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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).
Microbial Analysis
Published in Pradyot Patnaik, Handbook of Environmental Analysis, 2017
Tryptic soy agar/trypticase soy agar (TSA): The composition of this soy agar is: tryptone 15.0 g; soytone 5.0 g; sodium chloride (NaCl) 5.0 g; and agar 15.0 g. All the dry reagents above are added to 1 L of reagent-grade distilled water. The solution is heated to boiling to dissolve the agar completely. The solution is then autoclaved for 15 min at 121°C at 15-lb pressure. Transfer the agar solution into 9 × 50-mm Petri dishes, 5 mL/plate. Incubate the plates for 24–48 h to check for contamination. Discard any plates with growth. Discard all plates if >5% of the plates show contamination and prepare new medium. The final pH should be 7.3 ± 0.2. Store at 4°C.
Biological Analysis of Fungi and Associated Molds
Published in Christopher S. Cox, Christopher M. Wathes, Bioaerosols Handbook, 2020
Culture media suitable for these actinomycetes are nutrient agar or tryptone-soy agar, both at half-strength, supplemented with 2% casein hydrolysate. Cycloheximide at 50 μg/mL suppresses fungal growth. Rifampicin at 5 μg/mL inhibits unwanted bacteria and some actinomycetes while encouraging others, notably Saccharomonospora viridis. A medium containing tyrosine distinguishes the highly allergenic Thermoactinomycesvulgarisfrom T. thalpophilus.75 These species are visually similar and occur together in fermented composts. Actinomycetes, like most bacteria, prefer an alkaline pH of about 7.5.
Nutrient recovery of the hydrothermal carbonization aqueous product from dairy manure using membrane distillation
Published in Environmental Technology, 2023
Nicholas A. Silva, Sage R. Hiibel
Water flux was monitored throughout each trial to assess the membrane’s ability to treat each sample. Although each solution had the same initial concentration of TOC, the observed flux declined with increasing complexity of the TOC source (Figure 2(A)). For example, the low-carbon NUT samples, had the least flux decline, followed by the GLU samples, although the latter only had an average of 3% lower flux. Since glucose is a simple organic compound with high water solubility and hydrophilicity, it was not expected to interact significantly with the membrane. The fluxes for the TRP and YE solutions were lower than the GLU samples, likely due to the different carbon speciation. Both tryptone and yeast extract are produced by biological processes and consist primarily of various peptides. Tryptone is produced by the digestion of the protein casein by trypsin into amino acids and short chain peptides. Yeast extract contains the water-soluble chemicals after the autolysis of the Saccharomyces cerevisiae cell; it contains amino acids and short chain peptides like tryptone, but also other water-soluble species, such as minerals and vitamins, and more complex carbons such as fats, and ash [30]. Fats are hydrophobic, long chain carbon species and therefore may have an affinity towards the hydrophobic membrane [31]. The conductivity of the synthetic solutions’ distillate (Figure S1(A)) remained below 15 µS/cm, with the NUT and GLU samples having the lowest final conductivity (∼5 µS/cm).