Bacillus Bacteria

Table of Contents

• Definition & Meaning
• Scientific Classification
• Structure
• Characteristics
• Bacillus Species List
• Significance
• Frequently Asked Questions (FAQs)

Definition & Meaning

Bacillus, meaning “stick”, is a genus of rod-shaped, Gram-positive bacteria, a member of the Bacillota phylum, with 266 identified species. The term refers to the shape (rod) of other similarly shaped bacteria, and the plural name of the bacteria class is Bacilli.

Bacillus species can either be facultative anaerobes, which can exist with or without oxygen, or obligate aerobes, which require oxygen to survive.

Pseudomonas aeruginosa and Escherichia coli are two examples of rod-shaped bacteria that do not belong to the class Bacilli. These two Gram-negative bacteria are common in the environment and can harm people. Bacillus anthracis is an example of a rod-shaped bacteria from the Bacilli class.

Examples of Bacillus Bacteria

There are several Bacillus species, and they all serve a variety of purposes in both the environment and the human body. B. anthracis is one of these bacteria that produce the toxin that results in anthrax disease in individuals.

Pathogens of certain types of insects include Bacillus larvae, B. popilliae, B. lentimorbus, B. thuringiensis, and B. sphaericus. Although a few other species, such as B. cereus, occasionally cause disease in humans and animals, most Bacillus species are non-pathogenic saprophytes.

Scientific Classification

Structure

The Bacillus cell wall is an external component of the cell that serves as the second line of protection between the organism and its surroundings, supports the rod-like shape of the cell, and withstands pressure imposed by the turgor of the cell. Teichoic and teichuronic acids make up the cell wall.

Bacillus species are rod-shaped, Gram-positive, aerobic or facultatively anaerobic bacteria that produce endospores. In some species, cultures have the potential to mature into Gram-negative species. The diverse species of the genus have a wide range of physiological capabilities that enable them to survive in various types of natural environments. Each cell produces a single endospore. The spores are resilient to radiation, desiccation, heat, cold, and disinfectants.

Oxygen is required for Bacillus anthracis to sporulate; this restriction significantly affects epidemiology and control. B. anthracis forms a polypeptide or polyglutamic acid capsule in vivo to protect it from phagocytosis. The family Bacillaceae includes the genera Bacillus and Clostridium. Biochemical and morphological factors are used to classify species.

Characteristics

General characteristics of Bacillus spp. are as follows:

• Bacillus consists of bacilli producing heat resistant pores.
• They are Gram-positive but are susceptible to decolourisation, appearing Gram-negative.
• The spores are resistant to cold, heat, desiccation, radiation, and disinfectants.
• Extreme environmental conditions, such as high temperature (B. thermophilus), high pH (B. alcalophilus), and high salt concentrations (B. halodurans), can support the growth of Bacillus.
• Some Bacillus species are naturally capable of transforming DNA.

Key characteristics of Bacillus anthracis include the following:

• Gram-positive, large, box-car-shaped rod in long or short chains.
• Oval, non-swelling spores developed during culture media growth.
• Clinical specimens may contain encapsulated rods.
• Colonies have a ground-glass look.
• Non-hemolytic on sheep blood agar.
• Non-motile.
• MacConkey agar shows no growth.
• Positive for catalase test.
• Penicillin susceptible
• Positive for lecithinase test.

Bacillus Species List

• B. acidocaldarius
• B. aerius
• B. anthracis
• B. cereus
• B. fastidiosus
• B. subtilis
• B. thermoaerophilus
• B. thuringiensis

Significance

There are many different types of Bacillus in nature, including in soil. Extreme conditions like high temperature (B. thermophilus), high pH (B. alcalophilus), and high salt concentration (B. halodurans) can all lead to their occurrence. In plants, they are also frequently found as endophytes, which can be extremely important for the health of the plant’s immune system, capacity to absorb nutrients, and ability to fix nitrogen.

An important insect pathogen, B. thuringiensis, is usually employed to eradicate insects and pests. B. subtilis serves as a valuable model organism. Additionally, a well-known food spoiler makes bread and other foods ropy. Also capable of producing and secreting antibiotics is B. subtilis.

Some commercial and environmental B. coagulans strains may lead to the deterioration of extremely acidic tomato-based products.

Related Links:

• Bacillus Thuringiensis
• Rod-shaped Bacteria – Types and Diseases
• Difference Between Gram-positive and Gram-negative Bacteria

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