脂肪酶产生菌Geofrichum sp. AS 2.1135产酶条件及酶一般性质的研究

在92株能同化油的地霉属菌株中,Geotrichum sp. AS2．1135菌株产脂肪酶活力为50—60u／ml,对其产酶条件的研究表明,不饱和长链脂肪酸和油类有利于酶的形成。在4％豆饼粉作为有机氮源的培养基中,加入0．2％尿素,酶活力显著增加,酶活达150u／ml。用聚乙二醇橄榄油乳化系统测定酶的作用最适pH为8．0,最适温度为4O一42℃。在pH4一9时5℃下存放24小时,或在pH 5和8时45℃保持15分钟,酶活力不变。     

假单胞菌产脂肪酶条件的初步探索

对假单胞菌（Pseudomonassp）2106菌株产脂肪酶条件的初步探索表明,该菌株脂肪酶为组成型,不受油脂类底物的诱导。碳源的种类（单糖、双糖、多糖）和浓度对产酶影响不大,氮源以豆饼粉和玉米浆混合添加最好。最适发酵温度为32℃,摇瓶转速140r／min。实验中还通过正交试验优化了产酶培养基组成。     

高活力β-淀粉酶菌种的选育和发酵条件的研究

产β一淀粉酶的腊状芽孢杆菌(Bacillus cereus)Asl．447,通过紫外线、亚硝基胍和利福平的反复处理诱变,获得一株具有高活力β-淀粉酶的变异菌株M一3,产酶活力从74u／ml提高到5000—7000u／ml。牛肉汁液体培养基成分为：每100ml牛肉汁中加人蛋白胨1g,可溶性淀粉1g,酵母膏0．5g,NaCl 0．5g pH6．0。该变异菌的最适培养条件是：pH6—6．5 30℃48小时。酶的最适反应条件是：温度40℃,pH7 0,pH稳定范围是6—9,酶的抗热性较差,对可溶性淀粉水解率达85％以上。     

青霉素酰化酶产生菌的筛选和大肠杆菌AS 1.76产酶条件的研究

为筛选较优的产青霉素酰化酶的菌种,我们从9个属的232株纽菌中选出了19株产青霉素酰化酶的大肠杆菌,其中,AS 1．76和E 110为最好。还对大肠杆菌AS 1.76的产酶条件进行了研究。结果表明,最适的培养基成分是(％)：蛋白胨l,苯乙酸0．2,玉米浆0．3,氯化钠0．5;在250毫升的三角瓶中装30毫升培养基时,通气量正合适：培养基的初始pH以7.0为佳;培养时间15小时。在未加玉米浆的培养基中,少量的Fe2+(5馓克／毫升)对酶形成有刺激作用,过量的Fe2+(大于10教克／毫升)是不利的;在培养基中添加0．3％的玉米浆能降低Fe2+对酶形成毒害作用。     

氨基苄青霉素酰化酶产生菌AS1.586产酶条件的研究

选出了一栋产氨基苄青霉素酰化酶的北京棒状杆菌(Corynebacteria pekinense) AS1.586,并对其产酶条件进行了研究。结果表明,最适培养基成份为(％)：L-谷氨酸钠0．2,酵母膏0.2,磷酸氢二钾0.3,氯化镁0.1,硫酸亚铁0.01,葡萄糖2,硫酸镉0.1,牛肉蛋白胨0.7,起始pH7.0,通气量在250ml 三角瓶中装30ml发酵培养基为最适,于28℃,180转／分的旋转摇床上振荡培养24小时,在此条件下最终酶活力可达5．4u／ml。     

一株产碱性蛋白酶菌株的选育及其发酵条件的研究

从土壤中分离到的553株芽孢杆菌中选出一株产蛋白酶活力较高菌株,经紫外线和亚硝基胍诱变,获得一株产碱性蛋白酶的菌株,酶活力可达10000u／m1,此菌株经鉴定为地衣状芽孢杆菌(Bacillus licheniformis)。适宜的发酵条件：培养基由6％玉米粉(山芋粉或葡萄糖),4％豆饼粉(或其水解液),Na,HP0．·12Hz0 0．4％,KH：P0·0．03％,Na zc0,0．1％组成,pH7．O,37℃旋转摇床振荡培养{2一q6小时。酶作用的最适条件：60℃,pH9．0一10．5,在pH6．0—10．5范围内稳定。酶受DFP抑制。     

芽孢杆菌E2菌株纤维素酶形成条件的研究

芽孢杆菌E,菌株(Bacillus sp.strain E2)能在55℃下良好生长并在培养液中大量积累胞外纤维素酶(190 mu／ml培养液),所产生的纤维素酶为单一的CMCa se。对芽孢杆茁E2菌株产酶条件进行了研究． 该菌产酶的最适培养基装量为200ml/500mI三角瓶,最适起始pH为6 5,最适产酶温度为45℃,产酶高峰在培养时间8—12小时。E2菌株不能利用单一的无机氮源形成纤维素酶。酪蛋白是试验过的供E2菌株形成纤维素酶的最好氮源,其用量为3g／L。CMC—Na,纤维二糖,能作为碳源供芽孢杆菌E2菌株形成纤维素酶。高浓度的葡萄糖(8g／L)对芽孢杆菌E2菌株纤维素酶的形成有抑制作用。天然纤维素不能作为芽孢杆菌E2菌株形成纤维素酶的碳源。     

苯甲酸1，2-双加氧酶高活力菌株的筛选和发酵条件的研究

从176株细菌中,筛选出苯甲酸1,2-双加氧酶的高活力菌株假单胞菌(Pseudomonas)137。进行了该菌产酶的发酵条件试验。产酶的最适温度为32℃,最适起始pH为6．5—7．0。葡萄糖、麦芽糖和甘油对产酶有明显的抑制作用,苯甲酸钠对产酶有促进作用。氨态氮对菌体生长和产酶是必需的。琥珀酸钠是酶形成的有效诱导物,采用0．1％苯甲酸钠和0．2％琥珀酸钠培养基(pH6．5—7．0),于32℃振荡培养72小时,可获得高活力的苯甲酸1,2-双加氧酶,每克菌体酶活力可达5-8单位。     

细菌3-脱氧葡糖松还原酶产生面及产酶条件

从12株细菌菌株中筛选到一株产3-脱氧葡糖松还原酶的高产菌Bacillussp．2,并研究了该菌株的产酶条件。在所试验的细菌中,3-脱氧葡糖松氧化酶活性较低甚至检测不出,而还原酶活性普遍较高。该菌株最佳产酶条件为：培养基组成（％）：牛肉膏0．3,牛肉蛋白陈1．0,氯化钠0．5,0．5mmol／L3-脱氧葡糖松。培养基起始pH6．6,30℃振荡培养48h,产酶量最高,酶活力可达36．4u／g。3-脱氧葡糖松对产酶有诱导作用,而甲基乙二醛对产酶有抑制作用。     

克鲁维酵母Y-85合成菊粉酶最适条件的研究

采用响应面方法（ResponseSurfaceMethod,RSM）对克鲁维酵母（Kluyveromycessp．）Y－85产菊粉酶培养基成份进行了优选,和正交试验相比,该法选出的最适培养基的酶发酵水平提高28％。用15L自控发酵罐进行产酶条件控制试验,并在1000L罐上进行5批次酶发酵中试,平均菊粉酶活性达68.9u／ml。     

Production of a thermostable uricase by a novel Bacillus thermocatenulatus strain

A novel uricase-producing bacterium was identified based on its 16S rRNA sequence as Bacillus thermocatenulatus. The kinetic constants for this uricase, determined with uric acid as the substrate, were a V(max) of 0.99U/ml of enzyme and a K(m) of 0.25mM. After heat treatment at 75 degrees C for 45min, the uricase retained about 100% of its initial activity. The uric acid showed to be an inducer for uricase production. The effects of different factors on the enzyme production were studied. Pretreated cane molasses and corn steep liquor were the most promising carbon and nitrogen sources, respectively. When the strain was cultured at 30 degrees C at pH 7.0 for 30-36h, the uricase activity peaked at 1.25U/ml.     

Production of chitinolytic enzymes by a strain (BM17) of Paenibacillus pabuli isolated from crab shells samples collected in the east sector of central Tyrrhenian Sea

Nineteen bacterial isolates were grown in shaken cultures in media containing chitin as carbon source and different additional nitrogen sources such as yeast nitrogen base (YNB), yeast extract (YE), corn steep liquor (CSL) and ammonium sulfate. Strain BM17 showed the highest activity (200 U/l) in medium containing Chitin (1%) and YNB (0.5%). Molecular analysis of the 16S rRNA gene showed that strain BM17 belongs to the species Paenibacillus pabuli (99.72% homology). The enzyme activity started after 12-24 h; exponential enzyme production was recorded from the 24th h and lasted till the 96th h of incubation when activity peaked to decrease thereafter. Medium optimisation was carried out by Response Surface Methodology (RSM) considering the effects of chitin, corn steep liquor and yeast extract. BM17 chitinolytic activity was induced by chitin but the increase of its concentration did not have significant effects on the enzyme activity. By contrast, the nitrogen source, particularly YE, strongly affected the enzyme production.     

A cost effective fermentative production of succinic acid from cane molasses and corn steep liquor by Escherichia coli

AIM: Development and optimization of an efficient and inexpensive medium for succinic acid production by Escherichia coli under anaerobic conditions. METHODS AND RESULTS: Initially, 0.8 gl(-1) of succinic acid was produced in 60 h in 300-ml medium. On optimization, glucose and peptone were replaced by cane molasses and corn steep liquor. Three hundred ml of this medium was inoculated with 4% (v/v) of seed inoculum, incubated at 39 degrees C for 72 h, resulted in 7.1 gl(-1) of succinic acid in 36 h. Scale up in a 10-l fermentor under conditions of controlled pH and continuous CO2 supply in this medium resulted in 17 gl(-1) of succinic acid in 30 h. CONCLUSIONS: A ninefold increase in succinic acid production was obtained in 500-ml anaerobic bottles with optimized medium having cane molasses and corn steep liquor as against initial medium containing glucose and peptone. However, a subsequent scale up in a 10-l fermentor resulted in a 2.5-fold increase in succinic acid production as against optimized medium used in 500-ml anaerobic bottles. SIGNIFICANCE AND IMPACT OF THE STUDY: Succinic acid production was enhanced in medium consisting of inexpensive carbon and nitrogen sources in a shorter span of time.     

Production of a novel polygalacturonic acid bioflocculant REA-11 by Corynebacterium glutamicum

The production of a novel polygalacturonic acid bioflocculant REA-11 from a newly isolated strain, Corynebacterium glutamicum CCTCC M201005, was investigated. Sucrose was chosen as a carbon source for REA-11 production. Complex nitrogen sources containing urea and an organic nitrogen compound enhanced both bacterial growth and REA-11 production, among which urea plus corn steep liquor was shown to be the most efficient combination. A cost-effective medium for REA-11 production mainly comprised 17 g/l sucrose, 0.45 g/l urea, and 5 ml/l corn steep liquor, under which conditions the flocculating activity reached 390 U/ml. The molar ratio of carbon to nitrogen (C/N) significantly affected REA-11 production, where a C/N ratio of 20:1 was shown to be the best. Interestingly, by simultaneously feeding sucrose and urea at a C/N ratio of 20:1 at 24 h of fermentation, REA-11 production (458 U/ml) was enhanced by 17% compared to the control. In a 10 l jar fermentor, lower dissolved oxygen tension was favorable for REA-11 production: a flocculating activity of 520 U/ml was achieved at a kappaLa of 100 h(-1). REA-11 raw product is relatively thermo-stable at acidic pH ranges of 3.0-6.5. Preliminary application studies showed that REA-11 had stronger flocculating activity to Kaolin clay suspension compared to chemical flocculants. In addition, the capability of decolorizing molasses wastewater indicates the industrial potential of this novel bioflocculant.     

Effect of surfactants and inducers on increased uricase production under submerged fermentations by Bacillus cereus

Uricase is a clinical enzyme used for the oxidation of uric acid crystals in gout disease. The present study aimed to increase the suitable surfactant-mediated uricase production on induction by different concentrations of inducers. The efficiency of Bacillus cereus to produce extracellular uricase enzyme was studied in uric acid-containing agar plates. Among the studied inducers, uric acid is the potential inducer for uricase production under submerged fermentations (SMF), which induced 19.41?U/ml uricase in medium containing 2.0?g/L of uric acid, however further increase in the uric acid concentration decreased uricase production, which could be because of substrate inhibition. The physical parameters including agitation speed (rpm) and time duration (h) of uricase production were optimized and found to produce optimum uricase at 150?rpm in 26?h of SMF. Among the studied surfactants, nonionic surfactant, polyvinyl alcohol has shown a remarkable increase in the uricase production of 31.58?U/ml, which is a 61% increase under optimized conditions in SMF. The stability of produced uricase was found at pH 7.5 and temperature 30°C. Also the effects of various metal ions (1?mM) on the uricase activity were studied and observed to be inhibitory in nature in the descending order K⁺?>?Ca²⁺?>?Zn²⁺?>?Fe³⁺?>?Ni²⁺?>?Mg²⁺?>?Mn²⁺?>?Cu²⁺.     

Effect of nitrogen source on pullulan production by Aureobasidium pullulans grown in a batch bioreactor

Pullulan production by Aureobasidium pullulans ATCC 201253 using selected nitrogen sources was studied in a medium using corn syrup as a carbon source. Independent of the corn syrup concentration present, the use of corn steep liquor or hydrolysed soy protein as a nitrogen source instead of ammonium sulphate did not elevate polysaccharide production by ATCC 201253 cells grown in an aerated, batch bioreactor containing 4 litres of medium. Pullulan production on corn steep liquor or hydrolysed soy protein as a nitrogen source became more comparable as the concentration of corn syrup was increased. Cell weights after 7 days of growth on any of the nitrogen sources were similar. The viscosity of the polysaccharide on day 7 was highest for cells grown on ammonium sulphate and 12.5% corn syrup. The pullulan content of the polysaccharide elaborated by ammonium sulphate-grown cells on day 7 decreased as the corn syrup level rose in the medium while the pullulan content of polysaccharide produced by cells grown on corn steep liquor or soytone generally increased.     

Production of thermostable acid protease by Aspergillus niger

Aspergillus niger F2078 produces high levels of extracellular thermostable acid protease within 96 h. Although glucose and peptone were the best carbon and nitrogen sources, respectively, sucrose and a cheap nitrogen source, corn steep liquor, also gave satisfactory enzyme yields. Supplementation of groundnut meal to the basal medium enhanced enzyme production. Temperature and pH optima of the enzyme activity were 60°C and 3.0–4.0, respectively. The enzyme was stable between pH 3.0 and 6.0 and at temperatures up to 60°C.     

Comparison of corn steep liquor with other nutrients in the fermentation of D-Xylose by Pichia stipitis CBS 6054

Summary Pichia stipitis CBS 6054 ferments D-Xylose to ethanol in a medium containing corn steep liquor as the only source of nitrogen, amino acids, vitamins and other nutrients. The ethanol yield and fermentation rate compare favorably to those obtained with media containing more expensive sources of nitrogen, vitamins and amino acids. Corn steep liquor is a good source of nutrients that can support growth and fermentation activity of this xylose fermenting yeast.     

戊糖乳杆菌发酵培养基氮源条件的优化

对戊糖乳杆菌发酵培养基的氮源条件进行了优化。通过单因素实验及响应面分析优化利用木糖高产乳酸的戊糖乳杆菌发酵培养基的不同氮源组合。优化得到的牛肉膏与柠檬酸氢二铵复合的最佳组成为牛肉膏17.72 g/L,柠檬酸氢二铵1.91 g/L,得到乳酸实际最大产量42.37 g/L。添加玉米浆与酵母粉和无机氮源复合的最佳组成为玉米浆46.54 g/L,酵母粉21.95 g/L,柠檬酸氢二铵9.95 g/L,可得到乳酸最大产量41.06 g/L。通过响应面优化减少了有机氮源的种类。牛肉膏与柠檬酸氢二铵的复合得到了更高的乳酸产量,且减少了有机氮源用量,节约了成本。玉米浆与酵母粉的复合解决了单一玉米浆造成的木糖利用速率过低的问题,同样得到较高浓度的乳酸。     

Isolation of a thermostable uricase-producing bacterium and study on its enzyme production conditions

A uricase-producing bacterium was isolated from soil with a medium containing uric acid as the only carbon source. Based on its morphological and physiological characteristics, as well as 16S rDNA sequence and phylogenetic tree analysis, this new isolate belong to the genus Microbacterium. After heat treatment at 70 °C for 30 min, the uricase retained about 100% of the initial activity. The enzyme activity remained largely unchanged when it was stored in borate buffer at pH 8.5 at 37 °C for 40 days. The effects of different factors on the enzyme production were studied. Maize milk was the best C and N resources, and the uric acid showed to be an inducer for uricase production. When the strain was cultured at 30 °C at pH 7.5 for 30–36 h, the uricase activity peaked at 1.0 U/ml.