What are three methods of bacterial growth?

What are three methods of bacterial growth?

Physical agents include such methods of control as high or low temperature, desiccation, osmotic pressure, radiation, and filtration. Control by chemical agents refers to the use of disinfectants, antiseptics, antibiotics, and chemotherapeutic antimicrobial chemicals.

What are the different methods of maintaining cultures?

These methods include refrigeration, paraffin method, cryopreservation, and lyophilization (freeze drying).

• Periodic Transfer to Fresh Media.
• Refrigeration.
• Paraffin Method/ preservation by overlaying cultures with mineral oil.
• Cryopreservation.
• Lyophilization (Freeze-Drying)
• Advantage of Lyophilization.

What is bacteriological method?

Bacteriological water analysis is a method of analysing water to estimate the numbers of bacteria present and, if needed, to find out what sort of bacteria they are. It is a microbiological analytical procedure which uses samples of water and from these samples determines the concentration of bacteria.

Which methods are used for isolation of bacteria?

Method used for inoculating the solid media depends upon the purpose of inoculation- whether to have isolated colonies or to know the bacterial load of the sample (quantitative analysis). For obtaining the isolated colonies streaking method is used, the most common method of inoculating an agar plate is streaking.

What two methods are commonly used for separating a mixed culture of bacteria?

both procedures (streak & pour) involve diluting the bacterial calls in a sample to an end point where a single cell divides giving arise to a single pure colony.

How do you create a pure bacterial culture?

Obtaining a pure culture of bacteria is usually accomplished by spreading bacteria on the surface of a solid medium so that a single cell occupies an isolated portion of the agar surface. This single cell will go through repeated multiplication to produce a visible colony of similar cells, or clones.

What are the three main types of microbiological culture media?

ROUTINE LABORATORY MEDIA These are classified into six types: (1) Basal media, (2) Enriched media, (3) Selective (4) Indicator media, (5) Transport media, and (6) Storage media. 1. BASAL MEDIA. Basal media are those that may be used for growth (culture) of bacteria that do not need enrichment of the media.

What are the five main ingredients of culture media?

Components of culture media:

• Water– Source of hydrogen and oxygen.
• Electrolytes– NaCl & other electrolytes.
• Peptone– Mixture of partially digested proteins (animal or vegetable).
• Meat extract, yeast extract – Protein degradation products/carbohydrates/Inorganic salts/Growth factors.
• Blood– It enriches media.

What is bacterial culture media?

A microbiological culture medium is a substance that encourages the growth, support, and survival of microorganisms. Culture media contains nutrients, growth promoting factors, energy sources, buffer salts, minerals, metals, and gelling agents (for solid media) [2].

How do you prepare media for bacterial culture?

It is really very simple to make complex media these days:

1. rehydrate the powder form of the medium.
2. stir and boil the agar medium to get the agar powder dissolved (if making an agar medium rather than a broth medium)
3. distribute the medium into tubes.
4. autoclave to sterilize the tube media.

What does a bacterial culture test for?

A bacterial culture is a test used to determine whether bacteria or fungi are infecting a wound. Bacterial cultures are typically collected from infected (or potentially infected) tissue, but can also be taken from: Body fluids (blood, urine, sputum, pus)

What are the composition of culture media?

The formulation of all Oxoid culture media and the components can be divided into different roles or functions: 1 Nutrients: proteins/peptides/amino-acids. 2 Energy: carbohydrates. 3 Essential metals and minerals: calcium, magnesium, iron, trace metals: phosphates, sulphates etc.

What is the importance of adjusting the pH of culture media?

Apart from complete nutritional composition, right and stable pH is another important requirement for optimum microbial growth in culture media. The pH of a culture medium should be suitable to the microorganisms that will be grown. Most bacteria grow in pH 6.5 – 7.0 while most animal cells thrive in pH 7.2 – 7.4.

How do you change the pH of culture media?

If you need to adjust the pH of cell culture medium, use 1 N NaOH to raise the pH or 1 N HCL to lower the pH. Be very careful to only add a drop at a time because it is very easy to over-adjust the pH. You could try using a lower concentration of acid and base.

What is the pH of agar?

5.6 to 7.5

How pH is maintained in animal cell culture?

Bicarbonate buffering works through Le Chatelier’s principle. Increased acidity in the medium is manifested by an increase in Hydrogen (H+) ions; free bicarbonate ions then react with the extra H+ ions to form carbonic acid “shifting the reaction to the left”, stabilising pH.

How do you maintain pH in cell culture?

The growth medium controls the pH of the culture and buffers the cells in culture against changes in the pH. Usually, this buffering is achieved by including an organic (e.g., HEPES) or CO2-bicarbonate based buffer.

Why is 5 CO2 used in cell culture?

5%CO2 is needed to buffer the system to ensure that the normal physiological pH is maintained for optimum cell growth. CO2 will react with water to form carbonate.

Why is phenol red used in culture media?

Phenol red is used as a pH indicator. Phenol red is used widely in culture media to identify changes from neutral to acidic pH values. It is typically used in cell culture media at 11 mg/L. Phenol red in tissue culture media can act as a weak estrogen, especially with human breast cancer cells.

What is phenol red indicator?

Phenol red, also known as phenolsulfonphthalein, is a pH indicator dye that exhibits a gradual transition from yellow to red over a pH range of 6.2 to 8.2 (Figure 2). Above 8.2 the dye turns a bright fuchsia color.

What color is phenol red in basic conditions?

A small amount of phenol red added to this growth medium will have a pink-red color under normal conditions.

Is phenol red acidic or basic?

Most commonly, phenol red is an indicator dye, used as an acid pH indicator with a transition point of 7.5 (acid side to yellow / alkaline side to red)

Why is Dmem yellow?

DMEM contains phenol red, which is solely a pH indicator. At physiological pH, the media is a pink-red color. When the media is acidic it turns a yellow-orange color as you describe, and when basic it turns a deep purple (such as if you add bleach).

Why is phenol red yellow?

As the instructor, you supply the carbon source by blowing bubbles in phenol red. The carbon dioxide in your breath will dissolve in water to form carbonic acid, which lowers the pH of the solution. Phenol red turns yellow in a pH lower than 7, revealing in this case the presence of a carbon source.