Combining electrokinetic transport and bioremediation for enhanced removal of crude oil from contaminated marine sediments: Results of a long-term, mesocosm-scale experiment

Marine sediments represent an important sink of harmful petroleum hydrocarbons after an accidental oil spill. Electrobioremediation techniques, which combine electrokinetic transport and biodegradation processes, represent an emerging technological platform for a sustainable remediation of contaminated sediments. Here, we describe the results of a long-term mesocosm-scale electrobioremediation experiment for the treatment of marine sediments contaminated by crude oil. A dimensionally stable anode and a stainless-steel mesh cathode were employed to drive seawater electrolysis at a fixed current density of 11 A/m². This approach allowed establishing conditions conducive to contaminants biodegradation, as confirmed by the enrichment of Alcanivorax borkumensis cells harboring the alkB-gene and other aerobic hydrocarbonoclastic bacteria. Oil chemistry analyses indicated that aromatic hydrocarbons were primarily removed from the sediment via electroosmosis and low molecular weight alkanes (nC₆ to nC₁₀) via biodegradation.

The quantitative significance of Syntrophaceae and syntrophic partnerships in methanogenic degradation of crude oil alkanes

Libraries of 16S rRNA genes cloned from methanogenic oil degrading microcosms amended with North Sea crude oil and inoculated with estuarine sediment indicated that bacteria from the genera Smithella (Deltaproteobacteria, Syntrophaceace) and Marinobacter sp. (Gammaproteobacteria) were enriched during degradation. Growth yields and doubling times (36 days for both Smithella and Marinobacter) were determined using qPCR and quantitative data on alkanes, which were the predominant hydrocarbons degraded. The growth yield of the Smithella sp. [0.020 g_(cell-C)/g_(alkane-C)], assuming it utilized all alkanes removed was consistent with yields of bacteria that degrade hydrocarbons and other organic compounds in methanogenic consortia. Over 450 days of incubation predominance and exponential growth of Smithella was coincident with alkane removal and exponential accumulation of methane. This growth is consistent with Smithella's occurrence in near surface anoxic hydrocarbon degrading systems and their complete oxidation of crude oil alkanes to acetate and/or hydrogen in syntrophic partnership with methanogens in such systems. The calculated growth yield of the Marinobacter sp., assuming it grew on alkanes, was [0.0005 g_(cell-C)/g_(alkane-C)] suggesting that it played a minor role in alkane degradation. The dominant methanogens were hydrogenotrophs (Methanocalculus spp. from the Methanomicrobiales). Enrichment of hydrogen-oxidizing methanogens relative to acetoclastic methanogens was consistent with syntrophic acetate oxidation measured in methanogenic crude oil degrading enrichment cultures. qPCR of the Methanomicrobiales indicated growth characteristics consistent with measured rates of methane production and growth in partnership with Smithella.

Methanogenic degradation of petroleum hydrocarbons in subsurface environments remediation, heavy oil formation, and energy recovery

Hydrocarbons are common constituents of surface, shallow, and deep-subsurface environments. Under anaerobic conditions, hydrocarbons can be degraded to methane by methanogenic microbial consortia. This degradation process is widespread in the geosphere. In comparison with other anaerobic processes, methanogenic hydrocarbon degradation is more sustainable over geological time scales because replenishment of an exogenous electron acceptor is not required. As a consequence, this process has been responsible for the formation of the world's vast deposits of heavy oil, which far exceed conventional oil assets such as those found in the Middle East. Methanogenic degradation is also a potentially important component of attenuation in hydrocarbon contamination plumes. Studies of the organisms, syntrophic partnerships, mechanisms, and geochemical signatures associated with methanogenic hydrocarbon degradation have identified common themes and diagnostic markers for this process in the subsurface. These studies have also identified the potential to engineer methanogenic processes to enhance the recovery of energy assets as biogenic methane from residual oils stranded in petroleum systems.

Antibiotic-treated infections in intensive care patients in the UK

The purpose of this audit was to study reasons for starting antibiotic therapy, duration of antibiotic treatment, reasons for changing antibiotics and the agreement between clinical suspicion and microbiological results in intensive care practice. We conducted a multicentre observational audit of 316 patients. Data on demographic details, site, treatment and nature of infection were collected. The median duration of antibiotic therapy was 7 days. Infections were community-acquired in 160 patients (55%). Antibiotics were started on clinical suspicion of infection in 237 patients (75%). Pulmonary infections were the most common, representing 52% of all proven infections. Gram-negative organisms were the most common cause of proven infections (n = 90 (50%)). The antibiotic spectrum was narrowed in light of microbiology results in 78 patients (43%) and changed due to antibiotic resistance in 38 patients (21%). We conclude that the mean duration of treatment contrasts with existing published guidelines, highlighting the need for further studies on duration and efficacy of treatment in intensive care.

Mixed patterns of transmission of human herpesvirus-8 (Kaposi's sarcoma-associated herpesvirus) in Malawian families

To study transmission patterns of human herpesvirus-8 (HHV-8) (Kaposi's sarcoma-associated herpesvirus) in families in Malawi, nucleotide sequences derived from two hypervariable loci of the HHV-8 genome, the V1 and V2 regions of open reading frame K1 (K1/V1 and K1/V2, respectively), were amplified from blood and mouth rinse samples of 22 patients with treated and untreated Kaposi's sarcoma (KS) and their first-degree relatives (n=67). In patients with KS, vincristine therapy was significantly associated with non-detectability of circulating, but not oral, K1/V1 DNA. Intra-familial K1/V1 phylogenetic comparisons of eight families were possible. Both identical and non-identical sequences were observed between family members, suggesting transmission of HHV-8 along both intra- and extra-familial transmission routes.

Sentence completion tests: a review of the literature and results of a survey of members of the Society for Personality Assessment

Test usage surveys consistently find that sentence completion tests (SCTs) are among the most popular personality assessment instruments used by practitioners. What is not noted is which SCTs practitioners are using, why these tests are so popular, and whether practitioners are using formal scoring. We surveyed a random selection of 100 members of the Society for Personality Assessment. With a 60% return rate on a single mailing, we found that most psychologists who use incomplete sentence tests use the Rotter (1951) Incomplete Sentences Blank with children (18%), adolescents (32%), and adults (47%). Most practitioners said they do not read stems aloud and record answers themselves, and even fewer said they use formal scoring. The most common reasons for using an SCT are (a) to use it as part of an assessment battery (41 endorsements), (b) to determine personality structure (18 endorsements), and (c) to elicit quotable quotes (17 endorsements). Implications for practitioners and training suggestions for academicians who prepare future psychologists are noted.

Control of cell proliferation in human glioma by glucocorticoids

Survival and proliferation of cell cultures from human anaplastic astrocytomas were shown to be enhanced by glucocorticoids with an optimal concentration of approximately 2.5 x 10(-5)M (10 micrograms/ml). The stimulation of proliferation was only observed in a clonal growth assay and was reversed as the size of individual colonies reached approximately 50 cells. Above this size, and in regular monolayer cultures, glucocorticoids were found to inhibit cell proliferation as measured by direct cell counting and incorporation of [3H] thymidine. Cultures grown to maximum cell densities in non-limiting medium conditions reached a lower terminal cell density, and had a reduced labelling index with [3H] thymidine in the presence of glucocorticoids. Although there was little difference between the actions of beta-methasone, dexamethasone and ethyl prednisolone, methyl prednisolone was found to be more effective, both in terms of stimulation of clonal growth and inhibition of growth at high cell densities. There was no evidence of cytotoxicity with glucocorticoids up to 5 x 10(-5)M (20 micrograms/ml) and it is suggested that glucocorticoids act via a normal regulatory process, perhaps enhancing cell-cell recognition.