Name :Bacillus thuringiensis

Nick name : Bt

Bacillus thuringiensis bacteria. (Scanning electron micrograph (SEM) of bacillus thuringiensis colony during sporulation shows disfigured bacterial cells, often with pointed ends. The bacteria produce toxic protein cryst

Phase-contrast micrograph of Bacillus thuringiensis subsp

Bacillus thuringiensis colony in blood agar

Scientific classification Domain: Bacteria Phylum: Firmicutes Class: Bacilli Order: Bacillales Family: Bacillaceae Genus: Bacillus Species: B. thuringiensis

Delta-endotoxin Unlike typical nerve-poison insecticides, Bt acts by producing proteins (delta-endotoxin, the "toxic crystal") that reacts with the cells of the gut lining of susceptible insects. These Bt proteins paralyze the digestive system, and the infected insect stops feeding within hours. Bt-affected insects generally die from starvation, which can take several days. Occasionally, the bacteria enter the insect's blood and reproduce within the insect. However, in most insects it is the reaction of the protein crystal that is lethal to the insect. Even dead bacteria containing the proteins are effective insecticides.

The most commonly used strain of Bt (kurstaki strain) will kill only leaf- and needle-feeding caterpillars. In the past decade, Bt strains have been developed that control certain types of fly larvae (israelensis strain, or Bti). These are widely used against larvae of mosquitoes, black flies and fungus gnats. More recently, strains have been developed with activity against some leaf beetles, such as the Colorado potato beetle and elm leaf beetle (san diego strain, tenebrionis strain). Among the various Bt strains, insecticidal activity is specific. That is, Bt strains developed for mosquito larvae do not affect caterpillars. Development of Bt products is an active area and many manufacturers produce a variety of products. Effectiveness of the various formulations may differ.

occurs naturally in the gut of caterpillars of various types of moths and

butterflies, as well on leaf surfaces, aquatic environments, animal feces,

insect rich environments, flour mills and grain storage facilities.

Bacillus thuringiensis is a gram-positive bacterium that produces

large crystalline inclusions named δ-endotoxin during the

sporulation process.

• minimal medium contains glucose and salts supplemented with either

aspartate, glutamate, or citrate.

• These organic acids are required and cannot be replaced by vitamin

mixtures

The potential of Bacillus thuringiensis for producting of toxin and

its use as a biological control agent has been well documented.

During sporulation, B. thuringiensis produces some delta-

endotoxins, that are responsible for insecticidal activity of this

microorganism.

Delta-endotoxin can be soluble in the epidermis of an insect

midgut and release δ-endotoxin at the same time, which is then

degraded into active peptides under the special conditions of the

midgut . These peptides may bind with gut receptors so that the

films form bore, leading to blood poisoning and then to the

death of the larvae.

Bacillus thuringiensis, produces thuricin CD, a 1:1 mixture of

two compounds (peptides) that kills the potentially deadly

bacteria, Clostridium difficile. But unlike other antibacterial

agents, thuricin CD does no harm to other bacteria in the

human gut, which are necessary for a balanced state of health.

I’m really appreciate Dr Wan Zuhainis gives us assignment like this. Honestly , its really2 help me a lot how to do assignment by online and study about specific microorganism even just a little I guess. Its show me that , there is a lot of knowledge still undiscovered by scientist and microbiology is quiet unique. This scrapbook so attractive cause we can design our book depends on our creativity. There is a lot of online tools for education that I didn’t use yet and I hope can explore and use it next time.

http://microbewiki.kenyon.edu/index.php/Bacillus_thuringiensis

http://www.ext.colostate.edu/pubs/insect/05556.html

http://www.cdc.gov/niosh/topics/pesticides/Forrester_toxicol.html

http://pictures.life.ku.dk/atlas/microatlas/food/bacteria/Bacillus_thuring

iensis/

http://www.sciencedaily.com/releases/2010/05/100503092030.htm