• Title/Summary/Keyword: nisin

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Construction and Analysis of Food-Grade Lactobacillus kefiranofaciens β-Galactosidase Overexpression System

  • He, Xi;Luan, MingJian;Han, Ning;Wang, Ting;Zhao, Xiangzhong;Yao, Yanyan
    • Journal of Microbiology and Biotechnology
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    • v.31 no.4
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    • pp.550-558
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    • 2021
  • Lactobacillus kefiranofaciens contains two types of β-galactosidase, LacLM and LacZ, belonging to different glycoside hydrolase families. The difference in function between them has been unclear so far for practical application. In this study, LacLM and LacZ from L. kefiranofaciens ATCC51647 were cloned into constitutive lactobacillal expression vector pMG36e, respectively. Furtherly, pMG36n-lacs was constructed from pMG36e-lacs by replacing erythromycin with nisin as selective marker for food-grade expressing systems in Lactobacillus plantarum WCFS1, designated recombinant LacLM and LacZ respectively. The results from hydrolysis of o-nitrophenyl-β-galactopyranoside (ONPG) showed that the β-galactosidases activity of the recombinant LacLM and LacZ was 1460% and 670% higher than that of the original L. kefiranofaciens. Moreover, the lactose hydrolytic activity of recombinant LacLM was higher than that of LacZ in milk. Nevertheless, compare to LacZ, in 25% lactose solution the galacto-oligosaccharides (GOS) production of recombinant LacLM was lower. Therefore, two β-galactopyranosides could play different roles in carbohydrate metabolism of L. kefiranofaciens. In addition, the maximal growth rate of two recombinant strains were evaluated with different temperature level and nisin concentration in fermentation assay for practical purpose. The results displayed that 37℃ and 20-40 U/ml nisin were the optimal fermentation conditions for the growth of recombinant β-galactosidase strains. Altogether the food-grade Expression system of recombinant β-galactosidase was feasible for applications in the food and dairy industry.

Nisin Resistance of Listeria Monocytogenes

  • Kim, Yeong-Hui;Kim, Gwang-Hyeon;Kim, Byeong-U;Jeong, Gyeong-Tae;Gwon, Hyeon-Ju;Sin, Hyeon-Cheol;Lee, Dong-Jun;Kim, Deuk-Mi
    • Proceedings of the Korean Society of Life Science Conference
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    • pp.82-82
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    • 2003
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Status, Antimicrobial Mechanism, and Regulation of Natural Preservatives in Livestock Food Systems

  • Lee, Na-Kyoung;Paik, Hyun-Dong
    • Food Science of Animal Resources
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    • v.36 no.4
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    • pp.547-557
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    • 2016
  • This review discusses the status, antimicrobial mechanisms, application, and regulation of natural preservatives in livestock food systems. Conventional preservatives are synthetic chemical substances including nitrates/nitrites, sulfites, sodium benzoate, propyl gallate, and potassium sorbate. The use of artificial preservatives is being reconsidered because of concerns relating to headache, allergies, and cancer. As the demand for biopreservation in food systems has increased, new natural antimicrobial compounds of various origins are being developed, including plant-derived products (polyphenolics, essential oils, plant antimicrobial peptides (pAMPs)), animal-derived products (lysozymes, lactoperoxidase, lactoferrin, ovotransferrin, antimicrobial peptide (AMP), chitosan and others), and microbial metabolites (nisin, natamycin, pullulan, ε-polylysine, organic acid, and others). These natural preservatives act by inhibiting microbial cell walls/membranes, DNA/RNA replication and transcription, protein synthesis, and metabolism. Natural preservatives have been recognized for their safety; however, these substances can influence color, smell, and toxicity in large amounts while being effective as a food preservative. Therefore, to evaluate the safety and toxicity of natural preservatives, various trials including combinations of other substances or different food preservation systems, and capsulation have been performed. Natamycin and nisin are currently the only natural preservatives being regulated, and other natural preservatives will have to be legally regulated before their widespread use.

Quorum-Sensing Mechanisms in Bacterial Communities and Their Potential Applications (세균의 의사 소통(Quorum-Sensing) 기구와 그 잠재적 응용성)

  • Yoon, Sung-Sik
    • Food Science of Animal Resources
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    • v.26 no.3
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    • pp.402-409
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    • 2006
  • Although microorganisms are, in fact, the most diverse and abundant type of organism on Earth, the ecological functions of microbial populations remains poorly understood. A variety of bacteria including marine Vibrios encounter numerous ecological challenges, such as UV light, predation, competition, and seasonal variations in seawater including pH, salinity, nutrient levels, temperature and so forth. In order to survive and proliferate under variable conditions, they have to develop elaborate means of communication to meet the challenges to which they are exposed. In bacteria, a range of biological functions have recently been found to be regulated by a population density-dependent cell-cell signaling mechanism known as quorum-sensing (QS). In other words, bacterial cells sense population density by monitoring the presence of self-produced extracellular autoinducers (AI). N-acylhomoserine lactone (AHL)-dependent quorum-sensing was first discovered in two luminescent marine bacteria, Vibrio fischeri and Vibrio harveyi. The LuxI/R system of V. fischeriis the paradigm of Gram-negative quorum-sensing systems. At high population density, the accumulated signalstrigger the expression of target genes and thereby initiate a new set of biological activities. Several QS systems have been identified so far. Among them, an AHL-dependent QS system has been found to control biofilm formation in several bacterial species, including Pseudomonas aeruginosa, Aeromonas hydrophila, Burkholderia cepacia, and Serratia liquefaciens. Bacterial biofilm is a structured community of bacterial cells enclosed in a self-produced polymeric matrix that adheres to an inert or living surface. Extracellular signal molecules have been implicated in biofilm formation. Agrobacterium tumefaciens strain NT1(traR, tra::lacZ749) and Chromobacterium violaceum strain CV026 are used as biosensors to detect AHL signals. Quorum sensing in lactic acid bacteria involves peptides that are directly sensed by membrane-located histidine kinases, after which the signal is transmitted to an intracellular regulator. In the nisin autoregulation process in Lactococcus lactis, the NisK protein acts as the sensor for nisin, and NisR protein as the response regulator activatingthe transcription of target genes. For control over growth and survival in bacterial communities, various strategies need to be developed by which receptors of the signal molecules are interfered with or the synthesis and release of the molecules is controlled. However, much is still unknown about the metabolic processes involved in such signal transduction and whether or not various foods and food ingredients may affect communication between spoilage or pathogenic bacteria. In five to ten years, we will be able to discover new signal molecules, some of which may have applications in food preservation to inhibit the growth of pathogens on foods.

유전공학기술을 이용한 유산균개발

  • 정대균
    • Journal of Life Science
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    • v.4 no.3
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    • pp.113-118
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    • 1994
  • 유산균의 증식으로 인해 설사 등의 원인인 유해균들의 증식이 억제되는데 이것은 유산균들이 만드는 각종 유기산들, 과산화수소에 의한 직접적인 저해나 산생성에 부수되는 pH 저하가 원인이고 그 외 유산균들이 만드는 nisin이나 각종 bacteriocin 등도 관여한다. 유산균을 이용한 발효 유제품이 소비증가, 유산균의 약리작용 효과를 이용한 건강보조식품의 개발 등을 통하여 유산균의 중요성은 더욱 대두되고 있다. 이 같은 추세로 전세계적으로 유산균에 대한 연구가 활발히 진행되고 있으며, 최근에는 생명공학 분야에서 광범위하게 이용되고 있는 유전공학 기술에 의한 유산균의 개발연구가 관심을 모으고 있다. 본 논문에서는 현재까지 진행되고 있는 유산균 연구 중 유전공학기술을 이용한 연구결과와 이 분야의 향후 전망 등에 대하여 고찰하였다.

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내산성, 내답즙성이 높은 미생물을 이용한 생균제 개발

  • Kim, So-Yeong;Jeong, Hae-Yeong;Jo, Cheol-Hui;Park, Geun-Hyeong;Son, Seok-Min;Lee, Gi-Yeong;Lee, Geon-Sun;Kim, Hong;Chae, Hui-Jeong
    • 한국생물공학회:학술대회논문집
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    • pp.180-184
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    • 2003
  • Several bacteria and yeasts were isolated from soil and characterized for the development of functional probiotics which can be used as a livestock feed additive. From the soil, the microbial strains which have acid/bovine resistance, antibiotics resistance and high stability, were isolated. Most strains selected were very tolerable against acids and very stable in a broad range of pH. Some strains could survive 100% at pH 2.5. The growth of the strains was not affected in the presence of bile acid, pathogenic E. coli and several antibiotics such as tetracycline, nisin, kanamycin, streptomycin, ampicillin. Acidogenic capability test showed that all the strains can produce acids. The hydrolytic activities were analysed for amylase, protease, lipase and cellulase to decompose various organic compounds. All the strains were found to be gram negative, round type, non-kinetic and the color is yellow or white.

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Competitive Growth and Attachment of Listeria monocytogenes and Lactococcus lactis ssp. lactis ATCC 11454

  • Lee, Shin-Ho;Frank, Joseph-F.
    • 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.

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Inhibition of Microbial Growth in Cabbage-Kimchi by Heat Treatment and Nisin·Yucca Extract (열처리 및 나이신·유카추출물 첨가에 의한 김치의 미생물 증식 저해)

  • Kim, Ji-Sun;Kim, Yu-Jin;Park, Jung-Mi;Kim, Tae-Jip;Kim, Beom-Soo;Kim, Yeon-Mi;Kim, Hye-Rim;Han, Nam-Soo
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.39 no.11
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    • pp.1678-1683
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    • 2010
  • For extension of storage period of cabbage-kimchi, effects of heat treatment as well as nisin or yucca extract were examined on the growth of microbes. Firstly, when kimchi was heated at various temperatures in polyethylene plastic bottle or membrane pouch, the optimum inhibitory condition giving no sensory change was at $80^{\circ}C$ for 30 min in a plastic membrane pouch and this treatment made a reduction of $0.3\;log_{10}CFU/g$ in total microbes. The result showed that use of plastic bottle was inefficient due to low heat transfer rate. Interestingly, pasteurization of seasoning pastes at $80^{\circ}C$ for 30 min separately from cabbage resulted in better inhibitory effect reducing $0.5\;log_{10}CFU/g$ of total bacteria and $1.0\;log_{10}CFU/g$ of lactic acid bacteria, and this operation was regarded as a promising inhibitory method. Secondly, when nisin and yucca extract were separately added in kimchi, microbial growth was inhibited during storage period and their inhibition effects were enhanced at lower temperature.