不同pH调节剂对产琥珀酸放线杆菌NJ113发酵产丁二酸的影响

Effects of different neutralizing agents on succinate production by Actinobacillus succinogenes NJ113

摘要:

在3 L发酵罐中分别采用不同的碱性物质作为pH调节剂，考察其对产琥珀酸放线杆菌Actinobacillus succinogenes NJ113 厌氧发酵制备丁二酸的影响。结果表明：Ca2+、NH4+调节剂对菌体生长代谢有较大阻碍作用，丁二酸产量较低；采用含Na+调节剂，在发酵中后期菌体出现絮凝现象严重，且产丁二酸能力骤降；采用含Mg2+调节剂，整个发酵过程菌体代谢旺盛，发酵效果较佳。根据各碱性物质的调节能力以及对菌体生长代谢的影响，选择NaOH、Mg(OH)2和Na2CO3、Mg(OH)2分别作为混合碱组分调节pH，并对两组混合碱中各物质的质量比例进行优化。结果表明，以NaOH、Mg(OH)2混合，两者质量比为1∶1时，发酵效果最好，丁二酸质量浓度高达到69.8 g/L，质量收率74.5％。该种混合碱配比可有效替代碱式MgCO3调节pH，既达到高产丁二酸的目的，又可降低生物制备丁二酸的成本。

Abstract:

Different neutralizing agents were used as pH controller to investigate their effects on the growth and succinic acid production of Actinobacillus succinogenes NJ113. The fermentation results showed that Ca(OH)2, CaCO3 and NH4OH were not suitable for succinic acid production by A. succinogenes NJ113 because of their negative effects on cell growth. When Na-base was used, cells would flocculate and lump, and due to the sodium ion concentration reaching to a high level, OD660 dropped sharply after 12 h of fermentation. Mg-base was better because there was no significant inhibition by magnesium ion. Two combined neutralizing agents were used to maintain pH level, one with NaOH and Mg(OH)2 while the other with Na2CO3 and Mg(OH)2. The optimum ratios of the combined neutralizing agents were both 1:1(g:g) when using 100 g/L glucose. When NaOH and Mg(OH)2 were chosen with the ratio of 1:1(g:g), 69.8 g/L of the succinic acid and 74.5% of the yield was obtained.