I. Introduction

Except for a few sterile food, all foods harbor one or more types of microorganism. Some of them have desirable role in food, such as in the production of fermented food, while others cause food spoilage and foodborne diseases. To study the role of microorganisms in food and control them when necessary, it is important to isolate them in pure culture and study their characteristics. Some of the most simple technique in use today for studies were developed over the last 300 years; brief description is included here.