• Journal of Aquaculture
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• v.22 no.1
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• pp.105-111
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• 2009

In this study, we carried out an experiment for estimation the larval digestibility in aspects which digestive enzymatic activities and nutrition of the rotifers, Brachionus rotundiformis. Thus we enhanced the digestive enzymatic activity through the addition of starch for the increase of digestibility of rotifer (starch-rotifer), and compared with the feed efficiency through rearing of the olive flounder, Paralichthys olivaceus used rotifer lipid-enriched with Algamac $2000^{(R)}$ (CE-rotifer). The digestive enzyme activities (except for TG-lipase), total protein contents, total essential amino acid, essential amino acids (methionin and phenylalanine) of starch-rotifer (the rotifer used a starch as additive, and enriched not) was assayed significantly higher than CE-rotifer (P<0.05). And total lipid, lipid classes (except for sterol) and fatty acids as DHA and EPA showed higher in CE-rotifer than starch-rotifer (P<0.05). But, sterol contents and ST/TG ratio were shown significantly higher in starch-rotifer (P<0.05). The flounder larvae supplied the two rotifers showed standard length and body weight that not significantly differed with ranges $3.72{\sim}3.79\;mm$ and $32.9{\sim}37.8\;mg$/larva on 6 days after hatching (DAH), respectively (P>0.05). However, these of 12 DAH showed the values of significantly higher to $5.94{\pm}0.249\;mm$, $144.0{\pm}23.86\;mg$/larva and $26.2{\pm}12.13%$ in standard length, body weight and survival in CE-flounder than that of starch-flounder (P<0.05). The hydrolytic enzymatic activities of flounder larvae severally supplied the two rotifers showed the significantly higher activities in acidic -amylase, neutral -amylase, TG-lipase, lysozyme and acidic phosphatase in starch-flounder on 5 DAH (P<0.05). But neutral $\alpha$-amylase, three proteases and two phosphatases of CE-flounder on 11 DAH showed the significantly higher activities than that of starch-flounder (P<0.05). Therefore, for the flounder, Paralichthys olivaceus larvae just depleted yolk was more beneficial to supply the feed, rotifer, enhanced the digestibility than to supply the feed lipid-enriched for aspect of larval digestibility up to 6 DAH, thereafter nutrition of absorption due to the development of digestive organs suggested that enrichment effect appeared with larval somatic growth. Consequently, investigation more detailed about the larval digestive physiological and nutritional requirement variations after 6 DAH will be necessary, thereafter.

• Korean Journal of Microbiology
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• v.49 no.1
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• pp.78-82
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• 2013

A novel Chryseobacterium sp. JK1 strain isolated from soil had been reported that this isolate produced large amount of extracellular protease at mesophilic temperature in previous study. The optimal temperature and pH of extracellular protease were $40^{\circ}C$ and 7.0, respectively, showing narrow range of optimal temperature and relatively broad activity from pH 6.0 to 9.0. In addition, the protease showed greatest activity against skim milk and lowest against bovine serum albumin (BSA). The protease strongly inhibited by ethylenediaminetetraacetic acid (EDTA), ethylene glycol tetraacetic acid (EGTA) or phenylmethylsulfonyl fluoride (PMSF), and addition of cation $Ag^+$ or $Cu^{2+}$, and slightly inhibited by $Al^{3+}$. No significant inhibition was found with pepstatin, and addition of cation, $K^+$, $Ca^{2+}$, $Na^+$, $Fe^{2+}$ or $Mg^{2+}$. On the contrary, protease was enhanced by addition of divalent cation $Mn^{2+}$ (5 mM). Zymography analysis of concentrated culture supernatant revealed two major bands at 67 and 145 kDa. These results suggest that Chryseobacterium sp. JK1 strain produced extracellular neutral serine proteases which could apply in food industry.

• Journal of Microbiology and Biotechnology
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• v.21 no.8
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• pp.861-868
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• 2011

A xylanase gene, xyn7c, was cloned from Paenibacillus sp. 12-11, an alkalophilic strain isolated from the alkaline wastewater sludge of a paper mill, and expressed in Escherichia coli. The full-length gene consists of 1,296 bp and encodes a mature protein of 400 residues (excluding the putative signal peptide) that belongs to the glycoside hydrolase family 10. The optimal pH of the purified recombinant XYN7C was found to be 8.0, and the enzyme had good pH adaptability at 6.5-8.5 and stability over a broad pH range of 5.0-11.0. XYN7C exhibited maximum activity at $55^{\circ}C$ and was thermostable at $50^{\circ}C$ and below. Using wheat arabinoxylan as the substrate, XYN7C had a high specific activity of 1,886 U/mg, and the apparent $K_m$ and $V_{max}$ values were 1.18 mg/ml and 1,961 ${\mu}mol$/mg/min, respectively. XYN7C also had substrate specificity towards various xylans, and was highly resistant to neutral proteases. The main hydrolysis products of xylans were xylose and xylobiose. These properties make XYN7C a promising candidate to be used in biobleaching, baking, and cotton scouring processes.

• International Journal of Industrial Entomology and Biomaterials
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• v.22 no.2
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• pp.83-93
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• 2011

Biochemical and enzymatic characterization for extracellular protease isolated from Cordyceps militaris cultivated on rice bran medium was investigated. C militaris produced proteolytic enzymes from 10 days after inoculation, maximum enzyme production was found at 25 days. The optimum temperature and pH of proteases production was at $25^{\circ}C$ and pH 7.0, respectively. The protease activity was observed in the four peaks (Pro-I, Pro-II, Pro-III, and Pro-IV) separated through Sephadex G-100 column chromatography. The separated protease was optimally active at $25^{\circ}C$. Optimum pH of the protease was between 7 and 8. Enzyme was also stable over at $30-80^{\circ}C$. The enzyme was highly stable in a pH range of 4-9. Protease activity was found to be slightly decreased by the addition of $Mg^{2+}$, $Mn^{2+}$, $Zn^{2+}$, $Fe^{2+}$ and $Cu^{2+}$, whereas inhibited by the addition of $Ca^{2+}$ and $Co^{2+}$ Protease activity was inhibited by protease inhibitor PMSF. On the other hand, the partially purified protease was investigated on proteolytic protease activity by zymogram gel electrophoresis using three substances (casein, gelatin and fibrin). Four active bands (F-I, FII, F-III, and F-IV) of fibrin degradation were revealed on fibrin zymogram gels. Both of F-II and FIII showed caseinolytic, fibrinolytic and gelatinolytic activities in three gels. Thermostability, pH stability, and pH-thermostability of the enzyme determined the residual fibrinolytic activity also displayed on fibrin zymogram gel. The only one enzyme (F-II) displayed over a broad range of temperature at $30-90^{\circ}C$. The FII displayed fibrinolytic activity in the pH range 3-5, but was inactivated in the range of pH 6-11. The F-I and F-III showed enzyme activity in the pH range of 6-11. In the pH-thermostability, the F-II only kept fibrinolytic activity after heating at $100^{\circ}C$ for 10, 20 and 30 min at pH 3 and pH 7, respectively. On the other hand, the F-II was retained activity until heating for 10 min under pH 11 condition. By using fibrin zymogram gel electrophoresis, extracellular fibrinolytic enzyme F-II from C. militaris showed unusual thermostable under acid and neutral conditions.