Bacillus and related endospore-forming bacteria

The Genus Bacillus (page 6)

(This chapter has 6 pages)

© Kenneth Todar, PhD

Table 4. Characteristics of Bacillus and related aerobic endospore-forming bacteria

Acyclobacillus acidocaldarius Thermoacidophile. Limits of temperature for growth are 45^o and 65^oC. The limits of pH for growth around 2. Found in hot acidic environments. Spores have surprisingly weak thermal resistance.

Bacillus alcalophilus Alkaliphile. Tolerant to alkaline conditions and does not grow at pH 7. Capable of growth at pH >10.

Paenibacillus alvei Isolated from soil and from honeybee larvae suffering from European foulbrood disease. Not classified as an insect pathogen.

Bacillus anthracis The causative agent of anthrax in humans and in animals. Spores persist for long periods on contaminated materials.

Bacillus azotoformans. Has a negative Gram reaction. Can respire anaerobically using NO₃, NO₂, SO₄ or fumarate as a final electron acceptor. A vigorous denitrifying bacterium in soils, it converts NO₃, NO₂ and N₂O to large amounts of N₂.

Bacillus badius Forms a distinct colony with rhizoid outgrowths. Has been isolated from feces, dust, marine sources, foods and antacids.

Brevibacillus brevis Has been isolated chiefly from soils and foods. Requires a mixture of amino acids without vitamins for growth.

Bacillus cereus A close relative of B. anthracis, B. mycoides and B. thuringiensis. Spores are widespread in soil and air. Usually observed multiplying in foods such as cooked rice and may lead to food poisoning. Produces antibiotics.

Bacillus circulans Some strains are cellulolytic. Has a distinct rhizoid colony.

Bacillus coagulans Includes acidophilic strains. Spores are relatively sparse in soils. May multiply in acid foods such as canned tomato juice and silage. Found in medicated creams and antacids

Bacillus fastidiosis Uses only uric acid, allantoic acid or allantoin as an energy source. Isolated from soil and from poultry litter.

Bacillus firmus Isolated chiefly from soil. Pigmented strains occur in salt marshes.

Sporosarcina globisporus Forms spherical spores. Found in soil and river water.

Bacillus insolitus Growth and sporulation occur at 0 degrees. Vegetative cells are short and stout. Found in Arctic soils.

Paenibacillus larvae Causes American foulbrood in honeybees.

Brevibacillus laterosporus Produces a canoe-like body attached to the side of spore forcing the spore into a lateral position in the sporangium. Rarely isolated, but has been found in dead honeybee larvae, soil, water and antacids.

Paenibacillus lentimorbus More fastidious nutritionally and more widespread than P. popilliae, it also infects the Japanese beetle and the European chafer. Isolated from diseased larvae or infected honeycombs.

Bacillus lentus Similar to B. firmus, but more nutritionally-versatile. Isolated from soil, food and spices.

Bacillus licheniformis Produces same type of poly-D-glutamate capsule as B. anthracis. Red pigment produced by many strains. Spores occur in soil. Growth in foods, especially if held between 30 and 50 degrees. Industrial source of bacitracin, a medically useful antibiotic.

Paenibacillus macerans Most strains fix N₂ under anaerobic conditions. Degrades pectin and plant polysaccharides. Some strains moderately thermophilic. Also has been found in canned fruit at pH 3.8.

Paenibacillus macquariensis Grows and sporulates at 0 degrees. Otherwise similar to B. circulans.

Marinibacillus marinus Grows at 5-30 degrees but not at 37 degrees. Has an obligate requirement for Na⁺. Isolated routinely from marine sediments.

Bacillus megaterium "Megaterium" means "big beast". The largest cell diameter of any aerobic spore former (1.2 -1.5 micrometers). Grows in minimal medium without any added growth factors. Spores are common in soil. Subject of many basic studies of Gram-positive bacteria in the laboratory.

Bacillus mycoides Similar to B. cereus but non motile, and forms distinctive rhizoid colonies. High degree of relatedness with B. anthracis, B. cereus and B. thuringiensis.

Sporosarcina pasteurii Converts urea to ammonium carbonate more actively than any known bacterium. Requires alkaline medium (pH 9) for growth. Isolated from soil, water, sewage and encrustations on urinals.

Paenibacillus polymyxa Colonies are mucoid, slimy and tend to spread. Synthesizes profuse levan capsule from sucrose. Spores have longitudinal surface ridges so are star-shaped in cross-section. Degrades pectin and plant polysaccharides. Nitrogen fixed under anaerobic conditions. Spores are widespread. Multiplication occurs chiefly in decaying vegetation. Often isolated from foods. Found in medicated creams and antacids. Source of the antibiotic polymyxin. A very versatile and widespread sporeformer.

Paenibacillus popilliae Pathogen of scarabeid beetles that causes (one variety of) milky disease in the Japanese beetle. Together with B. lentimorbus, it is a biological agent for the Japanese beetle and the European chafer. The larvae become milky white because of the prolific production of spores in the insect hemolymph. Forms a distinctive parasporal crystal that distinguishes it from B. lentimorbus. Isolated from hemolymph of Japanese beetle grubs.

Bacillus pumilus Spores are ubiquitous; occurs in soil more frequently than those of B. subtilis.

Bacillus schlegelii Thermophile similar to B. sphaericus in its high G+C content, but differentiated because it is a facultative lithoautotroph. The bacterium can derive energy from the oxidation of H₂ or CO while obtaining carbon from either CO₂ or CO. Isolated from lake sediments and sugar factory sludge.

Bacillus sphaericus Isolated from soil, marine and fresh water sediments, milk and foods.

Geobacillus stearothermophilus Grows at 65^o C and has tolerance to acid. Occurs in soil, hot springs, desert sand, Arctic waters, ocean sediments, food and compost.

Bacillus subtilis Grows as a unicellular rod, seldom as chains. Degrades pectin and polysaccharides in plant tissues, and some strains cause rots in live potato tubers. Grows in a minimal defined medium with no added growth factors. Endospores are widespread. Vegetative organisms take part in various stages in the early breakdown of materials of plant and animal origin. Grows in non acid food under aerobic conditions. Causative agent of ropy (slimy) bread. This bacterium is the experimental "E. coli" of Gram-positive bacteria. Much of the information we have on the biology, biochemistry and genetics of the Gram-positive cell, indeed, of bacteria in general, has been derived from the study of B. subtilis.

Bacillus thuringiensis Distinguished from B. cereus by pathogenicity for lepidopteran insects, and production of a parasporal crystal in association with spore formation. In the larval gut, the protein (crystal) is toxic. The spores and crystals are marketed in garden centers as BT, for biological control of lepidopterans that attack garden and crop plants. Bt is encoded on a plasmid which can be spontaneously transferred to B. cereus, endowing it with the ability to produce the toxic crystal. Some taxonomists have argued that this is evidence of such a close genetic relationship between the two bacteria that B. thuringiensis should be considered a variant subspecies of B. cereus. The same argument has been made for the relationship between B. anthracis, the plasmid-encoded anthrax toxin, and B. cereus.

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