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Antimicrobial Preservative Efficacy and Microbial Content Testing*
Published in Philip A. Geis, Cosmetic Microbiology, 2020
Scott V.W. Sutton, Philip A. Geis
The method provides for harvesting the organisms with a sterile inoculating loop and transferring them to sterile distilled water. The optical density measured a McFarland Standard 32 to yield 1.0 × 108 bacteria/mL. Mold spores are dislodged from mycelial cultures by rubbing gently with a sterile inoculating loop or removal with a sterile glass hockey stick. Then the spores are filtered with sterile nonabsorbent cotton to remove the hyphae and break up any clumps. One may use a hemocytometer count to adjust the spore level to 1.0 × 107/mL.
Anti-oxidant and Anti-microbial Activities of Flavonoids from the Fruit Extract of Dacryodes edulis
Published in Parimelazhagan Thangaraj, Phytomedicine, 2020
R. O. Omosimua, B. D. Macham, A. Onanuga, B. T. Thomas, C. O. Ugbomor, G. Iyappan, S. Ramalingam, A. S. Afolabi, Sunday Asuquo Thomas
The isolated flavonoids were tested for their possible anti-bacterial and anti-fungal activities against Escherichia coli American Type Culture Collection (ATCC) 2592, Pseudomonas aeruginosa American type culture collection (ATCC) 27853, Proteus mirabilis ATCC 29906, Klebsiella pneumoniae ATCC 13883, Staphylococcus aureus ATCC 29923, and Candida albicans ATCC 10231. The bacterial organisms were grown on nutrient broth at 37°C for 24 hours, while the fungus, Candida albicans, was grown in a Sabouroud dextrose liquid medium (Oxoid, England) at 25°C for 48 hours. A bacterial suspension with a turbidity equivalent to 0.5 McFarland standards was prepared (Bauer et al. 1966). The in vitro anti-microbial screening was carried out using Mueller-Hinton Agar (Oxoid, England) for the bacteria and Sabouroud dextrose agar for the fungi using the agar well diffusion method as described by Perez et al. (1990). Plates were incubated at 37°C for 24 hours for the bacteria, and the fungi were incubated at 25°C for 48 hours. The standard drugs used were Ciprofloxacin and Chloramphenicol against the bacterial organisms, while Nystatin was used against the fungus. At the end of the incubation period, the inhibition zones were measured in millimeters (mm). These studies were carried out in triplicate.
In Vitro Calli Induction, Biomass Accumulation and Different Biological Activity of Leucas aspera (willd.) Linn.
Published in Parimelazhagan Thangaraj, Medicinal Plants, 2018
Masilamani Sri Devi, Krishnamoorthy Vinothini, Blassan P. George, Sudharshan Sekar, Heidi Abrahamse, Bettine van Vuuren, Arjun Pandian
The in vitro antimicrobial activity of different solvent extracts from leaves, stems and in vitro calli were determined by the well diffusion method described by Nagarajan et al. (2010). The Muller Hinton Agar (MHA) ingredients are beef infusion (300 g/L), casein acid hydrolysate (17.5 g/L), starch (1.5 g/L) and agar (1.7 g/L) at pH (7.3 ± 0.1) medium was poured onto sterile petriplates. Agar was allowed to set at ambient temperature. Fresh human pathogenic bacteria cultures of two gram-positive bacteria, B. subtilis and S. aureus and three gram-negative bacteria, E. coli, S. typhi and V. cholera were spread on the surface of MHA plates using cotton swabs. Wells were cut from the petriplates using a sterile cork (8 mm dia) borer. Different concentrations (25, 50 and 75 μL/mL) of the leaf, stem and in vitro calli were loaded into the wells using a sterile micropipette. The inoculated plates were initially incubated for 15 min at room temperature and then they were incubated at 37°C for 24 h. Turbidity was adjusted with sterile broth so as to correspond to 0.5 McFarland standards. Inhibition zones were recorded as the diameter of growth-free zones including the diameter of the well in mm at the end of incubation period.
Mechanistic study of copper oxide, zinc oxide, cadmium oxide, and silver nanoparticles-mediated toxicity on the probiotic Lactobacillus reuteri
Published in Drug and Chemical Toxicology, 2023
Aya M. Eid, Osama M. Sayed, Walaa Hozayen, Tarek Dishisha
The agar well-diffusion method was measured to evaluate the antibacterial activity of the synthesized NPs against L. reuteri (Holder and Boyce 1994). Briefly, L. reuteri was streaked on MRS agar. After incubation at 37 °C overnight, a single colony was moved to (5 mL) of MRS broth and incubated at 37 °C for 24 h. The bacterial growth was standardized to match a 0.5 McFarland standard, indicating 1–2 × 106 CFU/mL. One milliliter of bacterial culture was seeded under the MRS agar plates with proper mixing and then was left standing for 10 min to let the culture get absorbed. Then, wells (8 mm diameter) were punched using a sterile cork borer. Wells were then loaded with 50 µL of 2.5, 5, 10, 20, and 40 mg/mL for both CuO- and ZnO-NPs. On the other hand, 0.18, 0.37, 0.75, 1.5, and 3 mg/mL for CdO- and Ag-NPs were suspended in sterilized distilled water and allowed to diffuse for 10 min at 4 °C. After incubation for 24 h at 37 °C, the antibacterial activity of the tested NPs were evaluated by measuring the inhibition zone diameter around the wells.
An antimicrobial metabolite n- hexadecenoic acid from marine sponge-associated bacteria Bacillus subtilis effectively inhibited biofilm forming multidrug-resistant P. aeruginosa
Published in Biofouling, 2023
Arya Sajayan, Amrudha Ravindran, Joseph Selvin, Prathiviraj Ragothaman, George Seghal Kiran
The minimal inhibitory concentration of the MSI38 was determined using microdilution assay in a 96-well microtitre plate in triplicates based on CLSI guidelines (CLSI, 2012). To perform MIC, a stock solution of MSI38 was prepared and from these varying concentrations of 10, 20, 30, 40, 50, 100, 150, and 200 mg L−1 was used to determine MIC. The bacterial suspension was made in phosphate buffer saline to achieve the McFarland standard of 0.5. The inoculum of 1 × 108 cells/mL of FP012 was prepared by diluting in Mueller Hinton Broth (MHB) in the ratio of 1:300. Diluted bacterial suspension was added into a 96-well microtitre plate along with varying concentrations of MSI38. The plates were incubated at 37 °C for 24h. MIC was determined as the concentration of MSI38 where no visible bacterial growth was observed after 24 h of incubation.
Preparation and functional evaluation of electrospun polymeric nanofibers as a new system for sustained topical ocular delivery of itraconazole
Published in Pharmaceutical Development and Technology, 2022
Saba Mehrandish, Ghobad Mohammadi, Shahla Mirzaeei
To evaluate the antifungal efficacy of developed preparations, C. albicans (ATCC 10231) and A. fumigatus (ATCC 204305) as two of the most common cause of topical ocular fungal infections were utilized. C. albicans was activated on SDA by incubation at 28 °C for 72 h. The standard fungal suspension was prepared by suspending proper amounts of fungal strains in sterile distilled water to achieve equal turbidity as McFarland standard. A. fumigatus was activated on SDA at 28 °C for 96 h until the spores were formed. To prepare a standard spore suspension, a trace amount of sterile tween 80 was dissolved in 5 ml of sterile distilled water, the solution was transferred to the cultivated fungus plate and homogenized for 10 min then the suspension was transferred back into the sterile glass tube. The turbidity was compared to the McFarland standard.