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1.
Buatong Jirayu Phongpaichit Souwalak Rukachaisirikul Vatcharin Sakayaroj Jariya 《World journal of microbiology & biotechnology》2011,27(12):3005-3008
The aim of this work was to select endophytic fungi from mangrove plants that produced antimicrobial substances. Minimal inhibitory
concentrations (MIC) and minimal bactericidal concentrations (MBC) or minimal fungicidal concentrations (MFC) of crude extracts
from 150 isolates were determined against potential human pathogens by a colorimetric microdilution method. Ninety-two isolates
(61.3%) produced inhibitory compounds. Most of the extracts (28–32%) inhibited Staphylococcus aureus (MIC/MBC 4–200/64–200 μg ml−1). Only two extracts inhibited Pseudomonas aeruginosa (MIC/MBC 200/>200 μg ml−1). 25.5 and 11.7% inhibited Microsporum gypseum and Cryptococcus neoformans (MIC/MFC 4–200/8–200 μg ml−1 and 8–200/8–200 μg ml−1, respectively), while 7.5% were active against Candida albicans (MIC/MFC 32–200/32–200 μg ml−1). None of the extracts inhibited Escherichia coli. The most active fungal extracts were from six genera, Acremonium, Diaporthe, Hypoxylon, Pestalotiopsis, Phomopsis, and Xylaria as identified using morphological and molecular methods. Phomopsis sp. MA194 (GU592007, GU592018) isolated from Rhizophora apiculata showed the broadest antimicrobial spectrum with low MIC values of 8–32 μg ml−1against Gram-positive bacteria, yeasts and M. gypseum. It was concluded that endophytic fungi from mangrove plants are diverse, many produce compounds with antimicrobial activity
and could be suitable sources of new antimicrobial natural products. 相似文献
2.
Rasanthika Nayomi Jayatissa Rohan Prasantha Perera Chamari Madhu Hettiarachchi Pathum Manjula Weerawarna 《Indian journal of microbiology》2012,52(1):83-87
The continuing increase in the incidence of multi drug resistant pathogenic bacteria and shortage of new antimicrobial agents
are the prime driver in efforts to identify the novel antimicrobial classes. In vitro antibacterial activity of 4-phenyl-1-(2-phenylallyl)
pyridinium bromide was tested against Gram positive Staphylococcus aureus, Streptococcus species, Bacillus subtilis, and Gram negative Klebsiella aerogenes and Escherichia coli using disk diffusion method. Among them S. aureus showed strong antibacterial activity (21.99 ± 0.03 mm) while E. coli showed very little activity (8.97 ± 0.06 mm) towards the compound. The MIC of 4-phenyl-1-(2-phenyl-allyl)-pyridinium bromide
for 90% S. aureus was ≤20 μg/ml and was compared with phenoxymethylpenicillin, cloxacillin, erythromycin and vancomycin. When 4-phenyl-1-(2-phenyl-allyl)pyridinium
bromide showed MIC at ≤20 μg/ml, all others showed MIC at ≤100 μg/ml. Strong antibacterial activity of 4-phenyl-1-(2-phenyl-allyl)pyridinium
bromide against S. aureus indicates that there is a possibility to use it as an effective antibacterial agent. 相似文献
3.
Rohanah Hussain Christopher L. Joannou Giuliano Siligardi 《International journal of peptide research and therapeutics》2006,12(3):269-273
Microbes are increasingly developing defensive mechanisms against known drugs via mutations. There are signs of emergence of superbugs immune to most known antibiotics available. The need for a new class of drugs to counteract this problem is of paramount importance for continued general well being of mankind. A new class of drugs, antimicrobial peptides, has not been fully exploited primarily due to high cytotoxicity, poor lipophilicity preventing systemic distribution and stability. We have synthesised 9-amino acid residue cationic peptides RH01 and RH02 lipidated with myristoyl and octyl groups respectively. These peptides exhibited potent antimicrobial activity and low cytotoxicity. The lipopeptide RH01 has antimicrobial activity against a broad range of microorganisms including bacteria, yeast and filamentous fungi with greatest activity toward Gram-positive bacteria, including S. aureus MRSA stain, MIC’s ranging between 2–8 μM. The MIC for Gram-negative bacteria was higher ranging from between 30–250 μM. RH01 also had antimicrobial activity towards fungi showing good activity against the pathogenic yeast Candida albicans but was less active towards the filamentous fungi Aspergillus niger. The antimicrobial activity of RH01 as a measure of Ki(50) for E. coli and S. aureus was 35–60 μM and 3–7 μM, respectively. In-house data showed the compound is bactericidal even at higher bacteria concentration. The octylated lipopeptide RH02 has similar activities towards S. aureus (3.3 μM) and E coli (53.3 μM) as the myristolated RH01. There was no haemolytic activity of the lipopeptide RH01 towards human blood. Acute intravenous toxicity study in mice showed that both RH01 and RH02 induced no macroscopic abnormalities at their highest non-lethal dose of 75 mg/kg and 150 mg/kg bodyweight, respectively.Australian Peptide Conference Issue. 相似文献
4.
Kittisak Chawawisit Monthon Lertcanawanichakul 《World journal of microbiology & biotechnology》2008,24(10):2199-2204
Secondary metabolites, particularly bioactive compounds, from probiotic bacteria, are good candidates for replacing antibiotics
to which bacteria have become resistant. In order to compare bioactive crude material from strain SA14 of Brevibacillus laterosporus with two antibiotics, the MICs of this bioactive crude and those of antibiotics vancomycin and oxacillin, against methicillin-resistant
Staphylococcus aureus (MRSA), were determined. The result indicated that the MIC (3.6–19.2 μg/ml) of bioactive crude was higher than vancomycin
(MIC = 1.28–2.56 μg/ml) when tested against MRSA. Interestingly, all tested strains of MRSA were susceptible to bioactive
crude and were approximately 5.2-fold more potent than oxacillin (MIC > 100 μg/ml). Its activity against MRSA gives support
for further evaluation, and the development of this substance for therapeutic use. 相似文献
5.
The antibacterial effects of tea polyphenols (TPP) extracted from Korean green tea (Camellia sinensis) against clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) were evaluated. Characterization of the minimal inhibitory concentration (MIC) of oxacillin for 30 S. aureus strains isolated from patients treated with oxacillin identified 13 strains with an oxacillin MIC ≥ 4 μg/mL as methicillin-resistant
Staphylococcus aureus (MRSA) (range: 8 to 512 μg/mL), while 17 strains were methicillin-susceptible Staphylococcus aureus (MSSA) (range: 0.25–0.5 μg/mL). The MICs of TPP ranged from 50 to 180 μg/mL for both the MSSA and the MRSA strains. The MICs
of oxacillin for each of the 13 MRSA strains were reduced between 8- and 128-fold when these strains were coincubated with
sub-MIC (≤0.5× MIC) levels of TPP, demonstrating that the combination of TPP plus oxacillin was synergistic for all of the
clinical MRSA isolates. Two-dimensional polyacrylamide gel electrophoresis identified 14 extracellular proteins of MRSA-13
down-regulated and 3 proteins up-regulated by exposure to TPP. These studies demonstrate that TPP can differentially stimulate
the expression of various proteins in these bacteria and synergize the bactericidal activity of oxacillin for MRSA. 相似文献
6.
Tertiary structure-related activity of tick defensin (persulcatusin) in the taiga tick, <Emphasis Type="Italic">Ixodes persulcatus</Emphasis> 总被引:1,自引:0,他引:1
Emiko Isogai Hiroshi Isogai Kazuhiko Okumura Hatsuhiro Hori Hiroki Tsuruta Yoichi Kurebayashi 《Experimental & applied acarology》2011,53(1):71-77
Defensins are small cysteine-rich cationic proteins found in both vertebrates and invertebrates constituting the front line
of host innate immunity. To examine the importance of the tertiary structure of tick defensin in its antimicrobial activity,
we synthesized two types of the peptides with tertiary structure or primary one on basis of the information of the sequence
in the defensin originated from the taiga tick, Ixodes persulcatus. Chemically synthesized peptides were used to investigate the activity spectrum against Staphylococcus aureus, Borrelia garinii and flora-associated bacteria. Both synthetic peptides showed antimicrobial activity against S. aureus in short-time killing within 1 h, but they do not show the activity against B. garinii, Stenotrophomonas maltophila and Bacillus spp., which were frequently isolated from the midgut of I. persulcatus. The teriary structure brought more potent activity to S. aureus than primary one in short-time killing. We also examined its antimicrobial activity by evaluation of growth inhibition in
the presence of the synthetic peptides. Minimum inhibitory concentration (MIC) was ranged from 1.2 to 5.0 μg/ml in tertiary
peptide and from 10 to 40 μg/ml in primary peptide, when 10 strains of S. aureus were used. From the curve of cumulative inhibition rates, MIC50 (MIC which half of the strains showed) to S. aureus is about 1.2 μg/ml in the peptide with tertiary structure and about 10 μg/ml in the linear one. Corynebacterium
renale is 10 times or more sensitive to tertiary peptide than primary one. In conclusion, the presence of 3 disulfide bridges, which
stabilize the molecule and maintain the tertiary structure, is considered to have an effect on their antimicrobial activities
against Gram-positive bacteria such as S. aureus. 相似文献
7.
Wen Gu 《World journal of microbiology & biotechnology》2009,25(9):1677-1683
A total of 48 strains were isolated from the normal tissues of Malus halliana and the EtOAc extracts of their cultures were subjected to primary antimicrobial screening against four test bacteria and
three fungi. As a result, 22 strains exhibited antimicrobial activity against at least one test microbe. Among them, Alternaria brassicicola ML-P08 showing strong activity (MICs: 0.31–2.50 mg/ml) was selected for further investigation on its secondary metabolites.
Bioassay-guided fractionation of the EtOAc extract of its liquid culture afforded seven compounds, which were identified as
alternariol (1), alternariol 9-methyl ether (2), altechromone A (3), herbarin A (4), cerevisterol (5), 3β,5α-dihydroxy-(22E,24R)-ergosta-7,22-dien-6-one (6) and 3β-hydroxy-(22E,24R)-ergosta-5,8,22-trien-7-one (7), respectively, by spectral means (MS, IR, 1H- and 13C-NMR). In vitro antimicrobial assay showed that compound 3 was substantially active against Bacillus subtilis, Escherichia coli, Pseudomonas fluorescens and Candida albicans with the MICs of 3.9, 3.9, 1.8, and 3.9 μg/ml, respectively. Compound 4 also showed pronounced antifungal activity against Trichophyton rubrum and C. albicans with MICs of both 15.6 μg/ml. In addition, compound 1 exhibited strong xanthine oxidase inhibitory activity with the IC50 of 15.5 μM, comparable to that of positive control, allopurinol (IC50: 10.7 μM). 相似文献
8.
Ansari MA Khan HM Khan AA Sultan A Azam A 《Applied microbiology and biotechnology》2012,94(2):467-477
The reemergence of infectious diseases and the continuous development of multidrug resistance among a variety of disease-causing
bacteria in clinical setting pose a serious threat to public health worldwide. Extended-spectrum β-lactamases (ESBLs) that
mediate resistance to third-generation cephalosporin are now observed all over the world in all species of Enterobacteriaceae,
especially Escherichia coli and Klebsiella pneumoniae. In this work, ZnO nanoparticles (NPs) were synthesized by the sol–gel method and characterized by powder X-ray diffraction,
scanning electron microscopy (SEM) and atomic force microscopy (AFM). The image of synthesized ZnO NPs appeared spherical
in SEM with a diameter of ≈19 nm and as hexagonal crystal in AFM. Clinical isolates were assessed for ESBL production and
shown to be sensitive to ZnO NPs by different methods such as minimal inhibitory concentration (MIC) and minimal bactericidal
concentration, time-dependent growth inhibition assay, well diffusion agar methods and estimation of colony forming units
(CFU) of bacteria. The lowest MIC value for E. coli and K. pneumoniae was found to be 500 μg/ml. The results showed that ZnO NPs at 1,000 μg/ml completely inhibit the bacterial growth. The antibacterial
effect of ZnO nanoparticles was gradual, but time- and concentration-dependent. The maximum inhibition zone at100 μg/ml for
E. coli and K. pneumoniae was 22 and 20 mm, respectively. With the increasing ZnO NP loading, there is significant reduction in the numbers of CFU.
At the concentration of 1,000 μg/ml, the decline in per cent survival of E. coli and K. pneumoniae was found to be 99.3% and 98.6%, respectively. 相似文献
9.
Jones SE Burgos JM Lutnesky MM Sena JA Kumar S Jones LM Varela MF 《Current microbiology》2011,62(4):1139-1146
Antimicrobial agent usage is common in animal agriculture for therapeutic and prophylactic purposes. Selective pressure exerted
by these antimicrobials on soil bacteria could result in the selection of strains that are resistant due to chromosomal- or
plasmid-derived genetic components. Multiple antimicrobial resistances in Escherichia coli and the direct relationship between antimicrobial agent use over time has been extensively studied, yet the relationship
between the age of an animal agriculture environment such as a dairy farm and antibiotic resistance remains unclear. Therefore,
we tested the hypothesis that antimicrobial-resistance profiles of E. coli isolated from dairy farm topsoil correlate with dairy farm age. E. coli isolated from eleven dairy farms of varying ages within Roosevelt County, NM were used for MIC determinations to chloramphenicol,
nalidixic acid, penicillin, tetracycline, ampicillin, amoxicillin/clavulanic acid, gentamicin, trimethoprim/sulfamethoxazole,
cefotaxime, and ciprofloxacin. The minimum inhibitory concentration values of four antibiotics ranged 0.75 to >256 μg/ml,
1 to >256 μg/ml, 12 to >256 μg/ml, and 0.75 to >256 μg/ml for chloramphenicol, nalidixic acid, penicillin, and tetracycline,
respectively. The study did not show a direct relationship between antibiotic resistance and the age of dairy farms. 相似文献
10.
Ángeles Verástegui Julia Verde Santos García Norma Heredia Azucena Oranday Catalina Rivas 《World journal of microbiology & biotechnology》2008,24(7):1249-1252
The in vitro antimicrobial activity against pathogenic bacteria, yeast, and molds were examined in extracts of the Agave species A. lecheguilla, A. picta, A. scabra and A. lophanta using an agar diffusion technique. The extracts of A. picta produced zones of inhibition of 9–13 mm for E. coli, L. monocytogenes, S. aureus, and V. cholerae, while B. cereus and Y. enterocolitica were not inhibited. The other Agave species did not show any detectable inhibitory activity against the bacteria tested; however, all four Agave sp. were inhibitory against all yeast and molds analyzed as evident by 9–20 mm zones of inhibition. The minimum microbicidal
concentration (MMC) of the active extract ranged from 1.8 to 7.0 mg/ml for the sensitive bacteria, and 2.0–3.0 mg/ml for yeast.
In the case of molds, the minimum inhibitory concentration (MIC) of the active extracts ranged from 3.0 to 6.0 mg/ml. Together,
these data suggest that the Agave sp. analyzed are potential antimicrobial candidates with a broad range of activity. 相似文献
11.
High level expression and purification of antimicrobial human cathelicidin LL-37 in Escherichia coli
Ján Krahulec Marcela Hyršová Stanislav Pepeliaev Jana Jílková Zbyněk Černý Jana Machálková 《Applied microbiology and biotechnology》2010,88(1):167-175
The human antimicrobial peptide LL-37 is a cationic peptide with antimicrobial activity against both Gram-positive and Gram-negative
microorganisms. This work describes the development of an expression system based on Escherichia coli capable of high production of the recombinant LL-37. The fusion protein Trx-LL-37 was expressed under control of T7 promoter.
The expression of T7 polymerase in the E. coli strain constructed in this work was controlled by regulation mechanisms of the arabinose promoter. The expression plasmid
was stabilized by the presence of parB locus which ensured higher homology of the culture during cultivation without antibiotic selection pressure. This system
was capable of producing up to 1 g of fusion protein per 1 l of culture. The subsequent semipreparative HPLC allowed us to
isolate 40 mg of pure LL-37. LL-37 showed high antimicrobial activity against both Gram-negative and Gram-positive microorganisms.
Its activity against Candida albicans was practically nonexistent. Minimal Inhibition Concentration (MIC) determined for E. coli was 1.65 μM; for Staphylococcus aureus 2.31 μM, and for Enterococcus faecalis 5.54 μM. The effects of cathelicidin on E. coli included the ability to permeabilize both cell membranes, as could be observed by the increase of β-galactosidase activity
in extracellular space in time. Physiological changes were studied by scanning electron microscopy; Gram-positive microorganisms
did not show any visible changes in cell shapes while the changes observed on E. coli cells were evident. The results of this work show that the herein designed expression system is capable of producing adequate
quantities of active human antimicrobial peptide LL-37. 相似文献
12.
Annette C. Hurst Philip A. Gottlieb Boris Martinac 《European biophysics journal : EBJ》2009,38(4):415-425
The spider peptide GsMTx4, at saturating concentration of 5 μM, is an effective and specific inhibitor for stretch-activated
mechanosensitive (MS) channels found in a variety of eukaryotic cells. Although the structure of the peptide has been solved,
the mode of action remains to be determined. Because of its amphipathic structure, the peptide is proposed to interact with
lipids at the boundaries of the MS channel proteins. In addition, GsMTx4 has antimicrobial effects, inhibiting growth of several
species of bacteria in the range of 5–64 μM. Previous studies on prokaryotic MS channels, which serve as model systems to
explore the principle of MS channel gating, have shown that various amphipathic compounds acting at the protein–lipid interface
affect MS channel gating. We have therefore analyzed the effect of different concentrations of extracellular GsMTx4 on MS
channels of small conductance, MscS and MscK, in the cytoplasmic membrane of wild-type E. coli spheroplasts using the patch-clamp technique. Our study shows that the peptide GsMTx4 exhibits a biphasic response in which
peptide concentration determines inhibition or potentiation of activity in prokaryotic MS channels. At low peptide concentrations
of 2 and 4 μM the gating of the prokaryotic MS channels was hampered, manifested by a decrease in pressure sensitivity. In
contrast, application of peptide at concentrations of 12 and 20 μM facilitated prokaryotic MS channel opening by increasing
the pressure sensitivity. 相似文献
13.
Ahmad Asoodeh Adel Ghorani Azam JamshidKhan Chamani 《International journal of peptide research and therapeutics》2012,18(2):107-115
In this study, we extracted and purified antimicrobial peptides (AMPs) secreted from skin of Euphlyctis cyanophlyctis using reverse phase-high performance liquid chromatography. Three AMPs were isolated from skin secretions of this frog and
sequenced using tandem mass spectrometry. The purified peptides were named buforin-EC (1875.05 ± 0.5 Da), cyanophlyctin (2347.50 ± 0.5 Da)
and temporin-ECa (1013.33 ± 0.5 Da). Multiple alignments and homology search showed that buforin-EC, cyanophlyctin and temporin-ECa
had a homology of 71.43, 47.1, and 69.23% to buforin II, brevinin-2EC, and temporin-1CSc, respectively. Antimicrobial tests
demonstrated that our peptides have a great antimicrobial effect on both gram-positive and gram-negative bacteria. The results
indicated that they have an overall minimum inhibitory concentration (MIC) below 13 μM against E. coli. No hemolysis was observed in around of their MIC values. In conclusion, skin secretions of E. cyanophlyctis contain a novel class of AMPs with the proper characteristics. 相似文献
14.
Guo-Qiu Wu Jia-Xuan Ding Lin-Xian Li Hai-liang Wang Rui Zhao Zi-Long Shen 《Current microbiology》2009,59(2):147-153
The treatment of infections caused by bacteria resistant to the vast majority of antibiotics is a challenge worldwide. To
evaluate the effect of S-thanatin (an analog of thanatin, a cationic antimicrobial peptide isolated from the hemipteran insect
Podisus maculiventris) against microbial resistant to antibiotics, we studied its bactericidal kinetics, synergistic effect, resistance, and activity
on clinical isolates of Klebsiella pneumoniae resistant to conventional antibiotics with different structures. The bactericidal rate of S-thanatin was more than 99% against
K. pneumoniae ATCC 700603 when bacterial cultures were monitored for 60 min. The peptide was synergistic with β-lactam cefepime in most
of the clinical MDR isolates tested (7/8). An average value of FIC was 0.3708. No synergy was found between the peptide and
amoxicillin, gentamycin, tetracycline, or ciprofloxacin in all bacteria tested. A total of 48 isolates of K. pneumoniae with different resistance spectrum tested was susceptible to S-thanatin. The MICs were 6.25–25 μg/ml. No significant difference
in the MICs of S-thanatin between the sensitive isolates and the resistant isolates to single antibiotic was observed (P > 0.05). The resistance of K. pneumoniae ATCC 700603 to S-thanatin was slightly higher, when cultured at sub-inhibitory concentration for 5 days. S-thanatin may be
an attractive candidate for developing into an antimicrobial agent. 相似文献
15.
M. H. Hwang M. H. Kim E. Gebru B. Y. Jung S. P. Lee S. C. Park 《World journal of microbiology & biotechnology》2008,24(10):2277-2282
This study evaluated the killing rate as well as the antimycoplasmal effect of surfactins isolated from Bacillus subtilis complex BC1212, either alone or in combination with various antibacterials against Mycoplasma hyopneumoniae. Prior to the killing rate and the combination effect studies of surfactins, the minimal inhibitory concentrations (MICs)
of various antibacterials and surfactins (consisting of surfactins A, B, C, and D) against M. hyopneumoniae were investigated. The MIC of all surfactins was found to be 64 μg/ml. The MICs of colistin (COL), norfloxacin (NFX), oxytetracycline
(OTC), streptomycin (SM) and tiamulin (TIA) were >256, 0.063, 0.025, 4, and 0.015 μg/ml, respectively. In the killing rate
curve studies, surfactin C at 2× MIC and 4× MIC concentrations was found to reduce viability by >3 log10 c.c.u./ml within 2–4 h of incubation. Combination of surfactin C with other antibacterials showed additive interaction from
the viewpoint of fractional inhibitory concentration (FIC) index of >0.5 but ≤2 as a borderline. Taking all results into consideration,
surfactin C may be useful as a preventive or therapeutic adjuvant in the pathogenesis of mycoplasmal infection. 相似文献
16.
In the present study, we investigated the possible involvement of oxidative stress in ciprofloxacin-induced cytotoxicity against
several reference bacteria including Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 29213, and clinical isolate of methicillin-resistant Staphylococcus aureus (MRSA). Oxidative stress was assessed by measurement of hydrogen peroxide generation using a FACScan flow cytometer. The antibacterial activity of ciprofloxacin was assessed using the disk diffusion method and by measuring the minimum inhibitory
concentration (MIC). Ciprofloxacin induced a dose-dependent antibacterial activity against all bacteria where the highest
tested concentration was 100 ug/ml. Results revealed that E. coli cells were highly sensitive to ciprofloxacin (MIC = 0.21 μg/mL ± 0.087), P. aeruginosa and S. aureus cells were intermediately sensitive (MIC = 5.40 μg/mL ± 0.14; MIC = 3.42 μg/mL ± 0.377, respectively), and MRSA cells were highly resistant (MIC = 16.76 μg/mL ± 2.1). Pretreatment of E. coli cells with either vitamin E or vitamin C has significantly protected cells against ciprofloxacin-induced cytotoxicity. These
results indicate the possible antagonistic properties for vitamins C or E when they are used concurrently with ciprofloxacin. 相似文献
17.
Ling Ding Xi Li Peng Liu Shiqian Li Jiliang Lv 《Biological trace element research》2010,137(3):364-372
The biological effect of Se and Cu2+ on Escherichia coli (E. coli) growth was studied by using a 3114/3236 TAM Air Isothermal Calorimeter, ampoule method, at 37°C. From the thermogenesis
curves, the thermokinetic equations were established under different conditions. The kinetics showed that a low concentration
of Se (1–10 μg/mL) promoted the growth of E. coli, and a high concentration of Se (>10 μg/mL) inhibited the growth, but the Cu2+ was always inhibiting the growth of E. coli. Moreover, there was an antagonistic or positive synergistic effect of Se and Cu2+ on E. coli in the different culture medium when Se was 1–10 μg/ml and Cu2+ was 1–20 μg/ml. There was a negative synergistic effect of Se and Cu2+ on E. coli when Se was higher than 10 μg/ml and Cu2+ was higher than 20 μg/ml. The antagonistic or synergistic effect between Se and Cu2+ on E. coli was related to the formation of Cu–Se complexes under the different experimental conditions chosen. 相似文献
18.
Ping Su Anders Henriksson Christina Nilsson Hazel Mitchell 《World journal of microbiology & biotechnology》2008,24(9):1837-1842
The aim of this study was to assess the effect of a commercial green tea extract (TEAVIGO™) on the microbial growth of three
probiotic strains (Lactobacillus and Bifidobacterium), as well as three pathogenic bacteria. MIC and co-culture studies were performed. The MICs of the green tea extract against
Staphylococcus aureus and Streptococcus pyogenes (100 μg ml−1) were considerably lower than those against the probiotic strains tested (>800 μg ml−1) and Escherichia coli (800 μg ml−1). In co-culture studies, a synergistic effect of the probiotic strains and the green tea extract was observed against both
Staph. aureus and Strep. pyogenes. Green tea extract in combination with probiotics significantly reduced the viable count of both pathogens at 4 h and by
24 h had completely abolished the recovery of viable Staph. aureus and Strep. pyogenes. These reductions were more significant than the reductions induced by probiotics or green tea extracts used separately.
These results demonstrate the potential for combined therapy using the green tea extract plus probiotics on microbial infections
caused by Staph. aureus and Strep. pyogenes. As probiotics and the green tea extract are derived from natural products, treatment with these agents may represent important
adjuncts to, or alternatives to, conventional antibiotic therapy. 相似文献
19.
An endophytic Xylaria sp., having broad antimicrobial activity, was isolated and characterized from Ginkgo biloba L. From the culture extracts of this fungus, a bioactive compound P3 was isolated by bioactivity-guided fractionation and
identified as 7-amino-4-methylcoumarin by nuclear magnetic resonance, infrared, and mass spectrometry spectral data. The compound
showed strong antibacterial and antifungal activities in vitro against Staphylococcus aureus [minimal inhibitory concentrations (MIC) 16 μg·ml−1], Escherichia coli (MIC, 10 μg·ml−1), Salmonella typhia (MIC, 20 μg·ml−1), Salmonella typhimurium (MIC, 15 μg·ml−1), Salmonella enteritidis (MIC, 8.5 μg·ml−1), Aeromonas hydrophila (MIC, 4 μg·ml−1), Yersinia sp. (MIC, 12.5 μg·ml−1), Vibrio anguillarum (MIC, 25 μg·ml−1), Shigella sp. (MIC, 6.3 μg·ml−1), Vibrio parahaemolyticus (MIC, 12.5 μg·ml−1), Candida albicans (MIC, 15 μg·ml−1), Penicillium expansum (MIC, 40 μg·ml−1), and Aspergillus niger (MIC, 25 μg·ml−1). This is the first report of 7-amino-4-methylcoumarin in fungus and of the antimicrobial activity of this metabolite. The
obtained results provide promising baseline information for the potential use of this unusual endophytic fungus and its components
in the control of food spoilage and food-borne diseases. 相似文献
20.
Photodynamic treatment by the cationic TMPyP photosensitizer was undertaken on the multiple antibiotic-resistant bacteria
Acinetobacter baumannii and Escherichia coli. Total eradication of the bacterial cultures was determined immediately after initiation of illumination when these bacteria
were treated with 5, 10, 15, 20-tetra (4-N methylpyridyl)porphine (TMPyP) at a concentration of 29.4 μmol/L and illuminated
by blue, green, or red light. Total eradication of both bacteria was obtained also after treatment of bacterial cultures with
3.7 μmol/L TMPyP and illumination with blue light (400–450 nm). On the other hand, an 8- or 16- to 20-fold higher light intensity,
respectively, was required for total eradication upon illumination with green (480–550 nm) or red light (600–700 nm). A 407-nm
blue light only 7 and 9 joules/cm2, respectively, was needed for total eradication of both bacteria even at a concentration of 3.7 μmol/L TMPyP. X-ray-linked
microanalysis demonstrated loss of potassium and a flood of sodium and chloride into the cells, indicating serious damage
to the cytoplasmic membrane. Transmission electron microscopy (TEM) revealed structural changes and damage to the membrane
of treated E. coli. In A. baumannii-treated cells, mesosomes and black dots that resemble aggregation of polyphosphate polymers could be seen. DNA breakage appeared
only after a long period of illumination, when the bacterial cell was no longer viable. It can be concluded that cytoplasmic
membrane damage and not DNA breakage is the major cause for bacterial death upon photosensitization.
Received: 13 October 2000 / Accepted: 17 November 2000 相似文献