Classification of Microorganisms based on Water Activity

Study Notes

Microbiology Subfields

Phycology is the study of algae.
Virology is the study of viruses.

Applied Microbiology

Medical microbiology studies the relationship between micro-organisms and human health.
Agricultural microbiology examines the relationship between micro-organisms and the environment.
Industrial microbiology/biotechnology focuses on the application of micro-organisms in industry.
Food microbiology investigates the relationship between micro-organisms and food.

Food Microbiology

Food microbiologists need to understand microbial structure, classification, and identification of micro-organisms.
They must also know how micro-organisms grow, the factors that influence growth, and how growth can be controlled.
Food microbiologists should be aware of microbial nutrition and how to culture micro-organisms in a laboratory.
The discipline of food microbiology emerged in the 1800s, with pioneer work by Schwann and Pasteur.

Microorganisms and Food

Protozoa and algae have minimum direct impact on food production, processing, and consumption.
Algae are used to produce alginates and have potential for use in single-cell protein production.
Some marine algae species produce toxins that can enter the food chain through seafood.

Importance of Microorganisms in Food

Micro-organisms play a role in food bioprocessing, food-borne diseases, and food spoilage.

Useful Bacteria in Food Processing

Acetobacter sp. is necessary for vinegar production and causes spoilage in the wine industry.

Classification of Microorganisms

By water activity requirement: halophillic bacteria, osmophillic yeasts, and xerophillic fungi.
By nutrient degradation capacity: proteolytic, lipolytic, sacchrolytic, and pectinolytic microorganisms.
By staining: Gram-positive and Gram-negative bacteria.

Growth of Microorganisms

Growth of microorganisms in food is dependent on various parameters.

Description

Explore the classification of microorganisms based on their requirement of water activity, including halophilic bacteria, osmophilic yeasts, and xerophilic molds. Understand the growth preferences of these organisms and their adaptation to different environmental conditions.