What Makes Bacillus Bacteria Essential in Biology?
Gram-positive rod-shaped bacteria known as Bacillus (Latin for "stick") belong to the phylum Firmicutes and have 266 recognised species. The plural Bacilli is the name of the class of bacteria to which this genus belongs, and the term is also used to describe the form (rod) of specific bacteria.
One of the largest species of Bacillus is B. megaterium, which is approx 1.5 μm (micrometres; 1 μm = 10−6 m) across 4 μm long. These bacteria majorly occur in chains. Ferdinand Cohn in 1877 provided a full description of two different forms of hat bacillus. One is that it could be killed when kept in exposure to heat and another shows resistivity towards heat.
Bacillus can be reduced to oval endospores and remain dormant for years in this state.
Bacillus is a genus of bacteria that comprises both free-living (nonparasitic) and parasitic harmful species.
Endospores are resistant to heat, chemicals, sunlight and they are widely distributed in nature, majorly in soil, from which they invade dust particles.
Classification, Nature of Cell Wall, Uses, Importance, and Diseases: Bacillus Bacteria
Classification
Domain: Bacteria
All of the members are prokaryotic. They have peptidoglycan in their cell walls. Peptidoglycan is made up of amino acids and sugars. It also aids in the formation of the cell wall. The majority of prokaryotes are unicellular. They have no membrane-bound nucleus, mitochondria, or chloroplast.
Kingdom: Eubacteria
This kingdom's members are all single-celled and prokaryotic. The solitary kingdom of bacteria is Eubacteria.
Phylum: Firmicutes
Firmicutes are gram-positive with a low DNA percentage.
Class: Bacilli
The morphological shape of the organisms is implied in the name of this class.
Order: Bacillales
The members can form endospores.
Family: Bacillacae
Bacillacae members are all Aerobic and use oxygen in cellular respiration.
Genus: Bacillus
Bacillus species live in soil, can be found in water, and have peritrichous flagella that help them move.
Species: Bacillus cereus
Bacillus cereus is differentiated from its counterparts. Bacillus anthracis and Bacillus thuringiensis are distinguished by phenotypic and pathogenic consequences.
Bacillus are Further classified into Different Types based on Rod-Shape Cells
Bacillus: Single unattached cell, that looks like a rod. Examples are Bacillus cereus, Salmonella enterica, etc.
Diplobacilli: In these bacteria, two rods are attached and found in pairs after cell division. Examples are Moraxella Bovis, Klebsiella rhinoscleromatis, etc.
Streptobacilli: In them, bacilli are arranged in a single chain due to cell division in a single plane. Examples are Streptobacillus moniliformis, Streptobacillus felis, etc.
Coccobacilli: They are of oval shape and short in comparison to other bacteria. Examples: Chlamydia trachomatis, Haemophilus influenzae, Gardnerella vaginalis, etc.
Palisades: In these bacteria, cells bends after cell division and they arranged themself in a palisade.Example: Corynebacterium diphtheriae
Nature of Cell Wall
The structure which is found outside the cell, which forms a second barrier between the bacterium and the environment is called cell structure.
The cell wall also maintains the rod shape and withstands the pressure generated by the cell's turgor.
Its cell structure is made up of an inner membrane and thick peptidoglycan. Peptidoglycan keeps the cell in shape.
The polysaccharide part of the cell wall accounts for half of the cell wall.
It's a neutral polysaccharide made up of N-acetylglucosamine, N-acetylmannosamine (ManNac), N-acetylgalactosamine, and glucose in a 4: 1: 1: 1 molar ratio.
A repeating tetrasaccharide molecule is indicative of the acidic section of the cell wall.
Techoic acids, which are composed of N-acetylglucosamine, galactose, glycerol, and phosphorus in a molar ratio of 1: 1.4: 1: 1, make up 5% of the cell wall.
Some B. cereus strains have unique peptidoglycan with only a few oligomers.
Muropeptides that have been cross-linked are dimmers, and many of them lack the N-acetyl group.
In pathogenic strains, these differentiating traits impact cell surface charge, which contributes to the attachment of an outer capsule or an S-layer.
The very first bacteria for which the role of actin as cytoskeleton in cell shape determination and peptidoglycan synthesis was identified in Bacillus subtilis. One of the major roles of the cytoskeleton is to maintain the shape of bacteria.
Importance and Uses
Bacillus spp. are widespread in a wide range of environments, including soil, and are resistant to harsh environmental conditions. These Bacillus bacteria have the capability to survive in extreme conditions like high pH (B. alcalophilus), high temperature (B. thermophilus), and high salt concentrations, because of this nature they are ubiquitous in nature.
The majority of Bacillus species, as well as their products, are deemed safe for use in the environment.
Because of their potential to release many bioactive compounds, these bacteria are recommended for commercialization.
They keep their viability and are simple to store.
Bacillus-based commercial preparations are created and distributed all over the world.
Bacillus coagulans can also make foods that are very acidic, like tomato-based foods, taste bad.
One of species of Bacillus bacteria i.e. Bacillus thuringiensis has the ability to produce toxins that can kill insects and thus they are insecticides in nature.
Bacteria B. siamensis can inhibit plant pathogens from entering as they have antimicrobial compounds in them.
Few species of Bacillus act as naturally competent for DNA uptake by transformation.
Disease
Some of the common diseases caused by Bacillus bacteria are:
Infections caused by Bacillus subtilis are endocarditis, pneumonia, and septicemia. This problem mainly occurs in patients who have an immune disorder.
Bacillus anthracis, as it causes skin, lungs, and bowel infections and these diseases are deadly to the human body.
Bacillus cereus causes food spoilage which can cause food poisoning.
About Bacillus
Gram-positive Bacilli form bacteria are Actinomyces, Clostridium, Bacillus or gram-negative bacteria, e.g. Escherichia, Klebsiella, Salmonella, Streptobacillus, etc.
They have the capability of serving at high temperatures i.e. at 4200 C.
They are mostly non-parasitic and free-living in nature.
They are known to be one of the most abundantly found bacteria.
FAQs on Bacillus Bacteria: Key Facts, Structure & Roles
1. What are Bacillus bacteria and what is their characteristic shape?
Bacillus is a genus of bacteria known for its distinctive rod-like shape. These microorganisms are typically found in soil, water, and dust. They belong to the phylum Bacillota and are characterised by their ability to form tough, dormant endospores under stressful environmental conditions, allowing them to survive for extended periods.
2. Are Bacillus bacteria Gram-positive or Gram-negative, and what does this mean?
Bacillus bacteria are predominantly Gram-positive. This classification is based on the Gram stain test, where they retain the crystal violet stain due to a thick peptidoglycan layer in their cell wall. This thick wall provides structural integrity and contributes to their resilience in various environments.
3. What are some important examples of Bacillus species and their roles?
The Bacillus genus includes a wide variety of species with different roles:
- Bacillus anthracis: The pathogenic agent that causes the disease anthrax.
- Bacillus subtilis: A model organism used extensively in scientific research and genetic engineering. It is also used to produce enzymes and antibiotics.
- Bacillus cereus: A common cause of food poisoning, as it can produce toxins in improperly stored food.
- Bacillus thuringiensis (Bt): An important insect pathogen used as a biological pesticide in agriculture.
- Bacillus coagulans: A beneficial probiotic species that helps in maintaining gut health.
4. What are the main industrial applications of Bacillus bacteria?
Many Bacillus species are industrial powerhouses because they secrete large quantities of enzymes. Key applications include:
- Detergents: Production of proteases like subtilisin that help break down protein-based stains.
- Food Industry: Production of alpha-amylase for starch hydrolysis in baking and brewing.
- Biotechnology: Use of Bacillus subtilis as a host for producing recombinant proteins and antibiotics.
- Agriculture: Use of Bacillus thuringiensis as an eco-friendly biopesticide to protect crops.
5. How does the endospore-forming ability of Bacillus bacteria make them both useful and dangerous?
The ability to form endospores is a key survival mechanism that gives Bacillus a dual nature.
- Useful: This resilience makes species like Bacillus coagulans excellent probiotics, as they can survive the harsh acidic environment of the stomach to reach the intestines. It also ensures the stability of bio-pesticides and industrial enzyme cultures.
- Dangerous: For pathogenic species like Bacillus anthracis and Bacillus cereus, endospores allow them to remain dormant for years in soil or on surfaces. They can become active and cause disease upon entering a host or when food is improperly stored, making them difficult to eradicate and control.
6. Are all Bacillus species harmful to humans? Explain the difference between pathogenic and probiotic species.
No, not all Bacillus species are harmful. The genus contains both pathogenic and beneficial (probiotic) species. Pathogenic species, like Bacillus anthracis, cause disease by producing toxins or invading host tissues. In contrast, probiotic species, such as Bacillus coagulans and certain strains of Bacillus subtilis, are considered "good" bacteria. They contribute to a healthy gut microbiome, aid digestion, and can help prevent the growth of harmful bacteria.
7. How do Bacillus thuringiensis (Bt) bacteria function as a bio-pesticide?
Bacillus thuringiensis (Bt) produces crystalline proteins called Cry toxins during sporulation. When an insect larva (like a caterpillar) ingests the Bt spores, these toxins are activated in the alkaline environment of its gut. The activated toxins bind to specific receptors on the gut wall, creating pores that lead to cell lysis, gut paralysis, and ultimately, the death of the insect. This mechanism is highly specific to certain insect groups and is harmless to humans, animals, and most beneficial insects, making it an ideal eco-friendly pesticide.
8. Where are Bacillus bacteria typically found, and what allows them to survive in such diverse environments?
Bacillus bacteria are ubiquitous, meaning they are found almost everywhere. Their primary habitats include soil, water, dust, and decomposing organic matter. Their remarkable ability to survive in diverse and often extreme environments (high/low temperature, pH, radiation) is due to their formation of highly resistant endospores. These dormant structures protect the bacterium's genetic material from environmental stress until conditions become favourable for growth again.
9. Why is Bacillus anthracis so dangerous, and how does it cause the disease anthrax?
Bacillus anthracis is particularly dangerous because it possesses two key virulence factors: a protective polypeptide capsule and potent toxins. The capsule helps the bacteria evade the host's immune system. Once inside the body, the bacteria multiply and release a complex of three toxins (Protective Antigen, Lethal Factor, and Edema Factor). These toxins work together to disrupt cellular signalling, cause massive fluid buildup (edema), and lead to cell death (necrosis), resulting in the severe symptoms and high mortality rate associated with anthrax.
