Microbial Techniques

Culturing Microorganisms

The process of growing microorganisms in a controlled environment is known as culturing.
Nutrient-rich substances such as agar or broth are commonly used for culturing bacteria.
Important factors in the growth of cultures include temperature, pH, and oxygen levels.

Inoculation and Isolation Methods

Inoculation is the process of introducing microorganisms into a culture medium.
Common inoculation methods include streaking and spreading.
The goal of isolation is to obtain a pure culture, composed of a single type of organism.

Microbial Staining Techniques

Staining is a technique used to enhance the contrast of microorganisms under a microscope.
The most common types of stains are Gram stain and acid-fast stain.
Gram stain differentiates bacteria into Gram-positive (purple) and Gram-negative (red). These differences indicate differences in cell wall structures and can hint at susceptibilities to different antibiotics.
Acid-fast stain is used to identify bacteria with waxy cell walls, such as Mycobacterium tuberculosis.

Analyzing Microbial Growth

Microbial growth is often analyzed and represented in a growth curve, which consists of four distinct phases: lag, log (exponential), stationary, and death.
The lag phase is a period of adjustment where there is little growth.
The log phase is a period of rapid reproduction.
The stationary phase is where growth rate equals death rate, so total population remains stable.
During the death phase, the environment can no longer support the population, so death rate exceeds growth rate.

Determining Antibiotic Sensitivity

Kirb-Bauer disc diffusion test is often used to measure the effectiveness of different antibiotics on a particular bacterial culture.
Interpretation of the test involves measuring the zone of inhibition where bacterial growth has been prevented by the antibiotic.

By utilising these techniques, we can better understand microbial life and responses, allowing for improved study and control of these microscopic organisms. This is particularly vital in medical and biotechnological applications, such as antibiotic development and waste management.