Dissolve the components in the beaker using a magnetic stirrer. (Heat may be applied to dissolve the medium completely). Adjust the pH of the medium to 5.6 or the desired value. Adjust the broth to a final volume of 1L using ddH2O.
What chemicals are used to adjust pH? Sulfuric acid and sodium hydroxide (caustic) are most commonly used for neutralizing acids or bases. Caution must be used for pH adjust applications as an exothermic reaction will occur generating heat.
For agar-based culture media, take the pH of the solidified sample. 1. Place the tip of the flat pH electrode on the surface of the culture medium sample to measure the pH. Make sure that the tip touches the culture medium and no gap between them.
Identify how and why the pH of culture media is controlled. When bacteria are cultured in the laboratory, they often produce acids that eventually interfere with their own growth. To Neutralize the acids and maintain the proper pH, chemical buffers are included in the growth medium.
Most tissue cultures are grown at pH 5.2 to 5.8 with pH adjustments being made prior to autoclaving. This paper reports that there are significant differences between initial pH levels and pH levels following autoclaving, particularly in the pH range of 5.7 to 8.5.
Pure water has a neutral pH of 7. pH values lower than 7 are acidic, and pH values higher than 7 are alkaline (basic).
What does it mean for a solution to be acidic or basic (alkaline)?
| pH Value | H+ Concentration Relative to Pure Water | Example |
|---|
| 10 | 0.001 | Great Salt Lake, milk of magnesia |
Vinegar is acidic. Vinegar's pH level varies based upon the type of vinegar it is. White distilled vinegar, the kind best suited for household cleaning, typically has a pH of around 2.5. Vinegar, which means “sour wine†in French, can be made from anything containing sugar, such as fruit.
Nutrient Broth, pH 6.9 without NaCl
| Quality Control |
|---|
| Appearance | Cream to yellow homogeneous free flowing powder |
|---|
| Reaction | Reaction of 0.8% w/v aqueous solution at 25°C. pH : 6.9±0.2 |
| pH | 6.70-7.10 |
| Cultural Response | Cultural characteristics observed after an incubation at 35-37°C for 18-48 hours. |
Preparation of Acidic Culture MediumDissolve 4.75 g of DMEM powder without L-glutamine in 500 mL of water. Prepare 0.33 M NaHCO3 solution in a pressure-tight bottle. Caution: It is important to use a pressure tight bottle since NaHCO3 emits CO2 gas when heated and thermally decomposed.
pH affects the physical appearance of culture media and their ability to grow microorganisms. Most bacteria grow in pH 6.5 - 7.0 while animal cells thrive in pH 7.2 – 7.4.
Nutrient agar is used as a general-purpose medium for the growth of a wide variety of non-fastidious microorganisms. It consists of peptone, beef extract, and agar. This relatively simple formulation provides the nutrients necessary for the replication of a large number of non-fastidious microorganisms.
Complex media usually provide the full range of growth factors that may be required by an organism so they may be more handily used to cultivate unknown bacteria or bacteria whose nutritional requirement are complex (i.e., organisms that require a lot of growth factors, known or unknown).
Most bacteria grow best around neutral pH values (6.5 - 7.0), but some thrive in very acid conditions and some can even tolerate a pH as low as 1.0. Such acid loving microbes are called acidophiles.
Changes in pH in the cell culture environment can alter virtually every cellular process like metabolism, cell growth, and membrane potential. Extracellular pH is slightly alkaline and typically 7.3-7.4, while intracellular pH is slightly lower at 7.2.
Which of the following is the main effect of cytokines in the tissue culture system? Explanation: Cytokines promote shoot formation while it inhibits the formation of roots. It also promotes cell division and callus formation.
The pH meter measures the difference in electrical potential between a pH electrode and a reference electrode, and so the pH meter is sometimes referred to as a "potentiometric pH meter".
Animal cells are cultured using a completely natural media, or an artificial media along with some of the natural products. 1. Body fluid such as plasma, serum, lymph, amniotic fluid and much more are used. These fluids used as animal cell culture media after testing for toxicity and sterility.
When microbiological media has been made, it still has to be sterilized because of microbial contamination from air, glassware, hands, etc. Within a few hours there will be thousands of bacteria reproducing in the media so it has to be sterilized quickly before the microbes start using the nutrients up.
