• KSBB Journal
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• v.23 no.3
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• pp.187-192
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• 2008

Lysozyme-producing microorganisms were isolated to obtain bacteria which can efficiently solubilize microbial cells. Cells of normal and chloroform-treated Escherichia coli and Micrococcus Iysodeikticus were used as model substrates to isolate lysozyme-producing microorganisms and investigate the efficiency of cell lysis. The culture supernatant of the isolate New1 (98% similarity of 16S rDNA sequence with Thermomonas haemolytica) showed different lytic characteristics for different substrates. Thermal treatment (autoclave) of substrate cells showed a significant effect on cell solubilization by culture supernatant of the New1. For autoclaved substrate cells, E. coli, M. Iysodeikticus and chloroform-treated E. coli were solubilized by 58.7%, 49.4% and 79.1%, respectively, in the culture supernatant of New1. The lytic activity of New1 was mainly caused by lysozyme produced by the isolate. It was also showed that New1 exhibited high protease activity and a little cellulase activity.

• The Korean Journal of Ecology
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• v.22 no.1
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• pp.45-50
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• 1999

A bacteriocin-producing strain was isolated from kimchi at the early stage of kimchi fermentation. It was identified as Lactococcus lactis by morphological, cultural and physiological characteristics and partial sequence of 16S rDNA. The bacteriocin from isolate had antimicrobial activity against gram positive pathogenic bacteria, such as Listeria monocytogenes. Staphylococcus aureus and several strains of lactic acid bacteria but not to gram negative bacteria, Yersinia enterocolitica. The bacteriocin was sensitive to protease, protease ⅩⅣ, a-chymotrypsin and pepsin but not to lipase, trypsin and lysozyme. The bacteriocin activity was stable at pH 2-11 and temperature of 100 for 10 min. Thus, Listeria monocytogenes could be inhibited by Lactococcus lactis at early stage of fermentation.

• Microbiology and Biotechnology Letters
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• v.16 no.2
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• pp.150-155
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• 1988

In order to produce L-lysine from cellulosic substrates by the intergeneric protoplast fusion between cellulolytic bacteria, Cellulomonas flavigena KFCC31221 and amino acid producing bacteria, Brevibacterium flavum ATCC14067, Corynebacteriurn glutamicum ATCC13032, conditions for protoplast formation and regeneration of these strains were investigated. After the strains were mutated with 500$\mu\textrm{g}$/$m\ell$ N-methyl-N'-nitro N-nitrosoguanidine for 30 min and the mutants were enriched by treating 300$\mu\textrm{g}$/$m\ell$ penicillin-G for 2 hrs, B. flavum Hse- Str$^{r}$ , C. glutamicum Met$^{-}$Thr$^{-}$ Rif$^{r}$ and Cellulomonas flavigena Thr$^{-}$Val$^{-}$Kan$^{r}$ were isolated. The rate of protoplast formation ranged from 95 to 98% when strains were treated at the concentration of 500$\mu\textrm{g}$/$m\ell$ of lysozyme, pH 6.5, 33$^{\circ}C$, for 6 hrs. in Tris- malate buffer supplemented with 0.4M sucrose as osmotic stabilizer. Approximately 30-33% protoplast was regenerated on the regeneration complete medium(RCM) containing 1.5% agar and 0.5M sodium succinate overlaid with the same medium except 0.7% agar.

• Journal of Microbiology and Biotechnology
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• v.30 no.10
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• pp.1552-1558
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• 2020

With an increase in the consumption of non-heated fresh food, foodborne shiga toxin-producing Escherichia coli (STEC) has emerged as one of the most problematic pathogens worldwide. Endolysin, a bacteriophage-derived lysis protein, is able to lyse the target bacteria without any special resistance, and thus has been garnering interest as a powerful antimicrobial agent. In this study, rV5-like phage endolysin targeting E. coli O157:H7, named as LysECP26, was identified and purified. This endolysin had a lysozyme-like catalytic domain, but differed markedly from the sequence of lambda phage endolysin. LysECP26 exhibited strong activity with a broad lytic spectrum against various gram-negative strains (29/29) and was relatively stable at a broad temperature range (4℃-55℃). The optimum temperature and pH ranges of LysECP26 were identified at 37℃-42℃ and pH 7-8, respectively. NaCl supplementation did not affect the lytic activity. Although LysECP26 was limited in that it could not pass the outer membrane, E. coli O157: H7 could be effectively controlled by adding ethylenediaminetetraacetic acid (EDTA) and citric acid (1.44 and 1.14 log CFU/ml) within 30 min. Therefore, LysECP26 may serve as an effective biocontrol agent for gram-negative pathogens, including E. coli O157:H7.

• Food Engineering Progress
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• v.14 no.3
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• pp.263-270
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• 2010

An alkalophilic microorganism named DK-2386, which produces xylanase, was isolated from soil of Taejo-mountain, Cheonan-si, Chungnam, Korea. The isolated strain was characterized as Gram-positive, with size of 0.4${\times}$2.5 ${\mu}$m, spore forming, anaerobic, catalase positive, possessed with hydrolysis abilities of casein, starch, sodium carboxy methyl cellulose, and xylan, reduction of nitrate to nitrite, resistant against lysozyme, urease positive, and motility positive. The color of culture broth was reddish yellow. The strain DK-2386 was identified as Bacillus agaradhaerens by whole cell fatty-acid composition analysis and 16S rDNA sequence analysis. However, it was not identical to Bacillus agaradhaerens 40952 obtained from the Korean Culture Center of Microorganism in its colour of culture broth. Therefore, we have named the newly isolated strain as Bacillus agaradhaerens DK-2386.

• Journal of Microbiology and Biotechnology
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• v.31 no.1
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• pp.63-69
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• 2021

Carotenoids, which have biologically beneficial effects and occur naturally in microorganisms and plants, are pigments widely applied in the food, cosmetics and pharmaceutical industries. The compound 4,4'-diaponeurosporene is a C30 carotenoid produced by some Lactobacillus species, and Lactobacillus plantarum is the main species producing it. In this study, the antioxidant activity of 4,4'-diaponeurosporene extracted from L. plantarum subsp. plantarum KCCP11226 was examined. Maximum carotenoid content (0.74 ± 0.2 at A470) was obtained at a relatively low temperature (20℃). The DPPH radical scavenging ability of 4,4'-diaponeurosporene (1 mM) was approximately 1.7-fold higher than that of butylated hydroxytoluene (BHT), a well-known antioxidant food additive. In addition, the ABTS radical scavenging ability was shown to be 2.3- to 7.5-fold higher than that of BHT at the range of concentration from 0.25 mM to 1 mM. The FRAP analysis confirmed that 4,4'-diaponeurosporene (0.25 mM) was able to reduce Fe3+ by 8.0-fold higher than that of BHT. Meanwhile, 4,4'-diaponeurosporene has been confirmed to be highly resistant to various external stresses (acid/bile, high temperature, and lysozyme conditions). In conclusion, L. plantarum subsp. plantarum KCCP11226, which produces 4,4'-diaponeurosporene as a functional antioxidant, may be a potentially useful strain for the development of functional probiotic industries.