发酵酸菜中嗜热链球菌的分离鉴定与特性研究

Study on Isolation,Identification and Characteristics of a Streptococcus thermophilus from Fermentation Sauerkraut

从东北自然发酵酸菜中分离筛选得到一株乳酸菌,经形态学鉴定、显色培养基初步鉴定和API鉴定为嗜热链球菌,命名为ST-111,对其进行生理特性及耐酸、耐盐试验的初步研究,该嗜热链球菌在pH 4以下几乎不生长,最适生长pH为7~10,最适盐浓度为0%~3%;在MRS液体培养基中菌株生长较快,2 h即达到对数期,12 h达到稳定期时OD600可以达到4.5左右;该菌株产酸能力较强,培养24 h后发酵液pH可降到3.6以下;耐胆盐试验和胆固醇移除率试验结果表明,该菌株具有较强的胆盐耐受力和较高的胆固醇移除率,在0.1%胆盐条件下生长良好,在0.1%的胆盐条件下的胆固醇移除率为42.3%。

One strain of Streptococcus was separated and screened from natural fermentation sauerkraut, and identified as Streptococcus thermophilus by morphological identification, color-display medium preliminary appraisal and API test, named ST-111. The growth and fermentation characteristics of this strain were studied in detail. The result indicate that this strain＇s optimum growth pH value is 7-10, optimum growth salt concentration was 0 %-3 %. The strain grows well and performs high acid-producing ability in liquid MRS, and achieve the log phase in 2 hours and stable phase in 12 hours while the OD600 can reach 4.5 or so; the broth pH can drop below 3.6 after cultured for 24 h. Bile tolerance test and cholesterol removal test indicate that the strain has high bile salt tolerance and cholesterol-removing ability. The strain grows well in the MRS broth containing 0.1% bile salt and the cholesterol-removing rate can reach to 42.3 %.