PRODUCTION AND CHARACTERISTICS OF BIOSUSFACTANTS BY BACILLUS SP. NPPI-LP-2 AND BACILLUS SUBTILIS NPPI-LG-9 SCREENED FROM TAIWAN

• Main Authors: Hu, Yao-Huang, 胡耀湟
• Other Authors: Wen-Ing Hwang
• Format: Others
• Language: zh-TW
• Published: 1996
• Online Access: http://ndltd.ncl.edu.tw/handle/89758457419455410926

碩士 === 國立屏東技術學院 === 環境工程技術研究所 === 84 === This study was conducted to isolate biosurfactant producing microorganismsfrom contaminated soil and wastewater in southern Taiwan area. Two Bacillusspecies, NPPI-LP-2 and NPPI-LG-9 were isolated from soil and showed good emul-sifying activity against kerosene. When Bacillus sp. NPPI-LP-2 was cultivatedunder optimal conditions (pH 7.0, 30℃, 150rpm) and optimal medium composition(20g glucose, 2.0g CH3COONH4,1.0g K2 HPO4, 1.0g yeast extract, 0.2g MgSO4.7H20,0.001g FeSO4.7H2O, 0.001g MnSO4.4H2O in one liter of medium ), 1.2g/L of abiosurfactant was produced. The crude biosurfactant could be precipitated byammonium sulfate with chemical composition of carbohydrate (21.9%), protein(16.5%),and lipid (11.1%),mannose was defected by HPLC after being hydrolysed,indicating that it might be a mannolipoprotein. The biosurfactant was heatstable and produced an effective and stable oil-in-water emulsion over a widepH range (5~11). The critical micelle concentration (CMC) of biosurfactant was500mg/L and lowered the surface tension of water from 72mN/m to 39mN/m. Themedian lethal concentration ( LC50 ) for Gambusia affinis after 24 hourstreatment was 850mg/L. The results also indicated that the biosurfactant wasbiodegradable. The optimal medium composition for production of biosurfactant by Bacillussubtilis NPPI-LG-9 was (per liter) : glucose 20.0g, NaNO3 4.0g , K2HPO4 1.5g,yeast extract 0.5g, MgSO4.7H2O 0.05g, KH2PO41.0g,FeSO4.7H2O 0.001g, ZnSO4.7H2O0.001g, MnSO4.4H2O 0.001g. Maximum emulsifying activity was obtained when thebacterium was cultured under optimal conditions (pH 7.0, 30℃, 150rpm) with abiosurfactant yield of 0.9g/L. The crude biosurfactant which was precipitatedby ammonium sulfate then extract by methanol , contained 5.6% carbohydrate,35.6%protein and 48.9% lipid. The CMC of this biosurfactant was 100mg/L ,it could lower the surface tension of water from 72mN/m to 32mN/m . The LC50for Gambusia affinis after 24 hours treatment was 45mg/L. The heat stablebiosurfactant produced by NPPI-LG-9 was biodegradable and could enhance thedegradation of crude oil. Key words : Bacillus, biosurfactant, screen, culture condition, recovery,characteristics. creen, culture condition, recovery, characteristics.