Extractable Soil Lipids and Microbial Activity as Affected by Bt and Non Bt Maize Grown on a Silty Clay Loam Soil

J Environ Sci Health B. 2003 Mar;38(2):211-9. doi: 10.1081/PFC-120018450.

Abstract

Pyrolysis-gas (Py-GC) chromatography was used to characterize extractable lipids from Bt and non-Bt maize shoots and soils collected at time of harvesting. Py-GC-MS (mass spectrometry) showed that the concentrations of total alkenes identified in non-Bt shoots and soils were 47.9 and 21.3% higher than in Bt maize shoots and soils, respectively. N-alkanes identified were of similar orders of magnitude in Bt and non-Bt maize shoots, but were 28.6% higher in Bt than in non-Bt soils. Bt maize shoots contained 29.7% more n-fatty acids than non-Bt maize shoots, whereas the concentrations of n-fatty acids in Bt soils were twice as high as those in non-Bt soils. Concentrations of unsaturated fatty acids in Bt maize shoots were 22.1% higher than those in non-Bt maize shoots, while concentrations of unsaturated fatty acids were 22.5% higher in non-Bt than in Bt soils. The cumulative CO2-C evolved from soils under Bt and non-Bt crops was 30.5% lower under Bt as compared to non-Bt crops, whereas when maize shoots were added to Bt and non-Bt soils, the decrease in CO2-C evolved were 16.5 and 23.6%, respectively. Our data showed that the cultivation of Bt maize significantly increased the saturated to unsaturated lipid ratios in soils which appeared to negatively affect microbial activity.

MeSH terms

  • Bacillus thuringiensis / genetics
  • Bacterial Toxins / genetics
  • Chromatography, Gas / methods
  • Fatty Acids, Unsaturated / analysis*
  • Fatty Acids, Unsaturated / pharmacology*
  • Gas Chromatography-Mass Spectrometry / methods
  • Insect Control / methods
  • Plant Shoots / chemistry
  • Plants, Genetically Modified / chemistry*
  • Soil / analysis*
  • Soil Microbiology
  • Zea mays / chemistry*

Substances

  • Bacterial Toxins
  • Fatty Acids, Unsaturated
  • Soil