pH对兼性嗜碱菌Alcaligenes sp.XJ-T-1产生物破乳剂性能的影响

Impact of pH on properties of bio-demulsifier produced by facultative alkaliphilic strain Alcaligenes sp.XJ-T-1

从受石油污染土壤中筛选出一株生物破乳剂产生菌Alcaligenes sp.XJ-T-1,生长的最适初始pH范围为9.0～11.0,为兼性嗜碱菌,能在初始pH 6.0～pH 11.0生长并产生生物破乳剂,但只有在碱性环境下才产生胞外产物。XJ-T-1菌悬液和胞外产物溶液可将蒸馏水表面张力分别降低到30 mN/m左右和35 mN/m左右。经过TLC分析,初步推测XJ-T-1产生的胞外产物为脂肽类和糖脂类的混合物。XJ-T-1菌悬液主要针对O/W型乳状液破乳,胞外产物主要针对W/O型乳状液破乳,初始pH 9.0培养下的菌悬液和胞外产物破乳效果最好。投加210 mg/L菌悬液可使O/W型乳状液在24 h的破乳率达77.5%,投加40 mg/L胞外粗产物溶液可使W/O型乳状液在24 h的破乳率达90.0%。通过透射电镜照片推测,随着培养pH提高到9.0以上,胞外产物的产生使XJ-T-1利用石蜡的过程发生变化。

A bio-demulsifier producing strain, Alcaligenes sp. XJ-T-1, was isolated from oil-contaminated soil . It was a facultative alkaliphile, which could grow and produce bio-demulsifer at initial pH ranging from 6.0 to 11.0. The optimal pH range for its growth was between 9.0 and 11.0. XJ-T-1 produced extracellular bio-demulsifier only in alkaline envir- onment. The surface tension of distilled water was reduced to 30 mN /m by its cell suspension and to 35 mN/m by its extracellular product. TLC analysis was preliminarily inferred that the extraceUular bio-demulsifier produced by XJ-T-1 was a mixture of lipopeptide and glycolipid. Moreover, it was found that celt suspension had better demulsifying performance with O/W emulsion while extracellular product worked more efficiently with W/O emulsion. Within 24 hours, the demulsifying rate reached 77.5 % in O/W emulsion by addition of 210mg/L cell suspension while it achieved 90 % in W/O emulsion with 40 mg/L extracellular products solution. The best demulsifying performance was achieved when it was cultured at initial pH of 9.0. By speculate of TEM images,the utilization process of paraffin by XJ-T-1 was changed because more extracellular biosurfactant were produced at alkaline pH.