L-丝氨酸生产菌的选育及不同碳源对发酵的影响

以一株黄假单胞属(Pseudomonas flava)菌株A3为出发菌株,经过紫外(UV)诱变和硫酸二乙酯(DES)逐级诱变处理和选育,选育出一株能够以甲醇为唯一碳源的兼性甲基营养型菌JW-01(Mth^R、Gly^R)。在含甘氨酸30g/L、甲醇1%的发酵培养基中发酵3d后L-丝氨酸产量为6．2g/L,较出发菌株提高了67．6%。该菌具有较好的传代稳定性。     

琥珀酸放线杆菌的耐高浓度钠离子菌株选育

以琥珀酸放线杆菌Actinobacillus succinogenes CGMCC 1593为出发菌,经过紫外线和甲基磺酸乙酯(EMS)诱变处理,选育出一株耐高浓度钠离子菌株SE-6.该菌株在5 L发酵罐中进行分批发酵,单独使用Na2CO3控制发酵过程pH,发酵48 h琥珀酸产量达到35.8g/L,较出发菌(26.0 g/L)提高了37.7%;若采用MgCO3和Na2CO3共同调控发酵过程pH,发酵48 h琥珀酸产量达到45.0 g/L,较出发菌(37.4g/L)提高了20.4%.     

L-异亮氨酸高产菌选育及其培养基优化

旨在诱变选育L-异亮氨酸高产菌,并探索突变株最佳发酵条件。利用传统化学诱变结合常压室温等离子体生物诱变体系对实验室保藏的Brevibacterium flavum I-12进行逐级诱变,选育2-噻唑丙氨酸(2-TA)和磺胺胍(SG)高抗性和在琥珀酸平板上能快速生长的突变菌株。随后,在单因素实验的基础上,利用响应面设计优化出目的突变株摇瓶发酵培养基组分的最佳参数水平。结果显示,经过一系列诱变和筛选,成功选育出一株在40 g/L的2-TA和5 g/L的SG,且以琥珀酸为唯一碳源的培养基上快速生长突变株,命名为B. flavum TA-6,该菌株产酸达26.2±0.5 g/L,比出发菌株提高了44.75%,而副产物L-缬氨酸和L-亮氨酸积累量明显降低。经响应面法优化发酵条件后,突变株产酸可达27.8±0.5 g/L,比优化前提高了6.1%。通过传统化学诱变结合ARTP生物诱变体系,成功选育出一株杂酸降低的L-异亮氨酸高产菌TA-6,该菌株具有潜在生产应用价值。     

L-色氨酸生产菌的选育及其发酵条件的研究

以代谢控制发酵理论为指导 ,对L -色氨酸产生菌的定向选育、摇瓶发酵条件、30L发酵罐发酵条件进行了研究。以谷氨酸棒杆菌Tx5 - 32 (Phe- +Tyr- )为出发菌株 ,经硫酸二乙酯 (DES)多次诱变处理 ,定向选育出一株L -色氨酸产生菌TQ2 2 2 3(Phe- +Tyr- +5 -MTr+5 -FTr+SGr+CINr)。以摇瓶分批发酵最优条件为基础 ,对菌株TQ2 2 2 3进行了 30L发酵罐分批发酵试验 ,该菌株发酵 6 4h ,产L -色氨酸 7.2 8g·L- 1 。     

E.aero高产1.3-丙二醇菌株选育及发酵培养基研究(Ⅰ)

以淡水湖泊泥土中分离出的300多株肠杆菌(Enterobacter)为出发菌株,利用常规筛选方法选出2株1．3-丙二醇产生菌(Enterobacter)。经UV、DES、NTG、EMS、LiCl单独及复合诱变,选育出一株(E．aero-N-56)1．3-PD高产突变株。通过单因素实验,确定了E．aero—N-56菌株1．3-PD发酵培养基为：甘油90g/L,NH4CL1．50g/L,Fe^2 0．005％,Co^2 0．004％。微量元素液12mL／L。该突变株1．3-PD产量为36．8g/L。     

ε-聚赖氨酸高产菌株选育及分批发酵的研究

以北里孢菌(Kitasatospora sp.)PL6-3为出发菌株,经硫酸二乙酯诱变,获得遗传性能稳定的AECr突变株MY5-36。MY5-36摇瓶发酵产ε-聚赖氨酸达1.17 g/L,是出发株PL6-3的3倍;5 L发酵罐批式发酵产酸达7.72 g/L,较出发菌株提高了7倍以上。与PL6-3相比,MY5-36菌株形态发生了很大变化,菌丝和孢子颜色都发生了改变。     

米根霉乙醇脱氢酶(ADH)突变菌株的诱变选育

米根霉发酵生产L-乳酸过程中,由于丙酮酸在丙酮酸脱羧酶、乙醇脱氢酶(ADH)催化下生成乙醇,使得丙酮酸向乳酸转化的流量减少。采用亚硝基胍(NTG)诱变米根霉AS3．3462孢子液,诱变剂量为0．15 mg/ mL时,致死率为70%～80%。在含丙烯醇的YPD筛选培养基上筛选获得两株ADH活力降低的突变株mut-1和mut-2,检测突变株mut-1和mut-2的最大ADH活力分别为35．67和43．09U/mL,是原始菌株的41．63%和50．29%。发酵72h后,原始菌株的乙醇与乳酸浓度分别为28．9g/L和40．31g/L,而mut-1和mut-2突变株的乙醇产量分别为4．87g/L和6．56g/L,乳酸产量为54．45g/L和44．07g/L。在相同的发酵条件下,米根霉ADH突变株mut-1和mut-2对还原糖的利用速率高于出发菌株,其生物量积累亦高于出发菌株。     

耐铵型产琥珀酸放线杆菌的选育

以Actinobacillus succinogenes NJ113为出发菌株,经硫酸二乙酯(DES)诱变,在含8～20 g/L硫酸铵平板中筛选到一株耐铵型突变株YZ25,该菌株在含8 g/L硫酸铵培养基中厌氧发酵,琥珀酸产量达32.68 g/L,比出发菌提高了180.5%,对葡萄糖收率达65.4%,副产物乙酸、甲酸产量分别下降3.5%、28.7%,琥珀酸/乙酸比值由0.63提高到2.5。在7.5 L发酵罐中,用氨水调节pH分批实验,发酵34 h琥珀酸产量达27.13 g/L,较出发菌株提高了85.3%。     

紫外线和硫酸二乙酯复合诱变选育PHB高产菌株

【目的】获得高产聚β-羟基丁酸酯(Poly-β-hydroxybutyricacid,PHB)菌株。【方法】以假单胞菌属Pseudomonas koreensis PK3菌株为出发菌株,采用硫酸二乙酯和紫外线相结合的诱变方法进行多轮诱变。【结果】经过初筛和复筛得到一株高产PHB突变菌株,命名为Pseudomonas koreensis UVCN-18。连续传代9次后,发酵28 h条件下,PHB产量达到15.94 g/L,占细胞干重69.54%,较原出发菌株Pseudomonas koreensis PK3(4.42 g/L)提高了2.61倍,并且该菌株具有良好的遗传稳定性。【结论】采用硫酸二乙酯和紫外线相结合的诱变方法,成功获得了一株高产PHB突变菌株。     

原生质体诱变选育ε-聚赖氨酸高产菌株

以白色链霉菌UN2-71为出发菌株,对其原生质体进行硫酸二乙酯(DES)诱变,选育ε-聚赖氨酸高产菌株。经过试管初筛和摇瓶复筛,得到1株稳定性好的菌株D3-32,摇瓶产量达到1.56g/L,比出发菌株提高49.43%。采用2.3L发酵罐进行发酵试验,控制pH分两阶段培养后,ε-聚赖氨酸最高产量达到4.59g/L,比出发菌株提高了2.65倍。     

Characteristics of the membranes of the pellicle of the ciliatePseudomicrothorax dubius

Summary The membranes of the pellicle of the ciliatePseudomicrothorax dubius are investigated using thin section electron microscopy and freeze-fracture replicas. The plasma membrane is covered by a surface coat and is connected to the outer alveolar membrane by short, sometimes branched, bridges. The inner alveolar membrane is coated on both sides. The epiplasm lies in intimate contact with the cytoplasmic surface of this membrane, and there is a corresponding deposit on the other surface. This deposit is regularly striated.The epiplasmic layer and the alveoli are interrupted at sites of cytotic activity,e.g., the attachment sites of trichocysts, the cytoproct, and the parasomal sacs. The striated deposit ends where the epiplasm ends, indicating a direct relationship between these two epimembranous layers.There is a deposit along the sides of the first part of the tip of the trichocysts, and in this region the trichocyst membrane is free of intramembranous particles.The membrane of the parasomal sacs has a coat on both surfaces. That on the extraplasmic surface is similar to the surface coat of the plasma membrane. The origin of the cytoplasmic coat is unknown. The cytotic activity of these sacs is indicated by their highly irregular profiles.     

The early development of the tail and the transformation of the shape of the nucleus of the spermatid of the domestic fowl,Gallus gallus

Summary The differentiation of the spermatid, especially in reference to the formation of the flagellum, and transformation of the shape of the nucleus was investigated in the domestic fowl.In the early stage of the spermatid, a prominent Golgi apparatus appears around the centrioles. The Golgi vesicles then surround the axial-filament complex which develops from the distal centriole. These vesicles fuse to form continuous membrane at the earliest stage of flagellar formation, and in the succeeding stage Golgi lamellae are attached to the plasma membrane of the developing flagellum. From these observations, it is assumed that Golgi apparatus may be a source of the membrane system of the flagellum.The microtubules distributed around the nucleus form the circular manchette. The anterior region of the nucleus with the manchette is cylindrical in shape and the posterior region without it remains irregular in shape. When the circular manchette has been completed, the whole nucleus acquires a slender cylindrical shape. The circular manchette then changes into the longitudinal manchette. The nuclei of spermatids without a longitudinal manchette are abnormal in shape. In view of these observations it is assumed that the nuclear shaping of the spermatid may be accomplished by circular manchette and the maintenance of shape of the elongated nucleus by longitudinal manchette.The authors wish to thank Mr. Takayuki Mori for his helpful suggestions and technical advices     

Characterization of the composition of the aqueous humor and the vitreous body of the eye of the frog Rana temporaria L

This study aimed to analyze the aqueous humor (AH) and the vitreous body (VB) of the eye of the adult frog Rana temporaria L. as a representative species of amphibians, which lead a semi-terrestrial life. The presence of collagen, albumin, uric acid and electron donors was shown in both media; however, there are slight differences in their concentrations. To determine collagen, a spectral-fluorescent probe, cyanine dye, was used. The presence of collagen in AH of the frog was found at the first time. The total content of electron donors (ascorbic and uric acids, tryptophan, and tyrosine) in VB and HA was roughly estimated at ~ 1.5 × 10^− 4 mol/L. Both VB and AH absorb light in similar UV regions. The total protein and albumin contents in AH were found to be somewhat higher than those in VB. The uric acid content was at an equally low level in both intraocular media. It is supposed that the similarity of VB and AH compositions shown in this work is due to some exchange between VB and AH contents in the course of accommodation. The role of intraocular fluids in physiological functions of the eye and in protecting the retina against UV light is discussed.     

Observations on the permeability of the choriocapillaris of the eye

Summary The choriocapillaris is a fenestrated capillary bed located posterior to the retinal pigment epithelium. It serves as the main source of supply to the photoreceptors, retinal pigment epithelium, and other cells of the outer retina. The permeability of these capillaries to intravenously injected ferritin (MW — approx. 480,000; mol. diam. 11 nm) was examined in the mouse, rabbit, and guinea pig, each of which is characterized by a different type of retinal vascularization. In all three species, the bulk of the ferritin remained in the capillary lumina, where it appeared to be blocked at the level of the diaphragmed fenestrae. Some ferritin was present in endothelial cell vacuoles. The results confirm previous work on the rat choriocapillaris and indicate that the barrier function of the choriocapillary endothelium is present even among species in which the retinal circulation differs significantly.Supported by NIH grant EY03418