lutein to produce characteristic fragrance substances,and elucidate the mechanism of the degradation of lutein by microorganisms,and obtain the best fermentation conditions for the preparation of tobacco aroma substances for industrial biology solid foundation.Therefore,the subject has important theoretical value and practical production value.