Endospore
An endospore is a dormant, tough, and non-reproductive structure produced by certain bacteria from the Firmicute phylum. The name "endospore" is suggestive of a spore or seed-like form (endo means within), but it is not a true spore (i.e., not an offspring). It is a stripped-down, dor…
Why do bacteria form endospores?
Endospore formation is usually triggered by lack of nutrients, and usually occurs in Gram-positive bacteria. In endospore formation, the bacterium divides within its cell wall. One side then engulfs the other. Endospores enable bacteria to lie dormant for extended periods, even centuries.
Does this bacteria produce endospore?
Very few bacteria produce endospores. Only some of those species in the Firmicute phylum produce endospores, which are non-reproductive structures containing DNA and a portion of the cytoplasm. Endospores are not true spores since they are not offspring of the bacterium.
When do bacteria form an endospore?
The phenomenon where an endospore is formed is known as sporogenesis or sporulation. This process is usually observed in the cells of bacteria under nutrient-deficient conditions when the endospore core tends to become increasingly dehydrated. Sporulation is a complicated process and takes seven stages to complete.
Can Gram negative bacteria produce endospores?
The Gram-negative endospore-forming bacterium Sporomusa ovata belongs to the class Negativicutes within the Firmicutes. This class comprises only a few genera, which are Gram negative and form endospores. S. ovata was one of the first described species with this feature (1). How many endospores can a bacteria produce?
What is the importance of spores in bacteria?
Spores are involved in reproduction. Certain bacteria make spores as a way to defend themselves. Spores have thick walls. They can resist high temperatures, humidity, and other environmental conditions.
What is the most important part of the bacterial endospore?
The cortex is what makes the endospore so resistant to temperature. The cortex contains an inner membrane known as the core. The inner membrane that surrounds this core leads to the endospore's resistance against UV light and harsh chemicals that would normally destroy microbes.
What are endospore forming bacteria?
0:007:20Endospore formation in bacteria - YouTubeYouTubeStart of suggested clipEnd of suggested clipThis video we'll talk about endospore formation many gram positive bacteria can form endosporeMoreThis video we'll talk about endospore formation many gram positive bacteria can form endospore vegetative bacteria undergoes pore formation under extreme or adverse environmental condition.
What are three advantages of endospore formation?
From a bacterium's perspective, what are the advantages of endospore formation? - endospores are highly resistant to radiation and heat. - the endospore provides protection in dry conditions. -the endospore is more resistant to disinfectants.
What is endospores and its function?
Endospores are spores that are formed within the cells, mainly in bacteria. These spores are formed within bacteria vegetative cells or mother cells known as sporangia. Endospores ensure the survival of bacteria in adverse environmental conditions such as nutrient deficiency (carbon and nitrogen) and overpopulation.
Which of the following best describes endospores?
Which of the following correctly describes the function of bacterial endospores? Endospores are produced as resting stages of the bacterium that can survive inhospitable conditions.
Do all bacteria have endospores?
Very few bacteria produce endospores. Only some of those species in the Firmicute phylum produce endospores, which are non-reproductive structures containing DNA and a portion of the cytoplasm. Endospores are not true spores since they are not offspring of the bacterium.
Are spores and endospores the same?
The main difference between spore and endospore is that spore is an active reproductive structure mainly produced by plants and fungi whereas endospore is a dormant, non-reproductive structure of bacteria.
Where do endospores form?
Endospores can form within different areas of the vegetative cell. They can be central, subterminal, or terminal. Central endospores are located within the middle of the vegetative cell. Terminal endospores are located at the end of the vegetative cell.
What is the advantage of an endospore to a bacteria quizlet?
why is an endospore called a resting structure? of what advantage is an endospore to a bacterial cell? because it provides a method for one cell to rest, or survive, as opposed to grow and reproduce. the protective endospore wall allows a bacterium to withstand adverse conditions in the environment.
What is the primary purpose of the endospore produced by Bacillus subtilis?
B. subtilis is a rod-shaped bacterium, which produces endospores that allow the survival of extreme environmental conditions including heat and desiccation.
What importance are spore forming bacteria in the food industry?
Specific endospore formers have become important contaminants in industrial food processing. The direct or indirect soil route of contamination or dispersal is the start of events or processes in the agrofood chain that eventually leads to important problems or concerns for food safety and/or quality.
Which of the following is the major factor that stimulates endospore formation?
Endospore formation is usually triggered by a lack of nutrients; it is a stripped-down, dormant form to which the bacterium can reduce itself. The endospore consists of the bacterium's deoxyribonucleic acid (DNA), ribosomes, and large amounts of dipicolinic acid.
What is a endospore quizlet?
An endospore is an extremely resistant dormant cell structure produced by some bacterial species. If you break down the term endospore, 'endo-' means 'inside' and '-spore' refers to the 'dormant structure,' so the endospore is a structure formed inside the cell.
What is the significance of bacterial spore formation the bacterium quizlet?
A bacterial endospore is a structure formed within a bacterium that is resistant & dormant. The endospore's purpose is to protect the bacterium from poor or unfavorable conditions that hinder its survival. Spores are also resistant to heat & chemicals that would otherwise kill other bacteria.
Why do some bacteria form endospores quizlet?
Spores help increase chance of survival in stressful environment. The DNA is replicated, spore formation occurs, and the mother cell disintegrates. But the number of cells is not increased. Bacteria that produce endospores are resistant to disinfectants, many chemicals, heat and radiation.
What is an example of a bacterial spore?
An example of a bacterial spore is an endospore. This spore is highly resistant to heat, desiccation, radiation, chemicals, and some disinfectants.
What is the function of bacterial endospores?
The primary function of a bacterial endospore is to ensure the survival of a bacteria during harsh environmental conditions. These could be overpop...
How are bacterial spores formed?
Bacterial spore formation is triggered once nutrients such as carbon and nitrogen become deficient. The formation of the spores takes several hours...
What is a bacterial endospore?
A bacteria endospore is a type of spore that is formed within a vegetative or mother cell. The vegetative cell is mainly referred to as a sporangium.
What is B. cereus?
B. cereus sensu stricto (hereafter called B. cereus for simplicity) is a member of the B. cereus group or also called B. cereus sensu lato (Table 1 ), which can be divided into seven major phylogenetic groups each corresponding to a specific “thermotype”, showing clear differences in ability to grow at low or high temperatures [ 4 ]. B. cereus is a ubiquitous organism present in many types of soil, sediments, dust, and plants. Soil is heavily contaminated with B. cereus spores which can occur in a range from 4 up to 6 log spores per gram farm soil (Table 2 ). It has long been believed that this organism has a saprophytic life cycle in soil with the presence of spores that only germinate and grow upon contact with soil-associated organic matter (i.e., nutrient-rich conditions). However, in laboratory experiments with liquid soil extract and artificial soil microcosms, it was observed that B. cereus (as well as other soil-isolated Bacillus species) displayed a complete life cycle (germination, growth, and sporulation) and adapted to translocate in soil by switching from a single-cell phenotype to a multicellular one with the formation of filaments and clumps that encased the ensuing spores in an extracellular matrix [ 5 ]. In addition to a full life cycle in soil, B. cereus is also adapted to a lifestyle in the animal (e.g., soil animals such as earthworms [ 6 ]) or human gut, where it can behave as a pathogen or as a part of the intestinal microbiota, as well as to growth in food and feed. Bacillus thuringiensis, being an insect pathogen of the B. cereus group, is likewise a ubiquitous soil microorganism, but it is also found on the phylloplane and in insects. Presumably, B. thuringiensis proliferates in the guts of insects and is then released into soil where it can subsequently proliferate under favorable nutrient conditions [ 7 ]. Less is known on the ecology of the other members of the B. cereus group (the psychrotolerant species: Bacillus mycoides and Bacillus weihenstephanensis and the mesophilic species: Bacillus pseudomycoides ), except that they have been isolated from a wide variety of environmental niches such as soils, sludge, arthropods, earthworms, and rhizospheres [ 7 ]. It has been speculated that climate change may modify the spreading of B. cereus hosts (wildlife, insects, earthworms) [ 8 ]. Alternatively, B. cereus with its wide adaptive strategy to changing environments through signal transduction mechanisms likely will adapt to environmental (climate) changes for example, climate change could modify the distribution of the phylogenetic groups of B. cereus in soil. This adaptation might contribute at the end of the chain to a progressive change in prevalence or concentration in foods.
Why is pasteurization important?
It should be remembered that pasteurization activates spore germination and thus enhances vegetative cell growth. Growth of B. cereus in pasteurised milk is considered the main limiting factor determining the shelf life of this food product. Too high levels of B. cereus in pasteurized milk before the end of shelf life or prolonged refrigerated storage cause common structural defects known as sweet curdling and bitty cream (reviewed by Heyndrickx et al. [ 27 ]). B. cereus diarrhoeal cases or outbreaks associated with milk or dairy products are scarce, although B. cereus is commonly isolated from pasteurized milk. This may be due to the fact that in the cold dairy chain, selection occurs for psychrotolerant members of the B. cereus group, which are mostly strains of B. weihenstephanensis. It has been shown that these strains are less toxigenic than mesophilic B. cereus strains and are thus less likely to cause illness [ 28 ]. Emetic food poisoning related to the consumption of dairy products has been reported (see references in [ 28 ]). Although the overall prevalence of emetic strains in the dairy production chain is very low (<1%), colonization and proliferation of emetic B. cereus was observed at particular farms with saw dust bedding as a likely contamination source for the raw milk, and in a silo tank at a dairy plant [ 28 ]. As the general level of spores of emetic-toxin-producing strains in milk is low (<1000 cfu/litre), there is no risk associated with consumer milk provided that the milk is properly refrigerated. If contaminated milk is used for milk powder, a risk to the consumer exists if this milk powder is used in baby food or as raw ingredient in foodstuffs, where proliferation of B. cereus may occur, and there have been reports of emetic food poisoning episodes where contaminated milk powder was a likely source (see references in [ 28 ]).
How many spores of B. cereus are there in soil?
Soil is heavily contaminated with B. cereus spores which can occur in a range from 4 up to 6 log spores per gram farm soil (Table 2 ).
Where are Alicyclobacillus isolated?
Recently, several Alicyclobacillus species have been isolated from orchard soils: A. acidoterrestris and A. acidocaldarius from orchard soil (pH 5.9–6.7) collected from an apple and pear farm in South Africa [ 49 ], A. acidoterrestris and A. contaminans as major species (besides several other minor Alicyclobacillus species) from several fruit (banana, blueberry, chestnut, grape, kiwi, orange, pear, persimmon, strawberry) orchard soils in Japan [ 50 ]. Several of the isolated species produced guaiacol, but the production levels were strain dependent, even within A. acidoterrestris. By RAPD typing, it was shown that identical strains were present in pear concentrate and soil outside the factory, indicating soil as the source of the Alicyclobacillus spores [ 51 ].
What is the source of spores in food?
In many types of food and feed, soil can be considered as the initial contamination source for spore formers. Usually, when direct transfer from soil is involved, levels of these spore formers in foods, ingredients, or feeds are too low to cause problems. However, because of the complexity of the food chain, particular spore-forming species or types may encounter niches where proliferation occurs. This can happen on the primary production level (e.g., silage, bedding material), in the processing line (e.g., storage tanks), during distribution (e.g., temperature abuse during refrigerated storage), or in the final product (e.g., complex foods, fruit juice). These proliferation steps enable the endospore former such as B. cereus, A. acidoterrestris, C. tyrobutyricum, non-proteolytic C. botulinum or C. estertheticum, either to enter as a contaminant into a next step of the production chain or to provoke food quality or safety problems in the final product. For the food industry, it is a challenge to gain insight into the whole contamination flow of endospore formers originating from soil as well as in the conditions permitting their proliferation.
What is the primary source of spore formers in food?
In this paper, recent data revealing the role of soil as primary contamination source for spore formers in food ( B. cereus, Alicyclobacillus acidoterrestris, Clostridium tyrobutyricum) or extending our knowledge on specific soil-borne spore formers in food (several Clostridium spp. such as C. estertheticum) are discussed.
How long does a spore last in the chiller?
They are typically processed with a gentle heat treatment (65–95°C, enabling survival of spores) and are chill-stored with (frequently) modified-atmosphere packaging for an extended durability (from a few days up to 3 months), whilst preserving the product attributes such as organoleptic quality and safety.
What do SASPs do?
Ø The SASPs can also act as the carbon and nitrogen source of the newly formed vegetative cell during endospore germination . Ø The cortex of the endospore can remove water from the core osmotically (cause dehydration). Ø Dehydration can provide heat resistance in bacterial cells.
What is the acid in endospores?
Ø Endospores contain high amount of dipicolinic acid in its core (protoplast). Ø In some endospores, about 15% of the total dry weight of the spore is contributed dipicolinic acid. Ø The dipicolinic acid in bacterial endospore not occurs in free-state rather, it forms a complex with calcium ions (Ca2+).
Why are endospores important?
Another importance of endospores is that it can be easily dispersed by wind, water and through the gut of animals. Bacillus and Clostridium are the most studied endospore forming bacterial genera.
How do endospores germinate?
Ø Germination of spores can be triggered by exposing the activated endospores to nutrients such as sugars or amino acids.
Why are endospores resistant to heat?
Ø The thickness of the spore coat is one reason for the high resistance of endospores towards heat, radiation and chemicals.
What is the outermost layer of an endospore?
Ø The structure of endospore is very complex since they possess multilayered coverings. Ø The outermost layer of the spore is called exosporium which is relatively thin and delicate. Ø Beneath the exosporium is a Spore Coat composed of several layers of proteins. Ø Spore coat is comparatively thick.
What is the name of the spores produced by bacteria?
Bacterial endospores are special tough, dormant and resistant spores produced by some Gram-positive bacteria of Firmicute family during unfavorable environmental conditions. Endospores are developed within the vegetative cells (hence the name, endo = inside). They help the bacteria to endure the unfavorable environmental conditions.
What is the purpose of endospores?
The endospore's purpose is to protect the bacterium from poor or unfavorable conditions that hinder its survival. Spores are also resistant to heat & chemicals that would otherwise kill other bacteria.
Why are endospores important?
Endospores are especially important from a clinical standpoint because they are very resistant to processes or antibacterial methods that would normally kill off vegetative cells. This means that they are particularly difficult to kill. Endospores allow the bacterium to create a resistant & dormant cell that can preserve the original cell's genetic material when put under extremely unfavorable conditions.
Why do you steam a smear?
The smear needs to be steamed because this allows the stain to penetrate the wall of the endospore.
What color should the vegetative cells be?
The vegetative cells should appear red or pink.