Ecofunctional enzymes of microbial communities in ground water.

Biolog technology was initially developed as a rapid, broad spectrum method for the biochemical identification of clinical microorganisms. Demand and creative application of this technology has resulted in the development of Biolog plates for Gram-negative and Gram-positive bacteria, for yeast and Lactobacillus sp. Microbial ecologists have extended the use of these plates from the identification of pure culture isolates to a tool for quantifying the metabolic patterns of mixed cultures, consortia and entire microbial communities. Patterns that develop on Biolog microplates are a result of the oxidation of the substrates by microorganisms in the inoculum and the subsequent reduction of the tetrazolium dye to form a color in response to detectable reactions. Depending upon the functional enzymes present in the isolate or community one of a possible 4 x 10(28) patterns can be expressed. The patterns were used to distinguish the physiological ecology of various microbial communities present in remediated groundwater. The data indicate that one can observe differences in the microbial community among treatments of bioventing, 1% and 4% methane injection, and pulse injection of air, methane and nutrients both between and among wells. The investigation indicates that Biolog technology is a useful parameter to measure the physiological response of the microbial community to perturbation and allows one to design enhancement techniques to further the degradation of selected recalcitrant and toxic chemicals. Further it allows one to evaluate the recovery of the microbial subsurface ecosystem after the perturbations have ceased. We propose the term 'ecofunctional enzymes' (EFE) as the most descriptive and useful term for the Biolog plate patterns generated by microbial communities. We offer this designation and provide ecological application in an attempt to standardize the terminology for this relatively new and unique technology.

Occupational exposure of health care workers (HCWs) to human immunodeficiency virus (HIV): stress reactions and counseling interventions.

As more people become infected with HIV, Health Care Workers (HCWs) have a greater likelihood of being exposed at work. HIV exposure threatens the life of the HCW and can elicit a stress reaction. Although HCWs have reactions similar to those of people who have been exposed to other traumatic events, the nature of this stressor and the length of time it lasts is unique. This article presents counseling interventions that address the needs of the individual HCW during this event. These counseling guidelines promote the HCW's discussion of the event and any relevant past unresolved traumatic experiences; evaluate and aid the worker and his or her support system; provide information on stress reactions and HIV; examine the HCW's practice methods; and helps to reintegrate the HCW back into the work environment.

Isolation of Aeromonas hydrophila from the American alligator, Alligator mississippiensis.

Aeromonas hydrophila was isolated from the internal organs of nine adult alligators, Alligator mississippiensis, which died without apparent cause, suggesting the bacterium may have been a factor. One hundred and twenty-three alligators ranging in age from six months to over 10 years were captured from five locations in the southeastern United States and sampled for A. hydrophila. The bacterium was isolated from the oral cavity of 85% of the animals, on the external jaw area from over 50% and from 70% of the internal tissue samples. A. hydrophila is ubiquitous with alligators in their natural habitats, but apparently does not cause clinical disease. However, stress factors such as trapping, handling, and warm water temperatures may be conducive to the rapid proliferation of the bacteria, thereby facilitating disease.

Aeromonas distribution and survival in a thermally altered lake.

Par Pond is a thermally enriched monomictic southeastern lake which receives heated effluent from a production nuclear reactor. Fish populations in the lake have lesions of epizooty from which Aeromonas spp. are readily isolated. Distribution and population densities of Aeromonas in the water column were measured along an oxygen and temperature gradient as well as seasonally. Greater population densities of Aeromonas occurred below the oxygen chemocline when the lake was stratified. Survival of Aeromonas hydrophila under in situ conditions in both epilimnetic and hypolimnetic waters was determined through the use of polycarbonate membrane diffusion chambers during two separate reactor operating conditions. Survival levels of pure cultures of A. hydrophila corresponded to the distribution patterns of the naturally occurring Aeromonas-like populations. The greater survival of A. hydrophila during full reactor operation suggests that the fish populations may be exposed to Aeromonas for a longer period of time than when the reactor is not operating.

Modification of membrane diffusion chambers for deep-water studies.

Membrane diffusion chambers as modified for deep-water lakes provided an improved handling ease, freedom from external damage, extended sampling life, good diffusivity, and excellent statistical reproducibility.

Photoionization of CO2 -CO-O2 Mixtures. Formation and Reactions of Ion Clusters.

Various mixtures containing combinations of CO2, O2, or CO have been photoionized at 16.7 and 21.2 eV at pressures up to 1.5 torr in the NBS high pressure photoionization mass spectrometer. In CO2-CO mixtures the interactions of CO 2 + ions eventually lead to the formation of (CO) 2 + and [(CO)2-CO2]+ cluster ions, while photoionization of CO2-CO-O2 mixtures yields mainly oxygen-containing clusters at higher pressures. The investigation of O2-CO mixtures also revealed reactions between O 4 + and CO. The role of impurity reactions involving H2O is considered in some detail, and the implications of all of these data to the vapor phase radiolysis of CO2 is discussed.

Ion-Molecule Reactions in Isopropanol: Implications for Its Radiolysis.

The photoionization of isopropanol (i-PrOH) at 11.7 eV has been investigated in the NBS high pressure photoionization mass spectrometer over the pressure range 0.1 to approximately 200 millitorr. The major primary ion, CH3CHOH+, reacts with a total rate coefficient of 1.1 ±0.1× 10-9 cm3/mole-cule-s to yield mainly (i-PrOH)H+ and CH3(i-C3 H7)COH+. At pressures in excess of a few millitorr consecutive reactions of (i-PrOH)H+ and CH3(i-C3H7)COH+ were also detected, including the overall dehydration process ( i -PrOH ) H + + i -PrOH → H 2 O + ( i -C 3 H 7 ) 2 OH + These data are interpreted in light of a recent radiolysis study, and a thermal cationic chain mechanism for production of (I-C3H7)2O consistent with those results is proposed. The value for the proton affinity of SF6 is also discussed in some detail.

The Solid Phase Photolysis and Radiolysis of Ethylene at 20 to 77 K.

Films of ethylene condensed onto a cold finger maintained at 20 K were irradiated with photons whose energy ranged from 8.4 to 21.2 eV. At the higher photon energies the relative yields of products compare well with those seen in the radiolysis of solid ethylene. Experiments on CH2CD2 demonstrate that in the photolysis hydrogen is mainly formed by the elimination processes CH 2 CD 2 * → H 2 ( D 2 ) + C 2 D 2 ( C 2 H 2 ) and CH 2 CD 3 * → HD + C 2 HD . The relative probabilities of these three processes are independent of the energy of the incident photons from 8.4 to 11.6 eV and are within experimental error identical to those observed in earlier gas phase photolysis experiments. Relative to acetylene, cyclobutane is a minor product at 8.4 eV but increases by an order of magnitude at higher energies where ions play a role. Cyclobutane, 1-butene and methylcyclopropane formed upon irradiation of frozen C2H4 - C2D4 mixtures consisted mainly of C4D8, C4D4H.4, and C4H8. Plausible mechanisms which may account for the formation of the latter products are examined. In the solid phase as in the gas phase the relative importance of H-atom production is seen to increase with increasing photon energy. Cyclopropane, apparently formed by insertion of CH2 into C2H4, is observed as a product at all wavelengths in the photolysis, and in the radiolysis.