The effects of fermentation strategies on simultaneous 1,3-Propanedioland 2,3-Butanediol production by an isolated indigenous Klebsiella sp. Ana-WS5

• Main Authors: Fang-Tzu Li, 李芳慈
• Other Authors: Hong-Wei Yen
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/95349874039568511773

碩士 === 東海大學 === 化學工程與材料工程學系 === 102 === The effects of fermentation strategies on simultaneous production of 2,3-butanediol (BDO) and 1,3-propanediol (PDO) by using glycerol as a single carbon source were studied in a series of cultivations of Klebsiella sp.Ans-WS5. Based on the results of this work, glycerol (70 g/L) is shown to beas a suitable carbon source for BDO (21.7 g/L) and PDO (10.3 g/L) production in the cultivation.Using waste crude glycrol (70 g/L) as a carbon source would lead to less biomass concertration (2.2 g/L) but the pH of fermention mediumis preferable for to PDO (14.9 g/L) production.A mixed carbon source of glycerol (50 g/L) and glucose (20 g/L) led to less BDO (5.9 g/L) and PDO (2.1 g/L) production than when using glycerol alone.Previous research showed that the addition of acetic acid can increase the production of BDO, while this study found that lactic acid can also enhance the simultaneous production of BDO and PDO.With the addition of 10 g/L of lactic acid, an increase of about 30% in total diols production was obtained. Ca-alginate cell immobilization, small size of particle (1.3 mm) will promote production of BDO and PDO.The number of particle don’t have significant difference because the pH is too low.Repeated fed-batch fermentation with cell immobilization can repeat three times, and BDO and PDO production will be maintained at 20 g/L and 11 g/L, respectively. The continuous fermentation with immobilizedcellsproduce BDO and PDO productivity 0.27 g/Lh、0.20 g/Lh；yield 0.29 g/g、0.54 g/g. Cell immobilization can not particularly enhance production of BDO and PDO, but it can contribute to repeated batch operations. The strategy of fixing pH at 7.0 can result in about two-flod increase in the maximum concentration of PDO (25.0 g / L) andproductivity (0.33 g/Lh). Although the strategy adjusting the pH every 12 or 24 h did not enhance the maximum BDO and PDO concentration, it did greatly improve productivity compared to the batch without a pH control.The strategy adjusting the pH every 24 h with fed-batch can enhance maximum concentration (74.3 g / L), productivity (0.83 g/Lh) of Total Diols. 5-L Airlift fermenter is with good oxygen rate and less shear force, so it contribute to biomass (3.0 g / L) and BDO (22.2g / L) production In conclusion, the results of this work show that the ratio of BDO and PDO in the cultivation of isolated indigenous Klebsiella sp. Ana-WS5 is sensitive to the pH value and dissolved oxygen. In addition, lactic acid addition and the adjusting of pH level at fixed time intervals are both simple and efficient ways to enhancing simultaneous BDO and PDO production.