利用Acinetobacter calcoaceticus RAG-1生產生物乳化素及其乳化性質

Bioemulsifier Production by Acinetobacter calcoaceticus RAG-1 and Investigation the Properties of This Bioemulsifier.

邱保盛(Bau-Sheng Chiou)

指導教授 ： 陳文章

國立臺北科技大學/工程學院/化學工程所/碩士(2006年)

摘要

生物乳化素是由蛋白質或和多醣組成能穩定油/水乳化物，能應用在污染防治、生物復育、農業、清潔劑和化妝品工業。
利用不動桿菌屬醋酸鈣種(Acinetobacter calcoaceticus RAG-1)以酒精為碳源批式發酵生產生物乳化素，培養液離心去除菌體後以膜過濾系統濃縮接著以冰酒精沉澱多糖、然後透析和烘乾，3升發酵槽以攪拌轉速160rpm、16g/l乙醇、12.1g/l磷酸鹽等條件培養35小時，可得胞外多糖47%、乳化素1.1g/l，乳化素隨菌體生長逐漸分泌到發酵液中，並在進入穩定期時大量釋放出。
以滾動的方式乳化礦物油，改變乳化素濃度、礦物油量、pH值等條件測量乳化油滴粒徑、界達電位(zeta potential)、及濁度的變化，超過臨界微胞濃度時濁度會明顯的上升，乳化油滴粒徑分佈約500nm、800nm、1.1μm，當pH為2.25時微胞變小至30nm左右且有效油滴直徑和MSD粒徑分佈相近，因為多糖的pKa =3.05，在pH3~3.5間乳化素會沉澱無法乳化，pH9.6乳化濁度較低且不穩定，可能是因糖類水解的原因，在pH8.5時乳化素愈多MSD和有效油滴粒徑皆有增大的趨勢。界達電位在pH4以下愈酸電位會逐漸降低，pH7以上電位相近約在-35~ -43mv。

關鍵字

生物界面活性劑 ； 生物乳化素 ； 不動桿菌屬 醋酸鈣種

並列摘要

Bioemulsans are amphipathic proteins complexes polysaccharides that stabilize oil-in-water emulsions and have applications in industrial areas of pollution control, bioremediation, agriculture, detergent, and cosmetics.
The Acinetobacter calcoaceticus RAG-1 grew on ethanol medium as carbon source to secrete the bioemulsifier in batch cultivations. The cell-free culture broths were obtained by using centrifugation and membrane filtration, and then mixed with four volumes of chilled ethanol to precipitate polysaccharides, and then dialyzed, and oven dried. When cultivated in 3-liter bioreactor with agitation speed 160rpm for 35 hours, using the medium of 16g/l ethanol, 12.1g/l of phosphate, the exopolysaccharide 47% and emulsan 1.1g/l were obtained. Emulsan were gradually released into the medium with cells growth, and a large number released into the medium when the cells approach the stationary phase.
After the formation of oil-in-water emulsions by tumbling in a rolling mill, changing the concentration of emulsan、mineral oil volume and pH, the emulsion’s droplet diameter、zeta potential and turbidity were measured. When the concentration of emulsan exceeded the critical micelle concentration (CMC) the turbidity of emulsions will increase obviously. The sizes of oil droplets distribute over 500nm、800nm、1.1μm. At pH 2.25, the MSD and effective diameter are the same of about 30nm. At pH 3~3.5, the emulsan will precipitate because the pKa of polysaccharide is pH 3.05. At pH 9.6, the emulsion turbidity is lower and not stable due to the hydrolysis of polysaccharides. Zeta potentials were reduced with the decreasing of pH when below pH 4. Zeta potentials were around -35~ -43mv when pH above 4.

並列關鍵字

Biosurfactant ； Bioemulsans ； Acinetobacter calcoaceticus RAG-1

參考文獻

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