生物乳化剂产生菌及其产乳化剂条件初步研究

BIOSYNTHESIS OF EMULSIEIER BY A NEWLY ISOLATED RHODOCOCCUS RUBER STRAIN Eml

从胜利油田原油污染土壤边分离得到一株能降解多种石油芳烃和烷烃且能产生物乳化剂的细菌Em1,经生理生化及16S rRNA基因序列分析鉴定为赤红球菌(Rhodococcus ru-ber)。对菌株Em1产生乳化剂的条件进行了研究,结果表明,该菌株在以正十六烷为碳源时能较快速产乳化剂,其最佳条件为:正十六烷10g/L,酵母抽提物1g/L,初始pH值为7,30℃下200r/min摇床培养。在此条件下,发酵1d后,培养液的表面张力即降到最低值,约30mN/m,而乳化能力达100％;乳化剂浓度则在第5d达到最大,为68倍的CMC;经初步研究该乳化剂为脂类物质。

A bacterial strain Eml isolated from contaminated soil of Shengli oil field was identified as Rhodococcus ruber according to its phenotype, physiological and chemical properties, and its 16S rRNA gene sequence. This strain could degrade various polycyclic aromatic hydrocarbons as well as alkanes in petroleum, and produce bioemulsifier. The results indicated that strain Eml could produce bioemulsifier efficiently when n-hexadecane was used as sole carbon source. The optimal conditions for the synthesis of bioemulsifier were as followed: 10g/L of n-hexadecane, 1g/L of yeast extract, media initial pH 7, and cultivation was carried out at 30℃ on a rotary shaker at 200 rpm. Under these conditions the surface tension of culture decreased to the lowest value, around 30 mN/m, after 1 day, and the emulsifying capacity was 100% . The concentration of bioemulsifier reached to the highest value, around 68 times of CMC , after 5 days' cultivation. The results also showed that the bioemulsifier produced by this strain should be lipid.