Effects of the cultivation of genetically modified Bt crops on nontarget soil organisms - Microbial Ecology in Sustainable Agroecosystems - page 161

Table 8.3 Summary of Effects of Cultivation of Bt Crops or Amendment with Bt Proteins on Soil Bacteria (continued)

Organism/activity
tested

Bt crop plant/
experimental variable Methodology Study location Protein Effect on bacterial Source

Bacteria Culturing

technique

Laboratory Puriied Bt protein

added to pure or
mixed cultures

Cry1Ab
Cry3A
Cry4

No effect on bacterial
growth

Koskella and
Stotzky
(2002)

Heterotrophic bacteria
and carbon-cycling
microorganisms

Culturing
technique

Greenhouse Soybean grown in soil

inoculated with an
insecticidal crystal
protein producer of Bt
(Cry+), a mutant
nonproducer of Bt
(Cry-), or purified
insecticidal crystal
protein (ICP)

Cry1Ab No difference in

heterotrophic
bacterial populations
inoculated with Bt

Ferreira et al.
(2003)

Soil microbial biomass,
microbial activity
(N mineralization
potential, short-term
nitrification rate, and
soil respiration), and
bacterial community
structure

Terminal-
restriction
fragment length
polymorphism
(T-RFLP)

Field Soil with Bt (Event

MON863) and non- Bt
maize

Cry3Bb1 No negative effects of

Bt maize cultivation
on microbial activity
or community
structure over two
growing seasons

Devare et al.
(2004)

Rhizosphere bacterial
counts (copiotrophic,
oligotrophic, and
spore-forming
bacteria)
Rhizosphere bacterial
community structure

Culturing
methods
Community-level
catabolic
profiling (CLCP)
Automated
ribosomal
intergenic spacer
analysis (ARISA)

Greenhouse Soil with Bt maize

(Event 176) and
non- Bt maize

Cry1Ab No differences in

community structure
detected using
culturing methods or
CLCP, but differences
in community structure
detected using ARISA
suggest that changes in
root exudates may
influence rhizosphere
community

Brusetti et al.
(2004)

(continued)