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PubMed1995

Quality of hemodialysis water: a 7-year multicenter study.

Since dialysis was introduced 30 years ago, constant progress in technology permitted shortening the length of hemodialysis (HD) sessions. Through growing concerns about the inadequacy of tap water for dialysate production, hospitals soon opted for water treatment systems dedicated to HD. Nonetheless, persistent bacterial contamination and the occurrence of pyrogenic reactions were reported in some HD centers. Several factors contributing to this situation were identified. After the introduction of highly permeable synthetic membranes in the late 1970s, microbiologic problems reappeared. Thus, in 1977, the Centers for Disease Control and Prevention (CDC) issued proposed guidelines for HD water quality, followed in 1981 by an American National Standard for HD water, issued by the Association for the Advancement of Medical Instrumentation (AAMI). This Standard was also followed in Canada up to 1986, at which time a National Standard for Canada was released by the Canadian Standards Association (CSA). This prompted the Laboratoire de santé publique du Québec (LSPQ) to implement in the Province of Québec a voluntary HD water quality monitoring program. All 36 HD centers in the Province agreed to participate. The program was launched in February 1987. Water was sampled monthly for bacteria over a 7-year period (February 1987 to January 1994), and every 3 months for pyrogen and chemicals. Participation was more than 95%. Bacteriologic samples were processed in duplicate on heterotrophic plate count agar by the pour plate technique. Incubation was for 48 +/- 3 hours at 35 +/- 0.5 degrees C, and the colonies were counted on a Quebec colony counter (New Brunswick Scientific Co, New Brunswick, NJ). Pyrogen determinations were made using the limulus amebocyte lysate (LAL) test on 1:20 sample dilution by the gel-clot method. Chemical elements were measured by inductively coupled plasma emission, graphite furnace absorption, conductivity, ultraviolet light absorption, or colorimetry. Only fully treated HD water samples were selected from the 11,000 water samples received. Of the 5,820 samples retained for this study, 3,547 were for bacterial, 1,112 for pyrogen, and 1,161 for chemical analyses. Overall compliance to the CSA Standard was 70% for bacteria, 56% for pyrogen, and 86% for chemistry. The performance of different types of water treatments were compared and discussed; the best overall compliance was obtained by reverse osmosis combined with deionization (RO + DI). The type of water treatment that proved most popular was RO alone, which was used by 22 HD centers (61%).(ABSTRACT TRUNCATED AT 400 WORDS)

Bacteria↗
PubMed2002

An investigation on biological stability of product water generated by lab-scale and pilot-scale distillation systems.

Lab-scale and pilot-scale distillation systems were assessed in this study and the effectiveness of the treatment processes on Assimilable Organic Carbon (AOC) removal was also investigated. Seawater as one of the alternative water sources was used as the feed water and the resulting product water was intended for industry use. Acidification, ion trapping and anti-scaling chemical dosing were adopted as the pre-treatment processes to the feed water before distillation for pilot-plant system. The AOC assay was used to evaluate the efficiencies of various unit processes for AOC removal. Heterotrophic Plate Counts (HPC) was adopted in conjunction with AOC to determine the biological stability of the water samples. It is noted that the distillation system was able to produce a product water with an acceptable AOC concentration of less than 20 micrograms acetate-C L-1. This would suggest that the distillation system was capable of delivering a biologically stable product water. The results from lab-scale system indicated that pretreatment such as acidification, chlorination and antiscalant would increase AOC, although this does not affect the general performance of distillation system.

Carbon↗
PubMedDate not supplied

Myositis ossificans of the upper arm.

Myositis ossificans is a benign condition resulting from severe muscular contusion manifested by heterotrophic bone formation. The process is common in the anterior thigh but the literature dealing with myositis ossificans in the upper arm is limited. Ten cases of the condition in the upper arm were seen in our practice. All 10 were the result of football injuries and exhibited one or more of the triad of local pain, a hard palpable mass in the muscle, and a flexion contracture of the elbow. Seven of the cases (70%) were asymptomatic or signficantly improved in less than 3 months with conservative nonoperative management. Three patients (30%) underwent surgery because the painful mass persisted. In two (66%) of the surgically managed cases, there was clinical and radiographic evidence of recurrence postoperatively in spite of delaying excision until radiographic parameters of maturation were present.

Adolescent↗
PubMed1999

Psychrotrophic bacteria from a coastal station in the Ross sea (Terra Nova Bay, Antarctica).

Seawater samples were collected from a fixed, coastal station in the Terra Nova Bay at different depths during the Xth Oceanographic Cruise in the 1994-95 Antarctic summer. Picoplanktonic abundance, estimated by direct counts in epifluorescence microscopy, ranged from 2.2 x 10(7) to 1.6 x 10(8) cells.l-1. The heterotrophic bacterial densities, evaluated on Marine Agar 2216 (Difco) after incubation at +4 degrees C for 21 days, ranged from 2 x 10(3) to 4.5 x 10(6) CFU.l-1. The qualitative composition of the heterotrophic bacterial community was studied on 64 morphological and biochemical characters of the 125 strains isolated. Heterotrophic, psychrotrophic isolates were tentatively identified at genus level as Pseudomonas, Vibrio, Acinetobacter, and Flavobacterium/Cytophaga. In order to compare the characteristics of the isolates with those previously studied during 1989/90, the synthetical indices of the structure and the metabolic potentiality of the heterotrophic bacterial community were processed. Results showed that the bacterial community was metabolically more active and more homogenous than that previously studied.

Animals↗
PubMed2002

Improving the predictions of ASM2d through modelling in practice.

The paper presents the adjustments carried out on the structure and in some default values of the kinetic coefficients of the ASM2d model in order to get an improved prediction for the experimental results obtained in pilot scale plants studies with different activated sludge treatment processes for carbon, nitrogen and phosphorous removal. In order to predict the high effluent filtered COD experimentally observed in high rate processes for carbon removal, a new model structure has been proposed, incorporating into the carbon model a soluble fraction of the slowly biodegradable substrate. Studies with the step feed and the alternating processes showed simultaneous nitrification-denitrification in aerated reactors which was predicted with increased values in the oxygen saturation coefficients for heterotrophic and autotrophic biomass. Both processes also showed loss of the denitrification capacity under unfavourable conditions, such us rains and low anoxic fraction, which required a very large decrease in the value of the reduction factor for denitrification so as to improve the predictions for effluent nitrate experimental results. Regarding phosphorus removal, the ASM2d model showed a satisfactory predictive capacity. For improved predictions of phosphorus release in anaerobic conditions, high values of the rate constant for storage of X(PHA) and low values of the anaerobic hydrolysis reduction factor were used. For phosphorus uptake in aerobic and anoxic conditions satisfactory predictions were obtained using the default values.

Biodegradation, Environmental↗
PubMedDate not supplied

Specificity and potential applications of the biochemical acidogenic potential method for the anaerobic characterization of wastewater.

The biochemical acidogenic potential (BAP) test is an anaerobic characterization method for wastewater. Fermentable organic fractions are obtained through modeling BAP test results. This method was compared to more common fractionation methods such as settling, coagulation, and respirometry, but no direct relationship was found. Biochemical acidogenic potential testing was thus considered to bring new and complementary information. The settleable matter accounted for approximately 50% of the fermentable matter, with a rate comparable to that of aerobic hydrolysis, suggesting a potential assimilable carbon source that could be liberated in sewers or in anaerobic processes. It was also observed that respirometry could underestimate the amount of fermentable substrates while overestimating that of hydrolyzable matter and of heterotrophic biomass involved in anaerobic processes. The BAP fractions are related to the wastewater capacity to produce volatile fatty acids, which are the main substrates of the micro-organisms responsible for enhanced biological phosphorus removal (EBPR). The potential contribution of the BAP fractionation to assist the design, operation, and modeling of the activated-sludge EBPR processes was discussed.

Bacteria, Anaerobic↗
PubMed2004

Model-based evaluation of COD influence on a partial nitrification-Anammox biofilm (CANON) process.

A model evaluating COD influence on a partial nitrification-Anammox biofilm process is integrated on the basis of heterotrophic growth as described in ASM3, combined with a previously published model for the CANON process. This integrated model can simulate the activities of heterotrophs and autotrophs involved in a biofilm, and interactions between COD oxidation, denitrification, nitrification and Anammox can be evaluated. Simulations indicate that COD in the influent has no important influence on the trends in the partial nitrification-Anammox biofilm process. Besides full COD removal, a total nitrogen removal efficiency of about 90% can be expected for stable biofilm systems. Furthermore, Anammox is a major contributor to the total nitrogen removal in stable biofilm systems and conventional denitrification only takes a share of <20% in the total nitrogen removal.

Ammonia↗
PubMedDate not supplied

The role of flushing dental water lines for the removal of microbial contaminants.

OBJECTIVES: This study was designed to determine the role of flushing dental water lines for the removal of heterotrophic plate count bacteria, Legionella spp., and free-living protozoa. METHODS: Forty dental offices were surveyed in the study. An initial sample and a sample taken after three minutes of flushing were obtained from the air/water syringe at each location. All samples were quantitatively analyzed for heterotrophic bacteria using three bacteriological procedures. The samples were analyzed for the presence of Legionella spp. using cultural, immunological, and molecular procedures and for the occurrence of free-living protozoa using a killed bacteria plate procedure. RESULTS: The flushing process reduced the level of heterotrophic plate count bacteria by 1.1 to 1.5 log10 CFU/ml. Compliance with recommendations for bacterial levels varied depending on the methodology employed in the analysis. The flushing process did not reduce the occurrence of Legionella spp. or free-living protozoa. CONCLUSION: The results support recent U.S. Centers for Disease Control and Prevention recommendations that the process of flushing dental water lines cannot be relied upon as a sole means of reliably improving the quality of water used in dental treatment.

Bacteriological Techniques↗
PubMed2006

A quantitative measure of nitrifying bacterial growth.

Nitrifying bacteria convert ammonia (NH3) to nitrate (NO3-) in a nitrification reaction. Methods to quantitatively separate the growth rate of these important bacterial populations from that of the dominant heterotrophic bacteria are important to our understanding of the nitrification process. The changing concentration of ammonia is often used as an indirect measure of nitrification but ammonification processes generate ammonia and confound this approach while heterotrophs remove nitrate via denitrification. Molecular probe methods can tell us what proportion of the microbial community is nitrifying bacteria but not their growth rate. The technique proposed here was able to quantify the growth rate of the nitrifying bacterial populations amidst complex ecological processes. The method incubates [methyl-3H] thymidine with water samples in the presence and absence of an inhibitor of nitrification-thiourea. The radioactively labeled DNA in the growing bacteria was extracted. The rate of incorporation of the label into the dividing bacterial DNA was used to determine bacterial growth rate. Total bacterial community growth rates in full-scale and pilot-scale fixed-film nitrifying reactors and an activated sludge reactor were 2.1 x 10(8), 4.1 x 10(8) and 0.4 x 10(8)cell ml(-1)d(-1), respectively; the growth rate of autotrophic-nitrifying bacteria was 0.7 x 10(8), 2.6 x 10(8) and 0.01 x 10(8)cell ml(-1)d(-1), respectively. Autotrophic-nitrifying bacteria contributed 30% and 60% of the total bacterial community growth rate in the nitrifying reactors whereas only 2% was observed in the activated sludge reactor that was not designed to nitrify. The rates of ammonia loss from the nitrifying reactors corresponded to the rate of growth of the nitrifying bacteria. This method has the potential to more often identify factors that enhance or limit nitrifying processes in both engineered and natural aquatic environments.

Bacteria↗
PubMed1995

Microbial ecology of simultaneous thermophilic microbial leaching and digestion of sewage sludge.

The microbial population encountered during a simultaneous thermophilic microbial leaching and digestion process at 50 degrees C, based on microbial sulfur oxidation, was investigated. The cell count of the sulfuric acid producer Thiobacillus thermosulfatus increased, followed by a decrease. In the absence of sulfur (control: conventional thermophilic digestion), Thiobacillus thermosulfatus population decreased under the detection limit. Acidophilic and neutrophilic heterotrophic populations increased during the leaching process, and the final acidophilic population count was higher than the neutrophilic population. During the thermophilic digestion (control), the final neutrophilic population count was higher than the acidophilic. Six heterotrophic bacterial strains were isolated and partially characterized. Bacillus was the most predominant genus. The type of bacterial populations in thermophilic microbial leaching and digestion, as well as the thermophilic digestion process (control), were the same, while only the relative concentrations changed. In both processes, the bacterial indicators decreased under the detection limit after 12 h. Mesophilic heterotrophic population was more affected by the thermophilic microbial leaching process than by thermophilic digestion. Sludge mineralization was probably more influenced by the final cell concentration rather than the presence of an individual species or mixed population.

Bacteria↗
PubMed1991

Light-activated heterotrophic growth of the cyanobacterium Synechocystis sp. strain PCC 6803: a blue-light-requiring process.

A glucose-tolerant strain of Synechocystis sp. strain 6803 will not grow on glucose under complete darkness unless given a daily pulse of white light, typically 5 min of 40 mumol m-2 s-1 (light-pulsed conditions). The light pulse is insufficient for photoautotrophy, as glucose is required and growth yield is dependent on glucose concentration. Growth rate is independent of fluence, but growth yield is dependent on fluence, saturating at 40 to 75 mumol m-2 s-1. A Synechocystis strain 6803 psbA mutant strain grows under light-pulsed conditions at rates similar to those for the glucose-tolerant strain, indicating that photosystem II is not required for growth. The relative spectral sensitivity of the growth of light-pulsed cultures (growth only in blue light, 400 to 500 nm, maximum at 450 nm) precludes energetic contribution from cyclic electron transport around photosystem I. Pulses of long-wavelength light (i.e., 550 and 650 nm) did not support the growth of Synechocystis strain 6803 and, when supplied before or after a blue-light pulse, did not inhibit blue-light-stimulated growth of Synechocystis strain 6803. We conclude that the required blue-light pulse does not support growth via photosynthetic electron transport but appears instead to function as an environmental signal regulating heterotrophic metabolism, cell division, or other photomorphogenic processes. We have termed the growth of Synechocystis strain 6803 pulsed with light and kept otherwise in complete darkness light-activated heterotrophic growth. This observation of a blue-light requirement for the growth of Synechocystis strain 6803 represents a novel blue light effect on the growth of a cyanobacterium.

Cyanobacteria↗
PubMed2005

Fate of heterotrophic microbes in pelagic habitats: focus on populations.

Major biogeochemical processes in the water columns of lakes and oceans are related to the activities of heterotrophic microbes, e.g., the mineralization of organic carbon from photosynthesis and allochthonous influx or its transport to the higher trophic levels. During the last 15 years, cultivation-independent molecular techniques have substantially contributed to our understanding of the diversity of the microbial communities in different aquatic systems. In parallel, the complexity of aquatic habitats at a microscale has inspired research on the ecophysiological properties of uncultured microorganisms that thrive in a continuum of dissolved to particulate organic matter. One possibility to link these two aspects is to adopt a"Gleasonian" perspective, i.e., to study aquatic microbial assemblages in situ at the population level rather than looking at microbial community structure, diversity, or function as a whole. This review compiles current knowledge about the role and fate of different populations of heterotrophic picoplankton in marine and inland waters. Specifically, we focus on a growing suite of techniques that link the analysis of bacterial identity with growth, morphology, and various physiological activities at the level of single cells. An overview is given of the potential and limitations of methodological approaches, and factors that might control the population sizes of different microbes in pelagic habitats are discussed.

Bacteria↗
PubMed2001

A new process for integrated treatment of industrial wastewater at municipal wastewater treatment plants.

A new process for integrated treatment of industrial wastewater at a municipal WWTP is presented. The process uses the ability of heterotrophic bacteria of rapid substrate uptake and storage. The excess sludge from the municipal treatment line is fed to a contact tank, which receives the industrial wastewater via a separate pipeline. The contact tank is aerated to such a degree that secures complete substrate uptake but minimises oxygen consumption due to instant substrate degradation. The sludge from the contact tank is mechanically pre-thickened and then fed to an anaerobic digester. Hence, the major portion of the incoming COD load of the industrial wastewater is transferred to the anaerobic digester, where it contributes to an increased biogas production. The back load of the industrial wastewater treatment process to the municipal treatment line is very low.

Austria↗
PubMed2003

Control of metallic corrosion through microbiological route.

Involvement of biofilm or microorganisms in corrosion processes is widely acknowledged. Although majority of the studies on microbiologically induced corrosion (MIC) have concentrated on aerobic/anaerobic bacteria. There are numerous aerobic bacteria, which could hinder the corrosion process. The microbiologically produced exopolymers provide the structural frame work for the biofilm. These polymers combine with dissolved metal ions and form organometallic complexes. Generally heterotrophic bacteria contribute to three major processes: (i) synthesis of polymers (ii) accumulation of reserve materials like poly-beta-hydroxy butrate (iii) production of high molecular weight extracellular polysaccharides. Poly-beta-hydroxy butyrate is a polymer of D(-)beta-hydroxy butrate and has a molecular weight between 60,000 and 2,50,000. Some extracellular polymers also have higher molecular weights. It seems that higher molecular weight polymer acts as biocoating. In the present review, role of biochemistry on corrosion inhibition and possibilities of corrosion inhibition by various microbes are discussed. The role of bacteria on current demand during cathodic protection is also debated. In addition, some of the significant contributions made by CECRI in this promising area are highlighted.

Bacteria↗
PubMed1983

Starvation-survival processes of a marine Vibrio.

Levels of DNA, RNA, protein, ATP, glutathione, and radioactivity associated with [S]methionine-labeled cellular protein were estimated at various times during the starvation-survival process of a marine psychrophilic heterotrophic Vibrio sp., Ant-300. Values for the macromolecules were analyzed in terms of total, viable, and respiring cells. Electron micrographs (thin sections) were made on log-phase and 5.5-week-starved cells. On a per-cell basis, the levels of protein and DNA rapidly decreased until a constant level was attained. A second method in which radioactive sulfur was used for monitoring protein demonstrated that the cellular protein level decreased for approximately 2.5 weeks and then remained constant. An initial decrease in the RNA level with starvation was noted, but with time the RNA (orcinol-positive material) level increased to 2.5 times the minimum level. After 6 weeks of starvation, 45 to 60% of the cells remained capable of respiration, as determined by iodonitrotetrazolium violet-formazan granule production. Potential respiration and endogenous respiration levels fell, with an intervening 1-week peak, until at 2 weeks no endogenous respiration could be measured; respiratory potential remained high. The cell glutathione level fell during starvation, but when the cells were starved in the presence of the appropriate amino acids, glutathione was resynthesized to its original level, beginning after 1 week of starvation. The cells used much of their stored products and became ultramicrocells during the 6-week starvation-survival process. Ant-300 underwent many physiological changes in the first week of starvation that relate to the utilization or production of ATP. After that period, a stable pattern for long-term starvation was demonstrated.

Journal Article↗
PubMed1997

Extraction of lithium from spodumene by bioleaching.

The recovery of lithium from spodumene (6.9% Li2O) by bioleaching was investigated. This process was carried out using heterotrophic micro-organisms previously isolated from the mineral. Penicillium purpurogenum, Aspergillus niger and Rhodotorula rubra were assayed separately. Two different media were used for bioleaching; one of them (M2 medium) was highly limited in Mg2+, Fe2+ and K+. The assays were carried out in 500 ml Erlenmeyer flasks with 1 g of ground mineral at 50-80 mesh and 150 ml of leaching medium. Lithium extracted and accumulated in biomass during 30 d of bioleaching with P. purpurogenum was 6.35 mg % dry weight (d.w.) in M1 medium and 10.8 mg % d.w. in M2 medium, while in the leach liquor, Li concentration was 1.06 ppm (M1 medium) and 1.26 ppm (M2 medium). Results of leaching on day 30 with R. rubra were 5.87 mg % d.w. and 16.7 mg % d.w. of lithium accumulated in biomass in M1 medium and M2 medium, respectively. In leach liquor, lithium was 0.5 ppm (M1 medium) and 1.53 ppm (M2 medium). Aspergillus niger was able to accumulate 1.60 mg % d.w. (M1 medium) and 5.1 mg % d.w. of lithium (M2 medium) in biomass. Lithium in leach liquor was 0.37 ppm (M1 medium) and 0.75 ppm (M2 medium). Chemical analysis of the leach liquor showed gluconic and citric acids. It was possible to detect capsular exopolymers in the yeast. These metabolic products seem to be related to leaching but a more important factor for enhancing this process may be microbial adaptation to a low nutrient environment.

Aspergillus niger↗
PubMed2006

Nitrous oxide emissions from secondary activated sludge in nitrifying conditions of urban wastewater treatment plants: effect of oxygenation level.

In order to better understand the mechanisms of N(2)O emissions from nitrifying activated sludge of urban WWTPs, sludge from the Valenton plant (Paris conurbation) are subjected to lab-scale batch experiments under various conditions of oxygenation. The results show that the highest N(2)O emissions (7.1 microgN-N(2)OgSS(-1) h(-1) in average) occur at a dissolved oxygen (DO) concentration of around 1mgO(2)L(-1). These high emissions at low oxygenation (from 0.1 to 2 mg O(2)L(-1)) are due to two processes: autotrophic nitrifier denitrification and heterotrophic denitrification. Nitrifier denitrification always dominates, representing from 58% to 83% of the N(2)O production. This N(2)O production originating from nitrifying activated sludge becomes 8 times higher when nitrite is added at a DO of 1 mg O(2)L(-1); a decrease is observed both at higher and lower oxygenation. Heterotrophic denitrification represents less than 50% of the N(2)O production, decreasing from 42% to 17% when oxygenation increases from 0.1 to 2 mg O(2) L(-1). We show that ammonium oxidizing bacteria (AOB) can shift to nitrifier denitrification when oxygen is depleted in the environments including in the WWTPs, nitrite then plays the role of oxygen as the final electron acceptor. As opposed to what happens in nitrification, the end products of nitrifier denitrification are gaseous forms of nitrogen, where N(2)O is not negligible compared to N(2). Overall, N(2)O emissions represent 0.1-0.4% of oxidized NH(4)(+), depending on the oxygenation level. N(2)O emissions would range from 0.11 to 0.42 TN-N(2)O day(-1) for a tertiary treatment of the Paris wastewater effluents, consisting exclusively of activated sludge nitrification.

Ammonia↗
PubMed2004

Genome sequence of Silicibacter pomeroyi reveals adaptations to the marine environment.

Since the recognition of prokaryotes as essential components of the oceanic food web, bacterioplankton have been acknowledged as catalysts of most major biogeochemical processes in the sea. Studying heterotrophic bacterioplankton has been challenging, however, as most major clades have never been cultured or have only been grown to low densities in sea water. Here we describe the genome sequence of Silicibacter pomeroyi, a member of the marine Roseobacter clade (Fig. 1), the relatives of which comprise approximately 10-20% of coastal and oceanic mixed-layer bacterioplankton. This first genome sequence from any major heterotrophic clade consists of a chromosome (4,109,442 base pairs) and megaplasmid (491,611 base pairs). Genome analysis indicates that this organism relies upon a lithoheterotrophic strategy that uses inorganic compounds (carbon monoxide and sulphide) to supplement heterotrophy. Silicibacter pomeroyi also has genes advantageous for associations with plankton and suspended particles, including genes for uptake of algal-derived compounds, use of metabolites from reducing microzones, rapid growth and cell-density-dependent regulation. This bacterium has a physiology distinct from that of marine oligotrophs, adding a new strategy to the recognized repertoire for coping with a nutrient-poor ocean.

Adaptation, Physiological↗