Optimal Temperature For Hydrolysis Research Articles

Enhanced anaerobic digestion of waste-activated sludge by thermal-alkali pretreatment: a pilot-scale study.

The composition of waste-activated sludge (WAS) is complex, containing a large amount of harmful substances, which pose a threat to the environment and human health. The reduction and resource utilization of sludge has become a development demand in sludge treatment and disposal. Based on the technical bottlenecks in the practical application of direct anaerobic digestion technology, this study adopted two different thermal and thermal-alkali hydrolysis technologies to pretreat sludge. A pilot-scale experiment was conducted to investigate the experimental conditions, parameters, and effects of two hydrolysis technologies. This study showed that the optimal hydrolysis temperature was 70 °C, the hydrolysis effect and pH can reach equilibrium with the hydrolysis retention time was 4-8 h, and the optimal alkali concentration range was 0.0125-0.015 kg NaOH/kg dry-sludge. Thermal-alkali combination treatment greatly improved the performance of methane production, the addition of NaOH increased methane yield by 31.2% than that of 70 °C thermal hydrolysis. The average energy consumption is 75 kWh/m3 80% water-content sludge during the experiment. This study provides a better pretreatment strategy for exploring efficient anaerobic digestion treatment technologies suitable for southern characteristic sewage sludge.

Optimasi Suhu Hidrolisis dan Konsentrasi Asam Sulfat dalam Pembuatan Nanoselulosa Berbahan Dasar Serat Batang Pisang Kepok (Musa acuminata x balbisiana)

This research aims to investigate the optimal hydrolysis temperature and sulfuric acid (H2SO4) concentration in isolating nanocrystalline cellulose (NCC) from kepok banana pseudostem fiber with the best yield and water solubility. In this research, cellulose fiber was delignified with NaOH at 80°C for 5 minutes, then followed by bleaching with hydrogen peroxide (H2O2) for 30 minutes twice. NCC was isolated through acid hydrolysis with H2SO4 (40%, 45%, 50%, 55% v/v) at 45 °C, 50 °C, 55 °C, 60 °C for 1 hour and ultrasonicated for 5 minutes. NCC crystal was then characterized through Transmission Electron Microscopy (TEM), and water solubility. TEM analysis showed the isolated NCC has a measured length of 125 – 144 nm. The highest NCC yield was obtained at 60°C and 55% H2SO4 at 26.75%. This analysis showed that NCC yield increases with increasing H2SO4 concentration and hydrolysis temperature. The lowest water solubility obtained is 0%, which shows the purity of the cellulose used to isolate NCC.

Polysaccharides from pineapple pomace: new insight into ultrasonic-cellulase synergistic extraction and hypoglycemic activities

This study determined the optimal extraction conditions for ultrasonic-cellulase synergistic extraction of polysaccharides from pineapple pomace (PPP) using Plackett–Burman design and response surface methodology. The optimal hydrolysis temperature, ratio of material to water, pH value, hydrolysis time, ultrasonic power and the additive quantity of cellulase were 50 °C, 1:45 g/mL, 6.0, 100 min, 160 W and 2.0%, respectively, giving a extraction yield of 1.10 ± 0.03%. PPP was further isolated and purified by DEAE-52 cellulose and Sephadex G-100 chromatography columns, revealing four main elution peaks, named PPF0, PPF1, PPP2 and PPF3, were obtained. The molecular weight, monosaccharide compositions, structural features and appearance morphology of polysaccharide fractions (PPFs) were analyzed by high-performance liquid chromatography (HPLC), gel permeation chromatography (GPC), UV spectroscopy, fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). Furthermore, the hypoglycemic activities of PPFs with different concentrations were also investigated by insulin resistance HepG2 cells model in vitro. Results showed that PPF0, PPF1, PPF2 and PPF3 were composed of mannose, rhamnose, glucuronic acid, galacturonic acid, glucose, galactose, xylose, arabinose and fucose with molecular weight of 6.71 × 104, 1.11 × 104, 2.22 × 104 and 5.1 × 103 Da, respectively. All of them could alleviate the development of insulin resistance HepG2 cells with a dose-dependent relationship. The glucose consumption increased 46.4%, 50.5%, 82.1% and 53.6%; 86.8%, 81.6%, 86.8% and 84.2% at the concentration of 20 μg/mL, respectively, without or with insulin. These results suggested that PPFs can be explored as a potential hypoglycemic agent in biomedical and functional food.

Study on Hydrolysis Conditions of <i>Lactobacillus bulgaricus</i> on Casein Sodium by Method of Response Surface and the Antioxidant Activity of Hydrolysates

In order to study the ability ofLactobacillus bulgaricushydrolyzed protein, using casein sodium as substrate, the content of free amino acid and relative ORAC value were used as the index optimization. The conditions including: hydrolysis temperature, cultivation time,Lactobacillus bulgaricusdosage and pH values were investigated by single-factor experiment. In this paper we studied the hydrolysis conditions ofLactobacillus bulgaricuson casein sodium by the Box-Behnken response surface and the optimal hydrolysis temperature, cultivation time,Lactobacillus bulgaricusdosage and pH value were determined to be 43 °C, 36 h, 25 OD/ml, and pH 6.6, respectively. The optimum value of response surface is 857.75 mg/l. In addition, the analysis of relative ORAC value of response surface showed that there is no direct relationship between the degree of protein hydrolysis and radical scavenging activity, namely as extensive hydrolysis could have a negative impact on the antioxidant activity.

An on-line method for pressurized hot water extraction and enzymatic hydrolysis of quercetin glucosides from onions

A novel environmentally sound continuous-flow hot water extraction and enzymatic hydrolysis method for determination of quercetin in onion raw materials was successfully constructed using a stepwise optimization approach. In the first step, enzymatic hydrolysis of quercetin-3,4′-diglucoside to quercetin was optimized using a three level central composite design considering temperature (75–95°C), pH (3–6) and volume concentration of ethanol (5–15%). The enzyme used was a thermostable β-glucosidase variant (termed TnBgl1A_N221S/P342L) covalently immobilized on either of two acrylic support-materials (Eupergit® C 250L or monolithic cryogel). Optimal reaction conditions were irrespective of support 84°C, 5% ethanol and pH 5.5, and at these conditions, no significant loss of enzyme activity was observed during 72h of use. In a second step, hot water extractions from chopped yellow onions, run at the optimal temperature for hydrolysis, were optimized in a two level design with respect to pH (2.6 and 5.5), ethanol concentration (0 and 5%) and flow rate (1 and 3mLmin−1) Obtained results showed that the total quercetin extraction yield was 1.7 times higher using a flow rate of 3mLmin−1 (extraction time 90min), compared to a flow rate of 1mLmin−1 (extraction time 240min). Presence of 5% ethanol was favorable for the extraction yield, while a further decrease in pH was not, not even for the extraction step alone. Finally, the complete continuous flow method (84°C, 5% ethanol, pH 5.5, 3mLmin−1) was used to extract quercetin from yellow, red and shallot onions and resulted in higher or similar yield (e.g. 8.4±0.7μmolg−1 fresh weight yellow onion) compared to a conventional batch extraction method using methanol as extraction solvent.

Preparation of Chitooligosaccharides from Chitosan using Crude Enzyme of Bacillus cereus D-11

In order to enzymatically produce chitooligosaccharide using the crude enzyme preparation from Bacillus cereus D-11, we first studied the optimal reaction conditions. It was found that the optimal temperature for hydrolysis of chitosan was <TEX>$55^{\circ}C$</TEX>. The ratio of enzyme/substrate should not be lower than 0.13 U/mg in the reaction mixture. The enzyme activity was stable below <TEX>$50^{\circ}C$</TEX>. The products of enzymatic reaction were analyzed by both thin layer chromatography and high performance liquid chromatography. Under the appropriate condition, chitosan was hydrolyzed using the enzyme preparation. The resulting chitooligosaccharides were purified and separated by Dowex (<TEX>$H^+$</TEX>) ion exchange chromatography. From 4 g soluble chitosan, 0.95 g <TEX>$(GlcN)_2$</TEX>, 1.43 g <TEX>$(GlcN)_3$</TEX>, and 1.18 g <TEX>$(GlcN)_4$</TEX> were recovered.

Effect of temperature management on the hydrolytic degradation of PET in a calcium oxide filled tube reactor

Poly(ethylene terephthalate) (PET) was hydrolysed and decarboxylised, using a calcium oxide filled column under several thermal conditions, in order to obtain high yields of high purity benzene. The reactions of the hydrolysis of PET and the subsequent decarboxylation of the resulting terephthalic acid were successfully separated by a sophisticated temperature management. While hydrolysis proceeded well at temperatures below 500°C, the decarboxylation proceeded with a sufficient velocity at about 500°C. The yield and purity was strongly determined by the extent to which hydrolysis and decarboxylation were separated. At temperatures higher than the optimal temperature for hydrolysis, the resultant side reactions led to both a lower yield and purity of the product, while few by-products were observed when the hydrolysis was completed before the decarboxylation started. The best results were achieved at a heating rate of 2Kmin−1 between 300°C and 500°C, with a benzene yield of 74% and a purity of 97wt.%.

Effect of Bacillus circulans D1 thermostable xylanase on biobleaching of eucalyptus kraft pulp.

The alkalophilic Bacillus circulans D1 was isolated from decayed wood. It produced high levels of extracellular cellulase-free xylanase. The enzyme was thermally stable up to 60 degrees C, with an optimal hydrolysis temperature of 70 degrees C. It was stable over a wide pH range (5.5-10.5), with an optimum pH at 5.5 and 80% of its activity at pH 9.0. This cellulase-free xylanase preparation was used to biobleach kraft pulp. Enzymatic treatment of kraft pulp decreased chlorine dioxide use by 23 and 37% to obtain the same kappa number (kappa number) and brightness, respectively. Separation on Sephadex G-50 isolated three fractions with xylanase activity with distinct molecular weights.

Production, purification and characterization of an extracellular inulinase from Kluyveromyces marxianus var. bulgaricus

The yeast Kluyveromyces marxianus var. bulgaricus produced large amounts of extracellular inulinase activity when grown on inulin, sucrose, fructose and glucose as carbon source. This protein has been purified to homogeneity by using successive DEAE-Trisacryl Plus and Superose 6HR 10/30 columns. The purified enzyme showed a relative molecular weight of 57 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and 77 kDa by gel filtration in Superose 6 HR 10/30. Analysis by SDS-PAGE showed a unique polypeptide band with Coomassie Blue stain and nondenaturing PAGE of the purified enzyme obtained from media with different carbon sources showed the band, too, when stained for glucose oxidase activity. The optimal hydrolysis temperature for sucrose, raffinose and inulin was 55°C and the optimal pH for sucrose was 4.75. The apparent Km values for sucrose, raffinose and inulin are 4.58, 7.41 and 86.9 mg/ml, respectively. Thin layer chromatography showed that inulinase from K. marxianus var. bulgaricus was capable of hydrolyzing different substrates (sucrose, raffinose and inulin), releasing monosaccharides and oligosaccharides. The results obtained suggest the hypothesis that enzyme production was constitutive. Journal of Industrial Microbiology & Biotechnology (2000) 25, 63–69.

Purification and characterization of β‐amylase from leaves of potato (Solanum tuberosum)

Amylolytic activity is widely distributed in plants. In potato leaves (Solanum tuberosum L.) the abundant amylolytic activity was found to be β‐amylase (EC 3.2.1.2, a‐1,4‐D‐glucan maltohydrolase). β‐Amylase from potato leaves was purified to homogeneity for study of enzyme characteristics. The purification steps included ammonium sulphate precipitation, anion exchange chromatography, affinity chromatography and gel filtration. The end product of α‐1,4‐glucan degradation was maltose. The protein is a 111‐kDa homo‐dimer with a subunit molecular mass of 56 kDa and a pl of 5.6. The pH‐optimum is 6.5 using p‐nitrophenylmaltopentaoside (PNPG5) as substrate. The optimal temperature for hydrolysis is at 40°C. The enzyme is unstable at temperatures above 40°C. The Knt‐value for PNPG5 is 0.73 mM and the activity is inhibited by cyclodextrins. At a concentration of 1 mM, β‐cyclodextrin is a stronger inhibitor than α‐cyclodextrin (68 and 20% inhibition, respectively). Branched glucans (e.g. starch and amylopectin) are superior substrates as compared to long, essentially unbranched glucans (e.g. amylose). This study of the catalytic properties of β‐amylase from potato leaves indicates the importance of β‐amylase as a starch degrading enzyme.

Enzyme catalysis in organic solvents with low water content at high temperatures. The adenosinetriphosphatase of submitochondrial particles

A system composed of toluene, phospholipids, and Triton X-100 in which the ATPase activity of bovine heart submitochondrial particles can be studied at low water concentrations and high temperatures is described. In this system, ATPase activity starts to appear at 0.5% (v/v) water and increases as the concentration of water is increased. At 3.8% water, the enzyme exhibits saturation kinetics with respect to Mg-ATP with a Km similar to that observed in an all-water system (approximately 300 microM), but the Vmax is about 100 times lower (6 nmol min-1 mg-1) than that in water. At concentrations of water between 0.5% and 2%, the enzyme catalyzes ATP hydrolysis at temperatures of up to 91 degrees C. The conditions for achieving catalysis at high temperatures are described. Even though at low water concentrations the enzyme catalyzes ATP hydrolysis at temperatures significantly higher than in totally aqueous media, the optimal temperature for hydrolysis (approximately 58 degrees C) is independent of the water content. The half-life of the enzyme at high temperatures is significantly higher at low water concentrations than in aqueous media. In the system described, the enzyme is located in a compartment distinct from that of the substrate and products of the reaction. Apparently, the enhancement of catalytic rates by water is due to a higher conformational mobility of the protein; the same factor causes a decrease in the thermostability of the enzyme.

Purification and Characterization of Two Serratia marcescens Proteases

The exocellular proteases of two Serratia marcescens strains (strains SF 178 and SH 186; both of serotype 06/014:H12 and bacteriocin type 18) were separated from the culture supernatants through precipitation with ammonium sulfate, followed by hydroxylapatite adsorption chromatography, Sephadex G-100 gel filtration, and DEAE-Sephadex A-25 ion exchange chromatography. The molecular weights amounted to 54,400 Daltons (SDS-PAGE electrophoresis). Both enzymes contained 1 g-atom of zinc and 7 g-atoms of calcium per mol. The amino acid sequences were essentially identical. Serologically, both enzymes cross-reacted strongly, suggesting similar antigenic determinants. The two enzymes were microheterogeneous; isoelectric focusing revealed two protein bands at pH 5.4 and 5.5, respectively. The optimal temperature for hydrolysis of azocasein was 30°C. Both proteases revealed 2 optimal pH values (SF 178 = pH 6–7 and pH 8–10; SH 186 = pH 7 and pH 9).

An Adenosine Triphosphatase in Agrobacterium tumefaciens

AbstractCell‐free extracts from the phytopathogen Agrobacterium tumefaciens contained an enzyme(s) capable of cleaving nucleoside triphosphates, showing highest specific activity toward adenosine triphosphate. Differences are indicated between the adenosine triphosphate phospbohydrolase described hero and other microbial adenosine triphosphatases previously reported. The adenosine trit)hosphatasc activity was stimulated by Mg2+ and Mn2+ and inhibited by other divalent cations. Enzymatic activity was inhibited 100% by mercuric chloride, 38% by p‐chloromercuribenzoate, 22% by potassium fluoride, 12% by sodium azide, and 10% by iodoacetic acid, all at a final concentration of 10−2 M. The enzyme (s) had an optimal PH range of 7.8 to 8.0, and an optimal temperature for hydrolysis at 40deg;C.