Brevibacterium sp.DGCDC-82发酵罐中生产胆固醇氧化酶

用Brevibacterium sp.DGCDC-82在7L发酵罐中分批培养.分别对添加剂吐温-80、培养温度、培养基的pH、通风量和搅拌速度在胆固醇氧化酶的生产中的影响进行了研究.结果显示以上条件均对产酶有影响.在不同的发酵阶段改变发酵操作条件,发酵20 h最高酶活可达1203U/L,生产强度可达60 U/(L·h).既有效地提高了胆固醇氧化酶的产量,又防止了发酵过程中的泡沫外溢.     

L－缬氨酸菌种选育

以硫酸二乙酯（ＤＥＳ）诱变处理黄色短杆菌（Ｂｒｅｖｉｂａｃｔｅｒｉｕｍｆｌａｖｕｍ）ＸＱ５１２２，得到突变株Ｖ３－３６＜Ｌｅｕ￣１、α－ＡＢ￣ｒ、ＡＨＶ￣ｒ），在１０％葡萄糖培养基中可积累２．３％Ｌ－缬氨酸。以亚硝基胍（ＮＴＧ）诱变Ｖ４－１５３，得到一株突变株（Ｌｅｕ￣１、α－ＡＢ￣ｒ、ＡＨＶ￣ｒ、２－ＴＡ￣ｒ），再进行单菌落分离，得到突变株ＺＱ－２，能在培养基中积累Ｌ－缬氨酸４．２％～４．５％，最高达５．５７％．     

Management of long-term catheter-related Brevibacterium bacteraemia

Brevibacterium has been reported as a rare cause of implanted-device infection. In two cases of recurrent Brevibacterium casei bacteraemia associated with infection of surgically implanted intravascular devices, relapse occurred 2 and 5 months, respectively, after completion of therapy with vancomycin via the infected catheter. A second intravenous antibiotic therapy course by the antibiotic-lock technique led to bacteriological cure in one patient. Molecular typing results demonstrated that the recurrent bacteraemia was caused by the same strain. Implanted-device removal may be necessary, in addition to appropriate antibiotics, for successful management of such infections.     

Optimization of trehalose production by a novel strain Brevibacterium sp. SY361

Trehalose production by a novel strain of Brevibacterium sp. SY361 was optimized in submerged fermentation. Different chemical and physical parameters such as carbon and nitrogen sources, inoculum level, initial pH, incubation temperature, aeration and time-course of fermentation, were studied in order to increase trehalose productivity. An optimal production medium containing 3% (w/v) glucose, 0.9% (v/v) corn steep liquor, 0.5% (w/v) KH(2)PO(4) and 0.4% (w/v) MgSO(4).7 H(2)O was found suitable for trehalose production. An optimal volume of medium in a 500 ml flask was 80 ml. The optimal levels of other parameters were 4.0% (v/v) of inoculum, initial pH of 6.0, incubation temperature of 28-32 degrees C and time-course of 60 h. Optimized parameters gave a maximum trehalose of 12.2 mg/ml with a conversion rate of 58.4%.     

环己胺的微生物代谢及相关氧化酶的研究进展

环己胺氧化酶属于一种胺氧化酶,目前仅对动植物体内的胺氧化酶进行了系统研究,但对于不同微生物来源的环己胺氧化酶了解不够广泛。在微生物代谢途径中,参与上游代谢的基因具有丰富的多样性,而参与下游代谢途径的基因模块在不同的微生物中相对保守。因此,研究微生物代谢环己胺的关键是探讨催化环己胺生成环己酮的环己胺氧化酶的催化机制。该文综述了目前国内外微生物降解环己胺的研究进展,介绍了环己酮单加氧酶和环己胺氧化酶在有机胺的微生物代谢途径研究中的作用,并对其潜在应用前景进行了展望。     

赖氨酸摇瓶发酵条件的优化

针对赖氨酸发酵的工业化要求,以黄色短杆菌（Ｂｒｅｖｉｂａｃｔｅｒｉｕｍｆｌａｖｕｍ）ＷＳＨＬ１为产生菌进行了摇瓶条件下的赖氨酸发酵条件研究．通过正交实验得到了较佳氮源配比;经在发酵过程中添加几种氮源的试验,发现发酵中后期添加适量有机氮源有利于发酵;考察不同初始硫酸铵和葡萄糖浓度对发酵的影响,确定了适合工业生产的浓度范围;采用分批补料培养方式,最终赖氨酸盐酸盐质量浓度为８５．５ｇ／Ｌ     

核苷磷酸化酶的产酶条件优化的研究

以鸟苷和5－氟尿嘧啶为底物,乙酰短杆菌菌体为酶源酶法合成5－氟尿苷,采用酵线浸膏培养基（酵母浸膏4．0％,葡萄糖0．4％,NaCl0.3%,pH7.0),较高的溶氧量,同时添加0．6％的豆油,培养12h,产酶量可提高30％。     

L-缬氨酸高产菌选育及营养需求研究

以黄色短杆菌 (Brevibacteriumflavum)L 缬氨酸产生菌ZQ -2为出发菌株 ,经硫酸二乙酯(DES)和亚硝基胍 (NTG)诱变处理 ,氨基酸结构类似物定向筛选 ,获得一株L 缬氨酸高产菌XQ -6 (LeulAHVrα ABhr2 TAhr)。在以 1 4 %葡萄糖为碳源、5 %硫酸铵为氮源的培养基中直接发酵72h,产酸达 5 8～ 6 2g/L。同时添加Fe2 + 和Mn2 + 比单独添加Fe2 + 更有效。还进行了氨基酸、核酸、维生素和其它营养对L 缬氨酸发酵影响的试验。