Transgenic Maize Containing the Cry1Ab Protein Ephemerally Enhances Soil Microbial Communities

摘要

Bacillus thuringiensis is a Gram~+ spore-forming bacterium that produces para-sporal crystals during sporulation that are pathogenic to insect and some other organisms (1). Preparations of bacterial spores and crystalline proteins are widely used as Bt-insecticides for the control of insect pests of crops. fir-toxins are classified based on their specific activity against invertebrates, with proteins Cryl and Cry2 being lethal to Lepidoptera, Cry3 to Coleoptera, Cry 2 and Cry4 to Diptera, and Cry5 to Nematoda (2, 3). CrylAb is a toxin commonly used against the European and Asian corn borer complex, particularly the species Ostrinia nubilalis and O. furnacalis (4). Besides reports of facultative phytophagous insects that seem to have acquired resistance to larvicidal toxins belonging to the Cryl protein family, nontarget effects of the toxin produced by the insecticidal cryl Ab gene released in the root exudates of B. thuringiensis maize (Zea mays L.) are unclear. Microbial communities occurring below ground under genetically engineered fir-crops are less investigated, and possible effects on microbes remain a concern. Toxins may accumulate in soil after postharvest maize straw is plowed under (a common practice in agriculture), and high concentrations of the CrylAb toxin seem to persist for several months (5). In this paper, the following questions will be addressed: Is there microbial evidence of environmental disturbance in relation to plowed leaves and straw of fir-maize in soils? Can a better ecological insight in the microbial community be obtained using metabolic fingerprints of soil bacteria?