Antibacterial activity and action mechanism of a novel chitosan oligosaccharide derivative against dominant spoilage bacteria isolated from shrimp Penaeus vannamei

With the aim of exploring the potential application of a novel chitosan oligosaccharide derivative (COS-All-Tio) in shrimp preservation, six dominant spoilage bacteria in the spoiled shrimp (Penaeus vannamei) were isolated and identified as Shewanella putrefaciens (RMS1), S. putrefaciens (S2), Pseudomonas weihenstephanensis (P1), P. gessardii (P2), Aeromonas bestiarum (A1) and Aeromonas molluscorum (A2). The antibacterial effect of COS-All-Tio against the six bacterial isolates were studied. Bacterial inhibition zone determination, and minimum inhibitory concentration and minimum bactericidal concentration assays indicated that the antibacterial activity of COS-All-Tio was greatly improved when compared to that of chitosan oligosaccharide (COS). The antibacterial mechanism investigation against S. putrefaciens (RMS1) revealed that COS-All-Tio could inhibit bacterial growth by influencing of membrane integrity. Such disturbance of membrane structure resulted in the leakage of intracellular substance of the bacteria. A strong synergistic antibacterial effect against S. putrefaciens (RMS1) was observed when COS-All-Tio was used in combination with food preservatives (e.g. ε-polylysine hydrochloride). Therefore, COS-All-Tio might have potential in shrimp preservation.     

Antimicrobial activity of LFchimera synthetic peptide against plant pathogenic bacteria

The present study was designed to evaluate potential antibacterial activities of synthetic LFchimera against five plant pathogenic bacteria such as Ralstonia solanacearum, Erwinia amylovora, Xanthomonas campestris, Pseudomonas syringae and Pectobacterium carotovorum. The agar disc-diffusion method with different concentrations (0.2, 0.4, 0.6 and 0.8 μM) of peptide was used to study the antibacterial activity of LFchimera against bacteria. The Minimum Inhibitory Concentration (MIC) of the LFchimera peptide were tested using serial dilution method at concentration ranging from 0 to 10 μM. The Results from agar disc-diffusion method revealed that LFchimera was effective against all bacterial strain in a dose-dependent manner. LFchimera showed highest activity in 0.8 μM which was significant compared to the standard antibiotic. LFchimera pepetide showed low MIC values (4 μM) against all tested bacteria. LFchimera peptide was found to show antibacterial activity against important phytopathogenic bacteria and can improve the potential of an antimicrobial peptide in plant disease management.     

Antimicrobial activity of sodium citrate against Streptococcus pneumoniae and several oral bacteria

Aims: The aim of this study is to assess the antibacterial activity of sodium citrate against Streptococcus pneumoniae and several oral bacteria. Methods and Results: The antibacterial activity was determined by broth microdilution method. The results showed that although Enterocuccus faecium OB7084 and Klebsiella pneumoniae OB7088 had high tolerance to sodium citrate, several oral bacteria including Fusobacterium nucleatum JCM8532^T, Streptococcus mutans JCM5705^T and Strep. pneumoniae NBRC102642^T were susceptible. Furthermore, the bactericidal activity of sodium citrate against Strep. pneumoniae NBRC102642^T was not influenced by pH in the range of 5·0–8·0, whereas that of sodium lactate was weakened at neutral or weak alkaline pH. When Strep. pneumoniae NBRC102642^T was treated with sodium citrate for 2 h, many burst cells were observed. However, addition of MgCl₂ or CaCl₂ to an assay medium weakened the antimicrobial activity although ZnCl₂ or MnCl₂ did not influence. Conclusions: Independent of pH, sodium citrate inhibited the growth of oral bacteria, which suggests that the mechanism is different from that of sodium lactate. Significance and Impact of the Study: The results presented in this study would be available for understanding the antimicrobial property of sodium citrate.     

Antimicrobial and antistaphylococcal biofilm activity from the sea urchin Paracentrotus lividus

Aims:  Staphylococcal biofilm-associated infections are resistant to conventional antibiotics. Consequently, new agents are needed to treat them. With this aim, we focused on the effector cells (coelomocytes) of the sea urchin Paracentrotus lividus immune system.
Methods and Results:  We tested the activity of the 5-kDa peptide fraction of the cytosol from coelomocytes (5-CC) against a group of Gram-positive, Gram-negative bacteria and fungi. We determined minimal inhibitory concentrations (MICs) ranging from 253·7 to 15·8 mg ml⁻¹. We observed an inhibitory activity and antibiofilm properties of 5-CC against staphylococcal biofilms of reference strains Staphylococcus epidermidis DSM 3269 and Staphylococcus aureus ATCC 29213. The antimicrobial efficacy of 5-CC against the biofilms of clinical strain Staph. epidermidis 1457 was also tested using live/dead staining in combination with confocal laser scanning microscopy. At a sub-MIC concentration (31·7 mg ml⁻¹) of 5-CC the formation of young (6-h old) and mature (24-h old) staphylococcal biofilms was inhibited.
Conclusions:  The biological activity of 5-CC could be attributed to three peptides belonging to the sequence segment 9–41 of a beta-thymosin of P. lividus .
Significance and Impact of the Study:  The effector cells of P. lividus represent an interesting source of marine invertebrates-derived antimicrobial agents in the development of new strategies to treat staphylococcal biofilms.     

Chemical composition and synergistic effect of three Moroccan lavender EOs with ciprofloxacin against foodborne bacteria: a promising approach to modulate antimicrobial resistance

The aim of this study was to determine the chemical profile of the essential oils (EOs) of three Moroccan lavender species (Lavandula pedunculata, LP; Lavandula angustifolia, LA; and Lavandula maroccana, LM) and to investigate, for the first time, the synergistic effect of the optimal mixture of the EOs with conventional antibiotic ciprofloxacin against three pathogenic foodborne bacteria. Gas chromatography/mass spectrometry analysis showed that eucalyptol (39·05%), camphor (24·21%) and borneol (8·29%) were the dominant compounds of LA-EO. LP-EO was characterized by the abundance of camphor (74·51%) and fenchone (27·06%), whereas carvacrol (42·08%), camphor (17·95%) and fenchone (12·05%) were the main constituents of LM-EO. EOs alone or combined showed a remarkable antimicrobial activity against the tested bacteria with minimum inhibitory concentrations (MICs) ranging from 3·53 to 15·96 mg ml⁻¹. The optimal mixture, calculated using a mixture design, corresponded to 19% LA, 38% LP and 43% LM. All combination of the EOs and the best EO mixture with ciprofloxacin exhibited a total synergism with fractional inhibitory concentration index values ranging from 0·27 to 0·37. The best EO mixture showed the highest gain of 128-fold, especially against Salmonella spp., more than that found testing the EOs separately. These findings should be taken into consideration for a possible application in the pharmaceutical and food industries.     

Antimicrobial efficacy of the alkaloid harmaline alone and in combination with chlorhexidine digluconate against clinical isolates of Staphylococcus aureus grown in planktonic and biofilm cultures

Aims: To investigate the antimicrobial efficacy of an alkaloid, harmaline alone and in combination with chlorhexidine digluconate (CHG) against clinical isolates of Staphylococcus aureus (S. aureus) grown in planktonic and biofilm cultures. Methods: Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) were determined for each micro‐organism grown in suspension and in biofilm using microbroth dilution method. Chequerboard assays were used to determine synergistic, indifferent or antagonistic interactions between harmaline and CHG, and the some of results were verified by confocal laser scanning microscopy. Results: Harmaline and CHG showed effective antimicrobial activity against suspensions and biofilm cultures of S. aureus, respectively. As determined by fractional inhibitory concentration index (FICI), synergistic antimicrobial effects between harmaline and CHG were observed in nine and 11 of the 13 S. aureus strains when in suspension and in biofilm, respectively. FICI values were from 0·375 to 1·25 when in suspension and from 0·25 to 1·25 when in biofilm. Conclusions: Synergistic activity of harmaline and CHG against clinical isolates of S. aureus (in suspension and in biofilm) was observed in vitro. Significance and Impact of the Study: This study might provide alternative methods to overcome the problem of drug‐resistance of S. aureus both in suspension and in biofilm.     

茅苍术挥发油对三种内生真菌及七种外源真菌的抑菌活性

为了研究宿主植物次级代谢产物对内生真菌生长的抑制作用,以药用植物茅苍术及其内生真菌为材料,采用有机溶剂萃取法提取茅苍术挥发油,应用滤纸片扩散法和平板涂布法研究茅苍术挥发油对茅苍术内生真菌及其他外源真菌的抑菌作用.结果表明: 挥发油对3种内生真菌生长具有抑制作用;对酵母、水霉有很强的抑菌活性;对根霉、犁头霉抑菌作用不明显;对绿色木霉、黑曲霉的产孢具有抑制作用;对疫霉生长无抑制作用.在高浓度挥发油胁迫下,内生真菌菌丝分支增多,分支间距离变短,气生菌丝生长受到抑制.两种内生真菌对挥发油具有代谢转化能力,降低了其主要成分的含量.表明茅苍术挥发油对内生真菌生长具有限制作用,但内生真菌能够通过自身分解代谢适应茅苍术挥发油.     

Antimicrobial activity of Paenibacillus peoriae strain NRRL BD-62 against a broad spectrum of phytopathogenic bacteria and fungi

AIMS: To investigate the potential antagonistic activity of Paenibacillus peoriae strain NRRL BD-62 against phytopathogenic micro-organisms and to determine the physiological and biochemical characteristics of the antimicrobial compound produced by this strain. METHODS AND RESULTS: Strain NRRL BD-62 showed a broad inhibition spectrum with activity against various phytopathogenic bacteria and fungi. Physico-chemical characterization of the antimicrobial activity showed that it was stable during heat treatment and was retained even after autoclave at 121 degrees C for 10 min. The compound was also stable after the treatment with organic solvents, hydrolytic enzymes and its activity was preserved at a wide range of pH. The partial purification carried out by Sephadex G25 gel filtration showed two profiles of inhibition against the indicator strains tested, suggesting at least two different substances with distinct molecular weight. CONCLUSIONS, SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report on the production of antimicrobial substances in P. peoriae. Besides the antimicrobial inhibition capability, the strain NRRL BD-62 is also able to effectively fix molecular nitrogen, and produce chitinases and proteases as well, suggesting that further studies should be addressed to use P. peoriae strain NRRL BD-62 as a plant growth promoter and/or as a biocontrol agent in field experiments.     

Photocytotoxic activity of a nitrosyl phthalocyanine ruthenium complex--a system capable of producing nitric oxide and singlet oxygen

The synthesis, structural aspects, pharmacological assays, and in vitro photoinduced cytotoxic properties of [Ru(NO)(ONO)(pc)] (pc = phthalocyanine) are described. Its biological effect on the B16F10 cell line was studied in the presence and absence of visible light irradiation. At comparable irradiation levels, [Ru(NO)(ONO)(pc)] was more effective than [Ru(pc)] at inhibiting cell growth, suggesting that occurrence of nitric oxide release following singlet oxygen production upon light irradiation may be an important mechanism by which the nitrosyl ruthenium complex exhibits enhanced biological activity in cells. Following visible light activation, the [Ru(NO)(ONO)(pc)] complex displayed increased potency in B16F10 cells upon modifications to the photoinduced dose; indeed, enhanced potency was detected when the nitrosyl ruthenium complex was encapsulated in a drug delivery system. The liposome containing the [Ru(NO)(ONO)(pc)] complex was over 25% more active than the corresponding ruthenium complex in phosphate buffer solution. The activity of the complex was directly proportional to the ruthenium amount present inside the cell, as determined by inductively coupled plasma mass spectroscopy. Flow cytometry analysis revealed that the photocytotoxic activity was mainly due to apoptosis. Furthermore, the vasorelaxation induced by [Ru(NO)(ONO)(pc)], proposed as NO carrier, was studied in rat isolated aorta. The observed vasodilation was concentration-dependent. Taken together, the present findings demonstrate that the [Ru(NO)(ONO)(pc)] complex induces vascular relaxation and could be a potent anti-tumor agent. Nitric oxide release following singlet oxygen production upon visible light irradiation on a nitrosyl ruthenium complex produces two radicals and may elicit phototoxic responses that may find useful applications in photodynamic therapy.     

Antimicrobial activity of Curcuma xanthorrhiza nanoemulsions on Streptococcus mutans biofilms

Abstract

In this study, an optimal nanoemulsion formulation for Curcuma xanthorrhiza oil (Xan) was investigated using different sonication times. The antimicrobial effects of the nanoemulsion, the original emulsion, distilled water (DW), and Listerine, on Streptococcus mutans biofilms were compared. The optimum ultrasonic time, determined in terms of droplet size and stability, was found to be 10?min. Cell viability was the lowest on exposure to the nanoemulsion, and significantly different compared with exposure to DW or Listerine. The emulsion’s effect was similar to that of the nanoemulsion, but was non-uniform with a high interquartile range. Confocal microscope analysis revealed that the live/dead cell ratio in the nanoemulsion was 50% and 40% less than those in DW and Listerine, respectively. Biofilm treated with the nanoemulsion was thinner than biofilms exposed to the other treatments. Xan nanoemulsions exhibited stable and strong antimicrobial effects due to nano-sized particles, highlighting their potential use in oral health treatment.     

DS6: anticandidal,antibiofilm peptide against Candida tropicalis and exhibit synergy with commercial drug

Antifungal peptides have gained interest as therapeutic agents in recent years because of increased multidrug resistance against present antifungal drugs. This study designed, synthesized and characterized antifungal activity of a small peptide analogue, DS6. This peptide was designed using the template from the N‐terminal part of the antifungal protein, Aspergillus giganteous. DS6 inhibited Candida tropicalis (ATCC 13803), as well as its clinical isolates. DS6 was found to be a fungicidal, killing the fungus very rapidly. DS6 is also non‐toxic to human cells. Synergistic interactions of DS6 with amphotericin B and fluconazole were also evident. DS6 is membrane lytic and exhibits antibiofilm activity against C. tropicalis. In conclusion, DS6 may have utility as an alternative antifungal therapy for C. tropicalis. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd.     

Antimicrobial effect of radiant catalytic ionization

The main purpose of micro-organisms elimination from the air and surfaces is to ensure microbiological safety in health care facilities or food production plants. Currently, many disinfection methods are used, both physical, chemical and, increasingly, biological. Scientists seek new solutions with high antimicrobial effectiveness (especially against the drug-resistant strains of bacteria), low production and operating costs, and, above all, the safety of patients and food consumers. The limitation of the methods used so far is primarily the micro-organisms acquire the resistance, mainly to antimicrobial agents. One of the new and alternative methods of disinfection is radiant catalytic ionization (RCI). RCI is an active method of air and surface purification. The technology proved high efficiency against viruses, Gram-positive and -negative bacteria, and fungi, both in the air and on surfaces (planktonic forms and biofilm). RCI has many advantages as well as some minor limitations. This overview summarizes the current knowledge about RCI technology.     

Antimicrobial activity of lemongrass oil against Salmonella enterica on organic leafy greens

Aims: We investigated the antimicrobial effectiveness of lemongrass essential oil on organic leafy greens, romaine and iceberg lettuces and mature and baby spinach, inoculated with Salmonella Newport. The influences of exposure times and abuse temperatures on bacterial survival were also investigated. Methods and Results: Leaf samples were washed, inoculated with Salm. Newport (6‐log CFU ml^?1) and dried. Inoculated leaves were immersed in solutions containing 0·1, 0·3 or 0·5% lemongrass oil in phosphate‐buffered saline for 1 or 2 min and then individually incubated at 4 or 8°C. Samples were taken at day 0, 1 and 3 for the enumeration of survivors. Compared to the PBS control, romaine and iceberg lettuces, and mature and baby spinach samples showed between 0·6–1·5‐log, 0·5–4·3‐log, 0·5–2·5‐log and 0·5–2·2‐log CFU g^?1 reductions in Salm. Newport by day 3, respectively. Conclusions: The antimicrobial activity of lemongrass oil against Salm. Newport was concentration and time dependent. The antimicrobial activity increased with exposure time; iceberg samples treated for 2 min generally showed greater reductions (P < 0·05) than those treated for 1 min (c. 1‐log reduction difference for 0·3 and 0·5% treatments). Few samples showed a difference between refrigeration and abuse temperatures. Significance and Impact of the Study: This study demonstrates the potential of lemongrass oil solutions to inactivate Salm. Newport on organic leafy greens.     

Antimicrobial activity of a porcine myeloperoxidase against plant pathogenic bacteria and fungi

Porcine myeloperoxidase was evaluated for its antimicrobial activity against plant pathogenic bacteria and fungi. The results indicated that the enzyme, in the presence of a small amount of hydrogen peroxide, was effective against a broad spectrum of plant pathogens. The growth of seven bacterial species, including nine pathovars, from the genera Erwinia , Pseudomonas and Xanthomonas , was significantly inhibited by the enzyme at a concentration as low as 0·4 U ml⁻¹, while 4·0 U ml⁻¹ was lethal to all plant pathogenic bacteria examined. Myeloperoxidase, at 40 U ml⁻¹, was lethal to germinating spores from three isolates of the fungal plant pathogen Fusarium solani and two isolates from each of Colletotrichum gloeosporioides and C. malvarum . The enzyme's antifungal effects on the rice blast pathogen Magnaporthe grisea were studied both in vitro and on host plants. The enzyme significantly inhibited spore germination of two isolates of M. grisea races IC17 and IB49 at concentrations over 16 U ml⁻¹, and disintegration of fungal spore walls was caused by 80 U ml⁻¹. The enzyme was even more effective in reducing disease incidence of blast on young rice plants treated with 0·5 U ml⁻¹, while 2·5 U ml⁻¹ resulted in complete inhibition of infection. These results support and further extend the suggestion that myeloperoxidase could be used as a broad-spectrum biocontrol agent or as a transgenically expressed protein to combat diseases caused by plant pathogenic bacteria and fungi.     

中药蛴螬多肽Probrelin抗白色念珠菌活性研究

[目的] 研究蛴螬多肽Probrelin对白色念珠菌的抗菌活性。[方法] 采用肉汤稀释法测定蛴螬多肽Probrelin对正常菌株及临床耐药菌株的最小抑菌浓度,同时结合平板计数法测定最小杀真菌浓度;通过不同浓度多肽处理后经平板计数绘制时间-杀菌动力学曲线;通过PI吸收实验检测多肽对白色念珠菌细胞膜完整性的影响;通过核酸阻滞实验检测多肽与核酸间是否具有结合作用;通过扫描电子显微镜检测多肽对白色念珠菌形态的影响;通过结晶紫染色法检测多肽对生物膜生成及成熟生物膜的影响;通过显微镜观察多肽对白色念珠菌菌丝形成的影响;通过棋盘法检测多肽与抗真菌药物间的相互效应;通过小鼠皮下感染模型检测多肽在生理条件下的抗白色念珠菌活性。[结果] 蛴螬多肽Probrelin对正常菌株及临床耐药菌株的最小抑菌浓度均为100 μg/mL,最小杀真菌浓度为100-200 μg/mL,且对白色念珠菌的杀菌动力学具有时间和浓度依赖性;该多肽以浓度依赖性的方式影响白色念珠菌细胞膜的完整性,并通过破坏白色念珠菌细胞壁的结构影响其形态,但与核酸间不具有结合作用;该多肽既可抑制白色念珠菌生物膜的形成,又可清除成熟生物膜,同时还可抑制白色念珠菌菌丝的形成;该多肽与抗真菌药物Clotrimazole间具有协同效应;在小鼠皮下感染模型中,该多肽可以有效杀灭白色念珠菌,进而抑制感染。[结论] 蛴螬多肽Probrelin对白色念珠菌具有良好的抑制杀灭活性,可以作为新的药物分子或模板分子用于抗白色念珠菌药物的研发。     

Antimicrobial Activity of Monascus pilosus IFO 4520 against Contaminant of Koji

Antimicrobial activity of Monascus pilosus IFO 4520 was examined to prevent contamination during beni-koji making in the open air. The antibacterial effect of the beni-koji prepared with this strain occured with 30 mg/ml of beni-koji extract in combination with 0.5% lactic acid against two contaminants of koji, Micrococcus varians and Bacillus subtilis. There were two compounds, antibacterial and antiyeast substances, in the beni-koji extract. These results suggest a possibility of inhibiting the growths of contaminants during beni-koji making using beni-koji extract and lactic acid.