关键词: 红砂, 早期选择, 优良家系, 主成分分析, 隶属函数法

Abstract: By using blood agar plate and blue agar plate as the primary screening media, and oil spreading as the re-screening method, 4 strains of coldadapted biosurfactantproducing bacteria were isolated from the straws under natural decay in low temperature environment. Among the four strains, B17 had the highest oil displacement activity, which could decrease the surface tension of fermentation broth from 75.47 mN·m-1 to 37.49 mN·m^-1 within 5 days. Through the analyses of morphological, physiological, and biochemical characteristics and 16S rDNA sequence, the strain B17 was preliminarily identified as Petrimonas sp. The results of FT-IR showed that the biosurfactant produced in the metabolic process of the B-17 was a kind of glycolipid. The emulsification activity of the fermentation liquor of the B-17 could maintain at 75% within 5 days, with good solubilizing effect. The optimal culture conditions for the growth of the B-17 and for its producing biosurfactant were initial pH 7, salt concentration 0.4%, and culture temperature 20℃. This study provided a basis for the exploitation of coldadapted biosurfactantproducing bacteria.

Key words: Reaumuria soongorica, early selection, superior family, principal component analysis, membership function method.