Dehydrated Culture Media for Cultivation of Bacillus

Some Bacillus species are crucial for advancing our understanding of bacteria, while others can be harmful, acting as spoilage organisms or pathogens. Nevertheless, all these species are significant in biotechnological research.Jvo Siegrist, Product Manager Microbiology

Bacillus: A Ubiquitous Bacteria Genus

Bacillus species are Gram-positive, rod-shaped bacteria that belong to the phylum Firmicutes. They can be either obligate or facultative aerobes and test positive for the catalase. Members of the Bacillus genus are known for their ability to form spores in response to stressful conditions. These endospores are highly resistant to heat and radiation, allowing them to remain viable for extended period.

Two Bacillus species are of medical significance: B. anthracis, which causes anthrax, and B. cereus, which is responsible for a foodborne illness similar to that caused by Staphylococcus. The type species is B. subtilis, an important model organism that is also recognized as a significant food spoiler, leading to ropiness in bread and similar products. Additionally, some environmental and commercial strains of B. coagulans may contribute to the food spoilage of highly acidic, tomato-based products.

Section Overview

• B. subtilis – Food Spoilage bacterium
• Bacillus thuringiensis – The biological pesticide
• Bacillus anthracis – Causative agent of anthrax
• Bacillus cereus – A Food Spoilage Bacterium
• Granulated Media for Bacillus Cultivation
• Related Products

B. subtilis – Food Spoilage bacterium

B. subtilis is one of the most well-studied bacteria, making it a popular choice in molecular biology and as a general model organism. Its non-pathogenic nature, excellent genetic adaptability, and relatively large genome size make it a valuable tool for scientific research and demonstrations. B. subtilis has been utilized to illustrate biochemical differentiation, gene and protein regulation, and cell cycle events in bacteria.

Bacillus thuringiensis – The biological pesticide

B. thuringiensis is a significant insect pathogen known for its Bt toxin, which is specifically effective against various pest insect species. The Cry and Cyt genes from this bacterium are used to create biological insecticides. In agriculture, these toxin genes are incorporated into crops to render them insect resistant. When insects ingest the toxin, it is activated in their alkaline digestive tract. The activated protein then inserts itself into the insect's gut cell membranes, forming pores that lead to swelling, cell lysis, and potentially the insect's death.

Bacillus anthracis – Causative agent of anthrax

B. anthracis is the causative agent of anthrax. The name "anthracis" derives from the Greek word "anthrakis," meaning "coal," because the most common form of the disease, cutaneous anthrax, results in large black skin lesions. This bacterium is relatively large (1–6 μm), facultative aerobe, and non-motile, capable of forming centrally located ellipsoid spores even under stress. The cells typically occur in chains. In vivo, B. anthracis produces a capsule made of polyglutamate, which protects it from phagocytosis, although this capsule is usually absent in blood agar cultures. Genotypically and phenotypically, B. anthracis is very similar to Bacillus cereus and Bacillus thuringiensis, but it has distinct characteristics that differentiate it from these species."

Bacillus cereus – A Food Spoilage Bacterium

B. cereus is responsible for a foodborne illness that accounts for 2 to 5% of foodborne illnesses, leading to severe nausea, vomiting, and diarrhea. It is a facultative aerobe and beta-hemolytic soil bacterium that produces exotoxins. B. cereus can cause two types of illnesses, depending on the contaminated food consumed: a diarrhea type (similar to that caused by C. perfringens) and a vomiting type (similar to that caused by Staphylococcus aureus). The minimum infectious dose is approximately 106 bacteria per gram.

Sources of infection for the diarrhea type of B. cereus include sweets (such as pudding and vanilla sauce), meats (like roast, goulash, and sausages), vegetables, salads, soups, and UHT milk products. The vomiting type of illness is typically linked to contaminated cooked rice that has been reheated. To minimize the risk of B. cereus growth and the resulting illness, foods should be stored at temperatures below 5 °C or above 65 °C, and rapid cooling should be employed to lower the pH to below 4.5, with a water activity (aw) value of less than 0.95.

Note: B. cereus spores are generally not destroyed by heating; instead, heating can activate spore germination. While heating eliminates spoilage bacteria, it does not effectively eliminate B. cereus spores.

Table 1. Differentiating characteristics of B. anthracis, B. cereus and B. thuringiensis

Characteristic	B. anthracis	B. cereus and B. thuringiensis
Growth requirement for thiamin	+	-
Hemolysis on sheep blood agar	-	+
Glutamyl-polypeptide capsule	+	-
Lysis by gamma phage	+	-
Motility	-	+
Growth on chloral hydrate agar	-	+
String-of-pearis test	+	-

Granulated Media for Bacillus Cultivation

We offer dehydrated culture media specifically designed for cultivating Bacillus, that meets the stringent performance standards outlined in ISO 11133. Our unique granulated format produces significantly less dust compared to powdered media and ensures excellent solubility and uniformity. The granules dissolve easily in water, with minimal separation or clumping, even in warm or humid conditions. The exceptional properties of our dehydrated culture media make them easy to handle and highly effective for laboratory use.

To learn more about many advantages of our granulated culture media visit the webpage: Comparison of Granulated and Powdered Dehydrated Culture Media