Do conventionally and biologically cultivated soils differ in bacterial diversity and community structure? 
The effects of a long-term herbicide treatment on the microbial community of an agricultural soil were investigated.  Therefor, molecular techniques were used to evaluate the structure and diversity of the soil microbial community.  Eubacterial and group-specific primers for methanotrophs type I and II were used to amplify 16S rRNA gene fragments from total soil DNA.  These fragments were subsequently separated by denaturing gradient gel electrophoresis (DGGE).  The structure of the methanotrophic community was affected by the herbicides as the patterns obtained from a herbicide treated soil (conventional) clustered separately from the control soil (biological).  It seems that group-specific PCR followed by DGGE is a very powerful and sensitive technique to differentiate fields, which have received a herbicide treatment from those who did not.  The diversity of the methanotrophic community was quantified by calculating the Shannon-Weaver index of biodiversity.  The type I methanotrophs showed a significant decreased biodiversity due to the herbicide treatment but the diversity of the methanotrophs type II was slightly higher in the herbicide treated soil.