低温植酸酶菌株Y1的发酵条件研究

目的:提高低温植酸酶产量.方法:通过单因素和正交实验研究温度、pH、发酵时间、接种量、装液量对菌株Y1的发酵影响.结果:最适发酵条件为温度15℃,pH 5.0,发酵时间24h,接种量10%,装液量200ml/500ml.其最终酶活力达到了162.39U/mL.结论:经单因素和正交实验研究后其低温植酸酶酶活力比优化前提高了29.43%.     

樟树内生细菌EBS05发酵条件的研究

枯草芽胞杆菌EBS05是从樟树中分离的1株对多种植物病原真菌具有拮抗作用的内生细菌。以小麦纹枯病菌为靶标菌,通过单因素试验和正交设计试验对其发酵条件进行了优化。结果表明,内生细菌EBS05适宜的发酵培养基主要营养成分的组成和配比分别为可溶性淀粉3%、蛋白胨2%、NaCl 0.25%。最佳发酵条件为:初始pH5~9,最适温度34℃,装液量25 mL/250 mL三角瓶,接种量3%,发酵时间72 h。     

Agarivorans albus RZW1-1产琼胶酶的发酵条件优化

为了提高菌株Agarivorans albus RZW1-1的产琼胶酶能力,本研究通过单因素实验探究碳源、氮源、海盐浓度、琼脂浓度、初始pH、装液量、培养时间、培养温度等因素对产酶的影响,得到该菌株的最佳发酵条件。在单因素实验的基础之上,运用正交试验的方法,得到菌株RZW1-1产酶最高的培养基组分。综合单因素实验和正交设计,最终确定了最佳产酶条件为:葡萄糖0.2 g/L、酵母粉9 g/L、海盐浓度4%、琼脂粉浓度0.1%,在装液量25 m L (250 m L三角瓶)、初始pH7.0、28℃、130 r/min条件下培养48 h酶活力达到最高为23.020 U/mL,较基础培养基提高了2.01倍。     

南极海冰细菌中产低温 α-淀粉酶菌株的发酵和酶学特性的初步研究

从147株南极海冰细菌中筛选出一株高产低温a-淀粉酶的菌株Pseudoalteromonas sp.AN175。生长发酵单因素试验表明,菌株AN175在1%麦芽糖、0.5%酵母粉、0.01%磷酸铁、0.5%氯化钙、1%可溶性淀粉、5%NaCl、pH 6.0的培养基,10℃,30%装液量,130 r/min条件下振荡培养9 d可达到最大酶活132.5 U/mL,为优化前的2倍多。生长和产酶试验表明,该菌生长较常温菌缓慢,酶分泌时间滞后。粗酶特性研究显示,该酶催化的最适条件为温度30℃,pH值8.0。     

褐藻胶裂解酶产生菌的分离鉴定及产酶发酵优化

对一株从腐烂海带中筛选得到的产褐藻胶裂解酶的菌株进行鉴定,并对其产酶条件进行发酵优化。经形态学、生理生化特征和分子生物学鉴定,将其鉴定为盐单胞菌属,并命名为Halomonas sp. WF6。通过在摇瓶培养水平上进行单因素和多因素正交试验,确定褐藻胶裂解酶产生菌WF6的最适产酶培养基为：褐藻酸钠6.0 g/L,蛋白胨5.0 g/L,酵母粉2.5 g/L,NaCl 30 g/L,K⁺ 5 mmol/L。进而采用最适培养基进行产酶条件的优化,优化后的发酵产酶条件为：初始pH 8.0,培养温度25℃,接种量为2%,摇瓶装液量30 ml/250 ml,培养时间39 h。优化后的褐藻胶裂解酶酶活达117.66 U/ml,是优化前的2.1倍。该酶对褐藻酸钠的酶解产物主要由聚合度为二和三的褐藻寡糖组成。     

酿酒酵母by1.1b产D-(-)-扁桃酸脱氢酶的发酵条件优化

对一株产D-(-)-扁桃酸对映选择性脱氢酶的酿酒酵母菌(Saccharomyces cerevisiae sp. strain by1.1b)发酵产酶条件进行了优化。研究各种碳源、氮源及无机盐对产酶的影响, 应用正交试验优化发酵培养基组成, 结果为: 蛋白胨 60 g/L, 麦芽糖 30 g/L, MgSO4 0.5 g/L, ZnSO4 0.01 g/L, KCl 1.0 g/L。优化后酶产量提高了7.9倍(由2.56 U/mL增至20.21 U/mL)。摇瓶培养最佳条件为: 装液量40 %, 发酵pH 6.5, 接种量10 %, 发酵温度30 ℃。考察了细胞生长及产酶的时间进程, 最佳培养时间为25 h。     

酿酒酵母by1.1b产D-(-)-扁桃酸脱氢酶的发酵条件优化

对一株产D-(-)-扁桃酸对映选择性脱氢酶的酿酒酵母菌(Saccharomyces cerevisiae sp.strain by1.1b)发酵产酶条件进行了优化.研究各种碳源、氮源及无机盐对产酶的影响,应用正交试验优化发酵培养基组成,结果为:蛋白胨60 g/L,麦芽糖30 g/L,MgSO4 0.5 g/L,ZnSO4 0.01 g/L,KCl 1.0 g/L.优化后酶产量提高了7.9倍(由2.56 U/mL增至20.21 U/mL).摇瓶培养最佳条件为:装液量40%,发酵pH 6.5,接种量10%,发酵温度30℃.考察了细胞生长及产酶的时间进程,最佳培养时间为25 h.     

一株Bacillus sublitisJH-1发酵产木聚糖酶培养基的响应面优化

利用刚果红透明圈法从秸秆堆肥中筛选出一株产木聚糖酶菌株Bacillus sublitis JH-1,以单因素试验为基础,采用响应面试验设计对Bacillus sublitis JH-1液态发酵产木聚糖酶的培养基进行了优化,得到产木聚糖酶发酵最适条件为:培养温度33℃,p H值6.0,麦芽糖浓度为2.6%,酵母粉浓度为1.2%,KH2PO4浓度为1.2%,发酵产酶量比优化前提高了1.8倍。     

梳棉状嗜热真菌发酵产耐热木聚糖酶培养条件的优化

通过多个单因素实验对该菌株发酵产酶的培养条件进行优化,包括碳源、氮源、无机盐、培养基起始pH、培养时间以及培养温度等因素,得出了一个适合该嗜热真菌产酶发酵的条件:麸皮浓度为4%(w/v)、牛肉膏浓度为0.5%(w/v)、NaCl浓度为0.25%(w/v)、K_2HPO_4浓度为0.2%(w/v)、CaCl_2浓度为0.02%(w/v)。培养基初始pH为7.0,装液量为60 mL,发酵温度为55℃,发酵时间为60 h,摇瓶转速为125 r/min。优化之后酶活可达到68.5 U/mL,比未优化之前提高了71.2%。嗜热真菌可以利用麸皮、玉米芯粉等农业废弃物作为能源产木聚糖酶,既可以很好地处理此类农业副产品,又可以获得对人类有利的产物。     

蛹虫草液体发酵产多糖的条件优化

多糖是蛹虫草Cordyceps militaris产生的重要活性成分。为提高其液体发酵胞外多糖的产量,通过单因素轮换法、方差分析、正交试验对蛹虫草菌株YCC-H产胞外多糖的发酵条件进行了优化。单因素结果表明液体发酵最适初始pH为5,最适葡萄糖浓度(质量分数)为6%,最适氮源为酵母膏,最适装液量为80 mL/250 mL,最适接种量(体积分数)为12%;在不同培养条件下菌体生物量变化较大;通过方差分析及正交试验进一步优化,结果显示：装液量(A)、氮源(B)、接种量(C)对蛹虫草产胞外多糖影响程度为B>A>C,最佳条件组合为A₂B₃C₂,即装液量80 mL/250 mL、酵母膏为唯一氮源、接种量(体积分数)为12%,其余因素选择单因素中最佳水平。经验证,该菌株合成胞外多糖的质量浓度达247.06 mg/L,较未优化前胞外多糖的产量23.67 mg/L提高了9.43倍。     

Stabilization of dextranase from Penicillium funiculosum and Fusarium solani during heating and freeze-drying

Freeze-drying of highly purified dextranse from Penicillium funiculosum and Fusarium solani was accompanied by 90% losses of enzyme activity and solubility. Many carbohydrates were tested as stabilizers, e.g. glucose, maltose, lactose, polyglucine, dextranase hydrolyzate of polyglucine as well as mannitol and ammonium sulfate. Polyglucine, its hydrolyzate, and glucose proved most effective stabilizers. The stabilizing effect of polyglucine hydrolyzate of dextranase during its heating and freeze-drying was compared. The effective concentration of the stabilizer during freeze-drying was 10 times lower than during heating.     

Food-Grade Expression and Characterization of a Dextranase from Chaetomium gracile Suitable for Sugarcane Juice Clarification

The microbial production of dextranase using cheap carbon sources is beneficial to solve the economic loss caused by the accumulation of dextran in syrup. A food-grade microbial cell factory was constructed by introducing the dextranase encoding gene DEX from Chaetomium gracile to the chromosome of Bacillus subtilis, and the antibiotic resistance marker gene was subsequently deleted via the Cre/loxP strategy. The dual-promoter system with a sequentially arranged constitutive P43 promoter resulted in an 85 % increase in DEX expression. Under the optimal fermentation conditions of 10 g/L maltose, 15 g/L casein, 1 g/L Na₂HPO₄, 1 g/L FeSO₄ and 8 g/L NaCl, DEX activity was increased from 2.625 to 64.34 U/mL. Recombinant DEX was purified 5.98-fold with a recovery ratio of 26.67 % and specific activity of 3935.02 U/mg. Enzyme activity was optimal at 55 °C and pH 5.0 and remained 80.34 % and 71.36 % of the initial activity at 55 °C and pH 4.0 after 60 min, respectively. The enzyme possessed high activity in the presence of Co²⁺, while Ag⁺ showed the strongest inhibition ability. The optimal substrate was 20 g/L dextran T-2000. The findings could facilitate the low-cost, large-scale production of food-grade DEX for use in the sugar industry.     

Screening,production, and characterization of dextranase from Catenovulum sp.

A psychrotolerant dextranase-producing bacterium was isolated from the Gaogong island seacoast near Jiangsu, China. The bacterium, denoted as DP03, was identified as Catenovulum sp. based on its phenotype, biochemical characteristics, and 16S rRNA gene comparison. The optimal enzyme production time, initial pH, temperature, and aeration conditions of strain DP03 were found to be 28 h, 8.0, 30 °C, and 25 % volume of liquid in 100-ml Erlenmeyer flasks, respectively. The ability of 1 % dextran T20 to induce dextranase was investigated. Dextranase from strain DP03 displayed its maximum activity at pH 8.0 and 40 °C and was found to be stable at 30 °C and over a broad range of pH values (pH 6–11). Scanning electron microscopy showed that dextranase from the isolate DP03 could at least partially prevent Streptococcus mutans from forming biofilms on glass coverslips.     

一株产右旋糖苷酶海洋细菌的筛选鉴定

【目的】筛选鉴定产右旋糖苷酶的海洋细菌,并对其所产右旋糖苷酶的酶学性质及在变异链球菌牙菌斑生物膜中的应用进行初步研究。【方法】利用平板透明圈法从海洋环境中筛选产右旋糖苷酶的细菌,根据菌株形态特征、生理特征及16S rDNA序列确定其分类学地位,采用体外生物膜模型研究该酶对变异链球菌牙菌斑生物膜形成的抑制作用。【结果】从海泥中筛选出一株产右旋糖苷酶的细菌KQ11,初步鉴定为节杆菌(Arthrobacter sp.)。该菌株的最适生长温度为30°C,最适生长pH 7.5,最适生长NaCl浓度为0.4%。右旋糖苷酶的最适作用温度为45°C,最适作用pH为5.5。该酶能有效地抑制变异链球菌牙菌斑生物膜的形成。【结论】菌株KQ11右旋糖苷酶能够抑制变异链球菌牙菌斑生物膜的形成,可望用于漱口液等口腔护理产品中。     

Production of surfactant and detergent-stable,halophilic, and alkalitolerant alpha-amylase by a moderately halophilic <Emphasis Type="Italic">Bacillus</Emphasis> sp. Strain <Emphasis Type="Italic">TSCVKK</Emphasis>

A moderately halophilic alkalitolerant Bacillus sp. Strain TSCVKK, with an ability to produce extracellular halophilic, alkalitolerant, surfactant, and detergent-stable alpha-amylase was isolated from soil samples obtained from a salt-manufacturing industry in Chennai. The culture conditions for higher amylase production were optimized with respect to NaCl, substrate, pH, and temperature. Maximum amylase production of 592 mU/ml was achieved in the medium at 48 h with 10% NaCl, 1% dextrin, 0.4% yeast extract, 0.2% tryptone, and 0.2% CaCl₂ at pH 8.0 at 30 °C. The enzyme activity in the culture supernatant was highest with 10% NaCl at pH 7.5 and 55 °C. The amylase that was partially purified by acetone precipitation was highly stable in various surfactants and detergents. Glucose, maltose, and maltooligosaccharides were the main end products of starch hydrolysis indicating that it is an alpha-amylase.     

The use of titanium (IV) oxide for the immobilisation of carbohydrate-directed enzymes.

The use of particles of porous titanium (IV) oxide as a suitable matrix for enzyme immobilisation has been investigated with dextranase. Treatment of the particles with enzyme in the presence and absence of ammonium ions showed that the presence of ammonia induced a greater coupling of protein, whereas a greater retention of enzyme specific activity was achieved in the absence of ammonia. Properties of the immobilised enzyme include a pH-dependence and reversibility of the coupling between enzyme and matrix. The immobilised dextranase was most stable at pH 5.0. Automated analytical techniques for measuring the activity of dextranase and other polysaccharidases in soluble and insoluble forms are also reported.     

Penicillium notatum 1 a new source of dextranase

Summary Two hundred and fifteen fungal strains were screened for extracellular dextranase production with a diffusion plate method. The best enzymatic activity (12–19 DU ml^–1) was achieved byPenicillium notatum 1, a species for which the dextranase productivity has not yet been published. Some of the parameters affecting enzyme production have been standardized. The enzyme in crude state was relatively stable, its maximal activity was at 50°C and at pH 5.0. Conidia of the selected strain were mutagenized, and isolated mutants were tested for production of dextranase in submerged culture. The most active mutant,P. notatum 1-I-77, showed over two-times higher dextranase activity than the parentP. notatum 1     

Overexpression and characterization of a thermostable trehalose synthase from Meiothermus ruber

A thermostable trehalose synthase (TreS) gene from Meiothermus ruber CBS-01 was cloned and overexpressed in Escherichia coli. The purified recombinant TreS could utilize maltose to produce trehalose, and showed an optimum pH and temperature of 6.5 and 50°C, respectively. Kinetic analysis showed that the enzyme had a twofold higher catalytic efficiency (k _cat/K _m) for maltose than for trehalose, indicating maltose as the preferred substrate. The TreS also had a weak hydrolytic property with glucose as the byproduct, and glucose was a strong competitive inhibitor of the enzyme. The maximum production of trehalose by the enzyme reached 65% at 20°C. The most importantly the enzyme could maintain very high activity (above 90%) at pH 4.0–8.0 and 60°C 5 h. These results provided that the stable TreS was suitable for the industrial production of trehalose from maltose in a one-step reaction.     

极地适冷菌Pseudoalteromonas sp. QI-1产适冷蛋白酶发酵条件的优化

对极地适冷菌Pseudoalteromonas sp. QI-1产适冷蛋白酶的发酵条件进行优化。结果表明:菌株QI-1的最适生长和产酶温度均为5℃;最佳接种量为1%;发酵培养基的最适初始pH和最佳装样量分别为5和10%;盐度为2%时对菌株的生长和产酶最为有利;麸皮和醋酸钠分别为最佳N源和C源;添加0.75%酪蛋白时菌株QI-1胞外蛋白酶的活性最高;10 mmol/L Mg2+和0.5%Tween-80有利于产酶。正交试验结果表明:菌株Pseudoalteromonassp. QI-1产蛋白酶较佳培养基配方(g/L)为麸皮5,酵母粉2.5,酪蛋白3,MgCl2.6H2O 3,KCl 1.5;发酵液比酶活为166.20 U/mL,较优化前提高了约56%。     

蜡质芽孢杆菌AR156发酵培养基及发酵条件的优化

对前期筛选得到的在田间试验中防治根结线虫效果较好的蜡质芽孢杆菌(Bacillus cereus)AR156,通过单因素筛选及正交试验的方法进行了发酵培养基优化,得到的最佳配比为:麦芽糖0.25%,玉米粉0.5%,黄豆粉0.5%,胰蛋白胨0.5%,CaCl2·2H2O0.05%,MnSO4·H2O0.05%,K2HPO40.1%。同时对实验室摇瓶条件下液体发酵的主要影响因子温度、转速、初始pH值等进行实验探讨,确定了最佳培养条件:初始pH值7.0,装液量200mL/L,接种量5%,发酵温度28℃,转速200r/min,发酵时间48h。优化后芽孢产量为1.03×109CFU/mL,芽孢生成率在97%以上,明显高于初始发酵培养基发酵结果。