本研究所篩選TKU004這株生物界面活性劑生產菌,經由16SrDNA序列比對及API試驗鑑定為Bacillus licheniformis 。
B. licheniformis TKU004 生產生物界面活性劑之較適培養條件為含有1%烏賊軟骨粉、0.1% K2HPO4 及0.05% MgSO4.7H2O之50 mL液態培養基 (pH 7)充填於250 mL 通氣錐形瓶並經滅菌20分鐘後,進行接菌並於37℃搖瓶(150 rpm)培養1天。所得醱酵上清液,經酸沈澱、乙酸乙酯萃取、甲醇萃取等步驟,進行生物界面活性劑之純化,其產量為0.551 g/L。TKU004生產之生物界面活性劑能降低水的表面張力至25.42 mN/m,乳化指數(E24)為70%,而且熱穩定性高,不會受高溫影響而失活。此生物界面活性劑之pH 安定性、鹽度安定性分別為pH>7、鹽濃度<2 %。
此外,2 mg/mL之生物界面活性劑對Fusarium oxysporun生長具有40%抑制效果。 The biosurfactant producing strain, Bacillus sp. TKU004, was identified further as Bacillus licheniformis by 16S rDNA gene sequencing and API(Analyitcal Profile Index)tests.
The optimized culture condition for biosurfactant production was composed of 1% squid pen powder (SPP), 0.1% K2HPO4, 0.05% MgSO4.7H2O (pH 7),with autoclave treatment for 20 min, afterward, TKU004 was incubated in 50 mL of above liquid medium in an areation flask (250 mL) and kept shaking at 37℃ for one days.
The biosurfactant was extracted from the culture supernatant by acid precipitation, extraction of ethyl acetate and methanol .The yields of biosurfactant was 0.551g/L. TKU004 biosurfactant could reduce surface tension of water from 72 to 29 dyne/cm.The emulsification index against machine oil was 80%.The biosurfactant had good thermal stability and was resistant to higher temperatures. The pH stability and salinity stability were pH>7 and salinity <2%, respectively.
Besides, 2 mg/mL of the biosurfactant had 40% antifungal activity against mycelia growth of Fusarium oxysporun.