• Microbiology and Biotechnology Letters
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• v.21 no.2
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• pp.176-180
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• 1993

Survival and heat resistance of Listeria monocytogenes Scott A in various nutritional environments and cell type on stainless steel were determined. Viable cell of L. monocytogenes Scott A was most rapidly decreased in phosphate buffer among various media such as NSM (30 g TSB/1 l D.W.), LNM (2 g TSB/1 l D.W.) and phosphate buffer (pH=7) during incubation at 21 and 35C but survived for 15 days at 21C. Vegetative and starved L. monocytogenes Scott A were survived after heat treatment for 5 min at 65C while not detected at 72C.

• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.2
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• pp.293-297
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• 1994

The effect of organic acids on growth and heat resistance of Listeria monocytogenes Scott A were investigated. The growth of L. monocytogenes was inhibited in Tryptic Soy Broth(TSB) with 0.1 or 0.2% of acetic , tartic , propionic , citric and lactic acid at 35$^{\circ}C$, respectively. The growth of l. Monocytogenes did not occur in TSB with 0.2% of acetic acid or propionic acid during 48h of incubation. The heat resistance of L.monocytogenes was affected by kind of organic acid, ph and heating substrate. L.monocytogenes showed more heat resistant in TSB with various organic acids than in 0.1M sodium phosphate with the same organic acids. Heat resistance decreased as pH of heating substrate decreased . Surface-adherent microcolony was more heat resistant than planktonic cell of L. monocytogenes. Propionic and lactic acids more affected on heat resistance of L.monocytogenes than acetic , tartaric and citric acids.

• Journal of Food Hygiene and Safety
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• v.10 no.4
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• pp.205-211
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• 1995

To investigate the antimicrobial effect of polyphosphates as a food additive, the growth and structural change of Listeria monocytogentes Scott A were examined in relation to polyphosphates concentration and incubation temperature. Up to 10,000 ppm of polyphosphates, the growth rate of strain was gradually inhibited with increasing polyphosphates concentration and decreasting the incubation temperature. Minimal inhibitory concentration of polyphosphates to the growth of strain was about 12,000 ppm. It was observed , using both scanning electron microscopy(SEM) and transmission electron microscopy(TEM), that 0.9% polyphosphates treatment was resulted in the destruction of cell wall and outflow of cell ingredients. The antimicrobial effects of polyphosphates were more effective than those of dehydroacetate and potassium sorbate at 13$^{\circ}C$ and 4$^{\circ}C$. The growth rate the strain in beef was significantly inhibited by the treatment of 0.9% polyphosphates and storaged at cooling temperature.

• Journal of Microbiology and Biotechnology
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• v.2 no.2
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• pp.73-77
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• 1992

The effect of a nisin-producing Lactococcus lactis spp. lactis (L. lactis) on the growth and attachment of Listeria monocytogenes Scott A and Brie 1 on stainless steel and their growth in Brain Heart Infusion broth was determined. Viable cells of Listeria decreased rapidly after 9~12 hr of incubation at $21^{\circ}C$ and after 6~9 hr of incubation at $32^{\circ}C$ in the presence of L. lactis. The number of L. monocytogenes Scott A attached to stainless steel in pure culture was $2.5{\times}10^3/\textrm{cm}^2{\;}at{\;}21^{\circ}C{\;}and{\;}2.3{\times}10^3/\textrm{cm}^2{\;}at{\;}32^{\circ}C$ after 48 hr of incubation, but was only $10/\textrm{cm}^2{\;}at{\;}21^{\circ}C{\;}and{\;}1.1{\times}10/\textrm{cm}^2{\;}at{\;}32^{\circ}C$ in the presence of L. lactis. Results from L. monocytogenes strain Brie 1 were similar to those from strain Scott A. The population of L. monocytogenes Scott A which attached to stainless steel with previously adherent L. lactis was $1.8{\times}10^2/\textrm{cm}^2{\;}at{\;}21^{\circ}C{\;}and{\;}8.2{\times}10^2/\textrm{cm}^2{\;}at{\;}32^{\circ}C$, whereas the population attached to sterile stainless steel was $1.2{\times}10^3/\textrm{cm}^2{\;}at{\;}21^{\circ}C{\;}and{\;}2.1{\times}10^2/\textrm{cm}^2{\;}at{\;}32^{\circ}C$. For L. monocytogenes Brie 1, the attached population of the control was $1.6{\times}10^4/\textrm{cm}^2{\;}at{\;}21^{\circ}C{\;}and{\;}3.2{\times}10^2/\textrm{cm}^2{\;}at{\;}32^{\circ}C$, and on stainless steel with adherent L. lactis, it was $1.1{\times}10/\textrm{cm}^2{\;}at{\;}21^{\circ}C{\;}and{\;}6.9{\times}10/\textrm{cm}^2{\;}at{\;}32^{\circ}C$. Surface adherent L. lactis was less inhibitory to attachment of L. monocytogenes on stainless steel than a liquid culture inoculum. Listeria attached to stainless steel survived dry storage for 20 days both in the presence and absence of adherent lactococci.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.2
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• pp.333-337
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• 2002

To develope food preservative, antimicrobial activities of Pinus densiflora (PD) ethanol extract against Listeria monocytogenes Scott A. Listeria monocytogenes Brie I and Listeria monocytogenes ATCC 19111 were investigated. The ethanol extracts of PD showed strong antimicrobial activities on Listeria monocytogenes. The crude ethanol extracts of PD were further fractionated by ether, ethyl acetate and butanol. The ether fraction from ethanol extract showed the strongest antimicrobial effects on Listeria monocytogenes in tryptic soy broth containing 40 mg/mL ether fractions compared with other fractions. The effect of ethanol extract of pinus densiflora against Listeria monocytogenes culture for growth stage in tryptic soy broth at 35$^{\circ}C$ showed the strongest antimicrobial activites for lag phase. The morphological changes of the cells were observed with transmission electron microscope (TEM) and scanning electron microscope (SEM) and the cells were injured by treatment of 40 mg/mL ethanol extract of Pinus densiflora.

• Microbiology and Biotechnology Letters
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• v.25 no.5
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• pp.442-447
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• 1997

To development food preservative, antimicrobial activities of Schizandra chinensis (SC) against Listeria monocytogenes Scott A, L. monocytogenes Brie I and L. monocytogenes ATCC 19111 were investigated. The growth of L. monocytogenes Scott A, L. monocytogenes Brie I and L. monocytogenes ATCC 19111 was inhibited apparently in Tryptic Soy Broth (TSB) containing 1% SC at 35$\circ$C and it was found that these had antibacterial effects against a broad spectrum of pathogenic bacteria such as S. aureus ATCC 29737, B. subtilis KCTC 1021, E. coli ATCC 11775. The growth of L. monocytogenes was also inhibited about 3 to 5 log$_{10}$ cycle by 0.1% of three fractions of the alcohol extract such as ether, ethyl acetate and butanol. Acidic, weakly acid and neutral fraction of ether fraction showed inhibitory properties against L. monocytogenes.

• Microbiology and Biotechnology Letters
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• v.21 no.3
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• pp.200-206
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• 1993

The effect of pH (7, 5 and 4) and nisin (100 and 200IU/ml) on heat resistance of Listeria monocytogenes Scott A were determined using citrate-phosphate buffer system. Heat resistance of vegetative and starved cell was decreased as pH value was lower at 65 and 72C. Starved L. monocytogenes was more resistant than vegetative cell at both temperature. Heat resistance of vegetative and starved cell was decreased significantly with treatment of nisin. The effect of nisin was increased significantly at low pH(5, 4). Adherent microcolony was more resistant to heat and nisin than planktonic cell. Contamination of L. monocytogenes may be prevent by using nisin in food and food processing environments.

• Applied Biological Chemistry
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• v.42 no.1
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• pp.63-67
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• 1999

Growth rate and osmolyte accumulation of L. monocytogenes were measured at the varying concentrations of NaCl. L. monocytogenes accumulated glycine betaine and glutamate intracellularly when grown under osmotic stress by NaCl, and the amounts of them increased as the concentration of NaCl was increased. They were 685 and 345 nmol/mg protein, respectively, when grown in the BHI supplemented with 4% NaCl. In order to inhibit L. monocytogenes effectively, both NaCl and Morus alba L. leaf extract were supplemented in TSB, and antibacterial effect of those supplements on L. monocytogenes was tested. Growth of L. monocytogenes grown in TSB supplemented with 2% NaCl and 100 ppm M. alba leaf extract decreased by 10 times in CFU/ml unit comparing to the growth of control. When grown in TSB, supplemented with 2% NaCl plus 500 ppm M. alba leaf extract and 2% NaCl plus 1,000 ppm M. alba leaf extract, growth of L. monocytogenes decreased by $10^5\;and\;10^8$ times in CFU/ml unit, respectively.

• Korean Journal of Veterinary Research
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• v.32 no.1
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• pp.91-98
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• 1992

Listeria monocytogenes antigens were detected with the avidinbiotinperoxidase complex(ABPC) method in formalin-fixed, paraffin-embedded tissues from experimentally infected rats, mice and guinea pigs. The anti-Lirteria monocytogenes serum used as first antibody was prepared by immunizing rabbits with Listeria monocytogenes serotype 1/2a. Rats, mice and guinea pigs that had been given inoculation of L monocytogenes(serotype 4b, Scott A strain) via intraperitoneally allotted to 3 groups. Rats were pretreated with the dexamethasone(DM-rats) for 7 consecutive days, mice and guinea pigs were inoculated intraperitoneally with L. monocytogenes At necropsy white necrotic foci of the liver, spleen and kidney were seen in mice and DM-rats, whereas not in guinea pigs. Organisms stained by the ABPC method were identified as pleomorphic dark brown staining structures in the livers, spleens and kidneys of mice and DM-rats. They were present in high numbers in center and peripherial regions of necrobiotic and necrotic foci of the liver and spleen as well as in glomerulus of the renal cortex. and liable tool for confirmative diagnosis of these bacterial diseases.

• Food Science and Preservation
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• v.16 no.6
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• pp.985-990
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• 2009

Fatty acid composition, protein content, and shape change of Listeria monocytogenes treated with ethanol extracts from Schizandra chinensis were examined. Transmission electron micrography of cells treated with ethanolic S. chinensis extracts showed development of morphological changes. Cell surfaces were irregular, swollen, or even disrupted after treatment with ethanol extracts, compared with the smooth surfaces of normal cells. Interestingly, cell protein content was decreased by ethanol extract treatment. Cell fatty acid composition was also changed after treatment with ethanol extracts. The levels of 13-methylpentadecanoic acid (i-15:0), 12-methylpentadecanoic acid (a-15:0) and 15-methylpentadecanoic acid (i-17:0) of L. monocytogenes Scott A and L. monocytogenes ATCC 19111 were decreased, but the concentrations of Cis-9,12 octadecanoic acid ($18:2^{9,12}$) and cis-9-octadecanoic acid ($18:1^9$) were increased. 13-methylpentadecanoic acid (i-15:0) and 12-methylpentadecanoic acid (a-15:0) levels in L. monocytogenes Brie I were decreased but the concentrations of Cis-9,12 octadecanoic acid ($18:2^{9,12}$) and cis-9-octadecanoic acid ($18:1^9$) were increased after treatment with ethanolic extracts. Notably, the levels of 12-methylpentadecanoic acid (a-15:0) significantly were decreased but those of cis-9,12 octadecanoic acid ($18:2^{9,12}$) significantly were increased in all tested microorganisms.