Identification Of A Gordonia Strain And Optimization Of Its Fermentation Process For Carotenoids Production

Actinomycetes compared to production of yeast carotenoids, Photosynthetic bacteria has its unique advantages, this paper, a strain of actinomycetes producing carotenoid were identified and optimized the medium and fermentation conditions, And after the bacterium fluid of fermentation cytoplasmic processes break homogenate were studied.first of all, identification of a bacterium strain (HBUT–Y) producting carotenoids was performed through 16S rDNA sequencing and physiological and biochemical method. 16S rDNA fragments of results show that HBUT–Y than strains with Gordon - Y's (the homology of gordonia) bacteria reached 99%. System growth tree analysis, and found that the strain of gordonia bacteria with three strains of the bacteria's closest relative,Combined with the bacterium physiological and biochemical experiments identified preliminarily determined that this for the(gordonia alkanivorans).It could growth on the conditions of the light and no light, but in light conditions,compare the with no light conditions, pigment produced was higher than 56.8%, it could not grow under anaerobic conditions. The bacteria strain cultivated for 6 days, that is, 144 h. Its pigment extracted liquid in 465 nm⁴90 nm absorb strongly, in between 477 nm place has the maximum absorption peaks.Then, fermentation medium for carotenoids production by a gordonia strain were investigated.The single factor design method were used to screen the most suitable carbon source and nitrogen source for carotenoids production, Plackett-Burman design was adopted to screen inorganic salts effecting on carotenoids fermentation. The Results showed that most suitable carbon source and nitrogen source for carotenoids fermentation by gordonia was sucrose and KNO₃, separately. MgSO₄, FeSO₄ showed significance influence on carotenoids fermentation. The fermentation medium were screened as followings, 20 g/L sucrose, 4 g/L KNO₃, 0.4 g/L MgSO₄, 15 mg/L FeSO₄, 2 g/L KH₂PO₄, 3 g/L Na2HPO4, 2 g/L sodium citrate. Best fermentation conditions for: fermentation temperature is 28 oC, fermented initial PH 7.5, shake bed speed for 220 r/min.Using specific formation medium, The strain gordonia could produce 600.5mg/L carotenoid, Than initially selected medium carotenoids yield increased 212.5%.Finally, we research the bacteria cell for high-pressure homogenate broken. We found that during gordonia bacterial cells high-pressure homogenizer broken, homogenized pressure, frequency and homogenate suspension system is the major factor in breaking the bacterial cell. Experimentally determine the bacteria cell high-pressure homogenate broken process: Feeding bacterium fluid density for 60 g/L left and right sides, with phosphoric acid buffer as suspension, soliquoid and bacterium fluid ratio for 1:1. In 200 MPa pressure, high-pressure homogenate once, homogenate process temperature control is below 4℃.