Recovery of poly(3-hydroxybutyrate) from coagulated Ralstonia eutropha using a chemical digestion method

For economic recovery of poly(3-hydroxybutyrate) (PHB) from culture broths of Ralstonia eutropha containing PHB, Al-based and Fe-based coagulants were used in the pretreatment step. The coagulated cells were then separated by centrifugation, and PHB was extracted by chemical digestion with a sodium hypochlorite/chloroform dispersion solution. The practical upper limits of dosage were found to be 1, 500 mg-Al/L and 1,000 mg-Fe/L, respectively, for Al- and Fe-based coagulants. When the harvested cells were treated with a 50% sodium hypochlorite/chloroform dispersion solution, PHB recovery and purity were 90-94% and 98-99%, respectively. The influence of the use of coagulants on the PHB recovery process was found to be insignificant. Despite the residual Al and Fe in the recovered PHB (less than 450 mg-Al/kg-PHB and 750 mg-Fe/kg-PHB, respectively), no detectable amounts of Al and Fe were leached from films made of the recovered PHB under acidic conditions. The use of Fe-based coagulants is less recommended because the Fe impurity can cause an unwanted colorization problem in the final product.     

Use of coagulants in treatment of olive oil wastewater model solutions by induced air flotation

Natural polyelectrolytes are suitable coagulants for the treatment of industrial and minicipal wastewaters because they are safe and have environmental benefits. Chitosan, a natural cationic polyelectrolyte, and other similar coagulants were used in the treatment of an olive oil water suspension as a model for the processing wastewater. The effect of chitosan, starch, alum and ferric chloride on the coagulation of oil droplets were determined by the jar test apparatus and turbidometric measurements. Olive oil emulsion samples were prepared by the use of surface active agents and other agents that could form stable oil water emulsions. The effect of parameters such as pH, ionic strength and optimum dosage of the coagulants were determined in the jar test experiments. Following the jar experiments, with the optimum concentration of the suitable coagulant, the emulsions were placed in an induced air flotation (IAF) cell to separate the coagulated oil droplets from solution. In the air flotation experiments, the effect of temperature, surfactant concentration and air flowrate were determined on the decrease of turbidity and COD of the emulsion samples. In the jar experiments, chitosan and alum used together at concentrations of 15 and 25 ppm, respectively, at pH 6 produced the lowest turbidity values. In the air flotation experiments, a concentration of 100 ppm of chitosan, an air flowrate of 3 l/min, aeration time of 45 s, temperature of 20 degrees C and pH 6 produced optimum levels. At optimum conditions of coagulation and flotation stages, the COD of the olive oil emulsion could be reduced by 95%.     

Cell separation from high cell density broths of Alcaligenes eutrophus by using a coagulant

Summary Alcaligenes eutrophus was successfully recovered from high cell density broths by pre-treatment with polyaluminium hydroxide chloride silicate as a coagulant at 36–90 mg Al/l. The optimum pH range for cell coagulation was 10–12. Subsequent centrifugation (45×g) and filtration (pore size 0.5 mm) gave a cell recovery of higher than 90%. The energy demand for cell recovery with the coagulant was only 3–11% of that without it.     

Activation of hormone-sensitive lipase in extracts of adipose tissue

Rat adipose tissue was homogenized in 0.154 m KCl, and the supernatant fluid, obtained after centrifugation at 15,000 g, was extracted with benzene to remove triglycerides. Most of the lipase activity in the extracted fluid was precipitated with ammonium sulfate between 15 and 40% saturation. The specific activity of the lipase in this fraction was about three times that in the benzene-extracted supernatant fluid. The specific activity of the monoglyceride esterase was increased to a lesser extent. Lipase activity in the benzene-extracted fluid and in the ammonium sulfate fraction was increased 15-45% by incubation with 0.3 mm ATP, 10 mm MgCl(2), and 0.03 mm cyclic AMP for 10 min before assay. None of these compounds alone or in combinations of two was as effective as all three together. The specific activity of the 15-40% ammonium sulfate fraction prepared from fat cells exposed to epinephrine and glucagon was greater than that from portions of the same cell pool not exposed to hormones. In addition, the already elevated lipase activity in preparations from hormone-treated cells was not enhanced by incubation with ATP, MgCl(2), and cyclic AMP. Thus, it seems probable that the lipase activity in the ammonium sulfate fractions represents, at least in part, hormone-sensitive lipase.     

pH诱导絮凝-气浮收获雨生红球藻研究

为提高雨生红球藻(Haematococcus pluvialis)收获效率,文章发现一种通过pH调控诱导雨生红球藻絮凝-气浮收获方法。通过与自然沉降对比发现,在不添加混凝药剂的情况下,调节藻液的pH可以诱导雨生红球藻细胞自发团聚形成絮体,显著提高其沉降或气浮收获效率。pH小于3或大于11.5时,气浮可在2min内实现95%左右的收获效率,而自然沉降则需要30min,才能达到80%—90%的收获效率。气浮收获后的生物质含固率要显著高于沉降收获,当初始浓度为3.2 g/L时, pH诱导絮凝-气浮收获后的雨生红球藻生物质含固率可达到17%,实现了53倍浓缩。另外,与化学混凝剂(硫酸铝)和生物混凝剂(壳聚糖)混凝-气浮对比发现, pH诱导絮凝-气浮不仅可以实现传统药剂混凝-气浮的高收获效率,还可以有效避免混凝剂对生物质的污染(如金属离子残留等),且不会对雨生红球藻中虾青素提取产生影响。因此, pH调控诱导絮凝-气浮可以实现雨生红球藻的快速、高效和无污染收获,为雨生红球藻的收获提供新的解决方案。     

Microflotation performance for algal separation

The performance of microflotation, dispersed air flotation with microbubble clouds with bubble size about 50 μm, for algae separation using fluidic oscillation for microbubble generation is investigated. This fluidic oscillator converts continuous air supply into oscillatory flow with a regular frequency to generate bubbles of the scale of the exit pore. Bubble characterization results showed that average bubble size generated under oscillatory air flow state was 86 μm, approximately twice the size of the diffuser pore size of 38 μm. In contrast, continuous air flow at the same rate through the same diffusers yielded an average bubble size of 1,059 μm, 28 times larger than the pore size. Following microbubble generation, the separation of algal cells under fluidic oscillator generated microbubbles was investigated by varying metallic coagulant types, concentration and pH. Best performances were recorded at the highest coagulant dose (150 mg/L) applied under acidic conditions (pH 5). Amongst the three metallic coagulants studied, ferric chloride yielded the overall best result of 99.2% under the optimum conditions followed closely by ferric sulfate (98.1%) and aluminum sulfate with 95.2%. This compares well with conventional dissolved air flotation (DAF) benchmarks, but has a highly turbulent flow, whereas microflotation is laminar with several orders of magnitude lower energy density.     

Wet spinning of silk polymer. I. Effect of coagulation conditions on the morphological feature of filament

Regenerated silk fibroin (SF) filaments were prepared by the wet spinning technique. The effect of coagulation conditions, such as coagulant type and coagulation temperature, was investigated on the morphological feature of SF filaments and a theoretical approach was also performed to understand the coagulation phenomena. SEM observation revealed that as the R group size of alcoholic coagulant (ROH) increased, the cross-sectional shape deviated more from a circular form. This is attributed to the fact that as the R group size increased, the mass transfer rate difference increased, but the coagulation rate decreased due to a reduced diffusion rate. Most non-alcoholic coagulants exhibited this circular cross-sectional shape, except dioxane, which showed a clover shape. As the coagulation bath temperature increased, the cross-section deviated less from a circular form, with the reduction of fiber diameter. When methanol/water mixture was used as a coagulant, an ellipse or a dog-bone shape was obtained with higher water content in methanol, which was attributed to the decrease of coagulation rate. Although methanol exhibited a positive value of mass transfer rate difference, a circular shape of cross-section was obtained due to the density difference of the coagulated and uncoagulated parts in the coagulating SF filament.     

Colour removal from landfill leachate by coagulation and flocculation processes

A study was conducted to investigate the efficiency of coagulation and flocculation processes for removing colour from a semi-aerobic landfill leachate from one of the landfill sites in Malaysia. Four types of coagulant namely aluminium (III) sulphate (alum), ferric (III) chloride, ferrous (II) sulphate and ferric (III) sulphate were studied using standard jar test apparatus. Results indicated that ferric chloride was superior to the other coagulants and removed 94% of colour at an optimum dose of 800 mg/l at pH 4. The effect of coagulant dosages on colour removal showed similar trend as for COD, turbidity and suspended solids. This suggested that colour in landfill leachate was mainly contributed by organic matters with some insoluble forms that exhibited turbidity and suspended solids readings. The results from this study suggested that ferric chloride could be a viable coagulant in managing colour problems associated with landfill leachate.     

Effects of medium components on L-ornithine production byBrevibacterium ketoglutamicum

Effects of yeast extract, and ammonium sulfate were investigated on the production of L-ornithine by an arginine auxotroph.Brevibacterium ketoglutamicum in flask and batch cultures. Yeast extract as an arginine source and ammonium sulfate as an inorganic nitrogen source had significant effects on L-ornithine, production and cell growth. L-ornithine production was repressed by the excessive addition of arginine. Reversion of auxotrophic cells to the wild type was observed when the initial yeast extract concentration was too low. There existed optimum concentrations of yeast extract and ammonium sulfate for L-ornithine production. The effects of yeast extract and ammonium sulfate concentrations on the Leudeking-Piret model parameters were examined to analyze, the relationship between cell growth and L-ornithine production.     

Functional role of zinc in poly(A) synthesis catalyzed by nuclear poly(A) polymerase.

Three methods, chromatographic, spectrophotometric and tritium-release assay, were used and compared for the assay of deoxycytidylate methyltransferase. All three methods can be used for assay of this enzyme but the tritium-release assay appears to be the most simple and convenient. With the help of this assay the deoxycytidylate methyltransferase has been isolated and purified from sonically disrupted cells of Xp12-infected Xanthomonas oryzae. Using a procedure that involves fractionation with streptomycin sulfate and ammonium sulfate, filtration through Sephadex G-100 and chromatography on DEAE-cellulose, a 214-fold increase in specific activity was obtained. The enzyme displays a narrow pH optimum at 6.0 Among the buffers tested, 6-morpholinoethane sulfonate with the addition of Mg2 is the best. The enzyme can utilize dCMP as a substrate. The enzyme can also convert tetrahydrofolic acid into dihydrofolic acid. The Km value for dCMP is 31.3 micrometer and the Km value for tetrahydrofolic acid is 71.4 micrometer. There is no absolute requirement of ions for the activity of the enzyme; however, the presence of ions causes stimulating or inhibiting effects on enzyme activity that are dependent on the variety and concentration of ions used.     

Biological coagulation of skim latex using Acinetobacter sp. isolated from natural rubber latex centrifugation effluent

An Acinetobacter sp, isolated from latex centrifugation effluent, effectively coagulated skim rubber from skim latex. After coagulation for 48 h without the addition of any nutrients, at an optimum dilution of 1:10(v/v) and with an inoculum concentration of 6.4 mg dry cell /ml, the yield of the skim rubber was 8 % (w/v) and the COD of the residual solution was only 0.4 g/l. chemical coagulation at the same dilution resulted in 7 % (w/v) yield of dry rubber content and 2.2 g COD /l.     

Relationship between protein composition and coagulation reactivity, particulate formation, and incorporation of lipids in soymilk

Many studies have suggested that the 11S/7S ratio in soybeans affects the coagulation reaction at the first step. In this study, the 11S/7S ratio in soybeans showed significantly negative correlation with MgCl(2) concentrations for the maximum breaking stress of tofu for six Japanese varieties. To determine the effect of the 11S/7S ratio, soymilk was fractionated by centrifugation after the addition of MgCl(2), and the distribution of lipids and proteins was studied. The amount of precipitate increased as the MgCl(2) concentration or the 11S/7S ratio increased. More triglyceride was incorporated into the precipitate as the MgCl(2) concentration or the 11S/7S ratio increased. The stain intensity of bands after sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) indicated that the ratio of oleosin, a membrane protein of the oil body, increased in the precipitate as the MgCl(2) concentration or the 11S/7S ratio increased, while the ratios of glycinin and beta-conglycinin were less variable. These results indicate that the 11S/7S ratio and coagulant concentration may have an effect on the amount of coagulum and the concentration of oil globules in the coagulum at the beginning of coagulation.     

Thermostable chitosanase from Bacillus sp. strain CK4: its purification, characterization, and reaction patterns

A thermostable chitosanase, purified 156-fold to homogeneity in an overall yield of 12.4%, has a molecular weight of about 29,000 +/- 2,000, and is composed of monomer. The enzyme degraded soluble chitosan, colloidal chitosan, and glycol chitosan, but did not degrade chitin or other beta-linked polymers. The enzyme activity was increased about 2.5-fold by the addition of 10 mM Co2+ and 1.4-fold by Mn2+. However, Cu2+ ion strongly inhibited the enzyme. Optimum temperature and pH were 60 degrees C and 6.5, respectively. The enzyme was stable after heat treatment at 80 degrees C for 30 min or 70 degrees C for 60 min and fairly stable in protein denaturants as well. Chitosan was hydrolyzed to (GlcN)4 as a major product, by incubation with the purified enzyme. The effects of ammonium sulfate and organic solvents on the action pattern of the thermostable chitosanase were investigated. The amounts of (GlcN)3-(GlcN)6 were increased about 30% (w/w) in DAC 99 soluble chitosan containing 10% ammonium sulfate, and (GlcN)1 was not produced. The monophasic reaction system consisted of DAC 72 soluble chitosan in 10% EtOH also showed no formation of (GlcN)1, however, the yield of (GlcN)3 approximately (GlcN)6 was lower than DAC 99 soluble chitosan-10% ammonium sulfate. The optimal concentration of ammonium sulfate to be added was 20%. At this concentration, the amount of hexamer was increased by over 12% compared to the water-salt free system.     

Human red cell porphobilinogen deaminase. A simpler method of purification and some unusual properties

A simpler method for purifying human red cell deaminase, using a mixture of n-butanol and chloroform, which denatures hemoglobin, followed by ammonium sulphate fractionation, heat treatment, Sephadex G-100 and DEAE-cellulose chromatography, yielding a 3400 fold purified enzyme is described. Some properties of purified deaminase were studied. The enzyme seems to have a strict requirement for oxygen, neither PBG consumption nor uroporphyrinogens formation were measured under anaerobiosis. Uroporphyrinogens formation was linear with both protein and time over a wide range of enzyme concentration and up to 2 h. The optimum pH was 7.4 and the mol. wt was 40,000 +/- 4000. The enzyme was heat-stable and increased its activity by heating. Ammonium and hydroxylamine ions inhibited the reaction. K+ and Na+ ions did not greatly affect activity, while most divalent cations tested significantly diminished uroporphyrinogen formation and to a lesser degree PBG consumption. Direct plots of velocity against PBG concentration were hyperbolic, however double-reciprocal plots were non-linear, Hill plots gave an n value of 2 and Eadie plots were bell-shaped, indicating the existence of weakly positive cooperative effect between 2 binding sites for PBG per molecule of deaminase.     

Effects of the addition of different nitrogen sources in the tequila fermentation process at high sugar concentration

AIMS: To study the effect of the addition of different nitrogen sources at high sugar concentration in the tequila fermentation process. METHODS AND RESULTS: Fermentations were performed at high sugar concentration (170 g l(-1)) using Agave tequilana Weber blue variety with and without added nitrogen from different sources (ammonium sulfate; glutamic acid; a mixture of ammonium sulfate and amino acids) during the exponential phase of growth. All the additions increased the fermentation rate and alcohol efficiency. The level of synthesis of volatile compounds depended on the source added. The concentration of amyl alcohols and isobutanol were decreased while propanol and acetaldehyde concentration increased. CONCLUSIONS: The most efficient nitrogen sources for fermentation rate were ammonium sulfate and the mixture of ammonium sulfate and amino acids. The level of volatile compounds produced depended upon types of nitrogen. The synthesis of some volatile compounds increased while others decreased with nitrogen addition. SIGNIFICANCE AND IMPACT OF THE STUDY: The addition of nitrogen could be a strategy for improving the fermentation rate and efficiency in the tequila fermentation process at high sugar Agave tequilana concentration. Furthermore, the sensory quality of the final product may change because the synthesis of the volatile compounds is modified.     

铵离子对梅岭霉素生物合成的调控效应

通过考察不同浓度的硫酸铵对梅岭霉素生物合成的影响,证实在低浓度下,硫酸铵可以促进梅岭霉素的生物合成,当其浓度大于5mmol/L时,菌丝生长和产物合成均受到抑制,而耗糖速率却随着铵离子的浓度增大而增大。在此基础上,进一步测定了与梅岭霉素生物合成和糖代谢过程密切相关的6种酶的活性变化,结果表明较高浓度的铵离子对6_磷酸葡萄糖脱氢酶、柠檬酸合成酶、琥珀酸脱氢酶以及脂肪酸合成酶的活性均表现出一定的促进作用,而对缬氨酸脱氢酶和甲基丙二酰CoA羧基转移酶的活性进行抑制,由此产生的结果一方面是HMP途径和TCA循环得到了加强,促进了菌体的初级代谢,另一方面则是梅岭霉素生物合成所需前体的来源受到限制,从而造成了梅岭霉素的低产。     

Activation of acetate by Methanosarcina thermophila. Purification and characterization of phosphotransacetylase

Phosphotransacetylase (EC 2.3.1.8) was purified 83-fold to a specific activity of 2.5 mmol of acetyl-CoA synthesized per min/mg of protein from Methanosarcina thermophila cultivated on acetate. This rate was 10-fold greater than the rate of acetyl phosphate synthesis. The native enzyme (Mr 42,000-52,000) was a monomer and was not integral to the membrane. Activity was optimum at pH 7.0, and 35-45 degrees C. The enzyme was stable to air and to temperatures up to 70 degrees C, but was inactivated at higher temperatures. Phosphate and sulfate partially protected against heat inactivation. Potassium or ammonium ion concentrations above 10 mM were required for maximum activity of the purified enzyme; the intracellular potassium concentration of M. thermophila approximated 175 mM. Sodium, phosphate, sulfate, and arsenate ions were inhibitory to enzyme activity. Western blots of cell extracts showed that phosphotransacetylase was synthesized in higher quantity in acetate-grown cells than in methanol-grown cells.     

Affinity chromatographic purification of beta-glucosidase of Candida gulliermondii.

A beta-glucosidase was isolated from Candida guilliermondii, a yeast capable of growth on cellobiose. The enzyme was partially purified by treatment with polyethyleneimine and ammonium sulfate precipitation. Further purification was achieved by affinity chromatography using a Sepharose 4B matrix to which oxidized salicin was coupled through adipic dihydrazide. The final product was a 12.5-fold purification of the crude extract with a recovery of 27% of the initial enzyme activity. Polyacrylamide disc electrophoresis of the purified enzyme gave a single band. A km of 1.25 x 10(-4)M was obtained using p-nitrophenyl beta-D-glucopyranoside as the substrate. The optimum pH for enzyme activity was 6.8. Maximum activity was observed at temperature of 37 degrees C. Enzyme activity was completely inhibited by Hg++, Pb++, and Zn++ ions. The molecular weight of the enzyme is 48,000 as estimated by sucrose density gradient centrifugation.     

Removal of <Emphasis Type="Italic">Oocystis</Emphasis> algae from freshwater by means of tannin-based coagulant

The tannin-based coagulant agent Acquapol C1 was tested for algae removal. This coagulant can be used in drinking water treatment and consists of a chemically modified tannin extract from Acacia mearnsii. Low coagulant doses reached high algae removal percentage, and operational conditions of neutral pH and room temperature allow up 80 % algae removal with 5 mg L^?1 of coagulant. If compared with other natural or inorganic coagulants, Acquapol C1 is more efficient than aluminum sulfate, a classical metal salt for water clarification. Experiments also were carried out in a pilot plant installation which gives a similar efficiency as the discontinuous jar-test experiments for algae removal.     

A soluble fraction requirement in the transfer reaction of protein synthesis by rice embryo ribosomes

The requirements for the transfer of (14)C-phenylalanine from yeast soluble ribonucleic acid to protein in vitro by rice (Oryza sativa L. var. Bluebonnet) ribosomes have been investigated. An absolute requirement for polyuridylic acid, 2-mercaptoethanol, guanosine triphosphate, magnesium, and potassium or ammonium ions and ribosomes has been demonstrated. Ribosomes washed in 0.5% sodium deoxycholate also required the presence of rice supernatant. The optimum concentration of magnesium ion for the reaction was approximately 7 mm, while 60 mm of either ammonium or potassium ion gave maximum transfer of phenylalanine in this heterologous system. The optimum concentration of guanosine triphosphate required varied with the presence or absence of the phosphoenolpyruvate-pyruvate kinase generating system. Without the system, the optimum concentration was 1.5 mm, but in its presence the optimum was approximately 0.1 mm.