![]() 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. Since malachite green is water-soluble and does not adhere well to the cell, and since the vegetative cells have been disrupted by heat, the malachite green rinses easily from the vegetative cells, allowing them to readily take up the counterstain.Microorganisms sense and adapt to changes in their environment. The primary stain in the endospore stain procedure, malachite green, is driven into the cells with heat. Because of their tough protein coats made of keratin, spores are highly resistant to normal staining procedures. When spores are exposed to favorable conditions, they can germinate into a vegetative cell within 90 minutes. They can remain viable for thousands of years. ![]() Spores are metabolically inactive and dehydrated. The normally-growing cell that forms the endospore is called a vegetative cell. Bacteria can form endospores in approximately 6 to 8 hours after being exposed to adverse conditions. Spores are resistant to heat, dessication, chemicals, and radiation. By forming spores, bacteria can survive in hostile conditions. Endospores are formed by a few genera of bacteria, such as Bacillus. The endospore stain is a differential stain used to visualize bacterial endospores.
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