title: Activity and ecological implications of maize-expressed transgenic endo-1,4-β-D-glucanase in agricultural soils.
abstract: Plant expression of thermostable endoglucanase (E1) has been proposed for improved conversion of lignocellulose to ethanol for fuel production. Residues of E1-expressing maize may affect ecological services (e.g., C mineralization and biogeochemical cycling) on soils where they occur. Therefore, the activity of residual E1 was investigated using soils amended with bacterial and plant-solubilized E1 compared with soil endogenous activity and residual activity from a mesostable cellulase (Aspergillus and Trichoderma spp.). An optimized analytical method involving a carboxymethyl cellulose substrate and dinitrosalicylic acid detection effectively assayed endoglucanase activity in amended and unamended soils and was used for determining E1 activity in 3 representative soils. The effect of E1 on soil carbon mineralization was determined by comparing CO(2) evolution from soils amended with transgenic E1-expressing and wild-type maize tissue. Extraction and recovery of the mesostable comparator, bacterial E1, and plant-soluble E1 showed nearly complete loss of exogenous endoglucanase activity within a 24-h period. Carbon mineralization indicated no significant difference between soils amended with either the transgenic E1 or wild-type maize tissue. These results indicate that maize residues expressing up to 30 µg E1/g tissue negligibly affect soil endoglucanase activity and CO(2) respiration for representative soils where transgenic E1 maize may be grown.
authors.affiliation: Department of Agronomy, Iowa State University, Ames, Iowa, United States.
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Kenny
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Wolt
mesh_terms: D000192:Actinomycetales / Q000201:enzymology; D002244:Carbon / Q000032:analysis / Q000378:metabolism; D002480:Cellulase / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000201:enzymology* / Q000235:genetics; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology; D019076:Transgenes; D003313:Zea mays / Q000201:enzymology* / Q000235:genetics
chemical_list: D010940:Plant Proteins; D012987:Soil; D002244:Carbon; D002480:Cellulase
keywords: Acidothermus cellulolyticus; Cellulase; Dissipation; Endoglucanase; Genetically engineered; Thermostable