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Bacillus is a genus of Gram-positive, rod-shaped bacteria, a member of the phylum Firmicutes, with 266 named species. The term is also used to describe the shape (rod) of certain bacteria; and the plural Bacilli is the name of the class of bacteria to which this genus belongs. Bacillus species can be either obligate aerobes: oxygen dependent; or facultative anaerobes: having the ability to be anaerobic in the absence of oxygen. Cultured Bacillus species test positive for the enzyme catalase if oxygen has been used or is present.
Bacterial growth is proliferation of bacterium into two daughter cells, in a process called binary fission. Providing no event occurs, the resulting daughter cells are genetically identical to the original cell. Hence, bacterial growth occurs. Both daughter cells from the division do not necessarily survive. However, if the number surviving exceeds unity on average, the bacterial population undergoes exponential growth. The measurement of an exponential bacterial growth curve in batch culture was traditionally a part of the training of all microbiologists; the basic means requires bacterial enumeration by direct and individual, direct and bulk (biomass), indirect and individual, or indirect and bulk methods. Models reconcile theory with the measurements.
An endospore is a dormant, tough, and non-reproductive structure produced by some bacteria in the phylum Firmicutes. The name "endospore" is suggestive of a spore or seed-like form, but it is not a true spore. It is a stripped-down, dormant form to which the bacterium can reduce itself. Endospore formation is usually triggered by a lack of nutrients, and usually occurs in gram-positive bacteria. In endospore formation, the bacterium divides within its cell wall, and one side then engulfs the other. Endospores enable bacteria to lie dormant for extended periods, even centuries. There are many reports of spores remaining viable over 10,000 years, and revival of spores millions of years old has been claimed. There is one report of viable spores of Bacillus marismortui in salt crystals approximately 250 million years old. When the environment becomes more favorable, the endospore can reactivate itself to the vegetative state. Most types of bacteria cannot change to the endospore form. Examples of bacterial genera that can form endospores include Bacillus and Clostridium.
A microbiological culture, or microbial culture, is a method of multiplying microbial organisms by letting them reproduce in predetermined culture medium under controlled laboratory conditions. Microbial cultures are foundational and basic diagnostic methods used as a research tool in molecular biology.
Bacteriological water analysis is a method of analysing water to estimate the numbers of bacteria present and, if needed, to find out what sort of bacteria they are. It represents one aspect of water quality. It is a microbiological analytical procedure which uses samples of water and from these samples determines the concentration of bacteria. It is then possible to draw inferences about the suitability of the water for use from these concentrations. This process is used, for example, to routinely confirm that water is safe for human consumption or that bathing and recreational waters are safe to use.
Bacillus subtilis, known also as the hay bacillus or grass bacillus, is a Gram-positive, catalase-positive bacterium, found in soil and the gastrointestinal tract of ruminants and humans. A member of the genus Bacillus, B. subtilis is rod-shaped, and can form a tough, protective endospore, allowing it to tolerate extreme environmental conditions. B. subtilis has historically been classified as an obligate aerobe, though evidence exists that it is a facultative anaerobe. B. subtilis is considered the best studied Gram-positive bacterium and a model organism to study bacterial chromosome replication and cell differentiation. It is one of the bacterial champions in secreted enzyme production and used on an industrial scale by biotechnology companies.
Bacitracin is a mixture of related cyclic peptides produced by organisms of the licheniformis group of Bacillus subtilisvar Tracy, first isolated in 1945. These peptides disrupt Gram-positive bacteria by interfering with cell wall and peptidoglycan synthesis.
A growth medium or culture medium is a solid, liquid or semi-solid designed to support the growth of microorganisms or cells, or small plants like the moss Physcomitrella patens. Different types of media are used for growing different types of cells.
Paenibacillus is a genus of 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: Latin paene means almost, 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, so 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 shown in the pictures:
The science of pattern formation deals with the visible, (statistically) orderly outcomes of self-organization and the common principles behind similar patterns in nature.
Diauxie is a Greek word coined by Jacques Monod to mean two growth phases. The word is used in English in cell biology to describe the growth phases of a microorganism in batch culture as it metabolizes a mixture of two sugars. Rather than metabolizing the two available sugars simultaneously, microbial cells commonly consume them in a sequential pattern, resulting in two separate growth phases.
In microbiology, streaking is a technique used to isolate a pure strain from a single species of microorganism, often bacteria. Samples can then be taken from the resulting colonies and a microbiological culture can be grown on a new plate so that the organism can be identified, studied, or tested.
Asymmetric bacteria are bacteria that undergo "non-symmetrical" life cycles. This especially includes those that differentiate temporally, such as prosthecate bacteria.
Swarming motility is a rapid and coordinated translocation of a bacterial population across solid or semi-solid surfaces, and is an example of bacterial multicellularity and swarm behaviour. Swarming motility was first reported by Jorgen Henrichsen and has been mostly studied in genus Serratia, Salmonella, Aeromonas, Bacillus, Yersinia, Pseudomonas, Proteus, Vibrio and Escherichia.
Extracellular polymeric substances (EPSs) are natural polymers of high molecular weight secreted by microorganisms into their environment. EPSs establish the functional and structural integrity of biofilms, and are considered the fundamental component that determines the physiochemical properties of a biofilm.
L-form bacteria, also known as Sam Cannon, L-phase variants, and cell wall-deficient (CWD) bacteria, are strains of bacteria that lack cell walls. They were first isolated in 1935 by Emmy Klieneberger-Nobel, who named them "L-forms" after the Lister Institute in London where she was working.
Paenibacillus vortex is a species of pattern-forming bacteria, first discovered in the early 1990s by Eshel Ben-Jacob's group at Tel Aviv University. It is a social microorganism that forms colonies with complex and dynamic architectures. P. vortex is mainly found in heterogeneous and complex environments, such as the rhizosphere, the soil region directly influenced by plant roots.
Paenibacillus dendritiformis is a species of pattern-forming bacteria, first discovered in the early 90s by Eshel Ben-Jacob's group. It is a social microorganism that forms colonies with complex and dynamic architectures. The genus Paenibacillus comprises 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.
Bacillus subtilis is a rod-shaped, Gram-positive bacteria that is naturally found in soil and vegetation, and is known for its ability to form a small, tough, protective and metabolically dormant endospore. B. subtilis can divide symmetrically to make two daughter cells, or asymmetrically, producing a single endospore that is resistant to environmental factors such as heat, desiccation, radiation and chemical insult which can persist in the environment for long periods of time. The endospore is formed at times of nutritional stress, allowing the organism to persist in the environment until conditions become favourable. The process of endospore formation has profound morphological and physiological consequences: radical post-replicative remodelling of two progeny cells, accompanied eventually by cessation of metabolic activity in one daughter cell and death by lysis of the other.
The Phosphate (Pho) regulon is a bacterial regulatory mechanism used for the conservation and management of inorganic phosphate within the cell. It was first discovered in Escherichia coli as an operating system for the bacterial strain, and was later identified in other species. The Pho system is composed of various components including extracellular enzymes and transporters that are capable of phosphate assimilation in addition to extracting inorganic phosphate from organic sources. This is an essential process since phosphate plays an important role in cellular membranes, genetic expression, and metabolism within the cell. Under low nutrient availability, the Pho regulon helps the cell survive and thrive despite a depletion of phosphate within the environment. When this occurs, phosphate starvation-inducible (psi) genes activate other proteins that aid in the transport of inorganic phosphate.
References
- Matsushita, M.; Wakita, J.; Itoh, H.; Ràfols, I.; Matsuyama, T.; Sakaguchi, H.; Mimura, M. (1998). "Interface growth and pattern formation in bacterial colonies". Physica A: Statistical Mechanics and its Applications. Elsevier BV. 249 (1–4): 517–524. doi:10.1016/s0378-4371(97)00511-6. ISSN 0378-4371. Experiments on Bacillus subtilis by Matsushita et al.
- Lacasta, A. M.; Cantalapiedra, I. R.; Auguet, C. E.; Peñaranda, A.; Ramírez-Piscina, L. (1999-06-01). "Modeling of spatiotemporal patterns in bacterial colonies". Physical Review E. American Physical Society (APS). 59 (6): 7036–7041. arXiv: cond-mat/9904367 . doi:10.1103/physreve.59.7036. ISSN 1063-651X. Reaction-diffusion model for Bacillus Subtilis.