一株分离自北极海水红球菌(Rhodococcus sp.)B7740的生长条件及其粗类胡萝卜素提取方法的优化

OPTIMIZATION OF GROWING CONDITIONS AND A METHOD FOR THE EXTRACTION OF CRUDE CAROTENOIDS PRODUCED BY RHODOCOCCUS SP.(STRAIN B7740) ISOLATED FROM THE ARCTIC SEA

红球菌(Rhodococcus sp.)B7740分离自北冰洋海水样品,前期实验表明其能产生大量黄色素,但是该菌生物量很低。本实验通过碳源、氮源、培养温度、发酵液起始pH值、菌种接种量等单因素和正交实验优化了该菌株的培养条件,在此基础上,通过对提取剂种类及pH、提取时间、料液比等的研究,优化了色素的提取条件。实验结果表明,1 L陈海水中,添加5 g酵母粉,5 g葡萄糖,3 g乳糖,7 g牛肉膏;起始pH为7,培养温度为25℃,菌种接种量1.0%,160 r/min摇床培养7 d时,生物量从6.1 mg/mL上升到23.08 mg/mL,提高了278.4%。以上述培养条件下得到的干菌体为材料,采用pH为7的无水乙醇,当料液比为1∶30,浸提温度为75℃,浸提1 h重复提取2次时,色素含量为1 160.625μg/g干菌体。对色素的分析表明,该色素为类胡萝卜素,实验结果为进一步研究极地微生物红球菌(Rhodococcus sp.)B7740产类胡萝卜素的提取工艺提供了基础。

Rhodococcus sp. （ strain B7740） isolated from the Arctic Ocean can accumulate large numbers of yellow pig- ments, but the biomass of these bacteria is very low. In this study, an optimal growing medium was developed u- sing single factor and orthogonal experiments on carbon and nitrogen sources, temperature, initial pH and inoculum concentration. On this same basis, extraction conditions were optimized for the type of extraction solvent, pH, ex- traction time and solid to liquid ratio. Five grams of yeast extract, 5 g of glucose, 3 g of lactose and 7 g of beef ex- tract were added to 1 L of old sea water. With an initial pH of 7, a temperature of 25 ℃ and an inoculum concentra- tion of 1.0%, the sea water was cultured for 7 days on a shaker at a speed of 160 r/min and the biomass of B7740 increased from 6.1 mg/mL to 23.08 mg/mL, an increase of 278.4%. Dry cells were used for the experiment and anhydrous ethanol at pH7 was used as the extracting reagent with a ratio of sample to solution of 1 ： 30, temperature was set at 75℃ and the extraction time was 1 h, repeated twice. Using this method, the output of the pigment reached 1 160. 625 μg/g dry cells. Analysis showed that the pigment was carotenoid. The results of this experiment provide the foundation for the further study of extraction methods for carotenoids produced by the polar microbe, Rhodococcus sp. （strain B7740）.