• Journal of Environmental Health Sciences
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• v.31 no.4 s.85
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• pp.294-300
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• 2005

Food waste can be a valuable carbon source in biological nutrient removal (BNR) systems because of high C/N and C/P ratios. However, food waste should be pretreated to promote its hydrolysis rate because hydrolysis reaction would be a rate-limiting step. This study investigates the influence of the enzymatic pretreatment on acid fermentation of food waste. Solubilization of particulate matter in food waste by using commercial enzymes was examined. The acidification efficiency and the volatile fatty acids (VFAs) production potential of enzymatically pretreated food waste were also examined. The highest volatile suspended solids (VSS) reduction was obtained with an enzyme mixture ratio of 1:2:1 of carbohydrase:protease:lipase. An optimum enzyme dosage for solubilization of food waste was $0.1\%$(V/V) with the enzyme mixture ratio of 1:2:1. In the acid fermentation of enzymatically pretreated food waste, $0.1\%$(V/V) enzyme mixture dosage for pretreatment result in the maximum VFAs production and the best VFAs fraction in soluble COD(SCOD). The VFAs production at this addition level was 3.3 times higher than that of no-enzyme added fermenter. The dominant VFAs present was n-butyrate followed by acetate.

• KSBB Journal
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• v.14 no.4
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• pp.511-516
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• 1999

The effects of environmental and compositon factors, such as reaction time, metal ions, pH, agitation speed, the weight ratio of water to oil, and the weight of enzyme, on the hydrolysis of oils by Lipase-OF were investigated. In case of oils with low melting point, the optimum temperature of hydrolysis were the enzyme activity was maximum was 37$^{\circ}C$. However, when the melting temperature was higher than 4$0^{\circ}C$, the optimum temperature was around the fusion temperature. The activity of Lipase-OF decreased very rapidly with increase of temperature in the range of higher than 45$^{\circ}C$ and the activity perished above $65^{\circ}C$. The effect of agitation speed was investigated from 150 to 650 rpm. The hydrolysis of oils increased as the agitation speed increased up to 350 rpm, but it did not increase any more above 350 rpm. The weight ratio of water to oil was changed from 1 : 9 to 9 : 1 for the investigation of the effect on the hydrolusis. The weight ratio for maximum hydrolysis was 1 : 1. $Ca^{2+}\;and\;Mg^{2+}$ among various metal ions had some effect on the stimulation of hydrolysis. The optimum concentration of the ions was about 100ppm at which the hydrolysis increased, compared with that of distilled water, by 2 to 3%. The Optimum pH of Lipase-OF was 7. The hydrolysis decreased as the pH decreased as the pH decreased and also decreased as the pH increased. The content of enzyme affected the hydrolysis of oil. The hydrolysis increased with the content of Lipase-OF in the range of less than 0.013 wt% of substrate. However, the increase of hydrolysis with the content of Lipase-OF ceased above 0.013 wt%. The experiments investigating the effect of environmental and composition factors on the hydrolysis of oils showed that the optimum temperature was 37$^{\circ}C$, the pH 7, the concentration of $Ca^{2+}\;or\;Mg^{2+}$ 100 ppm, the agitation speed 350 rpm, the weight ratio of water to oil 1 : 1, and the content of Lipase-OF 0.013 wt% of substrate.

• Journal of the Korean Society of Clothing and Textiles
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• v.20 no.3
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• pp.550-559
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• 1996

The Effect of protease (subtilisin Carlsberg) on the removal of hemoglobin as protein soil was studied. The hydrolysis characteristics of subtilisin Carlsberg was examined by electrophoretic techniques. The fragmentation patterns of hemoglobin were analyzed by SDS-PAGE. The hydrolysis efficiency was evaluated by analysis of protein bands shown on gels before and after hydrolysis by using densitometer. 1. The hydrolysis of hemoglobin by subtilisin Carlsberg was increased markedly with the increase of the enzyme concentration. 2. The hydrolysis of hemoglobin by subtilisin Carlsberg was effectively increased in proportion to increasing of the hemoglobin concentration up to a certain point, but it began to decrease above the point. 3. The hydrolysis of hemoglobin by subtilisin Carlsberg followed the first order kinetics, yielding a rate constant of $4.05\time10^{-4}S^{-1}s$. 4. The hydrolysis of hemoglobin by subtilisin Carlsberg was highest at $50^{\circ}C$ and was decreased markedly at $80^{\circ}C$. 5. The hydrolysis of hemoglobin was comparatively low at pH 7.0~8.0, and highest at pH 11.0.

• Bulletin of the Korean Chemical Society
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• v.24 no.1
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• pp.65-69
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• 2003

The kinetic and chemical mechanisms of AChE-catalyzed hydrolysis of short-chain thiocholine esters are relatively well documented. Up to propanoylthiocholine (PrTCh) the chemical mechanism is general acid-base catalysis by the active site catalytic triad. The chemical mechanism for the enzyme-catalyzed butyrylthiocholine(BuTCh) hydrolysis shifts to a parallel mechanism in which general base catalysis by E199 of direct water attack to the carbonyl carbon of the substrate. [Selwood, T., et al. J. Am. Chem. Soc. 1993, 115, 10477- 10482] The long chain thiocholine esters such as hexanoylthiocholine (HexTCh), heptanoylthiocholine (HepTCh), and octanoylthiocholine (OcTCh) are hydrolyzed by electric eel acetylcholinesterase (AChE). The kinetic parameters are determined to show that these compounds have a lower Michaelis constant than BuTCh and the pH-rate profile showed that the mechanism is similar to that of BuTCh hydrolysis. The solvent isotope effect and proton inventory of AChE-catalyzed hydrolysis of HexTCh showed that one proton transfer is involved in the transition state of the acylation stage. The relationship between the dipole moment and the Michaelis constant of the long chain thiocholine esters showed that the dipole moment is the most important factor for the binding of a substrate to the enzyme active site.

• Journal of Microbiology and Biotechnology
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• v.16 no.8
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• pp.1255-1261
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• 2006

An alkaliphilic bacterium, Bacillus sp. strain BK, was found to produce extracellular cellulase-free xylanolytic enzymes with xylan-binding activity. Since the pellet-bound xylanase is eluted with 2% TEA from the pellet of the culture, they contain a xylan-binding region that is stronger than the xylan-binding xylanase of the extracellular enzyme. The xylanases had a different molecular weight and xylan-binding ability. The enzyme activity of xylanase in the extracellular fraction was 6 times higher than in the pellet-bound enzyme. Among the enzymes, xylanase had the highest enzyme activity. When Bacillus sp. strain BK was grown in pH 10.5 alkaline medium containing xylan as the sole carbon source, the bacterium produced xylanase, arabinofuranosidase, acetyl esterase, and $\beta$-xylosidase with specific activities of 1.23, 0.11, 0.06, and 0.04 unit per mg of protein, respectively. However, there was no cellulase activity detected in the crude enzyme preparation. The hydrolysis of agricultural residues and kraft pulps by the xylanolytic enzymes was examined at 50$^{\circ}C$ and pH 7.0. The rate of xylan hydrolysis in com hull was higher than those of sugarcane bagasse, rice straw, com cop, rice husk, and rice bran. In contrast, the rate of xylan hydrolysis in sugarcane pulp was 2.01 and 3.52 times higher than those of eucalyptus and pine pulp, respectively. In conclusion, this enzyme can be used to hydrolyze xylan in agricultural residues and kraft pulps to breach and regenerate paper from recycled environmental resources.

• Journal of Microbiology and Biotechnology
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• v.7 no.2
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• pp.151-156
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• 1997

Two commercially available lipases, Lipase OF (non-specific lipase from Candida rugosa) and Lipolase 100T (1, 3-specific lipase from Aspergillus niger), were immobilized on insoluble hydrophobic support HDPE (high density polyethylene) by the physical adsorption method. Hydrolysis performance was enhanced by mixing a non-specific Lipase OF and a 1, 3-specific Lipolase 100T at a 2 : 1 ratio. The results also showed that the immobilized lipase maintained its activity at broader temperature ($25~55^{\circ}C$) and pH (4-8) ranges than soluble lipases. In the presence of organic solvent (isooctane), the immobilized lipase retained most of its activity in upto 12 runs of hydrolysis experiment. However, without organic solvent in the reaction mixture, the immobilized lipase maintained most of its activity even after 20 runs of hydrolysis experiment.

• Archives of Pharmacal Research
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• v.11 no.4
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• pp.285-291
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• 1988

2-mercaptoethanol, thioglycolic acid, glutathione, 3-mercapto-1, 2-propanediol and 3-mercapto-2-butanol showed catalytic activities on the hydrolysis of $\alpha$-amino-phenylacetonitrile to phenylglycineamide at the rate of 12.19 $\times$ $10^{-2}$, 8.03 $\times$ $10^[-2}$, 6.83 $\times$ $10^{-2}$, 8.60 $\times$ $10^{-2}$ and 6.04 $\times$ $10^{-2}$ mM $min^{-1}$, respectively. hte hydrolysis rate was faster in buffer than in water. The hydrolysis of the nitrile compound to phenylglycine was limited.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.1
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• pp.84-90
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• 2011

It is imperative to study the hydrolysis of urea in high saline-sodic condition of a newly reclaimed tidal land in order to overcome the problems associated with use of urea fertilizer. The methodology adopted in this study tried to get a convenient way of estimating rate for N transformation needed in N fate and transport studies by reviewing pH and salt contents which can affect the microbial activity which is closely related to the rate of urea hydrolysis. The hydrolysis of urea over time follows first-order kinetics and soil urease activity in reclaimed soils will be represented by Michaelis-Menten-type kinetics. However, high pH and less microorganisms may delay the hydrolysis of urea due to decrease in urease activity with increasing pH. Therefore, the rate of urea hydrolysis should adopt $V_{max}$ referring enzyme activity ($E_0$) accounting for urease concentration which is indicative for urea hydrolysis, especially in a high saline and sodic soils.

• Proceedings of the Korean Society of Life Science Conference
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• 2003.05a
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• pp.130-130
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• 2003

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.2
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• pp.127-133
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• 1999

The purpose of this study was to determine the optimum hydrolysis conditions for the production of enzymatic hydrolysate from tuna boiled extract (TBE) using membrane (molecular weight cut off 10,000Da) reator. The tuna pyloric caeca crude enzyme (TPCCE) was identified as the most suitable enzymes for the hydrolysis of TBE. The optimum hydrolysis conditions of TBE in the batch reactor were $40^{\circ}C$, pH 9 and substrate to TPCCE ratio 50 (w/w). For 6hr under the above conditions, $70\%$ of the total amount of initial TBE was hydrolysed. The optimum hydrolysis conditions of TBE in the membrane reactor were $40^{\circ}C$, pH 9, enzyme 0,1 g/$\ell$, volume 1$\ell$ and substrate to enzyme ratio 100(w/w). The degree of hydrolysis of TBE was above $60\%$ for 3 hr. The TBE hydrolysate were prepared with $5\%$ TBE solution under the optimum hydrolytic conditions in the membrane reactor