Effects of the cultivation of genetically modified Bt crops on nontarget soil organisms - Microbial Ecology in Sustainable Agroecosystems - page 160

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

Organism/activity
tested

Bt crop plant/
experimental variable

Methodology Study location Protein Effect on bacteria Source

Bacteria Culturing

Substrate
utilization
Total DNA content
DNA fingerprints

Laboratory Soil amended with Bt

and non- Bt cotton
leaves

Cry1Ac Significant (but

transient) increase in
bacteria numbers in
soil of Bt cotton

Donegan et al.
(1995)

Bacteria Culturing

Substrate
utilization
Total DNA content
DNA fingerprints

Laboratory Soil amended with

purified protein
versus unamended
soil

Cry1Ab No effect of purified Bt

protein on bacteria

Donegan et al.
(1995)

Aerobic bacteria Culturing

technique

Field Soil with Bt and non- Bt

potato

Cry3A Few significant

differences in
microflora on Bt and
non- Bt potato leaves
and no difference in
rhizosphere
populations

Donegan et al.
(1996)

Leaf-litter- and fecal-
colonizing
microorganisms

Culturing
technique

Laboratory Bacterial growth on Bt

(X4334-EPR) and
non- Bt maize leaves
and on feces of
Porcellio scaber fed Bt
or non- Bt maize

Cry1Ab No difference in

bacterial growth on
leaves of Bt and
non- Bt maize; bacterial
growth lower on Bt -fed
P. scaber feces

Escher et al.
(2000)

Bacteria (8 Gram
negative, 5 Gram
positive, and
cyanobacteria)

Culturing
technique

Laboratory
(plant growth
room)

Soil with Bt
(NK4640Bt) and
non- Bt maize
Soil amended with
biomass of Bt and
non- Bt maize

Cry1Ab No significant

difference in
culturable bacteria in
soils cultivated with
or amended with Bt or
non- Bt maize

Saxena and
Stotzky
(2001a)

(continued)