The Fermentation And Purification Of Carotenoids In Photosynthetic Bacteria PSB-B

Carotenoids are a sort of natural pigment which possesshealthcare function and biological activitivities like delayingsenescence and preventing of tumor. There is a very broadapplication prospects of carotenoids in food and pharmaceuticalindustry. Photosynthetic bacteria is one of the ideal strains ofcarotenoids fermentation due to its rich content of carotenoids. Inthis work we isolated a PSB-B strain from sludge of Fenhe River inChina, which has a short growth cycle and rich carotenoids yield, andstudied the extraction conditions of carotenoids. In addition, itprovides theoretical basis and instruction for industrializedproduction of carotenoids. The main results as follows:1. Strain PSB-B has the strongest ability of fermentingcarotenoids among the11strains photosynthetic bacteriaisolated from the sludge of Fenhe River in China. Strain PSB-Bwas straight short-rod shaped Gram-negative bacteria, size0.6-0.8*1.2-2.0μm containing bacteriochlorin and carotenoids. The color of the colony in anaerobic environment is deep red.Based on phenotypic, physiological, biochemical andphylogenetic (16S rDNA) studies, strain PSB-B most resembledRhodopseudomonas faecalis strain gcT(99.93%similarity).2. We optimized the carotenoids fermentation conditions of strainPSB-B according to the principle of Central composite design.And the optimal conditions were30.88°C,2172lux and9.66%inoculum concentration. Under these conditions, the practicalyield of carotenoids was16.93mg/L.3. We studied the effects of carbon and inorganic salts of strainPSB-B fermenting carotenoids. It indicated that strain PSB-Bhad the largest yield of carotenoids with peptone and sodiumacetate as carbon. It was better for strain PSB-B fermentationwith MgSO40.1g/L、FeSO40.03g/L、NaHCO31g/L and Na2CO31g/L.4. The comparison of three methods ultrasonic-assisted, grindingand acid-head crushing on carotenoids extraction yield fromstrain PSB-B was carried out. Data ANOVA showed thatultrasonic-assisted was the best method. Based on theultrasonic method we studied the influence of the ultrasonicpower, ultrasonic time and ratio of organic solvent oncarotenoids extraction. According to the results ultrasonic power as195W, the extraction time as2min, the volume ratioof fermented liquid and organic solvent as10:15and organicsolvents methanol as n-hexane(1:5) was the best extractioncondition.5. This experiment adopted the methods of TLC and HPLC toseparat and purify the pigment. The best developing solvent ofTLC analysis is n-hexane: acetone: methyl alcohol (4:1:1). Thepigments were preliminary divided into6kinds of pigments byTLC analysis and6kinds of relatively pure pigments were getusing HPLC for further purification.