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Tìm kiếm VSV

vxthanh

Member
#1
Em dùng chức năng tim kiếm không được nên pót lên đây luôn.Mong anh em giúp đỡ giùm.
Em muốn tìm tài liệu về các chủng VSV Bacillus, Micrococus, Pseudomonas, Clostridium, Methanobacterium...
Cảm ơn anh em nhiều.
Mail em là vuchuong88@gmail.com
 

00792

Moderator
Clostridium perfringens is a Gram-positive anaerobic spore-forming bacterium known to be the most widely distributed pathogen in nature. It is commonly found in the environment (in soil and sewage) and in the intestines of animals and humans as a member of the normal flora.

C. perfringens has been shown to be a cause of human diseases such as gas gangrene (clostridial myonecrosis), food poisoning, necrotizing enterocolitis of infants, and enteritis necroticans (pigbel) . It is also the causative agent of animal diseases such as lamb dysentery, ovine enterotoxemia (struck) and pulpy kidney disease of sheep, and other enterotoxemic diseases of lambs and calves. Isolates of C. perfringens can be divided into five types (A to E) based on the particular extracellular toxins which they produce . Each of these toxin types are responsible for specific disease syndromes
C. perfringens diseases are generally mediated via the production of extracellular enzymes or toxins, with the exception of human food poisoning, which involves a sporulation- specific enterotoxin. C. perfringensC. perfringens strain involved, and each type of toxin induces a specific syndrome. Therefore, the correct identification of C. perfringens pathovars is critical for epidemiological studies and for the development of effective preventative measures, including vaccination.
Most of the virulence genes from C. perfringens have been characterized (Table 2 ). The genes encoding \u03b1, \u03b8-toxin, \u03ba-collagenase and \u03bc-hyaluronidase are located on variable regions of the chromosome near the origin of replication. Only the nanH and nanI genes, encoding neuraminidases, are localized on a conserved region. In contrast, the genes encoding \u03b21-toxin, \u03b22-toxin, \u03b5-toxin, \u03b9-toxin, \u03bb-protease are located on plasmids of various sizes (55-140 kb). The location of most of the toxin genes on extrachromosomal elements is probably responsible for the diversity of C. perfringens A.

Perfringens food poisoning is the term used to describe the common foodborne illness caused by C. perfringens type A. The actual cause of poisoning by C. perfringens is temperature abuse of prepared foods. Small numbers of the organisms are often present after cooking and multiply to food poisoning levels during cool down and storage of prepared foods. C. perfringens cells sporulate in the small intestine and generate large quantities of enterotoxin. This can result, 12 to 24 h later, in intense nausea, diarrhea, and, more rarely, vomiting, with the occasional fatality amongst the elderly and debilitated. C. perfringens, Type C causes the more serious Enteritis necroticans (pigbel) in humans.
does not invade healthy cells but produces various toxins and enzymes that are responsible for the associated lesions and symptoms. The toxins produced depend on the
 

00792

Moderator
Bacillus thuringiensis

Bacillus thuringiensis
Trade and Other Names: Trade names include Acrobe, Bactospeine, Berliner (variety kurstaki), Certan (variety aizawai), Dipel, Javelin, Leptox, Novabac, Teknar (variety israelensis), Thuricide, and Victory. Bacillus thuringiensis is also known at B.t.
RegulatoryStatus: This microbial insecticide was originally registered in 1961 as a General Use Pesticide (GUP). It is classified as toxicity class III - slightly toxic. Products containing B.t. bear the Signal Word CAUTION because of its potential to irritate eyes and skin.
Chemical Class: bacterium
Introduction: Bacillus thuringiensis (B.t.) is a naturally-occurring soil bacterium that produces poisons which cause disease in insects. B.t. is considered ideal for pest management because of its specificity to pests and because of its lack of toxicity to humans or the natural enemies of many crop pests. There are different strains of B.t., each with specific toxicity to particular types of insects: B.t. aizawai (B.t.a.) is used against wax moth larvae in honeycombs; B.t. israelensis (B.t.i.) is effective against mosquitoes, blackflies and some midges; B.t. kurstaki (B.t.k.) controls various types of lepidopterous insects, including the gypsy moth and cabbage looper. A newer strain, B.t. san diego, is effective against certain beetle species and the boll weevil. To be effective, B.t. must be eaten by insects during their feeding stage of development, when they are larvae. B.t. is ineffective against adult insects. More than 150 insects, mostly lepidopterous larvae, are known to be susceptible in some way to B.t.
B.t. forms asexual reproductive cells, called spores, which enable it to survive in adverse conditions. During the process of spore formation, B.t. also produces unique crystalline bodies. When eaten, the spores and crystals of B.t. act as poisons in the target insects. B.t. is therefore referred to as a stomach poison. B.t. crystals dissolve in the intestine of susceptible insect larvae. They paralyze the cells in the gut, interfering with normal digestion and triggering the insect to stop feeding on host plants. B.t. spores can then invade other insect tissue, multiplying in the insect's blood, until the insect dies. Death can occur within a few hours to a few weeks of B.t. application, depending on the insect species and the amount of B.t. ingested. Typical agricultural formulations include wettable powders, spray concentrates, liquid concentrates, dusts, baits, and time release rings.
Formulation: Typical agricultural formulations include wettable powders, spray concentrates, liquid concentrates, dusts, baits, and time release rings.
 

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