Transformation of lipids in activated sludge.

Transformation of lipids in activated sludge treatment plants is of interest for two reasons: lipids contribute 30-40% of the chemical oxygen demand (COD) in wastewater, and they may stimulate the growth of filamentous microorganisms in nutrient removal activated sludge plants. The transformation of lipids was investigated under aerobic and anoxic conditions by measuring the oxygen and nitrate uptake rates (OUR and NUR). The maximal OUR and NUR of long-chain fatty acid was found to be at the same level as acetate indicating that long-chain fatty acid was as easily consumable. However, the adsorption of long-chain fatty acid to surfaces of sludge flocs made it difficult to determine initial uptake rates of long-chain fatty acids. It was not possible to describe the hydrolysis rate of triacylglyceride by OUR and NUR to long-chain fatty acids because the hydrolysis rate was very slow. For a better description of the processes involved in transformation of lipids, a conceptual model was suggested. The processes in the suggested model were the adsorption/desorption of both triacylglyceride, and long-chain fatty acid onto surfaces of sludge flocs, hydrolysis of triacylglyceride by lipases and the uptake of long-chain fatty acid by bacteria under various conditions. The model can be helpful to structure design and evaluation of activated sludge experiment with lipids.

Intranasal bioavailability of buprenorphine in rabbit correlated to sheep and man.

The purpose of the present study of buprenorphine is to add information about the correlation between various animal models and nasal bioavailabilities in man. PEG 300 was added to one formulation to study whether the addition of the co-solvent results in the same absorption pattern as seen for sheep. The bioavailability of intranasal buprenorphine 0.6 mg in PEG 300 and 5% dextrose was assessed in a cross-over study in six rabbits. The mean bioavailabilities, Tmax and Cmax were 46% (S.D. +/-13) and 53% (S.D. +/-17), 8 and 12 min, 28 and 27 ng/ml for 30% PEG 300 and 5% dextrose, respectively. No significant differences were found between the nasal buprenorphine formulations. The bioavailabilities in rabbit and sheep, respectively, were approximately 2.5 and four times higher than for man. The absorption rate was faster for rabbit and sheep than for man. It appears that rabbit and sheep bioavailability differ from humans, especially with respect to rate. PEG 300 do not increase the bioavailability of buprenorphine.

Combination of fluorescent in situ hybridization and microautoradiography-a new tool for structure-function analyses in microbial ecology.

A new microscopic method for simultaneously determining in situ the identities, activities, and specific substrate uptake profiles of individual bacterial cells within complex microbial communities was developed by combining fluorescent in situ hybridization (FISH) performed with rRNA-targeted oligonucleotide probes and microautoradiography. This method was evaluated by using defined artificial mixtures of Escherichia coli and Herpetosiphon aurantiacus under aerobic incubation conditions with added [3H]glucose. Subsequently, we were able to demonstrate the potential of this method by visualizing the uptake of organic and inorganic radiolabeled substrates ([14C]acetate, [14C]butyrate, [14C]bicarbonate, and 33Pi) in probe-defined populations from complex activated sludge microbial communities by using aerobic incubation conditions and anaerobic incubation conditions (with and without nitrate). For both defined cell mixtures and activated sludge, the method proved to be useful for simultaneous identification and analysis of the uptake of labeled substrates under the different experimental conditions used. Optimal results were obtained when fluorescently labeled oligonucleotides were applied prior to the microautoradiographic developing procedure. For single-cell resolution of FISH and microautoradiographic signals within activated sludge flocs, cryosectioned sample material was examined with a confocal laser scanning microscope. The combination of in situ rRNA hybridization techniques, cryosectioning, microautoradiography, and confocal laser scanning microscopy provides a unique opportunity for obtaining cultivation-independent insights into the structure and function of bacterial communities.