The model organism used to study endospore formation is Bacillus subtilis. The process of forming an endospore is complex. Other species-specific structures and chemicals associated with endospores include stalks, toxin crystals, or an additional outer glycoprotein layer called the exosporium. These proteins tightly bind and condense the DNA, and are in part responsible for resistance to UV light and DNA-damaging chemicals. Small acid-soluble proteins (SASPs) are also only found in endospores. This endospore-specific chemical can comprise up to 10% of the spore's dry weight and appears to play a role in maintaining spore dormancy. The center of the endospore, the core, exists in a very dehydrated state and houses the cell's DNA, ribosomes and large amounts of dipicolinic acid. The inner membrane, under the germ cell wall, is a major permeability barrier against several potentially damaging chemicals. This layer of peptidoglycan will become the cell wall of the bacterium after the endospore germinates. A germ cell wall resides under the cortex. Proper cortex formation is needed for dehydration of the spore core, which aids in resistance to high temperature. Beneath the coat resides a very thick layer of specialized peptidoglycan called the cortex. The outer proteinaceous coat surrounding the spore provides much of the chemical and enzymatic resistance. ![]() The resilience of an endospore can be explained in part by its unique cellular structure. A variety of different microorganisms form "spores" or "cysts", but the endospores of low G+C Gram-positive bacteria are by far the most resistant to harsh conditions. The extraordinary resistance properties of endospores make them of particular importance because they are not readily killed by many antimicrobial treatments. These stresses include high temperature, high UV irradiation, desiccation, chemical damage and enzymatic destruction. It allows the bacterium to produce a dormant and highly resistant cell to preserve the cell's genetic material in times of extreme stress.Įndospores can survive environmental assaults that would normally kill the bacterium. This complex developmental process is often initiated in response to nutrient deprivation. One example of an extreme survival strategy employed by certain low G+C Gram-positive bacteria is the formation of endospores. When favored nutrients are exhausted, some bacteria may become motile to seek out nutrients, or they may produce enzymes to exploit alternative resources. One of the generations is the sporophyte, which produces spores by meiosis, and the other is the gametophyte with produces gametes.Microorganisms sense and adapt to changes in their environment. They germinated when conditions were right. This killed the bacteria, but not the spores. This survived even when the bacteria were boiled for five minutes. The origin of these spores was discovered in the 19th century, when a biologist noticed, under the microscope, a small, round, bright body inside bacterial cells. ![]() Spores of tetanus and anthrax, for example, can survive in the soil for many years. The morphology of these specialized conidiophores is often distinctive of a specific species and can therefore be used in identification of the species.īacterial spores are extremely resistant. They are haploid cells genetically identical to the haploid parent, can develop into a new organism if conditions are favorable, and serve in dispersal.Īsexual reproduction in Ascomycetes (the Phylum Ascomycota) is by the formation of conidia, which are borne on specialized stalks called conidiophores. Ĭonidia are asexual, non-motile spores of a fungus they are also called mitospores due to the way they are generated through the cellular process of mitosis. The asexual spores have inside them the genetic material to make a whole new organism identical to its parent. ![]() Fungi (for example, mushrooms) produce spores, which may be asexual or sexual.
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