Methods and Results: Using a disc diffusion assay, seven different doses of 10 GHP were tested against each bacteria. The results showed that the isothiocyanates were potent antibacterials, whilst the other GHP were much less efficient. Moreover, the antibacterial effects were dose-dependent, increasing with the dose applied; 2-phenylethylisothiocyanate and sulforaphane showed the strongest inhibitory effects. The overall results show a great potential for using the isothiocyanates as an alternative tool to control undesired bacterial growth in plants.
Conclusions: Glucosinolate hydrolysis products and more specifically the isothiocyanates: benzylisothiocyanate, 2-phenylethylisothiocyanate, the isothiocyanate Mix and sulforaphane, were effective phytochemicals against the in vitro growth of the phytopathogenic bacteria. The antibacterial activity exhibited by these phytochemicals reinforces their potential as alternatives to the traditional chemical control of phytopathogenic bacteria.
Significance and Impact of the Study: This current in vitro study is the first providing comparative data on GHP as potential control agents for plant pathogenic bacteria. However, more studies are needed to determine their possible allelopathic impacts e.g. inhibition of plant growth and negative effects on beneficial soil bacteria and fungi (mycorrhizae). 相似文献
Methods and Results: Both cultures, which were able to colonize the fish gut mucosal layer, comprised nonsporogenous, nonmotile, Gram-positive, catalase and oxidase-negative rods. The growth of both carnobacteria occurred between 0 and 37°C, in 0–10% (w/v) NaCl and at pH 5–10. Specifically, strain B26 grew in nutrient broth supplemented with 15% (w/v) NaCl. The most abundant cellular fatty acid of both cultures was 9-octadecenoic acid (18 : 1 n -9) (B26 = 52·6%; B33 = 40·6%), which was characteristic of Carnobacterium . Both cultures were inhibitory to Aeromonas salmonicida , Aer. hydrophila , Streptococcus iniae and Vibrio anguillarum , and strain B33 inhibited Listeria monocytogenes . Both carnobacteria, which did not contain plasmids, produced inhibitory compounds against Gram-positive and Gram-negative bacteria.
Conclusions: Both probiotic cultures, B26 and B33, had unique phenotypic characteristics and showed a broad spectrum of antibiotic resistance against varying pathogenic bacteria.
Significance and Impact of the Study: The results of this study contribute to new information and significance of carnobacterial species. 相似文献
Methods and Results: Microthecin and nine other AF derivatives were synthesized from AF. The 10 compounds were tested in vitro against Gram-positive (GP) and Gram-negative (GN) bacteria, yeasts and moulds using a well diffusion method and in a Bioscreen growth analyser. Of the test compounds, microthecin exhibited the most significant antibacterial activity at 100–2000 ppm against both GP and GN bacteria, including Ps. aeruginosa. Further tests with three malignant blood cell lines ( Mutu, Ramos, Raji ) and one normal cell line indicated that microthecin was a cell toxin, with a cell mortality >85% at 50 ppm. The other nine AF derivatives demonstrated low or no antimicrobial activity.
Conclusions: Microthecin was active 100–2000 ppm against GP and GN bacteria including Ps. aeruginosa , but was inactive against yeasts and moulds. Microthecin was also a cytotoxin to some mammalian cell lines.
Significance and Impact of the Study: Microthecin might have potential for development as a novel drug against Ps. aeruginosa and to target cancer cells. It might also be developed as a food processing aid to control bacterial growth. 相似文献
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
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. 相似文献
Methods and Results: A total of 15 Staphylococcus aureus , 10 Streptococcus dysgalactiae , 7 Strep. uberis , 1 Strep. agalactiae strains were isolated from 33 different mastitic dairy cattle, sourced from two dairies in Tandil-Argentina. Isolates from each of the bacterial species screened which developed the lowest inhibition zones in response to the peptide, were further evaluated in a series of time-killing curve studies. No survivors were detected in whole strains (from the three Streptococcal species isolated) within 120 min of incubation in presence of the peptide. The Staph. aureus isolates were less sensitive but, nevertheless, a drop in viable counts to below the detection limit was achieved for all the test strains by the final postincubation sampling point at 180 min.
Conclusions: The study demonstrated the in vitro efficacy of the AP-CECT7121 against a variety strains of Gram positives isolated from mastitic dairy cattle.
Significance and Impact of the Study: There is urgent global interest in the development of natural alternatives for the control and prevention of mastitis. Confirmation of the in vitro activity of the novel AP-CECT7121 against Gram-positive isolates encourages further research. 相似文献
Methods and Results: When tested against clinical bacterial isolates, the compound was particularly active against Gram-positive bacteria and its effect was not mitigated against isolates known as resistant to other antibiotics. The antifungal activity of flocculosin was found to be rapid and concentration-dependent. At lethal concentrations against Candida albicans , flocculosin caused a rapid leakage of intracellular potassium and inhibited acidification of the medium by plasma membrane ATPases suggesting a physical rather than a biochemical effect. TEM observations of cells exposed 6 h to flocculosin revealed disrupted membranes and disorganized mitochondria.
Conclusions: Data obtained in this study confirm that flocculosin acts by disrupting the membrane surface of sensitive micro-organisms.
Significance and Impact of the Study: The elucidation of an antifungal mode of action of flocculosin can be exploited in furthering its antimicrobial potential against fungi and bacteria whose cell membranes are particularly sensitive to the action of the molecule. 相似文献
Protonectin was a typical amphiphilic antimicrobial peptide with potent antimicrobial activity against Gram-positive and Gram-negative bacteria. In the present study, when its eleventh amino acid in the sequence was substituted by phenylalanine, the analog named phe-Prt showed potent antimicrobial activity against Gram-positive bacteria, but no antimicrobial activity against Gram-negative bacteria, indicating a significant selectivity between Gram-positive bacteria and Gram-negative bacteria. However, when Gram-negative bacteria were incubated with EDTA, the bacteria were susceptible to phe-Prt. Next, the binding effect of phe-Prt with LPS was determined. Our result showed that LPS could hamper the bactericidal activity of phe-Prt against Gram-positive bacteria. The result of zeta potential assay further confirmed the binding effect of phe-Prt with LPS for it could neutralize the surface charge of E. coli and LPS. Then, the effect of phe-Prt on the integrity of outer membrane of Gram-negative bacteria was determined. Our results showed that phe-Prt had a much weaker disturbance to the outer membrane of Gram-negative bacteria than the parent peptide protonectin. In summary, the introduction of l-phenylalanine into the sequence of antimicrobial peptide protonectin made phe-Prt show significant selectivity against Gram-positive bacteria, which could partly be attributed to the delay effect of LPS for phe-Prt to access to cell membrane. Although further study is still needed to clarify the exact mechanism of selectivity, the present study provided a strategy to develop antimicrobial peptides with selectivity toward Gram-positive and Gram-negative bacteria.
相似文献Methods and Results: A total of 1000 lactic acid bacteria were isolated from various Kimchi samples and screened for the production of bacteriocin. Pediocin K23-2, a bacteriocin produced by the Pediococcus pentosaceus K23-2 strain, showed strong inhibitory activity against Listeria monocytogenes . The bacteriocin activity remained unchanged after 15 min of heat treatment at 121°C or exposure to organic solvents; however, it diminished after treatment with proteolytic enzymes. The bacteriocin was maximally produced at 37°C, when the pH of the culture broth was maintained at 5·0 during the fermentation, although the optimum pH for growth was 7·0. The molecular weight of the bacteriocin was about 5 kDa according to a tricine SDS-PAGE analysis.
Conclusions: Pediococcus pentosaceus K23-2 isolated from Kimchi produces a bacteriocin, which shares similar characteristics to the Class IIa bacteriocins. The bacteriocin is heat stable and shows wide antimicrobial activity against Gram-positive bacteria, especially L. monocytogenes .
Significance and Impact of the Study: Pediocin K23-2 and pediocin K23-2-producing P. pentosaceus K23-2 could potentially be used in the food and feed industries as natural biopreservatives, and for probiotic application to humans or livestock. 相似文献
Methods and Results: Morphological, cultural, physiological and 16S rRNA homology studies revealed that the organism showed 99% similarity with Streptomyces griseoruber NBRC 12873. One bioactive metabolite (Py2) isolated from the fermented broth was characterized as actinomycin-D (act-D). It showed high activity against various Gram-positive and Gram-negative bacterial cultures, Mycobacterium tuberculosis H37Rv and human neoplastic cells in vitro using standard protocols.
Conclusions: The isolated strain S. griseoruber produced act-D predominantly (210 mg l
Significance and Impact of the Study: Streptomyces griseoruber may be exploited as a potential source for the commercial production of act-D, as this strain is not reported to produce act-D. Further investigations on the strain for commercial application will be of immense pharmaceutical importance. 相似文献
Methods and Results: Distilled water was activated for 5 min by a nonthermal quenched plasma of the glidarc type operating in humid air and at atmospheric pressure. The plasma-activated water (PAW) was then used to treat planktonic and adherent cells of Staphylococcus epidermidis , Leuconostoc mesenteroides (as models of Gram-positive bacteria), Hafnia alvei (a Gram-negative bacteria) and Saccharomyces cerevisiae (as a yeast model). The treatments were less efficient on adherent cells than on planktonic cells in the case of bacteria, but not of S. cerevisiae . Inactivation was more effective for bacteria than for the yeast.
Conclusions: Significant reductions in microbial populations were achieved in all cases, demonstrating the effectiveness of this new approach to treat contaminated media.
Significance and Impact of the Study: PAW is a promising solution with potential application to the decontamination of equipment and surfaces. 相似文献
Methods and Results: The root extracts of taiwanese wild grape ( Vitis thunbergii var. taiwaniana ) showed marked activities against Gram-positive bacteria using the disc diffusion method. After purification, the active compound 1 was confirmed as heyneanol A by mass spectroscopy and nuclear magnetic resonance. Heyneanol A showed an minimum inhibitory concentration (MIC) value of 2 μ g ml
Conclusions: The root extracts of grapevines have good antimicrobial activities towards some strains of Gram-positive pathogens. Heyneanol A, the major antimicrobial compound, is especially active towards MRSA. In addition, the abundances of heyneanol A and other stilbenes in the roots of grapevines make it possible to produce natural antimicrobial compounds from this plant species.
Significance and Impact of the Study: This study reports for the first time the antimicrobial compounds in the root extracts of grapevines. The results will have clinical significance owing to their activities against MRSA. 相似文献
Methods and Results: 106 bovine-derived faecal/intestinal LAB were tested in vitro for tolerance to pH 2·0, pH 4·0, 0·15% and 0·3% bile, aerobic incubation, and for inhibitory activity against E. coli O157 ( n = 3) and F5 ( n = 1). While no LAB grew at pH 2·0, LAB survivability varied between 35% and 100% on the other tests. Exactly 7·6% (8/106) of LAB supernatants inhibited the growth of E. coli in two assays, whereas 6·6% (7/106) of isolates enhanced the growth of all E. coli strains. Partial 16s rRNA gene sequencing of six best isolates (95th percentile) revealed that five were Lactobacillus plantarum and one Pediococcus acidilactici.
Conclusion: Lactobacillus plantarum with acid/bile and aerobic resistance and inhibitory activity against E. coli O157 and F5 inhabit the intestinal tract of healthy cattle. Some LAB may enhance E. coli growth.
Significance and Impact of the Study: Lactobacillus plantarum and P. acidilactici are natural plant micro-organisms and studied silage inoculants. Their identification from gastrointestinal samples of healthy cattle is prophylactically promising. 相似文献