Effect of Chitosan Physical Form on Its Antibacterial Activity Against Pathogenic Bacteria

The antibacterial activity of chitosan (CS) nanospheres, in comparison with other physical forms, was investigated against Salmonella enterica serovar Typhimurium and Staphylococcus aureus, which are 2 foodborne harmful pathogens. Results showed that the antibacterial efficacy of CS nanospheres: (1) was superior to that displayed by CS in powder and solution form; (2) was higher against S. aureus than against Salmonella Typhimurium; and (3) was dependent on the temperature and pH of the medium depending on the strain. For S. Typhimurium, a higher activity was displayed at 37 °C, in which 99.9% of the population was eradicated independently of the pH, followed by 20 °C and 7 °C, in which acidic pH conditions favored a higher susceptibility of bacteria to the effect of CS. On the contrary, S. aureus was less susceptible to the pH and temperature conditions of the medium, and no statistical difference in the antibacterial effect was observed for pH 5.8 and 8.0 at 20 °C and 37 °C. However, at 7 °C a slightly higher activity was displayed at pH 5.8 than at 8.0.     

Myrtus communis L. Infusions: The Effect of Infusion Time on Phytochemical Composition, Antioxidant, and Antimicrobial Activities

In traditional medicine, myrtle (Myrtus communis L.) is frequently consumed as an infusion and decoction. In this study, we investigate the phenolic and volatile compositions and antioxidant and antibacterial activities of leaf infusions prepared during 3 different times. The total phenolics contents (146.74 to 179.55 mg GAE/g DM) varied significantly between infusions. Eleven phenolic compounds were identified by reversed-phase high-performance liquid chromatography. Phenolic acids (7.64 to 14.28 μmol/g DM) and flavonol glycosides (7.05 to 12.11 μmol/g DM) were the major phenolic fractions of infusions. Significant quantitative variation in 6 phenolic components was observed between infusions. Sixteen volatile components were identified by gas chromatography (GC) and GC mass spectrometry analyses. The main constituents were 1,8-cineole (42.58% to 51.39%), α-terpineol (9.45% to 9.72%), methyl eugenol (6.69% to 7.11%), and linalool (5.91% to 6.06%). Quantitative variations of the volatile components of the analyzed oils in relation to the infusion time were observed. The antioxidant properties of infusions, assayed through DPPH (2,2- diphenyl-1-picrylhydrazyl) method, β-carotene bleaching test, chelating effect on ferrous ions, and ferric reducing power method, were considerable and varied according to the infusion time. Myrtle infusions exhibited a substantial antimicrobial activity against 6 tested bacteria.     

烟草青枯病拮抗菌的筛选及抑菌活性的测定

为有效防治烟草青枯病,从贵州省青枯病迟发烟地和不发烟地土壤中筛选出15株拮抗菌,对拮抗菌的拮抗能力进行了鉴定。筛选出拮抗力较强的3个菌株(LCA-9、PCM-4、SXM-2),并对3菌株的抗菌物质进行了粗提,检验其抑菌活性。结果表明:3种菌的发酵分泌液对烟草青枯病均有一定的抑制作用,其中SXM-2发酵液的抑菌活性较大、效果较好。     

大蒜乙醇提取物对几种腐败菌的抑制作用

以肴肉中3株特定腐败菌屎肠球菌（Enterococcus faecium）、中间耶尔森菌（Yersinia intermedia）和清酒乳杆菌（Lactobacillus sakei）为受试菌,采用大蒜提取物与茶多酚的复合物为抑制剂,研究其对三株腐败菌的抑制机制。结果表明,以0.84 mg/mL的复合物处理即可破坏3株菌的细胞超微结构,从而使处理10 h后的3株菌电导率显著增加,均大于14 ms/cm;使处理2 h后的三株菌PI染色率均显著提高,分别为36.34%（对照为0.42%）、99.64%（对照为3.72%）和92.95%（对照为28.67%）;并可使三株菌的细胞膜上硬脂酸含量及胞内苹果酸含量显著变化,但仅使屎肠球菌胞内蛋白合成发生改变。研究表明,大蒜提取物与茶多酚复合物通过破坏三株腐败菌的细胞膜和DNA结构,进而改变其胞内外的正常代谢,最终导致腐败菌的抑制或死亡。大蒜提取物-茶多酚复合物的抑菌机制尚需深入研究。     

Antibacterial Activity of Cabbage Juice Against Lactic Acid Bacteria

Fresh juice of Cecile cultivar cabbage (Brassica oleracea) was inhibitory to the growth of four species (including seven strains) of lactic acid bacteria. Inhibition was eliminated when the cabbage was heated (steamed 10 min) before juice extraction. When Lcuconostoc mes-enteroides C33 was tested in juices of three other cultivars of cabbage, growth inhibition was invariably noted in fresh juices, but was variable in heated juices. Fresh cabbage juice (CJ) adjusted to higher initial pH (6.5–7.5) showed greater antibacterial activities than at pH 5.0 to 6.0. When pH 4.0 precipitate from fresh CJ was added to noninhi-bitory CJ (cabbage heated before extraction), antibacterial activity was restored. A heat-labile and pH-dependent factor seemed responsible for activating a precursor into an inhibitory compound.     

Characterization of the Effect of Sprouting or Solid-State Bioprocessing by Dietary Fungus on the Antibacterial Activity of Soybean Extracts Against Listeria monocytogenes

Listeria monocytogenes is one of the most severe food-borne bacterial infections causing Listeriosis. As L. monocytogenes can survive harsh adverse conditions - such as low pH, high NaCl, and refrigeration temperatures - as well as resist current antimicrobial measures such as the use of disinfectants and antibiotics, there is a need for alternative anti-Listeria strategies. In the search for new antimicrobial agents, much recent research has focused on the potential of dietary phenolic compounds. In this study, soybean extracts enriched for phenolic content via dark-germination sprouting or solid-state bioprocessing by the dietary fungus Rhizopus oligosporus or Lentinus edodes were investigated for in vitro antibacterial activity against L. monocytogenes.L. monocytogenes growth was inhibited most effectively by R. oligosporus bioprocessed soybean extracts, which showed anti-Listeria activity at total phenolic concentrations as low as 10 µg 100 µL^-1. In both sprouted soybean extract and L. edodes-bioprocessed soybean extract the anti-Listeria activity was not observed until at least 200 µg total phenolic content 100 µL^-1 was used. Anti-Listeria activity by soybean extract was associated with phenolic mobilization but not with antioxidant activity. Further, R. oligosporus bioprocessed soybean extracts were shown to inhibit the growth of L. monocytogenes in fish and meat systems at refrigeration temperatures. The potential involvement of mobilization of antimicrobial versus non-antimicrobial phenolics during sprouting and solid-state bioprocessing was hypothesized and discussed.     

红果龙葵水提液与乙醇提取液的抑菌作用

使用无菌蒸馏水和70% 乙醇从红果龙葵果实中提取活性成分并探讨其抑菌作用。结果表明,提取物对微生物有明显的抑制作用。水提液的最低抑菌质量浓度分别为大肠杆菌2mg/mL、金黄色葡萄球菌1mg/mL、枯草杆菌0.5mg/mL、短小芽孢杆菌3mg/mL、产气芽孢杆菌0.5mg/mL;乙醇提取液的最低抑菌质量浓度分别为大肠杆菌2mg/mL、金黄色葡萄球菌2mg/mL、枯草杆菌1mg/mL、短小芽孢杆菌5mg/mL、产气芽孢杆菌1mg/mL。     

三种茶叶中多酚提取物的抑菌活性及其对致病菌膜渗透性的比较分析

目的:研究3种茶叶中茶多酚的抑菌活性及对菌株细胞膜渗透性的影响。方法:以西湖龙井、铁观音和普洱茶为材料提取茶多酚,以滤纸片法测定茶多酚的抑菌圈直径,二倍肉汤稀释法测定其最小抑菌浓度(MIC)和最小杀菌浓度(MBC),比较其抑菌效果。通过DNA渗透性实验、DNA损伤实验评价茶多酚对细胞膜完整性及对DNA损伤的影响。结果:相同条件下,绿茶(西湖龙井)中茶多酚含量最高为(48.12±3.22) mg/g,青茶(铁观音)次之为(37.36±2.64) mg/g,黑茶(普洱茶)最低为(31.61±1.92) mg/g。绿茶对金黄色葡萄球菌的抑菌作用最强,抑菌圈直径为(1.80±0.06) cm,MIC值为0.125 mg/mL、MBC值为0.25 mg/mL。随着茶多酚提取物浓度的增加,260 nm下的细菌渗透性物质逐渐增多,并且基因组DNA的损伤程度逐渐增大。结论:3种茶叶中绿茶具有更好的抑菌效果,并通过增强细菌细胞膜渗透性,进而对DNA产生一定的损伤。     

Preparation and Immunological Characteristics of Broad-Spectrum Antibodies Against Poly-Recombinant Toxins from Food-Borne Pathogenic Bacteria

Two recombinant toxin genes (HVSVS: Hc1-VT_1B-SEA-VT_2B-SEB1;VSVHS: VT_1B-SEA-VT_2B-Hc2-SEB2) of five toxin genes from three genera of bacteria, including E. coli O157:H7, Staphylococcus aureus, and Clostridium botulinum, were constructed by SOE PCR with two linkers encoding five amino acids (GlyProGlyProGly i.e. GPGPG or Gly₄Ser). The length of HVSVS gene fragment was 2,937 bp encoding 979 amino acids, and VSVHS was 2,346 bp encoding 782 amino acids. Two recombinant proteins including insoluble protein in pET-22b and inclusion body in pET-28a plasmids were obtained, respectively, and the molecular weights of recombinant fusion proteins were 112.369 kD and 88.899 kD, respectively. Serum antibodies against the five toxins were obtained from rabbits immunized with expressed products. The broad-spectrum antibodies showed high reactive specificity and sensitivity for the five toxins, as well as cross-reactivity with closely related toxins at the same time. These findings provide a foundation for the construction of fusion genes with linkers and for the establishment of broad-spectrum rapid screening methods for food-borne pathogenic bacteria or toxins.     

麦胚提取物的抗氧化性研究

麦胚是面粉生产的副产物，由于含有多种功能成分，往往被用作功能辅料来提高食品的营养价值。本文利用多种评价体系对麦胚水提物和醇提物的抗氧化性做了研究，并以BHT和抗坏血酸作为参照，结果发现：麦胚提取物显示了很强的DPPH自由基清除能力、羟基自由基清除能力、过氧化氢清除能力、络合能力、还原能力和脂质体自由基的清除能力，并且抗氧化能力随着浓度的增加而增加。实验结果表明，小麦胚芽提取物可以作为某些食品的抗氧化剂使用。     

Antioxidant and Antibacterial Activities of Punica granatum Peel Extracts

ABSTRACT: Pomegranate peels were powdered and extracted with ethyl acetate, acetone, methanol (MeOH), and water for 1 h each at room temperature. Radical-scavenging activity of dried ethyl acetate, acetone, MeOH, and water extracts of pomegranate peels were compared with butylated hydroxyanisole at 5, 10, 25, and 50 ppm by high-performance liquid chromatography method using 1, 1-diphenyl-2-picrylhydrazyl. MeOH extract exhibited stronger radical-scavenging effect than others. MeOH extract showed marked reducing power in potassium ferricyanide reduction method. Antibacterial activity of acetone, MeOH, and water extracts was evaluated by pour plate method against a few Gram-positive and Gram-negative bacteria. Acetone extract showed the highest antibacterial activity, followed by MeOH and water extract.     

石榴皮提取物的抑菌活性及其对冷却鸡肉保鲜效果

为了探讨石榴皮复合保鲜剂在冷却肉保鲜中的作用,该研究通过超声辅助和旋转蒸发浓缩法对石榴皮进行提取,采用单一或复合其他天然食品添加剂对5种食源性致病菌的抑菌活性进行分析,选择适宜浓度的单一或复合石榴皮提取物均匀涂抹于冷却鸡脯肉表面,紫外照射结合真空包装后于4℃冷藏,通过感官评定、微生物菌落总数、TVB-N、TBARS和pH指标的测定观察其保鲜效果。结果表明:0.25 g/mL石榴皮醇提物及与其他复合物对5种食源性致病菌均有明显的抑菌效果;与对照组相比,复合石榴皮保鲜剂(0.025 g/dL Nisin+1 g/dL壳聚糖+0.03 g/dL迷迭香提取物+0.25 g/mL石榴皮粗提物)的保鲜效果明显高于单一石榴皮保鲜剂,可将冷却鸡肉的保鲜期延长10 d左右。     

苹果多酚提取物的组成及其抗氧化性能的研究

研究了苹果多酚提取物的组成及其抗氧化作用。结果表明，苹果提取物具有较好的抗油脂氧化作用，其抗氧化效果同浓度，溶解性及其酚类物质的组成有关，当苹果提取物中富含原花青素低聚体、酚酸时，油溶性较好，抗氧化效果最好。此外，苹果提取物与Vc在猪油和菜油中均有很好的协同增效作用，而与柠檬酸的协同作用则在猪油中较显著。     

Control of Foodborne Pathogenic and Spoilage Bacteria by Garcinol and Garcinia indicaextracts, and their Antioxidant Activity

ABSTRACT: Spent rinds of Garcinia indica were extracted with hexane and benzene using a Soxhlet extractor for 4 h. The major compound present in both extracts was found to be garcinol, as confirmed by fractionation and spectroscopic studies. The minimum inhibitory concentrations of hexane extract, benzene extract, and garcinol against a few Gram-positive and Gram-negative bacteria were in the range of 15 to 1000, 20 to 1250, and 1.5 to 500 ppm, respectively. The antioxidant activity of these fractions at 25 ppm was 63.2%, 61.7%, and 92.4%, respectively, as evaluated by the 1,1-diphenyl-2-picrylhydrazyl method. Hexane extract, benzene extract, and garcinol showed 1027, 985.5, and 1195.9 μmol/g of ascorbic acid equivalents, respectively, at 100 ppm concentration using the phosphomolybdenum method. These findings may be useful for possible application of the previously described fractions as biopreservatives.     

核桃分心木粗提物抑菌活性的研究

以核桃分心木的四种粗提取液对几种常见的食品微生物进行抑菌活性监测发现,核桃分心木的四种提取液都具有不同程度的抑菌活性,对枯草芽孢杆菌、金黄色葡萄球菌、大肠杆菌、产气杆菌都有抑菌活性。其中乙醇提取液和水后乙醇提取液的抑菌效力较强,最低抑菌浓度(MIC)也较低,其抑菌活性随着提取物浓度的增大而逐渐增强。这为核桃分心木的开发和利用提供理论依据。     

Antioxidative Properties and Ability of Phenolic Compounds of Myrtus communis Leaves to Counteract In Vitro LDL and Phospholipid Aqueous Dispersion Oxidation

Antioxidant activities of Myrtus communis leaf phenolic compounds (McPCs) were investigated on 2,2′‐9‐azino‐bis‐3‐ethylbenzothiazoline‐6‐sulfonic acid (ABTS⁺?) and oxygen radical absorbance capacity (ORAC) tests or on oxidation of biological models, human low‐density lipoprotein (LDL) and phospholipid aqueous dispersion (l ‐α‐phosphatidylcholine stabilized by bile salts). Two extraction techniques, microwave‐assisted (MAE) and conventional (CE), were used to isolate McPCs, producing similar results of phenolic compound content. ABTS⁺? assay showed clearly that myrtle extracts exhibited a stronger scavenging effect than butylated hydroxyanisole and α‐tocopherol, with a slight advantage for myrtle CE extract. In ORAC assay, the both McPC extracts were similarly less effective than the pure compounds as caffeic acid and myricitrin (myricetin 3‐O‐rhamnoside) but stronger than butylated hydroxytoluene. Moreover, myrtle CE and MAE extracts, and myricitrin were able to inhibit similarly the production of conjugated dienes and to prolong the lag phase (Tlag) during Cu²⁺‐induced LDL oxidation with a dose‐response effect. The cryo‐electron microscopy observations on studied phospholipid dispersion stabilized by bile salts (BS) revealed the presence of bilayer vesicles and micelles. In 2,2′‐azobis (2‐amidinopropane) hydrochloride–induced phospholipid/BS oxidation, myrtle CE and MAE extracts gave similar effects to α‐tocopherol and caffeic acid but myricitrin showed a higher protective effect than myrtle extracts. We showed also that no synergic or additive effect between α‐tocopherol and myrtle extracts or caffeic acid in α‐tocopherol–enriched phospholipid/BS dispersion, but myricitrin showed an additive effect and thus promoted the total antioxidant activity. These data showed that myrtle extract could be used as potential natural antioxidants, food stabilizers, or natural health products.     

合浦珍珠提取物对金黄色葡萄球菌的体外抑菌活性及稳定性研究

目的:研究合浦珍珠提取物对金黄色葡萄球菌的体外抑菌活性及稳定性。方法:采用牛津杯法及96孔法测定合浦珍珠提取物对金黄色葡萄球菌的抑菌活性及最小抑菌浓度,并探讨温度、反复冻融、酸碱、紫外线、金属离子、胰蛋白酶和胃蛋白酶对合浦珍珠提取物抑菌活性的影响。结果:合浦珍珠提取物对金黄色葡萄球菌具有显著的抑菌活性,最小抑菌浓度为0.94 mg·mL^-1,且抑菌活性呈一定的剂量依赖效应。以8×MIC合浦珍珠提取物进行抑菌稳定性实验,以金黄色葡萄球菌的OD₆₀₀值为指标进行探讨,结果显示,合浦珍珠提取物在pH3.0~9.0抑菌活性保持稳定,但在pH11.0相比pH7.0抑菌活性,保留约70%;在-80~80 ℃抑菌活性保持稳定,但在100 ℃相比4 ℃处理30 min抑菌活性保留约68%;在-20 ℃反复冻融及20 W紫外灯照射条件下,提取物抑菌活性保持良好的稳定性;在25~200 mmol·L^-1的NaCl、KCl、CaCl₂条件下,提取物抑菌活性稳定,但在25~200 mmol·L^-1MgCl₂条件下,抑菌活性逐渐降低,在200 mmol·L^-1 MgCl₂时,抑菌活性相比未添加金属离子组保留约40%;提取物对胰蛋白酶处理保持良好的抑菌稳定性,但在胃蛋白酶处理下,抑菌活性消失,说明对胃蛋白酶敏感。结论:合浦珍珠提取物对金黄色葡萄球菌具有稳定的体外抑制活性,为其今后在食品工业上的应用和开发提供一定的理论基础。     

Phytochemical Profiles and Antimicrobial Activity of Aromatic Malaysian Herb Extracts against Food‐Borne Pathogenic and Food Spoilage Microorganisms

Preliminary phytochemical and flavonoid compounds of aqueous and ethanolic extracts of 6 aromatic Malaysian herbs were screened and quantified using Reverse‐Phase High Performance Liquid Chromatography (RP‐HPLC). The herbal extracts were tested for their antimicrobial activity against 10 food‐borne pathogenic and food spoilage microorganisms using disk diffusion assay. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC)/minimum fungicidal concentration (MFC) of herbal extracts were determined. In the phytochemical screening process, both aqueous and ethanolic extracts of P. hydropiper exhibited presence of all 7 tested phytochemical compounds. Among all herbal extracts, the aqueous P. hydropiper and E. elatior extracts demonstrated the highest antibacterial activity against 7 tested Gram‐positive and Gram‐negative bacteria with diameter ranging from 7.0 to 18.5 mm and 6.5 to 19 mm, respectively. The MIC values for aqueous and ethanolic extracts ranged from 18.75 to 175 mg/mL and 0.391 to 200 mg/mL, respectively while the MBC/MFC values for aqueous and ethanolic extracts ranged from 25 to 200 mg/mL and 3.125 to 50 mg/mL, respectively. Major types of bioactive compounds in aqueous P. hydropiper and E. elatior extracts were identified using RP‐HPLC instrument. Flavonoids found in these plants were epi‐catechin, quercetin, and kaempferol. The ability of aqueous Persicaria hydropiper (L.) H. Gross and Etlingera elatior (Jack) R.M. Sm. extracts to inhibit the growth of bacteria is an indication of its broad spectrum antimicrobial potential. Hence these herbal extracts may be used as natural preservative to improve the safety and shelf‐life of food and pharmaceutical products.     

外界因素和杜仲叶提取物对双乙酸钠的抑菌活性影响

本文研究了食品基质(蛋白质和碳水化合物浓度)和加工条件(温度和pH)对双乙酸钠(sodium diacetate,SDA)抑菌活性的影响,并考察了SDA与杜仲叶提取物(Eucommia ulmoides leaves extract,EULE)的联合抑菌作用.通过Modified Gompertz动力学方程拟合细菌生长...