Redox potentials of the blue copper sites of bilirubin oxidases

The redox potentials of the multicopper redox enzyme bilirubin oxidase (BOD) from two organisms were determined by mediated and direct spectroelectrochemistry. The potential of the T1 site of BOD from the fungus Myrothecium verrucaria was close to 670 mV, whereas that from Trachyderma tsunodae was > 650 mV vs. NHE. For the first time, direct electron transfer was observed between gold electrodes and BODs. The redox potentials of the T2 sites of both BODs were near 390 mV vs. NHE, consistent with previous finding for laccase and suggesting that the redox potentials of the T2 copper sites of most blue multicopper oxidases are similar, about 400 mV.     

The interactive effect of elevated temperature on deltamethrin-induced biochemical stress responses in Channa punctata Bloch

There are reports showing interactive effect of environmental factors with the toxic outcome of chemicals. We studied the interactive effect of elevated temperature as an abiotic stressor on deltamethrin-induced biochemical stress responses in a freshwater fish, Channa punctata Bloch. Heat stress (∼12 °C above ambient temperature for 3 h) and pesticide exposure (deltamethrin 0.75 ppb for 48 h) showed significant induction of heat shock protein-70 (HSP70) in liver, kidney and gills of fishes. Elevated temperature when followed by deltamethrin exposure showed synergistic effect showing a high level of HSP70 in liver and gills whereas response in the kidney was opposite. On the contrary, when deltamethrin exposure followed the heat stress, no significant difference was observed. Protein carbonylation was found to be more pronounced in heat-stressed group compared with control fish group. A significant increase in lipid peroxidation (LPO) was observed in different tissues of fish exposed to either of the stressors. In the kidney of fish exposed to heat stress followed by deltamethrin, LPO was relatively lower as compared to other treatments. Thiols content such as reduced glutathione (GSH), total thiols (T-SH), non-protein thiols (NP-SH) and protein thiols (P-SH) showed no consistent pattern in different tissues. In deltamethrin-exposed group that was subsequently exposed to heat stress, the GSH content was higher in liver and lower in both kidney and gills when compared with other groups. Alteration in the activities of antioxidant enzymes such as catalase (CAT), glutathione S-transferase (GST), glutathione reductase (GR) and glutathione peroxidase (GPx) was also observed when fish were exposed to heat stress and/or deltamethrin. Our study demonstrated that heat stress modulated biochemical stress responses in fish showing a tissue specific pattern. This implies that fish has the capacity to elicit differential response to exposure to abiotic stressors in order to reduce the systemic magnitude of stress which may otherwise lead to severe dysfunction of vital tissues.     

Optimisation of a microwave pretreatment of wheat straw for methane production

This study aims at the optimisation of a microwave pretreatment for wheat straw solubilisation and anaerobic biodegradability. The maximum yield of methane production was obtained at 150 °C with an improvement of 28% compared to an untreated sample. In addition, at this temperature, the time to reach 80% of the methane volume obtained from untreated straw was about 35%. The study of ramp time and holding time at targeted temperature showed that they had no improvement effect. Thus, the best conditions are the highest heating rate for a final temperature 150 °C without any holding time. The reading of energy consumed by pretreatment and energy overproduced by pretreated samples showed that increasing tVS amount and heating rate led to a saving of energy consumption. Nevertheless, to obtain a positive energy balance, a microwave device should consume less than 2.65 kJ/g_tVS.     

Effects of pulp and paper mill effluents on estuarine and marine ecosystems in Canada: a review

This review examines the impact of pulp and paper mill effluents by comparing effects from Canada's east and west coasts at a time when revisions to the federal Fisheries Act (Pulp and Paper Effluent Regulations) are being finalized. Pulp and paper mill effluents from Canadian coastal mills were usually acutely toxic at source, and in many cases had marked deleterious effects on receiving waters due to toxicity, high biochemical oxygen demand (BOD), and total suspended solids (TSS) loadings. Extreme reductions in ambient dissolved oxygen, impacts on benthic and intertidal organisms, changes in water colour and primary productivity, have been demonstrated over the years and continue to cause environmental damage. Contamination of biota by a wide range of chlorinated organic compounds has been more recently the focus of investigations.While sublethal effects of lowered dissolved oxygen levels and suspended solids on the water column and bottom communities are well known, the potential effects of major organochlorine contamination of water (measured as Adsorbable Organic Halogens=AOX), sediments, and biota are not fully understood, especially under natural and perturbated conditions. The findings of recent North American and Scandinavian studies which describe liver enzyme activation, histological damage, reproductive and population level changes in fish, are a major concern as they are a sign of ecosystem stress and pathology.The environmental effects described herein are long-term impacts which will not respond quickly to changes in pollutant loading. Integrated site-specific assessments need to be undertaken to document ecosystem response to process and treatment improvements at mill sites. Current biomonitoring techniques including measures of population structure and ecosystem function are needed in addition to sensitive biochemical indicators of contaminant exposure.     

A comparison of two different approaches to inventory analysis of dairies

Two different methods for Life Cycle Inventory (LCI) applied to the dairy industry was performed at two dairies. In the simplified method, total environmental loads from a dairy was registred and allocated to liquid milk. Energy and emissions are measured for each process step for the detailed method. Both methods have advantages and disadvantages. The simplified method captures all energy and emissions of dairy processing, but treats the dairy as a “black box”. The energy consumption was found to be 1, 27 MJ/1 and 2,55 MJ/1 for the two dairies. By use of the detailed method it is easy to “loose” information, and it is very time consuming. The energy consumption was lower than for the simplified method. The environmental loads can on the other hand be divided on the different process steps. The main conclusion is that choice of method depends on the purpose of the LCA-study.     

The use of vertical flow constructed wetlands for on-site treatment of domestic wastewater: New Danish guidelines

Official guidelines for the on-site treatment of domestic sewage have recently been published by the Danish Ministry of Environment as a consequence of new treatment requirements for single houses and dwellings in rural areas. This paper summarises the guidelines for vertical constructed wetland systems (planted filter beds) that will fulfil demands of 95% removal of BOD and 90% nitrification. The system can be extended with chemical precipitation of phosphorus with aluminium polychloride in the sedimentation tank to meet requirements of 90% phosphorus removal. The necessary surface area of the filter bed is 3.2 m²/person equivalent and the effective filter depth is 1.0 m. The filter medium must be filtersand with a d₁₀ between 0.25 and 1.2 mm, a d₆₀ between 1 and 4 mm, and a uniformity coefficient (U = d₆₀/d₁₀) less than 3.5. The sewage is, after sedimentation, pulse-loaded onto the surface of the bed using pumping and a network of distribution pipes. The drainage layer in the bottom of the bed is passively aerated through vertical pipes extending into the atmosphere in order to improve oxygen transfer to the bed medium. Half of the nitrified effluent from the filter is recirculated to the first chamber of the sedimentation tank or to the pumping well in order to enhance denitrification and to stabilise the treatment performance of the system. A phosphorus removal system is installed in the sedimentation tank using a small dosing pump. The mixing of chemicals is obtained by a simple airlift pump, which also circulates water in the sedimentation tank. The vertical flow constructed wetland system is an attractive alternative to the common practice of soil infiltration and provides efficient treatment of sewage for discharge into the aquatic environment.     

Improving the dynamic response of a mediator-less microbial fuel cell as a biochemical oxygen demand (BOD) sensor

The dynamic behavior of a mediator-less, microbial fuel cell (MFC) was studied as a continuous biochemical oxygen demand (BOD) sensor. The response time and the sensitivity were analyzed through the step-change testing of the fuel concentration. The MFC of 25 ml had the shortest response time of 36± 2 min at the fuel-feeding rate of 0.53 ml min^–1 and the resistance of 10 A smaller MFC of 5 ml had a response time of 5± 1 min.     

H3K4 methylation by SETD1A/BOD1L facilitates RIF1-dependent NHEJ

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A yeast co-culture-based biosensor for determination of waste water contamination levels

Artificial microbial co-cultures were formed to develop the receptor element of a biosensor for assessment of biological oxygen demand (BOD). The co-cultures possessed broad substrate specificities and enabled assays of water and fermentation products within a broad BOD range (2.4–80 mg/dm³) with a high correlation to the standard method (R = 0.9988). The use of the co-cultures of the yeasts Pichia angusta, Arxula adeninivorans and Debaryomyces hansenii immobilized in N-vinylpyrrolidone-modified poly(vinyl alcohol) enabled developing a BOD biosensor possessing the characteristics not inferior to those in the known biosensors. The results are indicative of a potential of using these co-cultures as the receptor element base in prototype models of instruments for broad application.     

Performance evaluation of mixed and pure microbial inocula as surrogate culture in a BOD5 test

The use of activated sludge (AS) to assess the environmental impact of chemicals and wastewaters suffers from several drawbacks related to the heterogeneity, absence of standardization and health risk associated with such a mixed sewage population. To search for reliable testing inoculum alternatives, the potential of a standardized soil inoculum and a pure culture (Pseudomonas sp.), as reference material in a 5-day BOD test, was evaluated using the dilution and manometric methods and testing the standard glucose-glutamic acid solution. The results obtained for the BOD₅ of the standard solution fall in the range referred for the AS in the standards of the cited methods, demonstrating the potential of these inocula as an alternative to AS in the BOD₅ test. Moreover, testing on real wastewater samples showed highly significant correlations (P < 0.001) between the BOD₅ values obtained with these two inocula and with the standard inoculum. Analysis of metabolic patterns also pointed to a similar catabolic profile between soil inoculum and AS and to the potential of a mixed Pseudomonas-soil inoculum as an AS surrogate culture.