Evaluation of Membrane Fragments Extracted from Escherichia coli and Pseudomonas aeruginosa on Campylobacter jejuni Growth under Normal Atmosphere

ABSTRACT Study on extraction of membrane fragments from Escherichia coli and Psuedomonas aeruginosa were determined for using to support Campylobacter cultivation under normal atmosphere. Crude membrane fragments were extracted from 45 strains of E. coli and 44 strains of P. aeruginosa. Strains that provided highest efficiency of oxygen reduction were selected to purify membrane fragments by French pressure cell and ultracentrifugation. The purified membrane fragments were characterized and investigated for supporting Campylobacter jejuni growth in Mueller-Hinton broth. The broth supplemented with and without membrane fragments was incubated under normal atmosphere at 37°C or 42°C. Campylobacter growth in the broth containing purified membrane fragments was initially observed within 6 to 12 hours of incubation while the media without supplemented with membrane fragments showed no growth of the bacteria. Therefore, oxygen reducing membrane fragments prepared from the selected strains could support Campylobacter cultivation under normal atmosphere

Proteome Analyses of Cellular Proteins in Methicillin-Resistant Staphylococcus aureus Treated with Rhodomyrtone, a Novel Antibiotic Candidate

The ethanolic extract from Rhodomyrtus tomentosa leaf exhibited good antibacterial activities against both methicillin-resistant Staphylococcus aureus (MRSA) and S. aureus ATCC 29213. Its minimal inhibitory concentration (MIC) values ranged from 31.25–62.5 µg/ml, and the minimal bactericidal concentration (MBC) was 250 µg/ml. Rhodomyrtone, an acylphloroglucinol derivative, was 62.5–125 times more potent at inhibiting the bacteria than the ethanolic extract, the MIC and MBC values were 0.5 µg/ml and 2 µg/ml, respectively. To provide insights into antibacterial mechanisms involved, the effects of rhodomyrtone on cellular protein expression of MRSA have been investigated using proteomic approaches. Proteome analyses revealed that rhodomyrtone at subinhibitory concentration (0.174 µg/ml) affected the expression of several major functional classes of whole cell proteins in MRSA. The identified proteins involve in cell wall biosynthesis and cell division, protein degradation, stress response and oxidative stress, cell surface antigen and virulence factor, and various metabolic pathways such as amino acid, carbohydrate, energy, lipid, and nucleotide metabolism. Transmission electron micrographs confirmed the effects of rhodomyrtone on morphological and ultrastructural alterations in the treated bacterial cells. Biological processes in cell wall biosynthesis and cell division were interrupted. Prominent changes including alterations in cell wall, abnormal septum formation, cellular disintegration, and cell lysis were observed. Unusual size and shape of staphylococcal cells were obviously noted in the treated MRSA. These pioneer findings on proteomic profiling and phenotypic features of rhodomyrtone-treated MRSA may resolve its antimicrobial mechanisms which could lead to the development of a new effective regimen for the treatment of MRSA infections

Occurrence of Arbuscular Mycorrhizal Fungi in Vegetables Grown in Nakornpathom Province, Thailand

ABSTRACT Arbuscular mycorrhizal colonization in the roots and spore numbers in the rhizosphere of vegetables grown in Nakornpathom province of Thailand were studied. A percentage of fungal infection in the roots was analyzed by a staining method of Phillip and Hayman. A quantity of mycorrhizal spores was determined by a modification of a wet-sieving and decanting technique, and centrifugation method. Spore numbers (mean±SD) of garlic, Chinese kale and broccoli plants were 64.59±28.23, 64.09±36.62 and 45.70±33.01 spores per 100 grams of dry soil, respectively. Three genera of spores were identified from these plants, including Acaulospora, Gigaspora and Glomus with occurrence of individuals ranging from 48.05% to 100%. Internal vesicules and arbuscules of mycorrhizal fungi were observed only in garlic roots for all samples with the infection rates of 28.95±26.75%. There was no relationship between spore numbers and mycorrhizal colonization levels in the garlic plants. An occurrence of mycorrhizal spores in soils for cultivation of broccoli and Chinese kale did not affect the fungal colonization in the roots

Identification of <i>Staphylococcus aureus</i> cellular proteins disappeared after rhodomyrtone treatment.

<p>Identification of <i>Staphylococcus aureus</i> cellular proteins disappeared after rhodomyrtone treatment.</p

Two dimensional electrophoresis of the of cellular methicillin-resistant <i>S. aureus</i> proteomes.

<p>Protein extracts were prepared from rhodomyrtone-treated cells (A) and untreated control cells (B).</p

Time-kill curves of rhodomyrtone against MRSA.

<p>Viability was counted at the indicated time points by serial dilution plating. Each point represented the mean of log₁₀ ± standard deviations of three different experiments performed in duplicate.</p

Transmission electron microscopy demonstrating the effects of rhodomyrtone on methicillin-resistant <i>S. aureus</i> NPRC 001R morphology and ultrastructure.

<p>The bacteria were incubated in CAMHB for 18 h, media containing 0.174 µg/ml of rhodomyrtone (C, D, E, and F) and untreated control cultures (A and B). Scale bars = 1 µm (A and C) and 0.5 µm (B, D, E, and F), respectively.</p

Identification of <i>Staphylococcus aureus</i> cellular proteins presented after rhodomyrtone treatment.

<p>Identification of <i>Staphylococcus aureus</i> cellular proteins presented after rhodomyrtone treatment.</p

Transmission electron microscopy demonstrating the effects of rhodomyrtone on <i>S. aureus</i> ATCC 29213 morphology and ultrastructure.

<p>The bacteria were incubated in CAMHB for 18 h, media containing 0.174 µg/ml of rhodomyrtone (C, D, E, and F) and untreated control cultures (A and B). Scale bars = 1 µm (A and C) and 0.5 µm (B, D, E, and F), respectively.</p