Paenibacillus
Encyclopedia
'Paenibacillus' is a genus of Gram-positive, facultative anaerobic, endospore-forming bacteria
, originally included within the genus Bacillus
and then reclassified as a separate genus in 1993. Bacteria belonging to this genus have been detected in a variety of environments such as: soil, water, rhizosphere
, vegetable matter, forage and insect larvae, as well as clinical samples. The name reflects this fact: Latin paene means almost, and so the Paenibacilli are literally almost Bacilli. The genus includes P. larvae, which is known to cause American foulbrood
in honeybees, the P. polymyxa
, which is capable of fixing nitrogen and therefore is used in agriculture and horticulture, the Paenibacillus sp. JDR-2 which is known to be a rich source of chemical agents for biotechnology applications and pattern forming strains such as P. vortex and P. dendritiformis discovered in the early 90s, which are known to develop complex colonies with intricate architectures as is illustrated in the pictures.
production. Various Paenibacillus spp. also produce antimicrobial substances that affect a wide spectrum of micro-organisms such as fungi, soil bacteria, plant pathogenic bacteria and even important anaerobic pathogens as Clostridium botulinium.
More specifically, several Paenibacillus species serve as efficient plant growth promoting rhizobacteria
(PGPR). PGPR competitively colonize plant roots and can simultaneously act as biofertilizer
s and as antagonists (biopesticide
s) of recognized root pathogens, such as bacteria, fungi and nematodes. They enhance plant growth by several direct and indirect mechanisms. Direct mechanisms include phosphate solubilization, nitrogen fixation, degradation of environmental pollutants and hormone production. Indirect mechanisms include controlling phytopathogens by competing for resources such as iron, amino acids and sugars, as well as by producing antibiotics or lytic enzymes. Competition for iron also serves as a strong selective force determining the microbial population in the rhizosphere. Several studies show that PGPR exert their plant growth-promoting activity by depriving native microflora of iron. Although iron is abundant in nature, the extremely low solubility of Fe at pH 7 means that most organisms face the problem of obtaining enough iron from their environment. To fulfill their requirements for iron, bacteria have developed several strategies, including (i) the reduction of ferric to ferrous ions, (ii) the secretion of high-affinity iron-chelating compounds, called siderophores, and (iii) the uptake of heterologous siderophores. P. vortex's genome for example, harbors many genes which are employed in these strategies, in particular it has the potential to produce siderophores under iron limiting conditions.
Despite the increasing interest in Paenibacillus spp. genomic information of these bacteria is lacking. More extensive genome sequencing could provide fundamental insights into pathways involved in complex social behavior of bacteria, and can discover a rich source of genes with biotechnological potential.
and cooperative behavior of individual cells while employing sophisticated chemical communication. Pattern formation and self-organization in microbial systems is an intriguing phenomenon, reflection social behaviors of bacteria that might provide insights into the evolutionary development of the collective action of cells in higher organisms. One of the most fascinating pattern forming Paenibacillus species is P. vortex, self-lubricating, flagella driven bacteria. P. vortex organizes its colonies by generating modules, each consisting of many bacteria, which are used as building blocks for the colony as a whole. The modules are groups of bacteria that move around a common center at about 10 µm/sec. Additional intriguing pattern forming Paenibacillus species is P. dendritiformis, which is known to be able to generate two different morphotypes – the Branching (or tip-splitting) morphotype and the Chiral morphotype that is marked by curly branches with well defined handedness (see pictures).
These two pattern forming Paenibacillus strains exhibit many distinct physiological and genetic traits including β-galactosidase-like activity causing colonies to turn blue on X-gal
plates and multiple drug resistance (MDR) (including septrin, penicillin
, kanamycin
, chloramphenicol
, ampicillin
, tetracycline, spectinomycin
, streptomycin
and mitomycin C. Colonies that are grown on surfaces in Petri dishes exhibit several folds higher drug resistance in comparison to growth in liquid media. This particular resistance is believed to be due to a surfactant-like liquid front that actually forms a particular pattern on the Petri plate.
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
, originally included within the genus Bacillus
Bacillus
Bacillus is a genus of Gram-positive, rod-shaped bacteria and a member of the division Firmicutes. Bacillus species can be obligate aerobes or facultative anaerobes, and test positive for the enzyme catalase. Ubiquitous in nature, Bacillus includes both free-living and pathogenic species...
and then reclassified as a separate genus in 1993. Bacteria belonging to this genus have been detected in a variety of environments such as: soil, water, rhizosphere
Rhizosphere
The rhizosphere is the narrow region of soil that is directly influenced by root secretions and associated soil microorganisms. Soil which is not part of the rhizosphere is known as bulk soil. The rhizosphere contains many bacteria that feed on sloughed-off plant cells, termed rhizodeposition, and...
, vegetable matter, forage and insect larvae, as well as clinical samples. The name reflects this fact: Latin paene means almost, and so the Paenibacilli are literally almost Bacilli. The genus includes P. larvae, which is known to cause American foulbrood
American foulbrood
American foulbrood , caused by the spore- forming Paenibacillus larvae ssp. larvae , is the most widespread and destructive of the bee brood diseases. Paenibacillus larvae is a rod-shaped bacterium, which is visible only under a high power microscope...
in honeybees, the P. polymyxa
Paenibacillus polymyxa
Paenibacillus polymyxa is a Gram-positive bacterium used as a soil inoculant in agriculture and horticulture. It is capable of fixing nitrogen....
, which is capable of fixing nitrogen and therefore is used in agriculture and horticulture, the Paenibacillus sp. JDR-2 which is known to be a rich source of chemical agents for biotechnology applications and pattern forming strains such as P. vortex and P. dendritiformis discovered in the early 90s, which are known to develop complex colonies with intricate architectures as is illustrated in the pictures.
Importance
There has been a rapidly growing interest in Paenibacillus spp. since many were shown to be important for agriculture and horticulture (e.g. P. polymyxa), industrial (e.g. P. amylolyticus), and medical applications (e.g. P. peoriate). These bacteria produce various extracellular enzymes such as polysaccharide-degrading enzymes and proteases, which can catalyze a wide variety of synthetic reactions in fields ranging from cosmetics to biofuelBiofuel
Biofuel is a type of fuel whose energy is derived from biological carbon fixation. Biofuels include fuels derived from biomass conversion, as well as solid biomass, liquid fuels and various biogases...
production. Various Paenibacillus spp. also produce antimicrobial substances that affect a wide spectrum of micro-organisms such as fungi, soil bacteria, plant pathogenic bacteria and even important anaerobic pathogens as Clostridium botulinium.
More specifically, several Paenibacillus species serve as efficient plant growth promoting rhizobacteria
Plant-growth promoting rhizobacteria
Plant growth-promoting rhizobacteria was first defined by Kloepper and Schroth to describe soil bacteria that colonize the roots of plants following inoculation onto seed and that enhance plant growth...
(PGPR). PGPR competitively colonize plant roots and can simultaneously act as biofertilizer
Biofertilizer
A bio-fertilizer is a substance which contains living microorganisms which, when applied to seed, plant surfaces, or soil, colonizes the rhizosphere or the interior of the plant and promotes growth by increasing the supply or availability of primary nutrients to the host plant.Bio-fertilizers add...
s and as antagonists (biopesticide
Biopesticide
Biopesticides include "naturally occurring substances that control pests , microorganisms that control pests , and pesticidal substances produced by plants containing added genetic material or PIPs."Biopesticides are biochemical pesticides that are naturally occurring substances that control pests...
s) of recognized root pathogens, such as bacteria, fungi and nematodes. They enhance plant growth by several direct and indirect mechanisms. Direct mechanisms include phosphate solubilization, nitrogen fixation, degradation of environmental pollutants and hormone production. Indirect mechanisms include controlling phytopathogens by competing for resources such as iron, amino acids and sugars, as well as by producing antibiotics or lytic enzymes. Competition for iron also serves as a strong selective force determining the microbial population in the rhizosphere. Several studies show that PGPR exert their plant growth-promoting activity by depriving native microflora of iron. Although iron is abundant in nature, the extremely low solubility of Fe at pH 7 means that most organisms face the problem of obtaining enough iron from their environment. To fulfill their requirements for iron, bacteria have developed several strategies, including (i) the reduction of ferric to ferrous ions, (ii) the secretion of high-affinity iron-chelating compounds, called siderophores, and (iii) the uptake of heterologous siderophores. P. vortex's genome for example, harbors many genes which are employed in these strategies, in particular it has the potential to produce siderophores under iron limiting conditions.
Despite the increasing interest in Paenibacillus spp. genomic information of these bacteria is lacking. More extensive genome sequencing could provide fundamental insights into pathways involved in complex social behavior of bacteria, and can discover a rich source of genes with biotechnological potential.
Pattern Formation, Self-Organization and Social Behaviors
Several Paenibacillus species can form complex patterns on semi-solid surfaces. Development such complex colonies require self-organizationSelf-organization
Self-organization is the process where a structure or pattern appears in a system without a central authority or external element imposing it through planning...
and cooperative behavior of individual cells while employing sophisticated chemical communication. Pattern formation and self-organization in microbial systems is an intriguing phenomenon, reflection social behaviors of bacteria that might provide insights into the evolutionary development of the collective action of cells in higher organisms. One of the most fascinating pattern forming Paenibacillus species is P. vortex, self-lubricating, flagella driven bacteria. P. vortex organizes its colonies by generating modules, each consisting of many bacteria, which are used as building blocks for the colony as a whole. The modules are groups of bacteria that move around a common center at about 10 µm/sec. Additional intriguing pattern forming Paenibacillus species is P. dendritiformis, which is known to be able to generate two different morphotypes – the Branching (or tip-splitting) morphotype and the Chiral morphotype that is marked by curly branches with well defined handedness (see pictures).
These two pattern forming Paenibacillus strains exhibit many distinct physiological and genetic traits including β-galactosidase-like activity causing colonies to turn blue on X-gal
X-gal
X-gal is an organic compound consisting of galactose linked to a substituted indole. The compound was synthesized by Jerome Horwitz and collaborators in Detroit, MI, in 1964. The formal chemical name is often shortened to less accurate but also less cumbersome phrases such as bromochloroindoxyl...
plates and multiple drug resistance (MDR) (including septrin, penicillin
Penicillin
Penicillin is a group of antibiotics derived from Penicillium fungi. They include penicillin G, procaine penicillin, benzathine penicillin, and penicillin V....
, kanamycin
Kanamycin
Kanamycin sulfate is an aminoglycoside antibiotic, available in oral, intravenous, and intramuscular forms, and used to treat a wide variety of infections. Kanamycin is isolated from Streptomyces kanamyceticus.-Mechanism:...
, chloramphenicol
Chloramphenicol
Chloramphenicol is a bacteriostatic antimicrobial that became available in 1949. It is considered a prototypical broad-spectrum antibiotic, alongside the tetracyclines, and as it is both cheap and easy to manufacture it is frequently found as a drug of choice in the third world.Chloramphenicol is...
, ampicillin
Ampicillin
Ampicillin is a beta-lactam antibiotic that has been used extensively to treat bacterial infections since 1961. Until the introduction of ampicillin by the British company Beecham, penicillin therapies had only been effective against Gram-positive organisms such as staphylococci and streptococci...
, tetracycline, spectinomycin
Spectinomycin
Spectinomycin is an aminocyclitol antibiotic, closely related to the aminoglycosides, produced by the bacterium Streptomyces spectabilis....
, streptomycin
Streptomycin
Streptomycin is an antibiotic drug, the first of a class of drugs called aminoglycosides to be discovered, and was the first antibiotic remedy for tuberculosis. It is derived from the actinobacterium Streptomyces griseus. Streptomycin is a bactericidal antibiotic. Streptomycin cannot be given...
and mitomycin C. Colonies that are grown on surfaces in Petri dishes exhibit several folds higher drug resistance in comparison to growth in liquid media. This particular resistance is believed to be due to a surfactant-like liquid front that actually forms a particular pattern on the Petri plate.
External links
- Paenibacillus Taxonomy
- Genome sequence of the pattern forming Paenibacillus vortex bacterium reveals potential for thriving in complex environments - manuscript
- Prof. Eshel Ben-Jacob home page
- Specific PCR for Paenibacillus genus based on rpoB gene
- Use of rpoB gene analysis for identification of nitrogen-fixing Paenibacillus species as an alternative to the 16S rRNA gene