A bioluminescent reporter plasmid for naphthalene catabolism (pUTK21) was developed by transposon (Tn4431) insertion of the lux gene cassette from Vibrio fischeri into a naphthalene catabolic plasmid in Pseudomonas fluorescens. The insertion site of the lux transposon was the nahG gene encoding for salicylate hydroxylase. Luciferasemediated light production from P. fluorescens strains harboring this plasmid was induced on exposure to naphthalene or the regulatory inducer metabolite, salicylate. In continuous culture, light induction was rapid (15 minutes) and was highly responsive to dynamic changes in naphthalene exposure. Strains harboring pUTK21 were responsive to aromatic hydrocarbon contamination in Manufactured Gas Plant soils and produced sufficient light to serve as biosensors of naphthalene exposure and reporters of naphthalene biodegradative activity. The robust and sensitive nature of the bioluminescent reporter technology suggests that new sensing methods can be developed for on-line process monitoring and control in complex environmental matrices.

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The environmental and ecological significance of catabolic plasmids and their host strains are discussed in the context of their potential application for environmental biotechnology. Included is a comprehensive list of naturally occurring discrete catabolic plasmids isolated from either natural habitats or selective enrichment studies. General properties, such as plasmid maintenance, stability and transfer, are discussed together with the techniques for plasmid detection and monitoring in the environment. The issues concerning the construction of catabolic strains with new or broader substrate ranges and the uses of monocultures or consortia for in situ treatment are addressed.

This study compared effects amino acid structure and type on the pasting properties and crystallinity of rice starch isolated from flour. Amino acids were added at 2 and 6% of the starch (dry basis) for RVA analyses. Charged amino acids had more of an influence on pasting properties than neutral amino acids. Our results indicated that the negatively charged amino acids had a similar effect as that of the positive charged amino acids for decreasing cooking stability of the starch, but opposite effects on retrogradation tendency. Charged amino acids increased the crystallinity of the starch, potentially enhancing resistant starch nature.

Samples containing various levels of vitamin D and riboflavin, with and without ascorbic acid or a-tocopherol were prepared in a model system. Samples were stored in the light or in the dark at 45°C for up to 8 h. Headspace oxygen was determined by gas chromatography with thermal conductivity detection. Oxidation of vitamin D was not observed in samples without riboflavin stored in the light nor in samples with riboflavin stored in the dark. Vitamin D with riboflavin was oxidized under light. ␣-Tocopherol quenched singlet oxygen at a rate of 2.52 x 10 8 M -1 sec -1 , whereas ascorbic acid quenched singlet oxygen at a rate of 2.23 x 10 7 M -1 sec -1 .