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Antibacterial activity of a chitooligosaccharide mixture prepared by cellulase digestion of shrimp chitosan and its application to milk preservation

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JOURNAL OF FOOD PROTECTION 2000年第6期63卷 747-752页

作者： Tsai, GJ Wu, ZY Su, WH Natl Taiwan Ocean Univ Dept Food Sci Keelung Taiwan

The antibacterial activity of a chitooligosaccharide mixture prepared by digestion of shrimp chitosan with cellulase at 50 degrees C for 14 h was evaluated. Sugars with 1 to 8 degrees of polymer (DP) were found in this chitooligosaccharide mixture, and the weight percentage of sugars with DP greater than or equal to 6 was 44.3%. Minimal lethal concentrations of this mixture against Aeromonas hydrophila, Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa, Salmonella Typhimurium, Shigella dysenteriae, Staphylococcus aureus, Vibrio cholerae, and Vibrio parahaemolyticus in nutrient broth were 5 to 29 ppm, which were much lower than those of the chitosan reactant (50 to 1,000 ppm). The antibacterial activity of this mixture in the sterilized milk against E. coli O157, L. monocytogenes, Salmonella Typhimurium, and S. aureus was much stronger at 4 degrees C than at 37 degrees C. When raw milk was supplemented with either 0.24% or 0.48% (wt/vol) of this oligosaccharide mixture and stored at 4 degrees C for 12 days, its mesophilic and psychrotrophic counts were reduced by at least 3 log cycles, and there was very little change in pH. In addition, this mixture retarded the growth of Salmonella species and caused quicker reduction of Staphylococcus species in raw milk. Accordingly, the shelf life of raw milk at 4 degrees C was extended by at least 4 days.

关键词：嗜水气单胞菌/药物作用纤维素酶/代谢壳多糖/类似物和衍生物壳多糖/代谢壳聚糖色谱法高压液相集落计数微生物十足目(甲壳纲) 消化大肠杆菌/药物作用食品保存/方法单核细胞增生利斯特菌/药物作用微生物敏感性试验乳鼠伤寒沙门菌/药物作用痢疾志贺菌/药物作用金黄色葡萄球菌/药物作用霍乱弧菌/药物作用副溶血性弧菌/药物作用动物

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Antimicrobial effect of herb extracts against Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella typhimurium associated with beef

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JOURNAL OF FOOD PROTECTION 2000年第5期63卷 601-607页

作者： Cutter, CN USDA ARS Roman L Hruska US Meat Anim Res Ctr Clay Ctr NE 68933 USA

The effects of plant extracts against pathogenic bacteria in vitro are well known, yet few studies have addressed the effects of these compounds against pathogens associated with muscle foods. A series of experiments was conducted to determine the effectiveness of a commercially available, generally recognized as safe, herb extract dispersed in sodium citrate (Protecta One) or sodium chloride (Protecta Two) against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes associated with beef. In the first experiment, E. coli O157:H7, Salmonella Typhimurium, and L. monocytogenes inoculated onto beef and subjected to surface spray treatments with 2.5% solutions of Protecta One or Protecta Two were not affected by immediate application (day 0) of the herbal extracts. However, after 7 days of storage at 4 degrees C, E. coli O157:H7 was reduced by >1.3 log(10) CFU/cm(2) by Protecta Two;L. monocytogenes was reduced by 1.8 and 1.9 log(10) CFU/cm(2) by Protecta One and Protecta Two, respectively;Salmonella Typhimurium was not reduced >0.3 log(10) CFU/cm(2) by either extract by day 7. In the second experiment, 2.5% Protecta Two (wt/vol or wt/wt) added to inoculated lean and adipose beef trim, processed, and packaged as ground beef chubs (80% lean, 20% adipose), did not reduce pathogen populations >0.5 log(10) CFU/g up to 14 days at 4 degrees C. In the third experiment, surface spray treatments of beef with 2.5% lactic acid or 2.5% solutions of Protecta One or Protecta Two, vacuum packaged, and stored up to 35 days at 4 degrees C did reduce E. coli O157:H7, L. monocytogenes, and Salmonella Typhimurium slightly. These studies suggest that the use of herb extracts may afford some reductions of pathogens on beef surfaces;however, the antimicrobial activity may be diminished in ground beef by adipose components.

关键词：大肠杆菌O157/药物作用食品微生物学食品保存/方法单核细胞增生利斯特菌/药物作用肉制品/微生物学植物提取物/药理学鼠伤寒沙门菌/药物作用表面特性动物牛

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Efficacy of nisin-coated polymer films to inactivate Salmonella Typhimurium on fresh broiler skin

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JOURNAL OF FOOD PROTECTION 2000年第9期63卷 1189-1196页

作者： Natrajan, N Sheldon, BW N Carolina State Univ Dept Food Sci Raleigh NC 27695 USA

Nisin is an antimicrobial peptide produced by the food-grade microorganism Lactococcus lactis subsp. lactis. This peptide inhibits many gram-positive bacteria, and when combined with chelating agents it inhibits gram-negative bacteria such as Salmonella sp. The efficacy of packaging films treated with nisin-containing formulations to reduce Salmonella contamination of fresh broiler drumstick skin and increase the refrigerated shelf life was investigated. Three films (5.1 cm(2)) of varying hydrophobicities (polyvinyl chloride [PVC], Linear low density polyethylene, nylon) were coated with one of three liquid formulations (pH 3.5 to 3.8) composed of 100 mu g/ml nisin and varying concentrations of citric acid, EDTA, and Tween 80. The treated films were applied either wet or dry to 5.1-cm(2) broiler drumstick skin samples inoculated with a nalidixic acid-resistant (NAr) strain of Salmonella Typhimurium. After incubation at 4 degrees C for 24 h the populations of surviving Salmonella Typhimurium(NAr) organisms were recovered from the skin and film samples using a rinse procedure and enumerated on brain heart infusion agar containing 800 ppm NA. Log reductions (untreated versus treated skin) in Salmonella Typhimurium(NAr) populations ranged from 0.4 to 2.1. Treatment formulation compositions and wet versus dry treatment application also influenced the extent of kill. The shelf life of refrigerated broiler drumsticks was extended by 0.6 to 2.2 days following a 3-min immersion in a nisin-containing treatment solution and subsequent storage in a foam tray pack containing a nisin-treated PVC overwrap and a nisin-treated absorbent tray pad. These findings demonstrated that Salmonella Typhimurium and spoilage microorganism populations on the surface of fresh broiler skin and drumsticks can be significantly reduced using immersion treatments, absorbent tray pads, and packaging films treated with nisin-containing formulations.

关键词：抗菌药/药理学鸡/微生物学集落计数微生物食品污染/预防和控制食品微生物学食品包装乳链球菌素/药理学聚合物/药理学家禽产品/微生物学家禽产品/标准鼠伤寒沙门菌/药物作用鼠伤寒沙门菌/生长和发育皮肤/微生物学时间因素水动物

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Interventions for the reduction of Salmonella Typhimurium DT 104 and non-O157:H7 enterohemorrhagic Escherichia coli on beef surfaces

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JOURNAL OF FOOD PROTECTION 2000年第10期63卷 1326-1332页

作者： Cutter, CN Rivera-Betancourt, M ARS USDA Roman L Hruska US Meat Anim Res Ctr Clay Ctr NE 68933 USA

A study was conducted to determine if slaughter interventions currently used by the meat industry are effective against Salmonella Typhimurium definitive type 104 (DT 104) and two non-O157:H7 enterohemorrhagic Escherichia coli (EHEC). Three separate experiments were conducted by inoculating prerigor beef surfaces with a bovine fecal slurry containing Salmonella Typhimurium and Salmonella Typhimurium DT 104 (experiment I), E. coli O157:H7 and E. coli O111:H8 (experiment 2), or E. coli O157:H7 and E. coli O26:H11 (experiment 3) and spray washing with water, hot water (72 degrees C), 2% acetic acid, 2% lactic acid, or 10% trisodium phosphate (15 s, 125 +/- 5 psi, 35 +/- 2 degrees C). Remaining bacterial populations were determined immediately after treatments (day 0), after 2 days of aerobic storage at 4 degrees C, and after 7, 21, and 35 days of vacuum-packaged storage at 4 degrees C. In addition to enumeration, confirmation of pathogen serotypes was performed for all treatments on all days. Of the interventions investigated, spray treatments with trisodium phosphate were the most effective, resulting in pathogen reductions of >3 log(10) CFU/cm(2), followed by 2% lactic acid and 2% acetic acid (>2 log(10) CFU/cm(2)). Results also indicated that interventions used to reduce Salmonella Typhimurium on beef surfaces were equally effective against Salmonella Typhimurium DT 104 immediately after treatment and again after long-term, refrigerated, vacuum-packaged storage. Similarly, E. coli O111:H8 and E. coli O26:H11 associated with beef surfaces were reduced by the interventions to approximately the same extent as E. coli O157:H7 immediately after treatment and again after long-term, refrigerated, vacuum-packaged storage. It was also demonstrated that phenotypic characterization may not be sufficient to identify EHECs and that the organisms should be further confirmed with antibody- or genetic-based techniques. Based on these findings, interventions used by the meat industr

关键词：醋酸/药理学集落计数微生物大肠杆菌/分类大肠杆菌/药物作用大肠杆菌/生长和发育食品处理和加工/方法食品微生物学乳酸/药理学肉/微生物学磷酸盐类/药理学鼠伤寒沙门菌/分类鼠伤寒沙门菌/药物作用鼠伤寒沙门菌/生长和发育血清分型动物牛

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Mutagenicity of nitroaromatic compounds

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CHEMICAL RESEARCH IN TOXICOLOGY 2000年第8期13卷 673-692页

作者： Purohit, V Basu, AK Univ Connecticut Dept Chem Storrs CT 06269 USA

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Lipid a modifications characteristic of Salmonella typhimurium are induced by NH₄VO₃ in Escherichia coli K12 -: Detection of 4-amino-4-deoxy-L-arabinose, phosphoethanolamine and palmitate

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JOURNAL OF BIOLOGICAL CHEMISTRY 1999年第26期274卷 18503-18514页

作者： Zhou, ZM Lin, SH Cotter, RJ Raetz, CRH Duke Univ Med Ctr Dept Biochem Durham NC 27710 USA Johns Hopkins Univ Sch Med Dept Pharmacol & Mol Sci Baltimore MD 21205 USA

Two-thirds of the lipid A in wild-type Escherichia coli K12 is a hexa-acylated disaccharide of glucosamine in which monophosphate groups are attached at positions 1 and 4', The remaining lipid A contains a monophosphate substituent at position 4' and a pyrophosphate moiety at position 1, The biosynthesis of the l-pyrophosphate unit is unknown, Its presence is associated with lipid A translocation to the outer membrane (Zhou, Z,,White, K, A, Polissi, A., Georgopoulos, C,, and Raetz, C. R, H, (1998) J, Biol. Chem. 273, 12466-12475), To determine if a phosphatase regulates the amount of the lipid A 1-pyrophosphate, we grew cells in broth containing nonspecific phosphatase inhibitors. Na2WO4 and sodium fluoride increased the relative amount of the 1-pyrophosphate slightly. Remarkably, NH4VO3-treated cells generated almost no 1-pyrophosphate, but made six major new lipid A derivatives (EV1 to EV6). Matrix-assisted laser desorption ionization/time of flight mass spectrometry of purified EV1 to EV6 indicated that these compounds were lipid A species substituted singly or in combination with palmitoyl, phosphoethanolamine, and/or aminodeoxypentose residues. The aminodeoxypentose residue was released by incubation in chloroform/methanol (4:1, v/v) at 25 degrees C, and was characterized by H-1 NMR spectroscopy. The chemical shifts and vicinal coupling constants of the two anomers of the aminodeoxypentose released from EV3 closely resembled those of synthetic 4-amino-4-deoxy-L-arabinose. NH4VO3-induced lipid A modification did not require the PhoP/PhoQ two-component regulatory system, and also occurred in E. coli msbB or htrB mutants, The lipid A variants that accumulate in NH4VO3 treated E. coli K12 are the same as many of those normally found in untreated Salmonella typhimurium and Salmonella minnesota, demonstrating that E, coli K12 has latent enzyme systems for synthesizing these important derivatives.

关键词：氨基糖类/分析碳水化合物序列大肠杆菌/药物作用大肠杆菌/代谢乙醇胺类/分析脂质A/化学脂质A/代谢磁共振波谱学分子序列数据棕榈酸盐类/分析磷酸单酯水解酶类/代谢鼠伤寒沙门菌/药物作用鼠伤寒沙门菌/代谢光谱法质量基质辅助激光解吸电离钒酸盐类/药理学

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Effect of diacetyl on controlling Escherichia coli O157:H7 and Salmonella Typhimurium in the presence of starter culture in a laboratory medium and during meat fermentation

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JOURNAL OF FOOD PROTECTION 1999年第9期62卷 975-979页

作者： Kang, DH Fung, DYC Kansas State Univ Dept Anim Sci & Ind Food Microbiol Lab Manhattan KS 66506 USA

Diacetyl is a flavor compound that possesses antimicrobial activity and is found in several dairy products. The effect of diacetyl on controlling the growth of two foodborne pathogens, Escherichia coli O157:H7 and Salmonella Typhimurium, when grown with Pediococcus acidilactici as a meat starter culture was evaluated in a laboratory medium and during salami fermentation. Diacetyl (50 ppm) added to each mixed culture system strongly inhibited the growth of E. coli O157:H7 and Salmonella Typhimurium in the laboratory medium (brain heart infusion, 2.3% of NaCl, 0.75% of dextrose) (P < 0.05). During meat fermentation, the growth of E. coli O157:H7 and Salmonella Typhimurium was inhibited significantly by addition of diacetyl (300 ppm) (P < 0.05) after 24 h fermentation. However, the acid production and growth of P. acidilactici were not affected by the addition of diacetyl (P > 0.05). After 24 h meat fermentation, about a 1.0-log CFU/g difference occurred in numbers of each foodborne pathogen mixed with P. acidilactici (P ( 0.05) with and without 300 ppm diacetyl. Diacetyl and the acid produced by the meat starter culture reduced the growth of the two foodborne pathogens during salami fermentation. These results suggest that diacetyl can be used as a food ingredient during meat fermentation to control E. coli O157:H7 and Salmonella Typhimurium without harmful effects on the growth and acid production of P. acidilactici.

关键词：细胞分裂/药物作用集落形成单位测定培养基二乙酰/药理学大肠杆菌/药物作用大肠杆菌/致病力发酵食品微生物学氢离子浓度肉制品/微生物学片球菌属/药物作用鼠伤寒沙门菌/药物作用鼠伤寒沙门菌/致病力香料调味品动物牛

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Occupational hazard evaluation of p-bromobenzyl bromide from tests for genotoxicity

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DRUG AND CHEMICAL TOXICOLOGY 1999年第4期22卷 583-593页

作者： Sargent, EV Sina, JF Barnum, JE Storer, RD Johnson, TE Galloway, SM Prato, MG Kirsten, NN Naumann, BD Merck & Co Inc Toxicol & Environm Hlth Whitehouse Stn NJ 08889 USA Merck Res Labs Genet & Cellular Toxicol W Point PA 19486 USA

As part of an occupational hazard evaluation, p-bromobenzyl bromide (p-BBB) was evaluated for genotoxic activity in the Ames microbial mutagenicity assay, the alkaline elution assay for DNA strand breaks in rat hepatocytes and the in vitro chromosome aberration assay in Chinese hamster ovary cells. The compound produced equivocal results in the microbial mutagenicity assay but was negative in the alkaline elution assay for DNA strand breaks in rat hepatocytes. The compound produced weakly positive results in the in vitro chromosome aberration assay. There was substantial cytotoxicity in all three assays. It is concluded that p-BBB is weakly genotoxic.

关键词：苄基化合物/毒性 CHO细胞/药物作用染色体畸变染色体/药物作用仓鼠亚科仓鼠属 DNA/化学 DNA/药物作用 DNA损伤/药物作用肝/药物作用诱变力试验诱变剂/毒性职业暴露大鼠 Sprague-Dawley 鼠伤寒沙门菌/药物作用鼠伤寒沙门菌/遗传学动物男(雄)性大鼠

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Nalidixic acid resistance in salmonellae isolated from turkeys and other livestock in Great Britain

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VETERINARY RECORD 1999年第12期144卷 320-322页

作者： Davies, RH Teale, CJ Wray, C McLaren, IH Jones, YE Chappell, S Kidd, S MAFF Cent Vet Lab Vet Labs Weybridge KT15 3NB Surrey England

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Genotoxicity of human milk extracts and detection of DNA damage in exfoliated cells recovered from breast milk (vol 257, pg 319, 1999)

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BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS 1999年第2期259卷 494-A326页

作者： Martin, FL Cole, KJ Weaver, G Grover, PL Phillips, DH Inst Canc Res Haddow Labs Sutton SM2 5NG Surrey England Queen Charlottes & Chelsea Hosp Dept Paediat London W6 0XG England

Genotoxic agents of environmental or dietary origin may play a role in breast cancer initiation. The ability of extracts of human milk to cause mutations in S. typhimurium TA1538 and YG1019 and to induce micronuclei and DNA strand breaks in MCL-5 cells was investigated. Twenty samples from different donors were analysed and of these, 6 were adjudged to produce a positive mutagenic response in one or both bacterial strains. The same samples also induced significant micronucleus formation in MCL-5 cells. In the comet assay, 13/20 samples caused DNA strand breaks in MCL-5 cells. Viable exfoliated breast cells were recovered from fresh milk samples and the ability of milk extracts to cause DNA damage in these cells was demonstrated. The results show that human milk can contain components capable of causing genotoxic damage in test systems and in human breast cells, events that may be significant in the initiation of breast cancer. (C) 1999 Academic Press.

关键词：乳房/细胞学乳腺肿瘤/病因学乳腺肿瘤/遗传学细胞系细胞培养的 DNA/药物作用 DNA/遗传学 DNA损伤上皮细胞/药物作用上皮细胞/超微结构泌乳微核试验乳人/化学乳人/细胞学诱变力试验诱变剂/分离和提纯诱变剂/药理学诱变剂/毒性突变试点项目鼠伤寒沙门菌/药物作用鼠伤寒沙门菌/遗传学时间因素女(雌)性人类

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