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PubMed1997

Trichloroethylene biodegradation by mesophilic and psychrophilic ammonia oxidizers and methanotrophs in groundwater microcosms.

This study investigated the efficiency of methane and ammonium for stimulating trichloroethylene (TCE) biodegradation in groundwater microcosms (flasks and batch exchange columns) at a psychrophilic temperature (12 degrees C) typical of shallow aquifers in the northern United States or a mesophilic temperature (24 degrees C) representative of most laboratory experiments. After 140 days, TCE biodegradation rates by ammonia oxidizers and methanotrophs in mesophilic flask microcosms were similar (8 to 10 nmol day-1), but [14C]TCE mineralization (biodegradation to 14CO2) by ammonia oxidizers was significantly greater than that by methanotrophs (63 versus 53%). Under psychrophilic conditions, [14C]TCE mineralization in flask systems by ammonia oxidizers and methanotrophs was reduced to 12 and 5%, respectively. In mesophilic batch exchange columns, average TCE biodegradation rates for methanotrophs (900 nmol liter-1 day-1) were not significantly different from those of ammonia oxidizers (775 nmol liter-1 day-1). Psychrophilic TCE biodegradation rates in the columns were similar with both biostimulants and averaged 145 nmol liter-1 day-1. Methanotroph biostimulation was most adversely affected by low temperatures. At 12 degrees C, the biodegradation efficiencies (TCE degradation normalized to microbial activity) of methanotrophs and ammonia oxidizers decreased by factors of 2.6 and 1.6, respectively, relative to their biodegradation efficiencies at 24 degrees C. Collectively, these experiments demonstrated that in situ bioremediation of TCE is feasible at the psychrophilic temperatures common in surficial aquifers in the northern United States and that for such applications biostimulation of ammonia oxidizers could be more effective than has been previously reported.

Ammonia↗
PubMed2006

Influence of freeze-thaw stress on the structure and function of microbial communities and denitrifying populations in soil.

Microbial N2O release during the course of thawing of soil was investigated in model experiment focusing on denitrification, since freeze-thaw has been shown to cause significant physical and biological changes in soil, including a surge of N2O and CO2. The origin of these is still controversially discussed. The increase in denitrification after thawing may be attributed to the diffusion of organic substrates newly available to denitrifiers from disrupted soil aggregates, leading to an increase in microbial activity. Laboratory experiments with upper soil layer of a grassland were conducted in microcosms for real-time gas measurements during the entire phase of freeze and thaw. Shifts in microbial communities were evident on resolution of 16S and 18S rRNA genes and transcripts by denaturing gradient gel electrophoresis (DGGE). Microbial expression profiles were compared by RNA-arbitrarily primed PCR technique and subsequent resolution of amplified products on acrylamide gels. Differences in expression levels of periplasmic nitrate reductase gene (napA) and cytochrome cd1 nitrite reductase (nirS) were observed by most-probable-number-reverse transcription-PCR, with higher levels of expression occurring just after thawing began, followed by a decrease. napA and nirS DGGE profiles showed no change in banding patterns with fingerprints derived from DNA, whereas those derived from cDNA showed a clear succession of denitrifying bacteria, with the most complex pattern being observed at the end of the N2O surge. This study provides insight into the structural community changes and expression dynamics of denitrifiers as a result of freeze-thaw stress. Also, the results presented here support the belief that the gas fluxes observed during thawing is a result of freezing initiated high microbial activity.

Bacteria↗
PubMed2004

Aquatic persistence of eight pharmaceuticals in a microcosm study.

The persistence of eight pharmaceuticals from multiple classes was studied in aquatic outdoor field microcosms. A method was developed for the determination of a mixture of acetaminophen, atorvastatin, caffeine, carbamazepine, levofloxacin, sertraline, sulfamethoxazole, and trimethoprim at microg/L levels from surface water of the microcosms using solid phase extraction and high-performance liquid chromatography-ultraviolet (HPLC-UV) and liquid chromatography tandem mass spectrometry (LC-MS-MS). Half-lives in the field ranged from 1.5 to 82 d. Laboratory persistence tests were performed to determine the relative importance of possible loss processes in the microcosms over the course of the study. Results from dark control experiments suggest hydrolysis was not important in the loss of the compounds. No significant differences were observed between measured half-lives of the pharmaceuticals in sunlight-exposed pond water and autoclaved pond water, which suggests photodegradation was important in limiting their persistence, and biodegradation was not an important loss process in surface water over the duration of the study. Observed photoproducts of several of the pharmaceuticals remained photoreactive, which led to further degradation in irradiated surface waters.

Half-Life↗
PubMed2001

Atrazine remediation in wetland microcosms.

Laboratory wetland microcosms were used to study treatment of atrazine in irrigation runoff by a field-scale-constructed wetland under controlled conditions. Three experiments, in which 1 ppm atrazine was added to the water column of three wetland, one soil control, and one water control microcosm, were conducted. Atrazine dissipation from the water column and degradate formation (deethylatrazine [DEA]; deisopropylatrazine [DIA]; and hydroxyatrazine [HA]) were monitored. Atrazine dissipation from the water column of wetland microcosms was biphasic. Less than 12% of the atrazine applied to wetland microcosms remained in the water column on day 56. Atrazine degradates were observed in water and sediment, with HA the predominant degradate. Analysis of day 56 sediment samples indicated that a significant portion of the initial application was detected as the parent compound and HA. Most probable number (MPN) assays demonstrated that atrazine degrader populations were small in wetland sediment. Wetland microcosms were able to reduce atrazine concentration in the water column via sorption and degradation. Based on results from this study, it is hypothesized that plant uptake contributed to atrazine dissipation from the water column.

Atrazine↗
PubMed2003

The lean service machine.

Jefferson Pilot Financial, a life insurance and annuities firm, like many U.S. service companies at the end of the 1990s was looking for new ways to grow. Its top managers recognized that JPF needed to differentiate itself in the eyes of its customers, the independent life-insurance advisers who sell and service policies. To establish itself as these advisers' preferred partner, it set out to reduce the turnaround time on policy applications, simplify the submission process, and reduce errors. JPF's managers looked to the "lean production" practices that U.S. manufacturers adopted in response to competition from Japanese companies. Lean production is built around the concept of continuous-flow processing--a departure from traditional production systems, in which large batches are processed at each step. JPF appointed a "lean team" to reengineer its New Business unit's operations, beginning with the creation of a "model cell"--a fully functioning microcosm of JPF's entire process. This approach allowed managers to experiment and smooth out the kinks while working toward an optimal design. The team applied lean-manufacturing practices, including placing linked processes near one another, balancing employees' workloads, posting performance results, and measuring performance and productivity from the customer's perspective. Customer-focused metrics helped erode the employees' "My work is all that matters" mind-set. The results were so impressive that JPF is rolling out similar systems across many of its operations. To convince employees of the value of lean production, the lean team introduced a simulation in which teams compete to build the best paper airplane based on invented customer specifications. This game drives home lean production's basic principles, establishing a foundation for deep and far-reaching changes in the production system.

Commerce↗
PubMed2004

Laboratory and field studies of Macrocyclops albidus (Crustacea: Copepoda) for biological control of mosquitoes in artificial containers in a subtropical environment.

The cyclopoid copepod Macrocyclops albidus (Jurine) was tested as a potential biological control agent of mosquitoes in laboratory microcosms, in controlled field conditions, and in a 22-mo field experiment using discarded tires. The predator was highly efficient in controlling mosquitoes in all three settings, reaching close to 90% reduction in larval survival under field conditions and exceeding the recommended predation rates for effective mosquito control in laboratory experiments. The predator was most effective on 1-4-d-old larvae. Alternate food and habitat structure significantly influenced the predation rates on mosquito larvae. Once established, the copepod was able to maintain reproducing populations in the field for the duration of the experiments. However, the predator failed to establish populations at four of the experimental field sites. Two of the failures can be attributed to characteristics of the individual tires, such as leaching chemicals, whereas the other two were probably due to site-specific factors. This copepod species is a promising candidate for control of mosquito larvae because it is a widespread and highly effective predator that is capable of establishing and maintaining populations under a wide variety of field conditions. Additionally, M. albidus is relatively easy to culture, maintain, and deliver to the target areas.

Aedes↗
PubMed2004

Green fluorescent protein as a marker for monitoring a pentachlorophenol degrader Sphingomonas chlorophenolica ATCC39723.

Sphingomonas chlorophenolica ATCC39723 was successfully labeled with the gfp (green fluorescent protein) gene inserted into the pcpB gene by homologous recombination. As the gfp recombinant was easily distinguished from other indigenous organisms, the population of gfp recombinant was monitored after being released into the soil microcosms. Their population density dropped from 10(8) to 10(6) (cfu/ml) in the non-sterilized soil microcosms during the first 6 days. Moreover, the gfp recombinant was not detected even at lower dilution rates after a certain time period. The recombinant, however, survived for at least 28 days in the sterilized soil microcosms. Although the gfp recombinant did not degrade pentachlorophenol (PCP), this experiment showed the possibility of using gfp as a monitoring reporter system for S. chlorophenolica ATCC39723 and potentially other species of Sphingomonas.

Biodegradation, Environmental↗
PubMed1998

Anaerobic biodegradation of pentachlorophenol in a contaminated soil inoculated with a methanogenic consortium or with Desulfitobacterium frappieri strain PCP-1.

Anaerobic biodegradation of pentachlorophenol (PCP) in a contaminated soil from a wood-treating industrial site was studied in soil slurry microcosms inoculated with a PCP-degrading methanogenic consortium. When the microcosms containing 10%-40% (w/v) soil were inoculated with the consortium, more than 90% of the PCP was removed in less than 30 days at 29 degrees C. Less-chlorinated phenols, mainly 3-chlorophenol were slowly degraded and accumulated in the cultures. Addition of glucose and sodium formate to the microcosms was not necessary, suggesting that the organic compounds in the soil can sustain the dechlorinating activity. Inoculation of Desulfitobacterium frappieri strain PCP-1 along with a 3-chlorophenol-degrading consortium in the microcosms also resulted in the rapid dechlorination of PCP and the slow degradation of 3-chlorophenol. Competitive polymerase chain reaction experiments showed that PCP-1 was present at the same level throughout the 21-day biotreatment. D. frappieri, strain PCP-1, inoculated into the soil microcosms, was able to remove PCP from soil containing up to 200 mg PCP/kg soil. However, reinoculation of the strain was necessary to achieve more than 95% PCP removal with a concentration of 300 mg and 500 mg PCP/kg soil. These results demonstrate that D. frappieri strain PCP-1 can be used effectively to dechlorinate PCP to 3-chlorophenol in contaminated soils.

Bacteria, Anaerobic↗
PubMed2004

[Experimental study on the microcosmic changes of compressed premaxillary suture with laser scanning confocal microscopy].

OBJECTIVE: The aim of this experiment is to know whether active orthopedic appliance is rationale to do presurgical treatment and seek some regularities. METHODS: Laser scanning confocal microscopy and triple fluorochrome labeling in bone were used to observe and study detailed changes occurred in compressed suture systematically. RESULTS: Widened suture and broken fibres between the adjoining bones was observed at the 3rd week postoperatively. At the 3rd week hyperplasia of organic tissue components was also seen. At the 6 and 9th week there were no apparent differences among all groups no matter whether in control group or experimental groups. CONCLUSION: Retarding injury of compressed suture and surrounding tissue hyperplasia exists. With growth and development wounded suture will gradually assimilate to control group structurally and functionally.

Animals↗
PubMed2003

Carbon dioxide and methane fluxes in boreal peatland microcosms with different vegetation cover--effects of ozone or ultraviolet-B exposure.

O(3) concentrations in the troposphere are rising and those in the stratosphere decreasing, the latter resulting in higher fluxes of solar ultraviolet-B (UV-B) radiation to the earth's surface. We assessed whether the fluxes of CO(2) and CH(4) are altered by enhanced UV-B radiation or elevated tropospheric O(3) concentrations in boreal peatland microcosms (core depth 40 cm, diameter 10.5 cm) with different vegetation cover. At the end of the UV-B experiment which lasted for a growing season, net CO(2) exchange (NEE) and dark ecosystem respiration ( R(TOT)) were sevenfold higher, and CH(4) efflux 12-fold higher, in microcosms with intact vegetation dominated by Eriophorum vaginatum L. and Sphagnum spp., compared to microcosms from which we removed E. vaginatum. Vegetation treatment had minor effects on CH(4) production and consumption potentials in the peat, suggesting that the large difference in CH(4) efflux is mainly due to efficient CH(4) transport via the aerenchyma of E. vaginatum. Ambient UV-B supplemented with 30% and elevated O(3) concentrations (100 and 200 ppb, for 7 weeks) significantly increased R(TOT) in both vegetation treatments. Elevated O(3) concentrations reduced NEE over time, while UV-B had no clear effects on the fluxes of CO(2) or CH(4) in the cloudy summer of the study. Field experiments are needed to assess the significance of increasing UV-B radiation and elevated tropospheric O(3) concentration on peatland gas exchange in the long-term.

Carbon Dioxide↗
PubMed2005

Decomposition of leaves of the metallophyte Arabidopsis halleri in soil microcosms: fate of Zn and Cd from plant residues.

In order to better understand the fate of metals during the biodegradation of organic matter in soils, an in vitro incubation experiment was conducted with metal-rich and metal-free leaves of Arabidopsis halleri introduced in a non-contaminated soil. During incubation of these microcosms, we followed the partitioning of Zn and Cd between the solution and their solid components, by determining the metal contents of six soil fractions and dissolved metals after granulo-densimetric separations at selected times. Microbial biomass and exchangeable metals in K(2)SO(4) solutions were also determined at the same times, and two main stages were identified. The first one takes place after a fast abiotic transfer of Zn and Cd from readily soluble plant tissues onto fine soil constituents, keeping metals away from the liquid phase: during about 14 days, microbial biomass increased as well as metal contents of some soil fractions, particularly those rich in particulate organic matter. During the second stage, between 14 and 60 days and for the metal-rich microcosms, Zn and Cd contents in solution increased, while microbial biomass decreased instead of staying constant as in control. A change of Zn and Cd speciation is assumed, from non-toxic adsorbed forms to more toxic species in solution. Remaining metal-rich plant residues seem to create a stable organic C compartment in the soil.

Arabidopsis↗
PubMed2002

Degradation of trichloroethylene in wetland microcosms containing broad-leaved cattail and eastern cottonwood.

Remediation of aquifers containing trichloroethylene (TCE) relies primarily on physical extraction of contaminated groundwater and soil. Unfortunately, this is typically expensive and does not always attain the desired treatment goals. In situ bioremediation via natural attenuation is an alternative treatment process in which TCE is transformed by indigenous microorganisms and plants. In this study, TCE was observed in a surficial aquifer that discharges into a wetland. Experiments were undertaken to determine whether natural attenuation of TCE in the wetland was possible. Microcosms were constructed using sandy soil+/-eastern cottonwoods (Populus deltoides) from the wetland's edge and organic soil+broad-leaved cattails (Typha latifolia) from the wetland's interior. [14C] TCE was added to each microcosm (1.27 microCi). Overtime, 14C was recovered from four microcosm compartments: (1) as 14C bound to soil and water, (2) as volatilized [14C] TCE, (3) as [14C] CO2 produced by mineralization of [14C] TCE, and (4) as 14C incorporated into the plants. Total recoveries of the 14C-label ranged from 73.6% to 95.8%. Volatilized [14C] TCE accounted for the majority ( > 50%) of the recovered label. In microcosms without plants, [14C] CO2 represented 3.2% (organic soil) to 15.6% (sandy soil) of the recovered 14C, indicating that TCE was mineralized by indigenous microorganisms. The presence of the broad-leaved cattail resulted in increased production of [14C] CO2 to 5.3% in the organic soil. The data thus suggest that natural attenuation is a potential bioremediative strategy for TCE-contaminated wetlands.

Biodegradation, Environmental↗
PubMed1991

A comparison of (Pb, Cd and Zn) accumulation in terrestrial slugs maintained in microcosms: evidence for metal tolerance.

The relative tissue accumulation of Pb, Cd and Zn were compared in two populations each of two species of slugs (Arion subfuscus and Deroceras reticulatum). One population was resident at a contaminated Pb/Zn mine site, and the other population was from an uncontaminated site and was transferred for 20 days to microcosms established at the mine site. It was found that when the experiment was conducted during late spring (May), but not in late winter (February), that the Pb and Zn concentrations in the tissues of the 'transplants', were significantly higher than in the tissues of 'residents'; the Cd concentrations in the transplants, although significantly higher in the May sample than in February, did not exceed those of their 'resident' counterparts. It was postulated that: (a) Pb and Zn tolerance in slugs is phenotypically expressed by a reduction in metal accumulation; (b) Cd tolerance, if present, may be characterized by enhanced storage capacity; and (c) the presence of local metal-tolerant ecotypes is a biotic variable that may confound the relationship between dry tissue and environmental metal concentrations that forms a basis of pollution biomonitoring.

Journal Article↗
PubMed1992

How to improve the quality of patient care and still save money in the radiology department.

1, A pediatric radiology department at an institution such as Minneapolis Children's Medical Center is a true microcosm of the gigantic radiology department of a general hospital. Our positive experiences with IMACS discussed above should be even more profound and profitable for the larger medical institutions. 2, IMACS did improve service and communications among radiologists, referring clinicians and the hospital staff. Both the old and new images needed for review and comparison are presently available for the clinicians on the nursing stations as soon as the current studies have been completed. 3, IMACS allowed us to reduce the number of films lost, misplaced or misfiled and reduced the interpretation delays by keeping all the films in the radiology department. This has resulted in improvement in the overall productivity of the radiology staff and the referring clinicians. 4, The cost of IMACS was paid for through additional revenue capture, increased productivity and a decrease in the expenses in the radiology department in less than one year. These benefits should continue for several more years without the need for any additional expenses. 5, Despite these initial successes, there are several issues which must be addressed before total computerization of the radiology services and a "filmless" radiology department can be created. A. The speed of an available workstation is totally inadequate for the day to day clinical use.(ABSTRACT TRUNCATED AT 250 WORDS)

Cost Control↗
PubMed2006

Bridging the divide: global lessons from evidence-based health policy in Mexico.

During the past 6 years, Mexico has undergone a large-scale transformation of its health system. This paper provides an overview of the main features of the Mexican reform experience. Because of its high degree of social inequality, Mexico is a microcosm of the range of problems that affect countries at all levels of development. Its health system had not kept up with the pressures of the double burden of disease, whereby malnutrition, common infections, and reproductive health problems coexist with non-communicable disease and injury. With half of its population uninsured, Mexico was facing an unacceptable paradox: whereas health is a key factor in the fight against poverty, a large number of families became impoverished by expenditures in health care and drugs. The reform was designed to correct this paradox by introducing a new scheme called Popular Health Insurance (Seguro Popular). This innovative initiative is gradually protecting the 50 million Mexicans, most of them poor, who had until now been excluded from formal social insurance. This paper reports encouraging results in the achievement of the ultimate objective of the reform: universal access to high-quality services with social protection for all.

Adult↗
PubMed2003

Long-term effect of Sea-Nine on natural coastal phytoplankton communities assessed by pollution induced community tolerance.

Sea-Nine211 has been introduced as a new biocide in antifouling paints with an immediate degradation when it is released from ship hulls. The active component of Sea-Nine211 is 4,5-dichloro-2-n-octyl-isothiazoline-3-one (DCOI). In the present study, the toxicity of DCOI and the occurrence of Pollution Induced Community Tolerance (PICT) were tested in microcosms containing eutrophic coastal water with its natural composition of phytoplankton. The experiment was performed in closed systems with a single addition of the nominal concentrations 0, 3.2, 10, 32 and 100 nM DCOI, for a period of 16 days. Pollution induced community tolerance (PICT) was observed in the phytoplankton communities exposed to the nominal concentrations 32 and 100 nM DCOI. Chemical analysis of DCOI in the coastal water utilised in the toxicity and PICT experiment was performed by GC-MS using a solid- phase extraction method. Half-life was calculated to be 2.5 days for the nominal concentrations 32 and 100 nM DCOI. The results of the present study show that nominal concentrations of 32 and 100 nM DCOI significantly increased the community tolerance already after 2 days of exposure and that the tolerance was maintained for a period of 16 days even when DCOI was degraded during this period. The causes for the persistent tolerance are discussed in relation to the degradation of DCOI and structural changes in the phytoplankton communities.

Adaptation, Physiological↗
PubMed2006

Microbial communities and fecal indicator bacteria associated with Cladophora mats on beach sites along Lake Michigan shores.

A high biomasses of Cladophora, a filamentous green alga, is found mainly during the summer along the shores of Lake Michigan. In this study, the abundance and persistence of the fecal indicator bacterium Escherichia coli and sulfate-reducing bacteria (SRB) on Cladophora mats collected at Lake Michigan beaches were evaluated using both culture-based and molecular analyses. Additionally, 16S rRNA gene cloning and sequencing were used to examine the bacterial community composition. Overall, E. coli was detected in all 63 samples obtained from 11 sites, and the average levels at most beaches ranged from 2,700 CFU/100 g (wet weight) of Cladophora to 7,500 CFU/100 g of Cladophora. However, three beaches were found to have site average E. coli densities of 12,800, 21,130, and 27,950 CFU/100 g of Cladophora. The E. coli levels in the lake water collected at the same time from these three sites were less than the recommended U.S. Environmental Protection Agency limit, 235 CFU/100 ml. E. coli also persisted on Cladophora mats in microcosms at room temperature for more than 7 days, and in some experiments it persisted for as long as 28 days. The SRB densities on Cladophora mats were relatively high, ranging from 4.4x10(6) cells/g (6.64 log CFU/g) to 5.73x10(6) cells/g (6.76 log CFU/g) and accounting for between 20% and 27% of the total bacterial counts. Partial sequences of the 16S rRNA gene clones revealed a phylogenetically diverse community, in which the Cytophaga-Flavobacterium-Bacteroides cluster and the low-G+C-content gram-positive bacteria were the dominant organisms, accounting for 40% and 12.8%, respectively, of the total clone library. These results further reveal the potential public health and ecological significance of Cladophora mats that are commonly found along the shoreline of Lake Michigan, especially with regard to the potential to harbor microorganisms associated with fecal pollution and odor-causing bacteria.

Bathing Beaches↗
PubMed1997

A dynamic state of a closed ecosystem and its significance to the generation of the Earth's environment.

The Earth forms a living-system composed of large materially closed ecosystems (CES). We are performing various experiments to study comparable living-systems, especially smaller samples we call "microcosmic type CES". CES have an ability to persist despite perturbation. We show experimental results of the behavior of CES mainly during the transition form a semi-open state to an entirely closed one. We report phenomena on CES instability which may be inherent in them. We suggest that CES possess some properties that may help elucidate the nature of the Earth as a living system. Climatic change on the Earth, such as oceanic anoxia and its consequences, may have been due to disturbances as modeled in a CES.

Earth, Planet↗