title: Effects of Cry1Ab Bt maize straw return on bacterial community of earthworm Eisenia fetida.
abstract: The eco-toxicological effects of Bacillus thuringiensis (Bt) maize on earthworm life-history traits were widely studied and the results were controversial, while their effects on earthworm bacterial community have been rarely studied. Here, effects of two hybrids of Bt maize [5422Bt1 (event Bt11) and 5422CBCL (MON810)] straw return on Eisenia fetida bacterial community were investigated by the terminal restriction fragment length polymorphism (T-RFLP) and polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) combing with DNA sequencing, compared to near-isogenic non-Bt maize (5422). Bt maize straw return had significant effects on soil nutrients, especially for available nitrogen (N). The significant differences were shown in soil bacterial community between Bt and non-Bt maize treatments on the 75thand 90thd, which was closely correlated with soil available N, P and K rather than Cry1Ab protein. There was no statistically significant difference in the bacterial community of earthworm gut contents between Bt and non-Bt maize treatments. The significant differences in the bacterial community of earthworm casts were found among three maize varieties treatments, which were closely correlated with Cry1Ab protein and N levels. The differentiated bacterial species in earthworm casts mainly belonged to Proteobacteria, including Brevundimonas, Caulobacter, Pseudomonas, Stenotrophomonas, Methylobacterium, Asticcacaulis and Achromobacter etc., which were associated with the mineralization, metabolic process and degradation of plants residues. Therefore, Bt maize straw return caused changes in the bacterial community of E. fetida casts, which was possibly caused by the direct (Cry1Ab protein) and non-expected effects (N levels) of Bt maize straw.
authors.affiliation: Key Laboratory of Agro-Environment in the Tropics, Ministry of Agriculture, South China Agricultural University, Guangzhou 510642, China; Key Laboratory of Agroecology and Rural Environment of Guangdong Regular Higher Education Institutions, South China Agricultural University, Guangzhou 510642, China; Guangdong Engineering Research Centre for Modern Eco-agriculture, Guangzhou 510642, China; Department of Ecology, College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China.
authors.forename: Yinghua
authors.initials: Y
authors.lastname: Shu
authors.affiliation: Key Laboratory of Agro-Environment in the Tropics, Ministry of Agriculture, South China Agricultural University, Guangzhou 510642, China; Key Laboratory of Agroecology and Rural Environment of Guangdong Regular Higher Education Institutions, South China Agricultural University, Guangzhou 510642, China; Guangdong Engineering Research Centre for Modern Eco-agriculture, Guangzhou 510642, China; Department of Ecology, College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China.
authors.forename: Yanyan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Agro-Environment in the Tropics, Ministry of Agriculture, South China Agricultural University, Guangzhou 510642, China; Key Laboratory of Agroecology and Rural Environment of Guangdong Regular Higher Education Institutions, South China Agricultural University, Guangzhou 510642, China; Guangdong Engineering Research Centre for Modern Eco-agriculture, Guangzhou 510642, China; Department of Ecology, College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China.
authors.forename: Huilan
authors.initials: H
authors.lastname: Zeng
authors.affiliation: Key Laboratory of Agro-Environment in the Tropics, Ministry of Agriculture, South China Agricultural University, Guangzhou 510642, China; Key Laboratory of Agroecology and Rural Environment of Guangdong Regular Higher Education Institutions, South China Agricultural University, Guangzhou 510642, China; Guangdong Engineering Research Centre for Modern Eco-agriculture, Guangzhou 510642, China; Department of Ecology, College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China.
authors.forename: Yahui
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Agro-Environment in the Tropics, Ministry of Agriculture, South China Agricultural University, Guangzhou 510642, China; Key Laboratory of Agroecology and Rural Environment of Guangdong Regular Higher Education Institutions, South China Agricultural University, Guangzhou 510642, China; Guangdong Engineering Research Centre for Modern Eco-agriculture, Guangzhou 510642, China; Department of Ecology, College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China. Electronic address: wangjw@scau.edu.cn.
authors.forename: Jianwu
authors.initials: J
authors.lastname: Wang
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis / Q000378:metabolism*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000633:toxicity*; D004731:Endotoxins / Q000633:toxicity*; D006460:Hemolysin Proteins / Q000633:toxicity*; D009835:Oligochaeta / Q000187:drug effects* / Q000254:growth & development; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology; D003313:Zea mays / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; D012987:Soil; C030956:insecticidal crystal protein, Bacillus Thuringiensis
keywords: Bacterial community; Bt maize straw return; Cry1Ab; Eisenia fetida; T-RFLP