BT Bacillus Thuringiensis
Classification
Domain; Phylum; Class; Order; family [Others may be used. Use NCBI link to find]
Species
Eubacteria (kingdom)
Bacteria (domain)
Firmicutes (phylum)
Bacilli (class)
Bacillales (order)
Bacillaceae (family)
Bacillus (genus); Bacillus cereus group
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NCBI: Taxonomy |
Genus species
Bacillus Thuringiensis
Habitat Information
Describe the location and conditions under which the organism was isolated.
Latitude: 30.14402 degrees Longitude: -97.78506 degrees
It was a cloudy day high of 58 degrees low of 44 degrees on Jan 30th 2015. A spade and a glass mason jar to collet the soil sample. The soil was collected after digging 1 foot below the surface. The location of the soil sample chosen was in a natural ravine off the end of a gated home property Rainfall was 0.0" and the pressure was 28.53" The location was mostly Lewisville silty clay at 1-2 percent slopes.
Description and Significance
Describe the appearance (colonial and cellular), possible antimicrobial activity etc. of the organism, and why the organism might be significant.
Cellular: gram-positive, forms spores, rod-shape
Colonial morphology: filamentous, raised, undulate, medium, aggressive grower, shiny, smooth, creamy white in color
This organism was placed in a lawn plate of Pseudomonas Aeruginosa and it had a zone of inhibition
Genome Structure
BT is a circular chromosome. It has a genome size of between 5.2–5.8 Megabases. The largest known group of BT is the Cry protein. These δ-Endotoxins are frequently expressed in recombinant cotton, potatoes, rice and corn. Bacillus thuringiensis strain ODB63 16S ribosomal RNA gene, partial sequence
PCR sequence: FOREWARD 1 ttccgcatgg acganttctg acggagcacg ccgcgtgagt gatgaaggct ttcgggtcgt 61 aaaactctgt tgttagggaa gaacaagtgc tagttgaata agctggcacc ttgacggtac 121 ctaaccagaa agccacggct aactacgtgc cagcagccgc ggtaatacgt aggtggcaag
PCR sequence: REVERSE 1 gggggtgggc gcgtcctata catgcaagtc gagcgaatgg attgagagct tgctctcaag 61 aagttagcgg cggacgggtg agtaacacgt gggtaacctg cccataagac tgggataact 121 ccgggaaacc ggggctaata ccggataaca ttttgaactg catggttcga aattgaaagg
Cell Structure, Metabolism and Life Cycle
Interesting features of cell structure; how it gains energy; what important molecules it produces.
BT has two phases of life cycle. One phase is the vegetative cell division and sporulation. The vegetative cell division cycle is a simple process of rod shapes dividing into daughter cells, however Sporulation happens in VII stages. There is a uniqueness about the sporulation process that produces crystals as a response of the water loss during the process. It provides the spore with a vegetative state and germination ability and toxic to any insect that tries to ingest it.
BT is a facultative anaerobe, gram-positive, it has a thick cell wall that is comprised of peptidoglycan (amino acid polypeptide and a sugar). A Periplasmic space which is essential for biosynthesis and protection is found between the cell wall and plasma membrane. The facultative anaerobe characteristic aspect of BT is it allows the bacteria to produce ATP by aerobic respiration if oxygen is present however can also use other gases through fermentation or anaerobic respiration.
Physiology and Pathogenesis
Biochemical characteristics, enzymes made, other characteristics that may be used to identify the organism; contributions to environment (if any).
If relevant, how does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms
BT is pathogenic to the insects that it is intended to be eaten by during crop growths that have been genetically modified to resist insects. It is swallowed by the bug and the crystals in the spore are release into the insects stomach. the toxin attaches to the gut lining which proceeds to breakdown the stomach and release both the spores and the stomach contents into the abdominal cavity of the insect. The crystals are very specific to each and every insect it is coded. Similar to a lock and key.
Toxins created by Bt are rapidly broken down by sunlight and in acidic soil. Other microbes in soil can also break it down. Bt does not readily leach in soil. It typically remains in the top several inches of soil. Bt remains dormant in most natural soil conditions. However, there has been some reproduction in nutrient rich soils. On the soil surface, dormant Bt cells last only a few days. However, below the soil surface, they can last for months or years. The half-life in unfavorable soil is about 4 months. Bt toxins break down much faster. In one study, 12% remained after 15 days. In water, Bt does not readily reproduce. A study found Bt toxins in the air were broken down rapidly by sunlight. Forty-one percent (41%) of the toxin remained after 24 hours. On plant surfaces, sunlight breaks down Bt; the half-life of Bt toxins is 1-4 days.
Concerns are raised over what happens in the soil and surrounding area other than just crops. The toxins are broken down in sunlight and acidic soil.
References
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3035146/
http://www.bt.ucsd.edu/how_bt_work.html
www.npic.orst.edu/factsheets/BTgen.pdf
Author
Page authored by _____, student of Prof. Kristine Hollingsworth at Austin Community College.
