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With the emergence of transgenic technologies, new ways to improve the agronomic performance of crops for food, feed, and processing applications have been devised. In addition, ability to express foreign genes using transgenic technologies has opened up options for producing large quantities of commercially important industrial or pharmaceutical products in plants. Despite this high adoption rate and future promises, there is a multitude of concerns about the impact of genetically modified (GM) crops on the environment. Potential contamination of the environment and food chains has prompted detailed consideration of how such crops and the molecules that they produce can be effectively isolated and contained. One of the reasonable steps after creating a transgenic plant is to evaluate its potential benefits and risks to the environment and these should be compared to those generated by traditional agricultural practices. The precautionary approach in risk management of GM plants may make it necessary to monitor significant wild and weed populations that might be affected by transgene escape. Effective risk assessment and monitoring mechanisms are the basic prerequisites of any legal framework to adequately address the risks and watch out for new risks. Several agencies in different countries monitor the release of GM organisms or frame guidelines for the appropriate application of recombinant organisms in agro-industries so as to assure the safe use of recombinant organisms and to achieve sound overall development. We feel that it is important to establish an internationally harmonized framework for the safe handling of recombinant DNA organisms within a few years.

Microbial degradation studies have pointed toward the occurrence of two distinct PNP catabolic pathways in Gram positive and Gram negative bacteria. The former involves 4-nitrocatechol (4-NC), 1,2,4-benzenetriol (BT), and maleylacetate (MA) as major degradation intermediates, whereas the later proceeds via formation of 1,4-benzoquinone (BQ) and hydroquinone (HQ). In the present study we identified a Gram negative organism viz. Burkholderia sp. strain SJ98 that degrades PNP via 4NC, BT, and MA. A 6.89 Kb genomic DNA fragment of strain SJ98 that encompasses seven putatively identified ORFs (orfA, pnpD, pnpC, orfB, orfC, orfD, and orfE) was cloned. PnpC is benzenetriol dioxygenase belonging to the intradiol dioxygenase superfamily, whereas PnpD is identified as maleylacetate reductase, a member of the Fe-ADH superfamily showing NADH dependent reductase activity. The in vitro activity assays carried out with purified pnpC and pnpD (btd and mar) gene products transformed BT to MA and MA to beta-ketoadipate, respectively. The cloning, sequencing, and characterization of these genes along with the functional PNP degradation studies ascertained the involvement of 4-NC, BT, and MA as degradation intermediates of PNP pathway in this strain. This is one of the first conclusive reports for 4-NC and BT mediated degradation of PNP in a Gram negative organism.

The introduction of culture-independent molecular screening techniques, especially based on 16S rRNA gene sequences, has allowed microbiologists to examine a facet of microbial diversity not necessarily reflected by the results of culturing studies. The bacterial community structure was studied for a pesticide-contaminated site that was subsequently remediated using an efficient degradative strain Arthrobacter protophormiae RKJ100. The efficiency of the bioremediation process was assessed by monitoring the depletion of the pollutant, and the effect of addition of an exogenous strain on the existing soil community structure was determined using molecular techniques. The 16S rRNA gene pool amplified from the soil metagenome was cloned and restriction fragment length polymorphism studies revealed 46 different phylotypes on the basis of similar banding patterns. Sequencing of representative clones of each phylotype showed that the community structure of the pesticide-contaminated soil was mainly constituted by Proteobacteria and Actinomycetes. Terminal restriction fragment length polymorphism analysis showed only nonsignificant changes in community structure during the process of bioremediation. Immobilized cells of strain RKJ100 enhanced pollutant degradation but seemed to have no detectable effects on the existing bacterial community structure.