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Natural Products from the Amazon Region as Potential Antimicrobials
Published in Mahendra Rai, Chistiane M. Feitosa, Eco-Friendly Biobased Products Used in Microbial Diseases, 2022
Josiane E. A. Silva, Iasmin L. D. Paranatinga, Elaine C. P. Oliveira, Silvia K. S. Escher, Ananda S. Antonio, Leandro S. Nascimento, Patricia P. Orlandi, Valdir F. Veiga-Júnior
Thymol was demonstrated to be more inhibitory of 12 strains of Salmonella typhimurium than eugenol. By the microdilution method, the MIC of thymol ranged from 32 to 128 µg/mL, while eugenol ranged from 512 to 1024 µg/mL. Both eugenol and thymol were also capable of eradicating Salmonella typhimurium biofilms, with minimum biofilm eradication concentrations ranging from 10.50 to 697.6 and 15.3 to 934.4 µg/mL, respectively (Miladi et al. 2017). Hamzah and coworkers (2018) also demonstrated that by the crystal violet method thymol and eugenol are prominent inhibitors and antibiofilm for the polymicrobial biofilm of Pseudomonas aeruginosa, Escherichia coli and Candida albicans. Against these bacterial strains individually, thymol had an average inhibition of 84.60% and eugenol of 83.82%. In addition, the minimum biofilm inhibitor concentration to polymicrobial biofilms for both compounds (at a concentration of 1%) was 0.10 and 0.31%, respectively.
Understanding Microbiology Culture Results
Published in Firza Alexander Gronthoud, Practical Clinical Microbiology and Infectious Diseases, 2020
Microbes can be directly visualized in bodily fluids and tissue samples with microscopy. The Gram stain is used for detection of bacteria. Bacteria can be classified as Gram positive or Gram negative based on their ability to retain crystal violet after decolourization with alcohol. Gram-positive bacteria retain crystal violet in their cell wall and have a purple colour. In contrast, in Gram-negative bacteria, the alcohol has removed the crystal violet (a process called decolourization) and a counterstain is used to make them visible and pink coloured. Counterstains used are safranin and carbol fuchsin. Counterstains are weaker stains than crystal violet and Gram-positive bacteria remain purple coloured. Gram stain can also be used to visualize common fungi such as Candida species, which are Gram positive.
Quorum Sensing and Essential Oils
Published in K. Hüsnü Can Başer, Gerhard Buchbauer, Handbook of Essential Oils, 2020
Isabel Charlotte Soede, Gerhard Buchbauer
Crystal violet assay is an indirect quantification method of death cells. Crystal violet binds to protein and DNA on detached cells. Reduced cell attachment because of cell death leads to reduced violet staining in a culture. This simple assay can be used for the effect of EO on biofilms (Feoktistova et al., 2016).
Synbiotic Musa acuminata skin extract and Streptococcus salivarius K12 inhibit candida species biofilm formation
Published in Biofouling, 2022
Nurul Alia Risma Rismayuddin, Puteri Elysa Alia Mohd Badri, Ahmad Faisal Ismail, Noratikah Othman, H.M.H.N. Bandara, Mohd Hafiz Arzmi
A crystal violet (CV) assay was performed according to the protocol by Alnuaimi et al. (2013) to quantify the biofilm biomass. Initially, the wells containing biofilms were washed twice with sterile PBS to remove the non-adherent cells. Later, the biofilms in the wells were fixed by adding 200 μL of methanol and incubating for 15 min at 25 °C. The supernatant was discarded, and the plate was air-dried for 45 min. Later, 200 μL of 0.1% (w/v) CV solution was added to each well and incubated for 20 min at 25 °C. The plate was washed gently twice using sterile distilled water to remove the unbound stain. Subsequently, the biofilms were de-stained with 200 μL of 33% (v/v) acetic acid for five minutes at room temperature. Finally, 100 μL of the acetic acid solution was transferred to a new sterile 96-well plate, and the absorbance was measured at OD620nm using a microtiter plate reader (Tecan NanoQuant Infinite M200, CA).
Enhanced acyclovir delivery using w/o type microemulsion: preclinical assessment of antiviral activity using murine model of zosteriform cutaneous HSV-1 infection
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2018
Amanpreet Kaur, Gajanand Sharma, Vishal Gupta, Radha Kanta Ratho, Om Prakash Katare
Plaque assay is one of the most important procedures in virology in measuring the virus titre (concentration of viruses) in a sample. To perform a plaque assay, 10-fold serial dilutions of a virus stock were prepared, and 0.2 mL aliquot was inoculated onto susceptible cell monolayers in each well and was incubated for 1–2 h at 36 ± 1 °C with 90% RH and 5% CO2 [33]. After the incubation period, the monolayers were overlaid with 0.6% agarose (causes the formation of a gel) in MEM containing 2% FBS and incubated for 2–3 days [31] to allow virus to attach to cells. When the plates were incubated, the original infected cells release viral progeny. Spreading of the new viruses is restricted to neighbouring cells by the gel. Consequently, each infectious particle produces a circular zone of infected cells called a plaque. Eventually, the plaque becomes large enough to be visible to the naked eye. Crystal violet was used as a dye to enhance the contrast between the living cells and the plaques. The titre of a viral stock was calculated in plaque-forming units (PFU) per millilitre. To determine the viral titre, the plaques were counted. To minimize error, only plates containing 10–100 plaques were counted. Each dilution was plated in triplicate to enhance accuracy. PFU/mL was calculated using formula given in Equation (4):
Pluronic lecithin organogel of 5-aminosalicylic acid for wound healing
Published in Drug Development and Industrial Pharmacy, 2018
Bharat Kumar Reddy Sanapalli, Elango Kannan, Shivaramakrishnan Balasubramanian, Jawahar Natarajan, Uday Krishna Baruah, Veera Venkata Satyanarayana Reddy Karri
Scratch assay was performed in HaCaT cells. The cells were grown in the Dulbecco's modified eagle's medium by supplementing with 10% phosphate buffer saline. The cells were seeded in the tissue culture plates with a confluence of approximately 70–80% as a monolayer. Two scratches were made in these tissue culture plates using a 1 ml pipette tip in such a way that the scratches should be perpendicular to the other. To these plates, fresh medium containing the test sample was added and these plates were kept aside for 48 h for the cells to grow. After the study, the cells were washed and fixed with formaldehyde 4%. Crystal violet was used as a staining agent for microscopical examination [25].