二價金屬無機鹽之添加對生物界面活性劑表面素生產之影響

魏毓宏

《化工》 48卷3期 (2001/06) Pp. 1-8

https://doi.org/10.29803/CE.200106.0001

摘要

表面素，一種由微生物如枯草桿菌所生產之脂胜?類生物界面活性劑。是目前文前上所發現最有效的生物界面活性劑，但其應用上長期侷限於產量低、生產成本高的瓶頸。為了提高表面素的產量，本研究提出了在發酵生產表面素時，簡單利用培養基中金屬鹽類之添加策略，並且透過發酵液pH值之調控，以探討其對菌體生長及表面素產能的影響。於眾多兩價金屬離子添加方面, 結果證實，在菌體生長及表面素產能方面，只有鐵、錳離子具明顯的促進作用，其中又以硫酸亞鐵之添加效應更為顯著。在硫酸亞鐵添加效應方面，實驗證實，菌體生長量與添加之硫酸亞鐵濃度成正比。且添加之硫酸亞鐵濃度增高，將刺激發酵過程中酸性物質的代謝生成，引發化現象，加快發酵液pH之降低，待pH值低於5.0，則表面素將快速自發酵液中消失。但研究證實，此現象若可以避免或加鹼調控。則表面素的產量可達3000mg/l 以上，以產量約為文獻值的十倍左右。此酸的發現及酸化現象的發生，在所有表面素合成的研究文獻中，從未被觀察到。初步研究顯示此酸性物質分子量約為150。未來的研究，尚需釐清該微生物對高濃度鐵離子之需求，及酸性物質代謝之路徑。

關鍵字

枯草桿菌 ； 生物界面活性劑 ； 表面素 ； 硫酸亞鐵 ； 酸化

並列摘要

Surfactin is a lipopeptide-type biosurfactant produced by various strain of Bacillus subtilis and is one of the most powerful biosurfactant so far known. It is from the economical point of view in a stiff competition with synthetic surfactants due to poor production yield. In order to enhance the production yield, in the present study, have achieved marked improvement in the yield of surfaction based on supplementing the medium with metal salts and controlling its broth pH. In the media improvement, experimental data showed that minueral salt medium is better than nutrient broth medium on cell growth and surfaction production. The study of the effect of the additions of other metals was done. Only iron and manganese salts caused significant enhancement of surfactin production.The additon of iron also increased the biomass and surfactin concentration. It shows that broth disappeared rapidly as soon as the pH level dropped below 5.0, however, if this acidification phenomenon was avoid, or re-versed by NaOH addition, surfactin production was highly enhanced to as high as 3000 mg/1, which was almost ten times over the previously reported level for this strain. The identity of the acidic metabolite resulting from the iron addition has not been determined yet, although preliminary tests indicated it is an acid with a molucular weight about 150. Further fundamental work is needed to understand the basis for the high iron requirement in this strain and the pathway that leads to the acidogenic metabolism.

並列關鍵字

Bacillus subtilis ； biosurfactant ； surfactin ； iron sulfate ； acidification