Different methods of classification of microbes.pptx

1. Morphological Classification
Cell Shape and Size
One of the oldest and simplest methods for classifying microbes is based on their morphology. Microbes, particularly bacteria, come in various shapes and sizes that provide clues about their classification. The three most common shapes observed among bacteria are:

Cocci (spherical): These bacteria are round or oval-shaped and can be further classified based on their arrangement. For example, Streptococci form chains, while Staphylococci form clusters.
Bacilli (rod-shaped): These bacteria are elongated, rod-like, and may appear singly or in chains.
Spirilla (spiral-shaped): These bacteria have a spiral or corkscrew shape. The more flexible spirals are often classified as spirochetes.
2. Biochemical Classification
Oxidase test: Determines the presence of cytochrome oxidase, an enzyme involved in the electron transport chain.
Catalase test: Identifies bacteria that produce the enzyme catalase, which breaks down hydrogen peroxide into water and oxygen. This is a key test for differentiating staphylococci (catalase-positive) from streptococci (catalase-negative).
Urease test: Detects the production of urease, an enzyme that breaks down urea into ammonia and carbon dioxide, important in distinguishing species like Helicobacter pylori.
Oxygen Requirements
Microorganisms differ in their need for oxygen, and this characteristic plays a significant role in their classification:

Obligate aerobes: Require oxygen for growth.
Obligate anaerobes: Cannot survive in the presence of oxygen.
Facultative anaerobes: Can grow with or without oxygen but typically grow better with oxygen.
Microaerophiles: Require a reduced level of oxygen to grow.
Aerotolerant anaerobes: Do not use oxygen for growth but can tolerate its presence.
Physiological Classification
Temperature Preferences
Microbes are classified based on their preferred temperature range for growth:

Psychrophiles: Thrive in cold environments (below 15°C), such as deep-sea habitats or polar regions.
Mesophiles: Prefer moderate temperatures (20–45°C), making them common in human bodies and soil environments. Most human pathogens are mesophiles.
Thermophiles: Grow at higher temperatures (45–80°C), found in hot springs or compost piles.
Hyperthermophiles: Thrive at extremely high temperatures (above 80°C), typically in environments like hydrothermal vents.
pH Preferences
Microbes also differ in their tolerance to acidity or alkalinity:

Acidophiles: Prefer acidic environments (pH below 5), such as those found in acid mine drainage.
Neutrophiles: Grow best in neutral pH environments (around pH 7), which include most pathogenic bacteria.
Alkaliphiles: Thrive in alkaline environments (pH above 9), such as soda lakes.
Salinity Preferences
Microbes can be classified based on their ability to tolerate or require high salt concentrations:

Halophiles: Require high salt concentrations for growth, found in environments like salt lakes or salt mines.

1. Pharm D Pharmaceutical Microbiology Different methods of classification of microbes Presented by Dr. Malkiet Kaur MM College of Pharmacy MM(DU), Mullana

2. COURSE OBJECTIVES This course deals with the various aspects of microorganisms, its classification, morphology, laboratory cultivation identification and maintenance COURSE OUTCOMES The students will understand the mode of transmission of disease-causing microorganism, symptoms of disease, and treatment