#gram-positive

[er-cryptid]

Patreon | Ko-fi    

[er-cryptid]

Gram Staining

-- invented by Hans Christian Gram in 1884

-- helped distinguish groups of bacteria

-- identifies cells based on their ability to absorb certain dyes

-- gram-positive = cell does not remove the dye

-- gram-negative = cell does not hold dye, and is stained with a counterstain

-- cell walls that absorb the dye are made of peptidoglycans

-- alcohol does not remove this dye

-- lipopolysaccharides do not hold the dye

-- these are bleached with alcohol easily

-- gram-negative examples      -- pseudomonas      -- legionella      -- hemophilus

-- gram-positive examples      -- staphylococcus      -- clostridium      -- listeria

Patreon | Ko-fi

[oaresearchpaper]

Antibacterial potential of methanolic extract of Syzygiumaromaticum (clove) against different…

The flower buds of Syzygium aromaticum (Cloves) are a well-known spice, prescriped for treatment from some microbial diseases since ancient civilizations and in traditional medicine today. In the currenrt investigation, the methanolic extract of cloves was tested against 4 Gram-positive bacteria , namely Bacillus cereus ATCC10876, Staphylococcus saprophyticus ATCC 43867, Enterococcus faecalis ATCC 29212 and Staphylococcus epidermidis ATCC 12228. In addition to 5 strains of Gram-negative bacteria , namely Proteus vulgaris ATCC 6380, Klebsiella pneumoniae ATCC 27736, Salmonella typhimurium ATCC 14028, Shigella flexneri ATCC 12022 and Escherichia coli ATCC 25922, using two diffusion methods (Cup-plate and disc diffusion methods), besides MIC and MBC testings. The extract showed noticable dose-dependant antibacterial activity against all tested bacterial strains with varied degrees, and there was no significant differences between the results of the cup-plate diffusion assay and the disc-diffusion assay. Moreover, MIC values were between 3.9 to 125 mg/ml, and MBC values ranged between 7.8 to 125 mg/ml, which was higher than the MIC’s, the MBC/MIC ratio indicating that the extract has a bactericidal attitude, which makes it suitable source for the formulation of new antibacterial drugs.

[oaresearchpaper]

Screening, identification and antimicrobial activity of mycoparasitic fungus (Aspergillus sp.) from Philippine aglibut sweet tamarind

Due to the increasing resistance of pathogenic microorganisms, Aspergillus sp. isolated from Aglibut Sweet Tamarind’s bark of Pampanga State Agricultural University was evaluated for potential mycoparasitism and antimicrobial activity. The micrograph obtained from Scanning Electron Microscopy (SEM) Analysis reveals that Aspergillus sp. is a potential mycoparasite; further, its identity was 99% which was confirmed through 18s rDNA of its ITS1 forward and ITS4 reverse sequences by Polymerase Chain Reaction (PCR) Amplification and Sequencing. Moreover, Thin-layer Chromatography (TLC) was used to identify the bioactive compounds of Aspergillus sp. The chemical groups such as Glycosidic flavonoid, Alkaloid and Anthrones were also present which can express the desired activity. Complete Randomized Design (CRD) was carried out with the following treatments; T1 (suspensions), – control (DMSO) and + control (streptomycin for bacteria: ketoconazole for fungus). Paper-disc Diffusion confirms that the suspensions of Aspergillus sp. have significant antimicrobial potential as shown in the zones of inhibition in S. aureus and S. cerevisiae but with lower activity in E. coli. Thus, Aspergillus sp. is a potential mycoparasite and source of new drugs and drug products.

[sbgridconsortium]

Targeting Bacteria Involved in Infections

Gram-positive bacteria, which have a cell wall composed of peptidoglycans, are primarily responsible for skin and soft tissue infections (SSTIs). These infections result in nearly 14 million ambulatory care visits each year in the United States. 

Recent developments demonstrate that the mechanism used by Gram-positive bacteria to produce heme, a cofactor, is unique to these bacteria as compared to humans. As a result, this is a potential target for antibiotics for SSTIs since heme is critical for the pathogens. SBGrid member Borden Lacy and other researchers have been working to identify molecules that can target this biosynthesis of heme. They have identified a small-molecule which activates coproporphyrinogen oxidase (CgoX) which is found in Gram-positive bacteria. This activator results in the buildup of coproporphyrin III, which causes the Gram-positive bacteria to become photosenstive. Importantly, testing this small-molecule activator in conjunction with light treatment has been shown to diminish the bacterial burden of the pathogens in murine models.

Read more about this research in PNAS.