Identifying Dnase Producing Bacteria from Leachates Under the Influence of Crop Species.

The extracellular DNA (eDNA) cycle is an interesting area in assessing the perceived unintended effects of genetically modified (GM) crops. Plants have diverse effects on soil functions through regular nutrient fluxes including eDNA. Extracellular DNases of microbial origin are perceived to be the main barrier to the persistence of eDNA which is crucial for horizontal gene transfer. Little is known on the diversity of DNase producing bacteria in agricultural soils under the influence of crop species. A greenhouse study was conducted using soil collected from agricultural fields and cultivated to four crop species; alfalfa, canola, soybean and wheat while unplanted pots were used as controls. DNase activity was evaluated on DNA-methyl green plate assay whereas DNase producing isolates were identified by partial 16S rDNA sequencing. Of the total culturable bacteria, the DNase producing bacteria proportion ranged between 5.57 to 52.08%. The current study classified most culturable DNase producing bacteria as members of the Bacillus followed by the Microbacterium genera while other minor genera included Chryseobacterium, Pseudomonas and Stenotrophomonas.Having an understanding of DNase producing bacteria present in the soil presents another avenue for possible exploitation for mitigating the possible risks of transgenic traits in the environment.

Key words: extracellular DNA, DNase, genetically modified (GM) crops, horizontal gene transfer