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EDTA, a common chelating agent, is becoming a major organic pollutant in the form of metal-EDTA complexes in surface waters, partly due to its recalcitrance to biodegradation. Even an EDTA-degrading bacterium, BNC1, does not degrade stable metal-EDTA complexes. In the present study, an ABC-type transporter was identified for possible uptake of EDTA because the transporter genes and the EDTA monooxygenase gene were expressed from a single operon in BNC1. The ABC-type transporter had a periplasmic-binding protein (EppA) that should confer the substrate specificity for the transporter; therefore, EppA was produced in Escherichia coli, purified, and characterized. EppA was shown to bind free EDTA with a dissociation constant as low as 25 nM by using isothermal titration calorimetry. When unstable metal-EDTA complexes, e.g., (Mg-EDTA)[2.sup.-], were added to the EppA solution, binding was also observed. However, experimental data and theoretical analysis supported EppA binding only of free EDTA. When stable metal-EDTA complexes, e.g., (Cu-EDTA)[2.sup.-], were titrated into the EppA solution, no binding was observed. Since EDTA monooxygenase in the cytoplasm uses some of the stable metal-EDTA complexes as substrates, we suggest that the lack of EppA binding and EDTA uptake are responsible for the failure of BNC1 cells to degrade the stable complexes.

Researchers have isolated and characterized an enzyme from the EDTA-degrading bacterium BNC1. Iminodiacetate oxidase appears to be the second enzyme in the pathway for degrading both EDTA and NTA.

Researchers report the isolation of an eight-gene cluster from the bacterium BNX1 that encodes some of the enzymes that degrade EDTA. Two of the gene products were identified as a reduced flavin mononucleotide-utilizing monooxygenase and an NADH:flavin mononucleotide oxidoreductase. The others include a transport system, a regulatory gene, and an iminodiacetate oxidase.

Synthetic chelating agents are used in a broad variety of applications such as in household cleaners, water treatment, rubber/metal processing and pulp/paper treatment. Roughly 70% of all chelating agents used globally are aminopolycarboxylic acids primarily EDTA, DTPA and NTA. A study was conducted to investigate the biochemistry of EDTA degradation by bacterium BNC1. The purification and characterization of EDTA monooxygenase that catalyzes the initial step of EDTA degradation by BNC1 is described.

The reverse transcriptase/polymerase chain reaction (RT-PCR) process is examined with particular attention to the common observation that control DNA reaction mixtures with RT do not provide DNA amplification during PCR while control DNA reaction mixtures without RT do not inhibit PCR. The findings indicate that the RT interaction with the specific mRNA or cDNA template mediates RT inhibition of the PCR and that such inhibitory effect is influenced by template concentration.

An assessment of the effects of environmental release of lignin peroxidase- overexpressing genetically engineered microorganisms (GEMS) and other GEMS in soils is discussed. A recombitant Streptomyces lividans TK23.1 was discharged into soil in flask- andmicrocosm-scale studies. Three independent laboratories were used for differentparts of the research. Results show that the release of the strain into soil significantly affected some environmental parameters. However, these effects were found to be ecologically insignificant.