Antimicrobial activity of perilla seed polyphenols against oral pathogenic bacteria

A perilla seed (Perilla frutescens Britton var. japonica Hara) extract was examined for its antimicrobial activity against oral cariogenic streptococci and periodontopathic Porphyromonas gingivalis. Luteolin, one of the components of perilla seed, showed the strongest antimicrobial effect among the phenolic compounds. According to our results, perilla seed may be the source of an antimicrobial agent that could prevent dental caries and periodontal diseases.     

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 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.     

Extraction and purification of lipoteichoic acids from gram-positive bacteria

Hot and cold, 80% aqueous phenol extraction procedures together with an aqueous extraction technique have been evaluated for the isolation of lipoteichoic acids from the cytoplasmic membrane of Gram-positive bacteria. Lipoteichoic acids of Staphylococcus aureusH, Micrococcus 2102, Bacillus subtilis 168, and Bacillus subtilis W-23 were examined as each of them emphasises a different problem of contamination. The purity of the lipoteichoic acids with respect to cell-wall material, nucleic acid, and protein is discussed together with the criteria of purity which enables critical structural analysis of lipoteichoic acids to be carried out.     

Antimicrobial activity and effects of resveratrol on human pathogenic bacteria

Resveratrol (3,4′,5-trihydroxistilbene) is a phytoalexin commonly found in food and drinks, which is thought to possess antimicrobial activity. These effects together with its well known antioxidant properties are beneficial for the prevention of some diseases, e.g. cancer. In this study we have verified that resveratrol has antibacterial activity against all tested Gram-positive bacteria using both the disk diffusion and broth microdilution methods. Time kill assays of this compound against Gram-positive bacteria showed that its effects on the growth of bacterial cells were due to bacteriostatic action. The addition of resveratrol has allowed the identification of changes in cell morphology and DNA contents, which have been assessed through microscopic analysis and flow cytometry; this suggests that the cell cycle is affected by resveratrol. This study indicates that this compound may have potential as a natural antibacterial agent for both food preservation and medicinal use.     

Absolute configuration of the ocimene monoterpenoids from Artemisia absinthium

The absolute configuration (AC) of the naturally occurring ocimenes (−)‐(3S ,5Z )‐2,6‐dimethyl‐2,3‐epoxyocta‐5,7‐diene ( 1 ) and (−)‐(3S ,5Z )‐2,6‐dimethylocta‐5,7‐dien‐2,3‐diol ( 2 ), isolated from the essential oils of domesticated specimens of Artemisia absinthium , followed by vibrational circular dichroism (VCD) studies of 1 , as well as from the acetonide 3 and the monoacetate 4 , both derived from 2 , since secondary alcohols are not the best functional groups to be present during VCD studies in solution due to intermolecular associations. The AC follows from comparison of experimental and calculated VCD spectra that were obtained by Density Functional Theory computation at the B3LYP/DGDZVP level of theory. Careful nuclear magnetic resonance (NMR) measurements were compared with literature values, providing for the first time systematic ¹H and ¹³C chemical shift data. Regarding homonuclear ¹H coupling constants, after performing a few irradiation experiments that showed the presence of several small long‐range interactions, the complete set of coupling constants for 3 , which is representative of the four studied molecules, was determined by iterations using the PERCH software. This procedure even allowed assigning the pro ‐R and pro ‐S methyl group signals of the two gem ‐dimethyl groups present in 3 .     

Antimicrobial activity of certain bacteria and fungi isolated from soil mixed with human saliva against pathogenic microbes causing dermatological diseases

Soil samples (collected from El-Madina El-Monawara, Kingdom Saudi Arabia) were mixed with human saliva, incubated in media suitable for bacterial and fungal growth and filtered. Eighteen bacterial and five fungal species were isolated and identified. The bacterial and fungal filtrates as well as the isolated species were evaluated for their antimicrobial activities against some pathogenic microbes causing dermatological diseases (Staphylococcus aureus, methicillin resistant S. aureus (MRSA) and Aspergillus niger). The bacterial filtrate showed significant antagonistic effect against S. aureus and methicillin resistant S. aureus (MRSA), whereas showed non inhibitory action on the pathogenic fungus. In contrast, the fungal filtrate antagonized the growth of the pathogenic fungus (A. niger) and did not produce any inhibitory effect on the two tested pathogenic bacteria. The isolated bacterial species showed different levels of antagonistic activities against the three tested microbes. Bacillus subtilis was described as potent isolate against the three pathogens, followed by Esherichia coli. However, Bacillus megaterium strongly inhibited the growth of the pathogenic bacteria only. On the other side, all the fungal filtrates of the isolated species, except Cochliobolus lanatus showed antagonistic activity against the pathogenic fungus (A. niger). The filtrate of Fusarium oxysporum and Emericella nidulans counteracted the growth of S. aureus, whereas, the growth of MRSA was inhibited only by the filtrate of E. nidulans. From the passage way of our respected prophet, how is never tells from him self, if any person complains from awound or ulcer, the messenger of Allah (prayers and peace be upon him) put his forefinger on the ground and lift it then he says: (In the Name of God, soil of our land, with the saliva of some of us, our sick person will get well after the permission of our God) Al-Bukhari. The meaning of this Hadith that the prophet takes his saliva on the forefinger then he put it on the soil and wipe on the wound place while saying the above Hadith that is shows the Prophet’s miracle, which is evidence of healing by using soil and saliva.     

Antibacterial activity of different honeys against pathogenic bacteria

To study the antimicrobial activity of honey, 60 samples of various botanical origin were evaluated for their antimicrobial activities against 16 clinical pathogens and their respective reference strains. The microbiological quality of honeys and the antibiotic susceptibility of the various isolates were also examined. The bioassay applied for determining the antimicrobial effect employs the well-agar diffusion method and the estimation of minimum active dilution which produces a 1 mm diameter inhibition zone. All honey samples, despite their origin (coniferous, citrus, thyme or polyfloral), showed antibacterial activity against the pathogenic and their respective reference strains at variable levels. Coniferous and thyme honeys showed the highest activity with an average minimum dilution of 17.4 and 19.2% (w/v) followed by citrus and polyfloral honeys with 20.8 and 23.8% respectively. Clinical isolates of Staphylococcus aureus subsp. aureus, Escherichia coli, Salmonella enterica subsp. Enterica, Streptococcus pyogenes, Bacillus cereus and Bacillus subtilis were proven to be up to 60% more resistant than their equal reference strains thus emphasizing the variability in the antibacterial effect of honey and the need for further research.     

An antibiotic with activity against gram-positive bacteria from the gentamicin-producing strain of Micromonospora purpurea

A mixture of polycyclic aromatic compounds with activity against gram-positive bacteria was isolated from a gentamicin-producing species of Micromonospora.     

Antimicrobial activity of food-related Penicillium sp. against pathogenic bacteria in laboratory media and a cheese model system

Food-related Penicillium species ( n ep fy1 = rs 34) and Geotrichum candidum ( n = 11) grown on Czapek Dox and brie agar were tested for their ability to suppress growth of pathogenic bacteria. Ten out of 13 P. camemberti showed antagonistic activity while the other species did not interact significantly with the bacterial growth. The order of inhibition was: Gram-negative bacteria and Bacillus cereus > Listeria monocytogenes , Lactococcus sp. > Micrococcus sp. whereas Lactobacillus sp., Staphylococcus aureus and some Micrococcus sp. were unaffected. When Salmonella typhimurium was inoculated together with P. camemberti P25 in brie agar, bacterial growth was inhibited during the first 6 d of incubation whereafter growth started. The inhibition of L. monocytogenes was similar but less pronounced. The antimicrobial activity produced by P. camemberti P25 and L84 was enhanced with increasing amount of sucrose in the medium. The activity was increased at low pH and destroyed at pH above 8. It was detectable at 15°C but not at 37°C indicating that volatile metabolites might be involved. No significant accumulation of organic acids and no secondary metabolites such as mycotoxins were detected. HSGC-MS analysis indicated that acetaldehyde, benzaldehyde, 3-methylbutanal and 1-octen-3-ol were produced by P. camemberti during the period when inhibitory activity was observed. Pure acetaldehyde and benzaldehyde were shown to be inhibitory to L. monocytogenes and Salm. typhimurium when grown at 15°C and pH 5·5 and 7·0.     

Antagonistic activity against pathogenic bacteria by human vaginal lactobacilli

This study attempted to isolate lactobacilli strains from healthy vaginal ecosystem to search for a new effective antibacterial probiotic strain. The strains were identified and characterized for their probiotic properties including bile salt and acid tolerance, growth at acidic pH, their ability to utilize protein, starch, and lipid, the production of hydrogen peroxide and bacteriocin as well as their antibiotic resistance patterns. The antibacterial activity of the culture supernatant of these strains were tested against a wide range of Gram-positive and Gram-negative pathogenic bacteria including Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae. Salmonella typhi, and Salmonella typhimurium. None of the strains inhibited the growth of Gram-negative bacteria. Contrastly, the culture supernatant of strain L 22, identified as Lactobacillus reuteri, significantly inhibited all of the clinical isolates of methicillin-resistant S. aureus (MRSA). The antibacterial effect of the selected strain L 22 was further investigated. In the presence of L 22, the bacterial growth was assessed in vitro by viable bacterial counting. The numbers of viable cells were significantly lower in L 22-containing broth than those in the control by 6h. This finding clearly demonstrates that strain L 22 can produce an anti-MRSA effect. The antibacterial ability of the strain L 22 was fundamentally attributed to their bacteriocin production which can cause both cell inhibition and cell death.     

Antibacterial activity of plasma from crocodile (Crocodylus siamensis) against pathogenic bacteria

ABSTRACT: BACKGROUND: The Siamese crocodile (Crocodylus siamensis) is a critically endangered species of freshwater crocodiles. Crocodilians live with opportunistic bacterial infection but normally suffer no adverse effects. They are not totally immune to microbial infection, but their resistance thereto is remarkably effective. In this study, crude and purified plasma extracted from the Siamese crocodile were examined for antibacterial activity against clinically isolated, human pathogenic bacterial strains and the related reference strains. METHODS: Crude plasma was prepared from whole blood of the Siamese crocodile by differential sedimentation. The crude plasma was examined for antibacterial activity by the liquid growth inhibition assay. The scanning electron microscopy was performed to confirm the effect of crude crocodile plasma on the cells of Salmonella typhi ATCC 11778. Effect of crude crocodile plasma on cell viability was tested by MTT assay. In addition, the plasma was purified by anion exchange column chromatography with DEAE-Toyopearl 650M and the purified plasma was tested for antibacterial activity. RESULTS: Crude plasma was prepared from whole blood of the Siamese crocodile and exhibited substantial antibacterial activities of more than 40% growth inhibition against the six reference strains of Staphylococcus aureus, Salmonella typhi, Escherichia coli, Vibrio cholerae, Pseudomonas aeruginosa, and Staphylococcus epidermidis, and the four clinical isolates of Staphylococcus epidermidis, Pseudomonas aeruginosa, Salmonella typhi, and Vibrio cholerae. Especially, more than 80% growth inhibition was found in the reference strains of Salmonella typhi, Vibrio cholerae, and Staphylococcus epidermidis and in the clinical isolates of Salmonella typhi and Vibrio cholerae. The effect of the crude plasma on bacterial cells of Salmonella typhi, a certain antibacterial material probably penetrates progressively into the cytoplasmic space, perturbing and damaging bacterial membranes. The effect of the crude plasma was not toxic by the yellow tetrazolium bromide (MTT) assay using a macrophage-like cell, RAW 264.7. The pooled four fractions, designated as fractions D1-D4, were obtained by column chromatography, and only fraction D1 showed growth inhibition in the reference strains and the clinical, human pathogenic isolates. CONCLUSIONS: The crude and purified plasma from the Siamese crocodile significantly showed antibacterial activity against pathogenic bacteria and reference strains by damage cell membrane of target bacterial cells. From the MTT assay, the Siamese crocodile plasma was not cytotoxic to the cells.     

In vitro inhibitory activity of human vaginal lactobacilli against pathogenic bacteria associated with bacterial vaginosis in Kenyan women

Lactobacilli have been shown to inhibit in vitro growth of many pathogens and have been used as probiotics to treat a broad range of gastrointestinal and/or vaginal disorders. We sought to determine the in vitro inhibitory potential of lactobacilli of vaginal origin to some bacteria associated with bacterial vaginosis (BV), to characterize the inhibitory substances produced by these lactobacilli and to assess H₂O₂ production. Vaginal specimens were obtained by swabbing the lateral vaginal walls from 107 women two months following BV treatment. One hundred and fifty eight Lactobacillus spp. were isolated in 82 of the 107 women. Lactobacillus jensenii was the predominant strain isolated among these women (29/158; 18.4%). Among 158 culture supernatants tested for antibacterial activity against BV-associated bacteria, none inhibited the growth of Bacteroides fragilis while 23% (37/158), 28% (45/158) and 29% (46/158) inhibited the growth of Prevotella bivia, Gardnerella vaginalis and Mobiluncus spp. respectively. The lactobacilli produced supernatants with a pH range between 2.62 and 6.71; the highly acidic (pH 2–3.99) supernatants were more inhibitory to the indicator strains. There was significant reduction in the mean zones of inhibition following chemical and physical treatment of the supernatants (p = 0.0025). Acid, bacteriocins and H₂O₂ demonstrated potential for antagonism of the bacterial pathogens. These substances may augment each other rather that each working independently on the pathogens.     

Pectin-like acidic polysaccharide from Panax ginseng with selective antiadhesive activity against pathogenic bacteria

Previous studies have revealed the inhibitory effects of an acidic polysaccharide purified from the root of Panax ginseng against the adhesion of Helicobacter pylori to gastric epithelial cells and the ability of Porphyromonas gingivalis to agglutinate erythrocytes. In this study, this acidic polysaccharide from P. ginseng, PG-F2, was investigated further, in order to characterize its antiadhesive effects against Actinobacillus actinomycetemcomitans, Propionibacterium acnes, and Staphylococcus aureus. The minimum inhibitory concentrations (MIC) were found to be in a range of 0.25-0.5mg/mL. However, results showed no inhibitory effects of PG-F2 against Lactobacillus acidophilus, Escherichia coli, or Staphylococcus epidermidis. PG-F2 is a pectin-type polysaccharide with a mean MW of 1.2 x 10(4) Da, and consists primarily of galacturonic and glucuronic acids along with rhamnose, arabinose, and galactose as minor components. The complete hydrolysis of PG-F2 via chemical or carbohydrolase enzyme treatment resulted in the abrogation of its antiadhesive activity, but limited hydrolysis via treatment with pectinase (EC. 3.2.1.15) yielded an oligosaccharide fraction, with activity comparable to the precursor PG-F2 (the MIC of ca. 0.01 mg/mL against H. pylori and P. gingivalis). Our results suggest that PG-F2 may exert a selective antiadhesive effect against pathogenic bacteria, while having no effects on beneficial and commensal bacteria.