Screening For Cry Genes From Bacillus Thuringiensis In Various Textural Classes Of Southwest Missouri Soils
Date of Graduation
Master of Science in Biology
Bacillus thuringiensis is a gram-positive endospore-forming bacterium that produces an insecticidal δ-endotoxin during sporulation. The δ-endotoxin consists of an inactive protein toxin crystal (protoxin) that becomes activated by the alkaline conditions in the intestinal lumen of specific insect species. Genes that code for the crystal protoxins (cry genes) are carried on plasmids. Multiple cry genes may be found in a single B. thuringiensis strain on one or more plasmids. The bacteria are found in a variety of environments, primarily in soil. Environmental strains of B. thuringiensis were isolated from 21 soil samples and each soil sample was classified texturally based on percentage of sand, silt, and clay. Population densities were used to analyze the frequency of B. thuringiensis and Bacillus isolates in each soil sample. Results indicated textural soil classification did not influence the populations of Bacillus or B. thuringiensis. However, the textural composition of the soil may affect the expression of certain cry genes. PCR was employed to screen the B. thuringiensis isolates for the presence of cry genes. Universal (Un9(d), Un9(r)) and specific primers (CJIII20, CJII21) were used in the screening process. The PCR products of the environmental isolates were compared to PCR products from known strains of B. thuringiensis. PCR products were cloned into E. coli plasmids and sequenced to identify the cry gene class for environmental isolates and to identify possible novel cry genes.
© Meghan Carter
Carter, Meghan, "Screening For Cry Genes From Bacillus Thuringiensis In Various Textural Classes Of Southwest Missouri Soils" (2002). MSU Graduate Theses. 1216.
Bacillus Thuringiensis ni bakteria ya gram-positive endospore-kuunda ambayo inazalisha dawa ya kuua wadudu ya δ-endotoxin wakati wa spora. Endotoxin ya D-protoxin ni protini isiyo na nguvu ambayo huanzishwa na hali ya alkaline katika lumen ya matumbo ya spishi maalum za wadudu. Jeni zinazotuma nambari kwa ajili ya protoksini za kioo (jini za kulia) hubebwa kwenye plasmidi. Jeni nyingi za kilio zinaweza kupatikana katika aina moja ya B. thuringiensis kwenye plasmids moja au zaidi. Bakteria hizo hupatikana katika mazingira mbalimbali, hasa katika udongo. Kwa mfano, B. thuringiensis ilichukuliwa kutoka kwa sampuli 21 za udongo na kila sampuli ya udongo iligawanywa kulingana na asilimia ya mchanga, matope na udongo. Idadi ya watu ilitumiwa kuchambua mzunguko wa B. thuringiensis na Bacillus isolates katika kila sampuli ya udongo. Matokeo yalionyesha textural udongo uainishaji hakuwa na ushawishi juu ya idadi ya Bacillus au B. thuringiensis. Hata hivyo, muundo wa udongo waweza kuathiri mwonekano wa chembe fulani za urithi za kilio. PCR ilitumika kuchunguza B. thuringiensis isolates kwa ajili ya uwepo wa jeni kulia. Unicorn (U) na Unicorn (R) na Unicorn (C) na Unicorn (R) na Unicorn (R) na Unicorn (R) na Unicorn (R) na Unicorn (R) na Unicorn (R) na Unicorn (R) na Unicorn (R) na Unicorn (R) na Unicorn (R) na Unicorn (R) na Unicorn (R) na Unicorn (R) na Unicorn (R). Kwa mfano, PCR ya isolates ya mazingira ya B. thuringiensis inaweza kuonekana kama chembe za DNA za chembe za DNA za B. thuringiensis. PCR bidhaa walikuwa cloned katika plasmids E. coli na sequenced kutambua cry gene darasa kwa ajili ya isolates mazingira na kutambua uwezekano wa mpya cry jeni. "Meghan Carter, ""Uchunguzi wa jeni la kulia kutoka Bacillus Thuringiensis katika madarasa mbalimbali ya textural ya Southwest Missouri Soils""" MSU Theses ya Uhitimu. 1216 - Utafiti wa Utafiti