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Investigation of microbially available phosphorus (MAP) in flemish drinking water.

Several researchers have reported phosphorus growth limitations of heterotrophic bacteria instead of main energy source--organic carbon. Usually this phenomenon was noticed in waters with high organic carbon content, where phosphorus concentration was deficient to maintain the growth on level suggested by high organic carbon amount. We analysed the microbially available phosphorus (MAP) and assimilable organic carbon (AOC) in several drinking waters in Flanders, Belgium. Our aim was the investigation whether organic carbon or phosphorus is the restricting nutrient in specific water and determination of the impact of some treatment processes on MAP content. We obtained a wide range of MAP concentrations being from 0.3 to 15.2 microg P-PO(4)/l in finished drinking water. In a treatment unit applying ozone, MAP was found to be the nutrient that limits bacterial growth instead of organic carbon. Moreover, ozone caused slight MAP decrease. Granular activated carbon (GAC) filtration was able to diminish further the MAP content significantly but not below a certain level. The biofilm monitor supplied with the MAP-limited water resulted in significantly lower biofilm formation rate (BFR) value than the same installation fed with AOC-limited water.

Belgium↗

Oxidation of nitric oxide by a new heterotrophic Pseudomonas sp.

A new bacterial strain isolated from soil consumed nitric oxide (NO) under oxic conditions by oxidation to nitrate. Phenotypic and phylogenetic characterization of the new strain PS88 showed that it represents a previously unknown species of the genus Pseudomonas, closely related to Pseudomonas fluorescens and Pseudomonas putida. The heterotrophic, obligately aerobic strain PS88 was not able to denitrify or nitrify; however, strain PS88 oxidized NO to nitrate. NO was not reduced to nitrous oxide (N2O). Nitrogen dioxide (NO2) and nitrite (NO2-) as possible intermediates of NO oxidation to nitrate (NO3-) could not be detected. NO oxidation was inhibited under anoxic conditions and by high osmolarity, but not by nitrite. NO oxidation activity was inhibited by addition of formaldehyde, HgCl2, and antimycin, and by autoclaving or disintegrating the cells, indicating that the process was enzyme-mediated. However, the mechanism remains unclear. A stepwise oxidation at a metalloenzyme and a radical mechanism are discussed. NO oxidation in strain PS88 seems to be a detoxification or a co-oxidation mechanism, rather than an energy-yielding process.

Nitric Oxide↗

Biodegradation of undecylbenzenesulphonate by mixed methane-oxidizing culture.

Biodegradation of undecylbenzenesulphonate (C(11)LAS) was performed in shake flasks at 21 degrees C by using a mixed methanotrophic-heterotrophic culture containing type II methanotrophs. Concentrations of C(11)LAS and aromatic intermediates were determined by reversed-phase high-performance liquid chromatography (RP-HPLC). Methane and carbon dioxide concentrations were measured in headspace samples by using gas chromatography. RP-HPLC analyses of aqueous samples show that the culture MM1 expresses the capability of C(11)LAS transformation in the presence or absence of methane. Simultaneous methane oxidation and C(11)LAS degradation, and the inhibition of both transformation processes by acetylene were observed. This suggests the possibility that C(11)LAS transformation is catalyzed by methane monooxygenase (MMO). Comparable affinity of culture MM1 for both methane and C(11)LAS ( [Formula: see text], respectively), and more than four times higher maximum transformation rate for methane than for C(11)LAS ( [Formula: see text] (dry weight) cells day(-1), respectively), were determined. This further supports the involvement of MMO enzyme system in transformation and suggests a pronounced competitive inhibition of C(11)LAS degradation by methane.

Journal Article↗

Investigation of biological and fouling characteristics of submerged membrane bioreactor process for wastewater treatment by model sensitivity analysis.

In this study, a mathematical model for the submerged membrane bioreactor (SMBR) was developed. The activated sludge model No. 1 (ASM1) was modified to be suitable for describing the characteristics of the SMBR, and the resistance-in-series model was integrated into the ASM1 to describe membrane fouling. Using the newly developed model, the biological and fouling characteristics of the submerged membrane bioreactor process for wastewater treatment was investigated by sensitivity analysis. The sensitivity of effluent COD and nitrogen, TSS in the reactor and membrane flux with respect to each parameter (K(h), mu(H), K(S), K(NHH), K(NOH), b(H), Y(H), mu(A), K(NHA), b(A), Y(A), K(m) and alpha) was investigated by model simulation. As a result, the most important factors affecting membrane fouling were hydrolysis rate constant (K(h)) and cross-flow effect coefficient (K(m)). Heterotrophic yield coefficient (Y(H)) had a great influence on effluent quality. Effluent quality was also somewhat sensitive to K(h). Peculiar operating conditions of the SMBR such as long solids retention time (SRT), absolute retention of solids by membrane and high biomass concentration in bioreactor could explain these model simulation results. The model developed in this study would be very helpful to optimize operating conditions as well as design parameters for a SMBR system.

Biofilms↗

Protein translocation within chloroplast is similar in Euglena and higher plants.

It is currently thought that chloroplasts of higher plants were derived from endosymbiont oxygenic photosynthetic bacteria (primary endosymbiosis), while Euglena, a photosynthetic protista, gained chloroplasts by secondary endosymbiosis (i.e., incorporation of a photosynthetic eukaryote into heterotrophic eukaryotic host). To examine if the protein transport inside chloroplasts is similar between these organisms, we carried out heterologous protein import experiments with Euglena precursor proteins and spinach chloroplasts. The precursor of a 30-kDa subunit of the oxygen-evolving complex (OEC30) from the thylakoid lumen of Euglena chloroplasts contained the N-terminal signal, stroma targeting, and thylakoid transfer domains. Truncated preOEC30s lacking the N-terminal domain were post-translationally imported into spinach chloroplasts, transported into the thylakoid lumen, and processed to a mature protein. These results showed that protein translocations within chloroplasts in Euglena and higher plants are similar and supported the hypothesis that Euglena chloroplasts are derived from the ancestral Chlorophyta.

Adenosine Triphosphate↗

Nitrogen-alkalinity interactions in the highly polluted Scheldt basin (Belgium).

We present results of one year observations in highly heterotrophic and oxygen-depleted rivers of the polluted Scheldt basin. Monthly measurements revealed a high variability for dissolved inorganic carbon and nitrogen, with the following strong parallelism: highest alkalinity and NH4+ were associated with lowest NO3- and oxygen and vice-versa. In river water incubations, nitrification lowered the alkalinity whereas denitrification raised it; in an anoxic, NO3(-)-free incubation an increase of alkalinity was observed, partially due to ammonification. A stoichiometric analysis, taking into account the amount of protons produced or consumed by each process involving nitrogen, revealed that monthly variations of NO3- and NH4+ with ammonification, nitrification and denitrification could explain the 28 and 62% alkalinity variations at all stations, except one. The remaining part of the alkalinity variations was attributed to other anaerobic processes (Mn-, Fe- and SO4-reductions). This trend seems to be the result of the whole catchment metabolism (riverine waters and sediments, sewage networks and agricultural soils). The observed HCO3- concentrations in the Scheldt basin were 2-10 times higher than the representative concentrations reported in pristine basins and used in chemical weathering models. This suggests the existence of an anthropogenic source, originating from organic matter decomposition. We conclude that in highly polluted basins, nitrogen transformations strongly influence the acid-base properties of water.

Anaerobiosis↗

On-line fluorescence profile of aerobic sludge digestion

An online fluorometer designed for following intracellular NAD(P)H was used to monitor aerobic sludge digestion experiments. The fluorescence showed an initial rise to a high plateau, a sharp decline after staying at the plateau for 20-60 h, and a trailing very slow decrease. The characteristic fluorescence profile was shown to result mainly from the solids-associated fluorescence, after ruling out other factors such as pH, temperature, and supernatant fluorescence. The fluorescence profile was, however, not a mere result of the decreasing solids concentration. The varying sludge viability and population composition (e.g., the decay of heterotrophs and the increasing fraction of nitrifiers) played important roles. The fluorescence profile correlated well with the profile of the viable heterotrophic cell number concentration evaluated with TSB-agar plates. The initial increase of the number concentration was attributed to the growth of multiple small bacteria from the lysate of each large microorganism, which was demonstrated in the experiments with baker's yeast as the starting culture for digestion. The fluorescence profiles observed in the yeast experiments were similar to those in the sludge experiments. Responding to glucose additions and the switch from aerobic to anaerobic conditions, the yeast systems showed typical step increases of fluorescence as expected from the change of NAD(P)H level associated with heterotrophic metabolism. However, no such fluorescence responses were detectable in the sludge digestion systems. NAD(P)H were thus uncertain to be responsible for the online fluorescence observed. Nonetheless, the initial fluorescence plateau corresponded to the period of rapid digestion and, for the plant studied, the EPA regulation criteria of VSS reduction >38% and/or SOUR <1.5 mg of O(2) (g of TS)(-)(1) h(-)(1) were satisfied at the end of the plateau. The online fluorescence provides an effective means of monitoring the aerobic sludge digestion process.

Journal Article↗

Lake Hoare, Antarctica: sedimentation through a thick perennial ice cover.

Lake Hoare in the Dry Valleys of Antarctica is covered with a perennial ice cover more than 3 m thick, yet there is a complex record of sedimentation and of growth of microbial mats on the lake bottom. Rough topography on the ice covering the lake surface traps sand that is transported by the wind. In late summer, vertical conduits form by melting and fracturing, making the ice permeable to both liquid water and gases. Cross-sections of the ice cover show that sand is able to penetrate into and apparently through it by descending through these conduits. This is the primary sedimentation mechanism in the lake. Sediment traps retrieved from the lake bottom indicate that rates of deposition can vary by large amounts over lateral scales as small as 1 m. This conclusion is supported by cores taken in a 3 x 3 grid with a spacing of 1.5 m. Despite the close spacing of the cores, the poor stratigraphic correlation that is observed indicates substantial lateral variability in sedimentation rate. Apparently, sand descends into the lake from discrete, highly localized sources in the ice that may in some cases deposit a large amount of sand into the lake in a very short time. In some locations on the lake bottom, distinctive sand mounds have been formed by this process. They are primary sedimentary structures and appear unique to the perennially ice-covered lacustrine environment. In some locations they are tens of centimetres high and gently rounded with stable slopes; in others they reach approximately 1 m in height and have a conical shape with slopes at angle of repose. A simple formation model suggests that these differences can be explained by local variations in water depth and sedimentation rate. Rapid colonization of fresh sand surfaces by microbial mats composed of cyanobacteria, eukaryotic algae, and heterotrophic bacteria produces a complex intercalation of organic and sandy layers that are a distinctive form of modern stromatolites.

Antarctic Regions↗

Community dynamics of a mixed-bacterial culture growing on petroleum hydrocarbons in batch culture.

The effects of various hydrocarbon substrates, and a chemical surfactant capable of enhancing crude-oil biodegradation, on the community structure of a mixed-bacterial inoculum were examined in batch culture. Of 1000 TSA-culturable isolates, 68.6% were identified at the genus level or better by phospholipid fatty acid analysis over 7-day time course experiments. Cultures were exposed to 20 g/L Bow River crude oil with and without 0.625 g/L Igepal CO-630 (a nonylphenol ethoxylate surfactant), 5 g/L saturates, 5 g/L aromatics, or 125 g/L refinery sludge. A group of six genera dominated the cultures: Acinetobacter, Alcaligenes, Ochrobactrum, Pseudomonas/Flavimonas, Stenotrophomonas, and Yersinia. Species from four of the genera were shown to be capable of hydrocarbon degradation, and counts of hydrocarbon degrading and total heterotrophic bacteria over time were nearly identical. Pseudomonas/Flavimonas and Stenotrophomonas normally dominated during the early portions of cultures, although the lag phase of Stenotrophomonas appears to have been increased by surfactant addition. Acinetobacter calcoaceticus was the most frequently isolated microorganism during exposure to the saturate fraction of crude oil. Regardless of substrate, the culture medium supported a greater variety of organisms during the latter portions of cultures. Understanding the community structure and dynamics of mixed bacterial cultures involved in treatment of heterogeneous waste substrates may assist in process development and optimization studies.

Biodegradation, Environmental↗

Mytilus galloprovincialis filter feeding on the bacterial community in a Mediterranean coastal area (Northern Ionian Sea, Italy).

This study was carried out seasonally, throughout a year, to evaluate the filtering activity on bacteria of Mytilus galloprovincialis. Six microbiological parameters were researched in the water and mussels samples collected along the coastal area of the Northern Ionian Sea in three stations, S. Vito, Lido Gandoli and Lido Silvana. We detected the densities of culturable heterotrophic bacteria by spread plate on Marine Agar, total culturable bacteria at 37 degrees C on Plate Count Agar and vibrios abundance on thiosulphate-citrate-bile-sucrose-salt (TCBS) agar. Total and fecal coliforms as well as fecal streptococci were determined by the Most Probable Number. Bacterial concentrations at 20 and 37 degrees C as well as vibrios concentrations were higher in the mussel samples compared to the corresponding seawater throughout the year. The results obtained could contribute to improve the information relatively either to the natural processes existing between bacteria and mussels or to the risk of human infections related to the consumption of mussels.

Animals↗

Comparison of bacterial regrowth in distribution systems using free chlorine and chloramine: a statistical study of causative factors.

Bacterial regrowth was investigated over a 15-month period in distribution systems (DSs) of Durham and Raleigh in North Carolina. These two water utilities were chosen because they are adjacent to one another, have similar service area characteristics, and treat surface waters of similar characteristics with conventional processes (coagulation-sedimentation and dual-media filtration). The finished waters have similar chemical quality and regrowth potential as measured by assimilable organic carbon (AOC). The major difference in treatment is the choice of final disinfectants (chlorine in Durham and chloramine in Raleigh). Ten sampling sites (monthly sampling) were chosen in each system to give wide geographic coverage and correspondingly, a wide range of water residence times. Significant losses were observed in both chlorine and chloramine residual in the DSs that produced bacterial regrowth as measured by heterotrophic plate count (HPC). The frequency distributions for log HPC (133 observations from Durham and 135 observations from Raleigh) were statistically the same in the chlorinated and chloraminated DSs. A correlation analysis indicated that disinfectant residual is the most important factor determining HPC level. However, the resulting R2 value for a non-linear regression model that also included AOC, temperature, and pH as independent variables was less than 0.7. Bacterial regrowth as measured by HPC, is dependent upon a complex interaction of chemical, physical, and operational parameters that may not be captured by such a simple statistical relationship.

Bacteria↗

Toxic effects on bacterial metabolism of the redox dye 5-cyano-2,3-ditolyl tetrazolium chloride.

The monotetrazolium redox dye 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) has been used as a vital stain of actively respiring bacteria for several years. In this study, inhibitory effects on bacterial metabolism of this redox dye have been examined in a brackish water environment (Kiel Fjord, Germany) and a freshwater environment (Elbe River, Germany). As the results from time series experiments (1 to 10 h) show, bacterial growth and respiration of the investigated natural communities were clearly reduced by CTC supply. Compared with untreated controls (100%), CTC-treated samples showed distinctly lower heterotrophic bacterial plate counts (0 to 24 and 11.8 to 23.7%, respectively), bacterial production (0.9 to 14.1 and 1.1 to 9.6%, respectively), bacterial respiration (4.1 to 9.4 and 6.8 to 43.8% for several concentrations of (sup14)C-labeled glucose), and [(sup14)C]glucose incorporation (0.2 to 4.2%). Additionally, toxicity of CTC was demonstrated by luminescence in a Microtox bioassay. CTC concentrations of 0.1 and 5.0 (mu)M required only 15 min for decreases of approximately 50 and 100%, respectively. The suppression of CTC on several bacterial metabolic processes suggests that determination by the CTC technique underestimates the actual number of active cells distinctly. This conclusion is confirmed by the comparison of generation times calculated on the basis of thymidine uptake data and active bacterial counts determined by the CTC assay and microautoradiography. While unrealistic short generation times (0.5 to 5 h) resulted from the CTC assay, the generation times calculated according to microautoradiography ranged within values (7 to 21 h) reported elsewhere for comparable aquatic environments. The inhibitory effect of CTC demonstrated in our experiments is an aspect with regard to the application of this tetrazolium dye for the estimation of active bacteria in natural aquatic environments which hitherto has not been considered.

Journal Article↗

Attached and unattached bacterial communities in a 120-meter corehole in an acidic, crystalline rock aquifer.

The bacteria colonizing geologic core sections (attached) were contrasted with those found suspended in the groundwater (unattached) by examining the microbiology of 16 depth-paired core and groundwater samples using a suite of culture-independent and culture-dependent analyses. One hundred twenty-two meters was continuously cored from a buried chalcopyrite ore hosted in a biotite-quartz-monzonite porphyry at the Mineral Park Mine near Kingman, Ariz. Every fourth 1.5-m core was acquired using microbiologically defensible methods, and these core sections were aseptically processed for characterization of the attached bacteria. Groundwater samples containing unattached bacteria were collected from the uncased corehole at depth intervals corresponding to the individual cores using an inflatable straddle packer sampler. The groundwater was acidic (pH 2.8 to 5.0), with low levels of dissolved oxygen and high concentrations of sulfate and metals, including ferrous iron. Total numbers of attached cells were less than 10(5) cells g of core material(-1) while unattached cells numbered about 10(5) cells ml of groundwater(-1). Attached and unattached acidophilic heterotrophs were observed throughout the depth profile. In contrast, acidophilic chemolithotrophs were not found attached to the rock but were commonly observed in the groundwater. Attached communities were composed of low numbers (<40 CFU g(-1)) of neutrophilic heterotrophs that exhibited a high degree of morphologic diversity, while unattached communities contained higher numbers (ca. 10(3) CFU ml(-1)) of neutrophilic heterotrophs of limited diversity. Sulfate-reducing bacteria were restricted to the deepest samples of both core and groundwater. 16S ribosomal DNA sequence analysis of attached, acidophilic isolates indicated that organisms closely related to heterotrophic, acidophilic mesophiles such as Acidiphilium organovorum and, surprisingly, to the moderately thermophilic Alicyclobacillus acidocaldarius were present. The results indicate that viable (but possibly inactive) microorganisms were present in the buried ore and that there was substantial distinction in biomass and physiological capabilities between attached and unattached populations.

Colony Count, Microbial↗

Microbial populations identified by fluorescence in situ hybridization in a constructed wetland treating acid coal mine drainage.

Microorganisms are an integral part of the biogeochemical processes in wetlands, yet microbial communities in sediments within constructed wetlands receiving acid mine drainage (AMD) are only poorly understood. The purpose of this study was to characterize the microbial diversity and abundance in a wetland receiving AMD using fluorescence in situ hybridization (FISH) analysis. Seasonal samples of oxic surface sediments, comprised of Fe(III) precipitates, were collected from two treatment cells of the constructed wetland system. The pH of the bulk samples ranged between pH 2.1 and 3.9. Viable counts of acidophilic Fe and S oxidizers and heterotrophs were determined with a most probable number (MPN) method. The MPN counts were only a fraction of the corresponding FISH counts. The sediment samples contained microorganisms in the Bacteria (including the subgroups of acidophilic Fe- and S-oxidizing bacteria and Acidiphilium spp.) and Eukarya domains. Archaea were present in the sediment surface samples at < 0.01% of the total microbial community. The most numerous bacterial species in this wetland system was Acidithiobacillus ferrooxidans, comprising up to 37% of the bacterial population. Acidithiobacillus thiooxidans was also abundant. Heterotrophs in the Acidiphilium genus totaled 20% of the bacterial population. Leptospirillum ferrooxidans was below the level of detection in the bacterial community. The results from the FISH technique from this field study are consistent with results from other experiments involving enumeration by most probable number, dot-blot hybridization, and denaturing gradient gel electrophoresis analyses and with the geochemistry of the site.

Acidithiobacillus↗

Bacterial microflora of nitrogen industry wastewaters.

The quantitative and qualitative composition of heterotrophic bacteria found in two types of wastewaters from the nitrogen industry was determined. The number of bacteria in the wastewaters was 10(4) to 10(6) cells/ml. Gram-negative bacteria accounted for 57% of the bacteria in the final retention reservoir whereas their number in the wastewaters discharged into surface waters was 90%. The dominating species among the Gram-negative bacteria was Pseudomonas, irrespective of the composition of the wastes and means by which they were discharged into the Wisła. The studied microflora utilized in different metabolic processes nitrogen compounds present in the wastes.

Bacteria↗

The removal of uranium from mining waste water using algal/microbial biomass.

We describe a three step process for the removal of uranium (U) from dilute waste waters. Step one involves the sequestration of U on, in, and around aquatic plants such as algae. Cell wall ligands efficiently remove U(VI) from waste water. Growing algae continuously renew the cellular surface area. Step 2 is the removal of U-algal particulates from the water column to the sediments. Step 3 involves reducing U(VI) to U(IV) and transforming the ions into stable precipitates in the sediments. The algal cells provide organic carbon and other nutrients to heterotrophic microbial consortia to maintain the low E(H), within which the U is transformed. Among the microorganisms, algae are of predominant interest for the ecological engineer because of their ability to sequester U and because some algae can live under many extreme environments, often in abundance. Algae grow in a wide spectrum of water qualities, from alkaline environments (Chara, Nitella) to acidic mine drainage waste waters (Mougeotia, Ulothrix). If they could be induced to grow in waste waters, they would provide a simple, long-term means to remove U and other radionuclides from U mining effluents. This paper reviews the literature on algal and microbial adsorption, reduction, and transformation of U in waste streams, wetlands, lakes and oceans.

Adsorption↗

The Delta8-desaturase of Euglena gracilis: an alternate pathway for synthesis of 20-carbon polyunsaturated fatty acids.

Desaturation of fatty acids is an important metabolic process. In mammals, 20-carbon and longer polyunsaturated fatty acids are not only incorporated into cellular membranes in a tissue-specific manner, but also serve as the precursors to synthesis of eicosanoid metabolic regulators. The processes of desaturation and elongation in human liver are well characterized, but an alternate Delta8 desaturation pathway that may be important in certain tissues or in cancer cells is less well examined. The Delta8-desaturase enzyme introduces a double bond at the 8-position in 20-carbon fatty acids that have an existing Delta11 unsaturation. We have isolated the first fatty acid Delta8-desaturase, from the protist Euglena gracilis, in order to explore this alternate pathway. A full-length cDNA was obtained after reverse transcription of mRNA purified from heterotrophically grown Euglena, followed by PCR amplification with primers degenerate to conserved histidine-rich regions of microsomal desaturases. The protein predicted from the cDNA sequence is highly homologous to Delta5 and Delta6 desaturases of Caenhorabditis elegans. When the cDNA was expressed in Saccharomyces cerevisiae, the yeast cultures readily desaturated appropriate 20-carbon fatty acids by inserting an additional double bond at the Delta8-position. The enzyme demonstrated a preference for substrates of metabolic significance, 20:3 Delta11,14,17 and 20:2 Delta11,14. Cloning of a Delta8 fatty acid desaturase offers the opportunity to examine an alternate pathway of long chain fatty acid biosynthesis.

Amino Acid Sequence↗

Light-dependent transformation of aniline to indole esters by the purple bacterium Rhodobacter sphaeroides OU5.

In an attempt to understand the aromatic hydrocarbon metabolism by purple bacteria that do not grow at their expense, we earlier reported 2-aminobenzoate transformation by a purple non-sulfur bacterium, Rhodobacter sphaeroides OU5 (Sunayana et al., 2005, J Ind Microbiol Biotech 32:41-45), which is extended in the present study with aniline, a major environmental pollutant. Aniline did not support photo (light anaerobic) or chemo (dark aerobic) heterotrophic growth of Rhodobacter sphaeroides OU5 either as a sole source of carbon or nitrogen. However, light-dependent aniline transformation was observed in the culture supernatants and the products were identified as indole derivatives. The transformation was dependent on a tricarboxylate intermediate, fumarate. Five intermediates of the aniline biotransformation pathway were isolated and identified as indole esters having a mass of 443, 441, 279, 189, and 167 with unstoichiometric total indole yields of 0.16 mM: from 5 mM: of aniline consumed. The pathway proposed based on these intermediates suggest a novel xenobiotic detoxification process in bacteria.

Aniline Compounds↗