• Microbiology and Biotechnology Letters
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• v.14 no.6
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• pp.467-471
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• 1986

Yeast cell wall lytic enzyme was purified from Fusarium moniliforme by ammonium sulfate fractionation and gel column chromatography. The lytic activity was found to consist of three enzyme activities which were resolved on Sephadex G-100. The first peak on chromatogram exhibited proteolytic, lytic and laminarinase activities, and the second had both lytic and laminarinase activities, whereas the third peak was shown to contain lytic activity only. Three enzyme activities showed the synergistic effect and reducing agents accelerated the yeast roil wall lysis. This indicates that lytic, proteolytic and laminarinase activity acted cooperatively in the lysis of intact cells. Tannic acid precipitate of crude enzyme constituted of three enzyme activities had a high lytic activity on viable yeast cell and has proved useful in yeast protoplast formation.

• Microbiology and Biotechnology Letters
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• v.23 no.6
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• pp.671-677
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• 1995

An extracellular enzyme showing lytic activity on E. coli peptidoglycan had been isolated from Bacillus sp. BL-29. The lytic enzyme was purified to homogeneity by ion-exchange chromatography and gel filtration, with a recovery of 5%. The enzyme was monomeric and had an estimated molecular weight of 31,000 Da. The mode of action of the purified enzyme was also investigated. When the purified lytic enzyme was incubated with cell wall peptidoglycan, N-terminal amino groups were released without the release of reducing groups. The N-terminal amino acid released was identified as dinitrophenylalanine (DNP-alanine) by analysis of terminal amino acid by dinitrophenylation method. This result suggests that the lytic enzyme should be a kind of N-acetylmura-myl-L-alanine amidase.

• Korean Journal of Ecology and Environment
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• v.37 no.2 s.107
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• pp.241-247
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• 2004

Isolation and identification of alga-lytic bacteria were carried out. Fifteen isolates of alga-lytic bacteria were screened by the double layer method using A. cylindrica NIES-19 as a sole nutrient and four isolates among them were compared with their alga-lytic activity. The isolate AK-05 exhibiting the highest alga-lytic activity was identified as Acidovorax temperans base on its 16S rDNA sequence. The culture supernatant of the isolate AK-05 was reliable for the alga-lytic. Alga-lytic activity assays of culture supernatant revealed that the major substances for alga-lytic activity were non-proteins and heat stable. The highest alga-Iytic activity was practical under alkaline conditions and at 25${\sim}$$30^{\circ}C$. It is indicating an advantage for the application of water blooms by cyanobacteria in eutrophic lakes where the pH is generally in alkaline region.

• Journal of Microbiology and Biotechnology
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• v.16 no.10
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• pp.1613-1621
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• 2006

Isolation and identification of algal lytic bacteria were carried out. Nine strains of algal lytic bacteria were isolated by the double-layer method using Anabaena flos-aquae as a sole nutrient. The isolate, AFK-13, showing the highest algal lytic activity was identified as Sinorhizobium kostiense based on the l6S rDNA sequence. The algal lytic experiments of the culture supernatants of AFK-13 demonstrated that the bacterial cell growth reached a maximum at 36-h culture, but the supernatant of 72-h culture exhibited the highest activity. Components among the extracellular products in the crude enzyme of the supernatant from S. kostiense AFK-13 culture were responsible for degradation of cell walls of Anabaena flos-aquae. Algal lytic assay tests of the culture supernatants suggest that the main substances for algal lytic activity could be proteinaceous. The activity of glucosidase was observed highly by polysaccharolytic analysis using the crude enzyme from S. kostiense AFK-13, whereas activities of galactosidase, mannosidase, rhamnosidase, and arabinosidase were also detected in low levels. The molecular weights (MW) of ${\alpha}-\;and\;{\beta}$-glucosidases were estimated to be approximately 50-100 kDa by the ultrafiltration method.

• Korean Journal of Microbiology
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• v.22 no.4
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• pp.215-222
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• 1984

A fungus producing cell wall lytic enzyme for Rhodotorula glutinis was isolated from local soil and identified partially as a species of Aspergillus fumigatus group. Thd cell wall lytic enzyme was an inducible exoenzyme and composed of at least lytic polysaccharidase and protease which act cooperatively in the lysis of intact cells. The lytic polysaccharidase was not able to hydrolyze ${\beta}-1,\;3\;and\;{\beta}-1$, 6-glucan which have the same types of bond as found in the cell wall of Ascomycetous yeasts. The lytic polysaccharidase alone was sufficient to hydrolyze the fractionated cell wall (alkali-insoluble residues) of R. glutinis, whereas it showed low activity against intact cells.

• Applied Biological Chemistry
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• v.20 no.1
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• pp.123-129
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• 1977

A potent lytic strain was selected by an extensive screening test of microorganisms isolated from soils and sewages on the medium containing baker's yeast as a carbon source. This strain (M-10) was identified to a strain of Humicola sp. by the Genera of Fungi (Clements, 1964). The strain was cultured on the basal medium composed of 2% of baker's yeast, 0.3% of $K_2HPO_4$, 0.01% of $MgSO_4{\cdot}7H_2O$, 0.1% of yeast extract in a shaking incubator. Cultural conditions for lytic enzyme production has been studied, and the results obtained were as follows: 1. The Optimal conditions for lytic enzyme production were: initial pH 5.5 to 6.0, temperature $33^{\circ}C$ in shaking culture. 2. Among the various carbon sources, baker's yeast (4%) was the best for lytic enzyme production, increasing the level of activity eight, times higher than when grown on glucose (1%). 3. The most effective concentration of $K_2HPO_4\;and\;MgSO_4{\cdot}7H_2O$ in the basal medium for lytic enzyme production was 0.1% and 0.01% respectively. 4. When the strain was cultured under the optimal conditions, the production of lytic enzyme was maximized in 72 hours.

• Journal of Microbiology and Biotechnology
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• v.14 no.6
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• pp.1142-1149
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• 2004

Streptococcus mutans has the capacity of inducing dental caries. Thus, to develop a novel way of preventing dental caries, a cell wall hydrolase-producing strain was isolated and its characteristics were investigated. Among 200 alkalophilic strains isolated from soil, 8 strains exhibited lytic activities against Streptococcus mutans. However, strain YU5215 with the highest cell wall hydrolase activity was selected for further study. Strain YU5215 was identified as a novel strain of Bacillus based on analyzing its 16S rDNA sequence and Bergey's Manual of Systematic Bacteriology, and thus designated as Bacillus mutanolyticus YU5215. The optimal conditions for the production of the cell wall hydrolase from Bacillus mutanolyticus YU5215 consisted of glucose ($0.8\%$), yeast extract ($1.2\%$), polypeptone ($0.5\%$), $K_{2}HPO_{4}\;(0.1\%$), $MgSO_{4}{\cdot}7H_{2}O$ ($0.02\%$), and $Na_{2}CO_{3}\;(1.0\%$) at pH 10.0. Bacillus mutanolyticus YU5215 was cultured at 30^{circ}C for 72 h to produce the cell wall hydrolase, which was then purified by acetone precipitation and CM-agarose column chromatography. The molecular weight of the lytic enzyme was determined as 22,700 Da by SDS-PAGE. When the cell wall peptidoglycan of Streptococcus mutans was digested with the lytic enzyme, no increase in the reducing sugars was observed, while the free amino acids increased, indicating that the lytic enzyme had an endopeptidase-like property. The amino terminus of the cell wall peptidoglycan digested by the lytic enzyme was determined as a glutamic acid, while the lytic site of the lytic enzyme in the Streptococcus mutans peptidoglycan was identified as the peptide linkage of L-Ala and D-Glu.

• Korean Journal of Food Science and Technology
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• v.35 no.6
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• pp.1143-1149
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• 2003

To elucidate a method of preventing dental caries, strains producing lytic enzymes were isolated and their characteristics were investigated. Among 5,00 alkalophilic strains isolated from soil, 22 strains showed lytic activity against Streptococcus mutans. Strain No. 4830, with the highest lytic activity, was selected for further study. Strain 4830 showed 94% sequence homology with the 16S rDNA sequence of Bacillus alcalophilus, but it was concluded to be different from Bacillus alcalophilus because of its biochemical characteristics. The strain was named Bacillus sp. 4830. The lytic enzyme from Bacillus sp. 4830 was purified by ethanol precipitation and CM-agarose column chromatography. The molecular weight of the lytic enzyme was determined to be 28 kDa by SDS-PAGE. The lytic enzyme was stable between pH 5.0 and pH 11 and up to $40^{\circ}C$. The optimal pH and temperature for the lytic activity was 9.0 and $50^{\circ}C$, respectively.

• 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.

• Microbiology and Biotechnology Letters
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• v.13 no.2
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• pp.137-144
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• 1985

Studies were conducted on the conditions for preparation of yeast protoplasts utilizing Hansenula anomala var. anomala FRI YO-32 as well as Saccharomyces cerevisiae KFCC 32356 and a lytic enzyme from the snail Helix pomatia. The cell wails of the strain FRI YO-32 and S cerevisiae were found to be resistant to activity of the snail lytic enzyme if they were not treated with thiol compounds. Dithiothreitol was found to be more effective than 2-mercaptoethanol, but the latter was considered to be practical. As factors influencing the formation of yeast protoplast, it was considered to be concentration and incubation time of 2-mercaptoethanol or the lytic enzyme, growth stages in yeast cultivation, initial number of yeast cells, and concentration of osmotic stabilizer (KCI). Optimum conditions for the preparation of yeast protoplasts were determined.