• The Korean Journal of Mycology
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• v.14 no.4
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• pp.273-280
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• 1986

The degree of autolysis and lytic enzyme production in the culture filtrate of Rhizopus oryzae was investigated. The formation of protoplast by using autolytic enzymes from Rh. oryzae was also attempted. Protoplasts were liberated from Rh. oryzae mycelium by lytic enzymes present in autolytic-phase culture filtrate. Maximum release of chitosanase and proteolytic enzyme into culture filtrate during autolysis was corresponded to maximum protoplast-liberating activity. High yields of protoplasts were obtained from 10 hr-age of Rh. oryzae mycelium with 0.5 M mannitol as osmotic stabilizer. The optimum temperature and pH for mycelium digestion were $25{\sim}30^{\circ}C$ and $6.0{\sim}6.5$ respectively. The mycelium of the 18 hours cultures were treated with autolytic enzyme in same volume of osmotic stabilizer at $30^{\circ}C$ for 5 hours and then it was confirmed by scanning electoron microscope that protoplast were produced beside the digesting cell wall of the fungi.

• Microbiology and Biotechnology Letters
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• v.17 no.1
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• pp.69-73
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• 1989

Cellular autolytic enzyme was isolated from the supernatant fluid of exponentially growing cuiture of Cl. butyricum ID-113. The autolysin was partially pruified by ammonium sulfate fractionation, chromatography on DEAE-Sephadex A-50 and gel filtration through Sephadex G-200. This autolytic enzyme lysed SDS-treated cell wall fractions of Cl. butyricum ID, but not whole cells at all. Its optimum pH and temperature were 5.0 and 37$^{\circ}C$, respectively. This enzyme was relatively stable at neutral pH, but sensitive to heat treatment. Enzyme activity was not influenced by the addition of various divalent cation, but inhibited by Cu$^{++}$.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.8
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• pp.1136-1140
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• 2011

This study was designed to evaluate the potential of using high pressure processing (HPP) for extending shelf life of seasoned squid during refrigerated storage. The vacuum-packed seasoned squid samples were subjected to 400 MPa for 20 min using a custom-made high pressure processor. Microbial counts, dimethylamine (DMA), trimethylamine (TMA), total biogenic amine, autolytic activity were determined on days 0, 7, 14, and 21 of refrigerated storage. The numbers of indigenous bacteria were effectively reduced by 2.77 log CFU/g after HPP treatment. The amounts of DMA and TMA produced in the control samples increased up to 15.99 and 42.82 mg/g after 7 days of refrigerated storage when compared to 5.27 and 10.21 mg/g the HPP-treated samples, respectively. The autolytic activity of the HPP-treated sample (4.32 nkat/g) significantly lower than that of the control (7.13 nkat/g) after 7 days of refrigerated storage. Therefore, HPP can be applied as a potential squid processing method microbiological safety and shelf life.

• Microbiology and Biotechnology Letters
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• v.17 no.1
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• pp.63-68
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• 1989

The optimum conditions for cellular autolysis in Clostridium butyricum ID-113 have been investigated. Cellular autolysis was optimal at pH 1.0 in 0.05 M potassium phosphate buffer and at 37$^{\circ}C$. The rate of cellular autolysis depended on the age of culture. The most rapid cellular autolysis occurred in the cells of mid-exponentially growing cultures, but cellular autolysis decreased sharply when the cultures entered the stationary phase. A growing culture of Cl. butyricum ID-113 was induced to autolyze and lost its turbidity spontaneously in the hypertonic NaCl, sucrose, or glucose medium. The autolytic enzyme activity was found In the autolysate of cells and the supernatant of the culture.

• Journal of Microbiology and Biotechnology
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• v.11 no.6
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• pp.957-963
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• 2001

Bacillus subtilis YL-1004 was isolated from soil for the development of agents to control dental caries. This strain produced an extracellular lytic enzyme that hydrolyzed the Streptococcus mutans cell wall. The lytic enzyme was purified to homogeneity by affinity chromatography and gel permeation chromatography to give a single band on SDS-PAGE and non-denaturing polyacrylamide gel electrophoresis. The molecular weight of the enzyme was deduced from SDS-PAGE and gel chromatography to be 38 kDa and the PI to be 4.3 from isoelectric focusing. Sirty $\%$ of its lytic activity remained after incubation at $50^{\circ}C$ for 30 min, and its optimal temperature was $37^{\circ}C$ . The enzyme showed its highest activity at pH 8.0 and was stable at pHs ranging from 4.0 to 9.0. Treatment with several modifiers showed that a cysteine residue was involved in the active site of the enzyme. This lytic enzyme from Bacillus subtilis YL-1004 exhibited specificity towards Streptococci and also showed autolytic activity on Bacillus subtilis YL-1004.

• Journal of Microbiology and Biotechnology
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• v.6 no.1
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• pp.1-6
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• 1996

A bacterial strain NS70 producing an alkaline protease was isolated from soil samples taken near a hot spring and identified as Bacillus licheniformis by its morphological and physiological properties and cellular fatty acid analysis. The isolated alkaline protease was purified by ammonium sulfate fractionation, DEAE-, CM-, and Phenyl-Sepharose column chromatography. The molecular weight of the purified enzyme was estimated to be 32, 000 Da by sodium dodecylsulfate polyacrylamide gel electrophoresis. Its optimal pH and temperature for proteolytic activity against Hammarsten casein were 12 and $65^{\circ}C$, respectively. The enzyme was stable at alkaline pH range from 6.0 to 12.0, and fairly stable up to $65^{\circ}C$. The enzyme was inhibited by phenylmethylsulfonyl fluoride but not by EDTA and N-ethylmaleimide indicating that the enzyme is serine protease. Enzyme activity was markedly inhibited by $Hg^{2+}$ and $Cu^{2+}$. Autolytic phenomena were observed on purified protease NS70 but autolysis was reduced by the addtion of $Ca^{2+}$ ion or bovine serum albumin.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.3
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• pp.191-196
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• 2011

In this study, we investigated the chemical and enzymatic properties of unmarketable cultured bastard halibut (UCBH) Paralichthys olivaceus harvested at different times (March, May, July, September, November, and January), and we examined the physical properties of surimi gel from UCBH as a potential source of surimi and surimi gel. The moisture and crude protein contents of UCBH harvested in July and January were >78% and <19%, respectively, which is greater than the moisture content in UCBH harvested in May, March, and September, but lower than the crude protein content. Regardless of the month of harvest, the UCBH had a higher crude protein content than Alaska pollock, which is the largest fishery biomass used for surimi and surimi gel, but a lower moisture content. Regardless of the month of harvest, the enzymatic activity in crude extracts of UCBH muscle ranged from 0.31-0.59 U/mg for casein (pH 6.0 and 9.0) and 11.7-12.7 U/mg for LeuPNA. These findings suggest that autolytic enzymes were unaffected by gel formation. Gel strength was highest in the surimi gel prepared from UCBH harvested in September, November, and January; second highest in that prepared from UCBH harvested in March and May; and lowest in that prepared from UCBH harvested in July. Compared to the gel strength of surimi gel from grade SA commercial Alaska pollock surimi, the strength of the surimi gels prepared from UCBH harvested in March, May, September, November, and January were superior, whereas that of the surimi gel prepared from UCBH harvested in July was similar.

• Journal of the Korean Society of Food Science and Nutrition
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• v.20 no.6
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• pp.629-636
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• 1991

Yellowtail fishes(Seriola quinqueeradiata) were submitted to the storages using ice-cooling($0^{\circ}C$), partial freezing($-3^{\circ}C$) and freezing $-20^{\circ}C$) method. Changes in the structures of muscle during storage at different temperatures were investigated. The ice-cooling and partial freezing storage caused early decomposition of glycogen granules and mitochondrial inner membrane, but it was accorded to much slower manner comparing with that of ice-cooling storage. The scars of ice crystals were appeared after three days of storage. The number and size of the crystal increased as progressing of the storage. They were circular and mostly located between fibers. When using the freezing storage, glycogen granules were mostly found from the muscle cell even after fourteen days of storage. Mitochonidral inner membrane maintained their integrity. The scars of ice crystals were also found, however, different from those of partial freezing storage. Their existing sites were random and their shapes were irregular. In many cases, they located in the fiber and had keen edges. Fibers were broken mostly at the Z-lines on fourteen days of storage. From these results, it was concluded that partial freezing storage can repress autolytic enzymic action and can reduce the physical damage from ice crystals which is caused by freezing.