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Biofilms in Fermentation for the Production of Value-Added Products
Published in Bakrudeen Ali Ahmed Abdul, Microbial Biofilms, 2020
Later on, the researchers optimized media components in both media with RSM statistical optimization in order to further enhance MK-7 concentrations. The optimum glycerol-based medium turned out to include 48.2 g/L of glycerol, 8.1 g/L of yeast extracts, and 13.6 g/L of soytone producing a maximum MK-7 concentration of 14.7 mg/L in biofilm reactors, which was similarly 57% higher compared to vitamin levels in the suspended-cell reactors. The notable change this time was that with even higher levels of glycerol in the optimized medium, glycerol depletion did occur within 120 h of fermentation (Mahdinia et al., 2019a). Optimization of the glucose-based medium set components of glucose at 152.6 g/L, yeast extract at 8 g/L, and casein tryptone at 17.6 g/L was slightly different from the original glucose fortified tryptic soy broth medium. With these modifications, the MK-7 maximum concentration reached 20.5 mg/L, which was 344% higher than the performance of planktonic cells. The huge gap was also observed with carbon source consumption rates, where the biofilm formations were able to deplete the initial glucose content within 72 h of fermentation when the planktonic cells could not fully utilize the glucose but left over 40 g/L of it at the end of the runs. These findings left no doubt, behind that the biofilm formations are highly more capable of metabolizing the nutrients and therefore secreting MK-7 (Mahdinia et al., 2018c).
Synthesis of nZVI/PVP nanoparticles for bioremediation applications
Published in Bioremediation Journal, 2022
Anatoli Sidorenko, Tatiana Gutul, Dmitri Dvornikov, Mine Gül Şeker, Tuğçe Arit, Evgenii Gutul, Anatoli Dimoglo, Ashok Vaseashta
All of the control microbial strains were grown in 5 mL of a LB medium at 30 °C overnight. Biofilm production assays were performed using a tryptic soy broth (TSB) medium with 1% glucose. After a 24-h incubation, fresh broth cultures of each bacteria were adjusted to 0.5 McFarland in 0.85% (wt/vol) sterile physiologic serum using a nephelometer. Stock solutions of all substances were prepared in DMSO to a concentration of 20 mg/mL. Fresh micro-organism cultures (0.5 McFarland) were directly mixed with 100 µL of Fe0 NPs (A1, A2 10 mg/mL) and TSB (1% glucose) in 96-well plates, which were incubated for 72 h at 37 °C. Bacteria cultures in a TSB medium with 1% glucose and in a DMSO/blank medium were used as positive and negative controls, respectively. All plates were washed with tap water and air dried after 72 h. All wells were filled with 30% acetic acid solutions (200 µL) and incubated at room temperature. Finally, the resulting biofilms were measured by using a microtiter plate reader at an optical density of 600 nm (OD600). Results were estimated with respect to control samples.
High rates of antibiotic resistance and biofilm production in Escherichia coli isolates from food products of animal and vegetable origins in Tunisia: a real threat to human health
Published in International Journal of Environmental Health Research, 2022
Souhir Badi, Mohamed Salah Abbassi, Mejdi Snoussi, Rim Werheni, Salah Hammami, Rasha Maal-Bared, Abdennaceur Hassen
This assay relies on colorimetric changes to measure cellular viability through metabolic activity and proliferation. The XTT (2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl]-2 H-tetrazolium hydroxide) is a yellow salt that is reduced by dehydrogenases of metabolically active cells to a colored formazan product. This product can be measured spectrophotometrically in a microtiter plate reader. The XTT assay was performed as previously reported [Toledo-Arana et al. (2001)]. In each experiment, 96-well microtiter plate wells were filled with 100 μL of tryptic soy broth (TSB) supplemented with 0.2% glucose each. Using a fresh bacterial culture, the suspension was adjusted to 0.5 McFarland in TSB supplemented with 0.2% glucose. Ten-fold dilutions were prepared at 105 CFU/mL and 100 μL of each suspension were inoculated into each well before incubating the plates at 37°C for 20–24 h. Planktonic cells were removed from each well by rinsing three times using saline. After drying the plates for 15 min, 50 µL of PBS containing 5% XTT (Sigma, St Louis, MO, USA) were added. The suspension was maintained at 37°C for 2 h. The color intensity of formazan was determined using a microplate reader at 540 nm. High OD values correlated with high number of viable E. coli isolates in the biofilm.
Two Zn(II)-organic frameworks: catalytic Knoevenagel condensation and treatment activity on spine surgery incision infection via inhibiting Staphylococcus aureus biofilms formation
Published in Journal of Experimental Nanoscience, 2021
Qiquan Hao, Lei Cheng, Zhen Dong
The real time RT-PCR was further conducted in this research for the evaluation of compounds 1 and 2’s inhibition against the S. aureus biofilms genes expression. This experiment was carried out totally according to instructions' instructions with a little modification. Briefly, the S. aureus bacterial cells were cultured in tryptic soy broth (TSB) medium + 0.5% glucose in an incubator at 37 °C. Then, compound 1, compound 2 and Ref 1 was added into wells combined with penicillin for 24 h and48 h treatment. After the treatment, the S. aureus bacterial cells were collected, washed with PBS. The TRIzol Reagent (Sigma, St. Louis, MO, USA) was used for the total RNA extraction. The RNA was reversely transcripted into the cDNA through the RNA reverse transcription kit after measuring the quantity as well as quality of RNA in the S. aureus bacterial cells. Ultimately, the expression of S. aureus biofilms genes was measured with RT-PCR. The results were acquired from three performs via utilizing 2−ΔΔCt approach. This conduction was performed at least three times.