Micro3, Lecture notes of Microbiology

Download Micro3 and more Lecture notes Microbiology in PDF only on Docsity!

Foundations in Microbiology

Chapter 3 PowerPoint to accompany Fifth Edition Talaro Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Tools of the Laboratory:

The Methods for Studying Microorganisms Chapter 3

Isolation

• (^) If an individual bacterial cell is separated from other cells & has space on a nutrient surface, it will grow into a mound of cells- a colony
• (^) A colony consists of one species

Isolation technique

Types of media

• (^) synthetic – contains pure organic & inorganic compounds in an exact chemical formula
• (^) complex or nonsynthetic – contains at least one ingredient that is not chemically definable
• (^) general purpose media - grows a broad range of microbes, usually nonsynthetic
• (^) enriched media - contains complex organic substances such as blood, serum, hemoglobin or special growth factors required by fastidious microbes

• (^) selective media - contains one or more agents that inhibit growth of some microbes and encourage growth of the desired microbes
• (^) differential media – allows growth of several types of microbes and displays visible differences among desired and undesired microbes

Selective media

Differential media

Carbohydrate fermentation media

• (^) magnification – ability to enlarge objects
• (^) resolving power – ability to show detail

Pathway of light

Effect of wavelength on resolution

Effect of magnification

Types of light microscopes

• (^) Bright-field – most widely used, specimen is darker than surrounding field
• (^) Dark-field – brightly illuminated specimens surrounded by dark field
• (^) Phase-contrast – transforms subtle changes in light waves passing through the specimen into differences in light intensity, best for observing intracellular structures