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PubMed2004

Influence of long-term diesel fuel pollution on nitrite-oxidising activity and population size of nitrobacter spp in soil.

Previous investigations have shown that ammonia oxidation is not inhibited by diesel fuel in a soil with a long history of contamination contrary to a non-contaminated soil. As a consequence, ammonia oxidation does not constitute a Limited step in nitrification process (Appl. Environ. Microbiol. 65 (1999) 4008). Moreover, this type of soil also has had the opportunity to develop an abundant microbial population able to metabolise the diesel hydrocarbons. Whether the properties of soil with a long history of diesel fuel contamination may affect the activity of nitrite-oxidising bacteria was investigated. It was observed that re-exposure of soil to diesel fuel apparently stimulated the proliferation of nitrite-oxidising bacteria, as determined by most probable number (MPN) culture technique and MPN-polymerase chain reaction technique. The potential of nitrite-oxidising activity in soil treated with diesel fuel was about 4 times higher than in the control without addition. In the presence of diesel fuel and ammonium, the potential nitrite-oxidising activity was 40% higher than in presence of ammonium only. However, in the presence of hydrocarbon only, low proliferation of Nitrobacter was observed, probably because the heterotrophic bacteria were strongly limited by lack of nitrogen and did not produce sufficient organic metabolites that could be used by the Nitrobacter cells.

Ecosystem↗
PubMed1984

Control of autotrophic carbon assimilation in Alcaligenes eutrophus by inactivation and reactivation of phosphoribulokinase.

Phosphoribulokinase in Alcaligenes eutrophus was partially inactivated when an autotrophic culture was shifted to heterotrophic growth with pyruvate as the sole source of carbon and energy. A similar response was observed on addition of various organic substrates to autotrophic cultures during the transition to mixotrophic growth. The extent of inactivation depended on the added substrate. Pyruvate or lactate caused the strongest inactivation among the tested substrates. Up to 75% of the phosphoribulokinase activity found in the autotrophic cells was lost within 30 min after supplementation of the cultures with either of these two substrates. This loss of enzyme activity was not the result of degradation of enzyme protein. Inactivation of phosphoribulokinase was accompanied by a decrease in the CO2 fixation rate of the cells. Reactivation of the enzyme occurred after exhaustion of pyruvate from the medium. Neither inactivation nor reactivation required de novo protein synthesis; however, continued energy conversion was necessary for the inactivation to occur. We suggest that the pyruvate metabolism of A. eutrophus is involved in these regulatory processes which act on phosphoribulokinase. They appear to contribute to the control of autotrophic CO2 assimilation in this organism.

Alcaligenes↗
PubMed1995

Long-term effects of metals in sewage sludge on soils, microorganisms and plants.

This paper reviews the evidence for impacts of metals on the growth of selected plants and on the effects of metals on soil microbial activity and soil fertility in the long-term. Less is known about adverse long-term effects of metals on soil microorganisms than on crop yields and metal uptake. This is not surprising, since the effects of metals added to soils in sewage sludge are difficult to assess, and few long-term experiments exist. Controlled field experiments with sewage sludges exist in the UK, Sweden, Germany and the USA and the data presented here are from these long-term field experiments only. Microbial activity and populations of cyanobacteria, Rhizobium leguminosarum bv. trifolii, mycorrhizae and the total microbial biomass have been adversely affected by metal concentrations which, in some cases, are below the European Community's maximum allowable concentration limits for metals in sludge-treated soils. For example, N2-fixation by free living heterotrophic bacteria was found to be inhibited at soil metal concentrations of (mg kg-1): 127 Zn, 37 Cu, 21 Ni, 3.4 Cd, 52 Cr and 71 Pb. N2-fixation by free-living cyanobacteria was reduced by 50% at metal concentrations of (mg kg-1): 114 Zn, 33 Cu, 17 Ni, 2.9 Cd, 80 Cr and 40 Pb. Rhizobium leguminosarum bv. trifolii numbers decreased by several orders of magnitude at soil metal concentrations of (mg kg-1): 130-200 Zn, 27-48 Cu, 11-15 Ni, and 0.8-1.0 Cd. Soil texture and pH were found to influence the concentrations at which toxicity occurred to both microorganisms and plants. Higher pH, and increased contents of clay and organic carbon reduced metal toxicity considerably. The evidence suggests that adverse effects on soil microbial parameters were generally found at surprizingly modest concentrations of metals in soils. It is concluded that prevention of adverse effects on soil microbial processes and ultimately soil fertility, should be a factor which influences soil protection legislation.

Bacteria↗
PubMed2001

Characterisation of extracellular polysaccharides produced by Crypthecodinium cohnii.

The valuable polyunsaturated fatty acid, docosahexaenoic acid, can be produced by cultivation of the heterotrophic microalga, Crypthecodinium cohnii. During batch growth of C. cohnii on glucose, sea salt and yeast extract for 5 days, so far unreported extracellular polysaccharides were produced. These caused an increased viscosity and a strong drop in the maximum oxygen transfer. The viscosity increased most markedly as cells entered the stationary phase. The polysaccharides varied in size (from 6 kDa to >1,660 kDa) and monomer distribution. A high molecular mass fraction (from 100 kDa to >1,660 kDa) and a medium molecular mass fraction (6-48 kDa) were prepared. The high molecular mass fraction contained (on a molar basis) 71.7% glucose, 13.1% galactose and 3.8% mannose, whereas the medium molecular mass fraction contained 37.7% glucose, 19.8% galactose and 28.1% mannose. Other monomers present in both fractions were fucose, uronic acid and xylose. Monomers were coupled mainly via alpha-(1-3) links. Increased viscosity due to polysaccharide production complicates the development of commercial, high cell-density processes for the production of docosahexaenoic acid.

Animals↗
PubMed2002

Natural attenuation of chlorinated solvents at Area 6, Dover Air Force Base: characterization of microbial community structure.

A polyphasic approach based on cultivation and direct recovery of 16S rRNA gene sequences was utilized for microbial characterization of an aquifer contaminated with chlorinated ethenes. This work was conducted in order to support the evaluation of natural attenuation of chlorinated ethenes in groundwater at Area 6 at Dover Air Force Base (Dover, DE). Results from these studies demonstrated the aquifer contained relatively low biomass (e.g. direct microscopic counts of < 10(7) bacteria/g of sediment) comprised of a physiologically diverse group of microorganisms including iron reducers, acetogens, sulfate reducers, denitrifiers, aerobic and anaerobic heterotrophs. Laboratory microcosms prepared with authentic sediment and groundwater provided direct microbiological evidence that the mineralization of vinyl chloride and cis-dichloroethene as well as each step in the complete reductive dechlorination of tetracloroethene to ethene can occur in the Area 6 aquifer. Enrichment cultures capable of the oxidative degradation of cis-1,2-dichloroethene (cis-DCE) and vinyl chloride (VC) were obtained from groundwater across the aquifer demonstrating the possible importance of direct, non-cometabolic oxidation of cis-DCE and VC in natural attenuation. Culture-independent analyses based upon recovery of 16S rRNA gene sequences revealed the presence of anaerobic organisms distributed primarily between two major bacterial divisions: the delta subdivision of the Proteobacteria and low-G + C gram positive. Recovery of sequences affiliated with phylogenetic groups containing known anaerobic-halorespiring organisms such as Desulfitobacterium, Dehalobacter, and certain groups of iron reducers provided qualitative support for a role of reductive dechlorination processes in the aquifer. This molecular data is suggestive of a functional linkage between the microbiology of the site and the apparent natural attenuation process. The presence and distribution of microorganisms were found to be consistent with a microbially driven attenuation of chlorinated ethenes within the aquifer and in accord with a conceptual model of aquifer geochemistry which suggest that both reductive and oxidative mechanisms are involved in heterogeneous, spatially distributed processes across the aquifer.

Biodegradation, Environmental↗
PubMed2006

All wet or dried up? Real differences between aquatic and terrestrial food webs.

Ecologists have greatly advanced our understanding of the processes that regulate trophic structure and dynamics in ecosystems. However, the causes of systematic variation among ecosystems remain controversial and poorly elucidated. Contrasts between aquatic and terrestrial ecosystems in particular have inspired much speculation, but only recent empirical quantification. Here, we review evidence for systematic differences in energy flow and biomass partitioning between producers and herbivores, detritus and decomposers, and higher trophic levels. The magnitudes of different trophic pathways vary considerably, with less herbivory, more decomposers and more detrital accumulation on land. Aquatic-terrestrial differences are consistent across the global range of primary productivity, indicating that structural contrasts between the two systems are preserved despite large variation in energy input. We argue that variable selective forces drive differences in plant allocation patterns in aquatic and terrestrial environments that propagate upward to shape food webs. The small size and lack of structural tissues in phytoplankton mean that aquatic primary producers achieve faster growth rates and are more nutritious to heterotrophs than their terrestrial counterparts. Plankton food webs are also strongly size-structured, while size and trophic position are less strongly correlated in most terrestrial (and many benthic) habitats. The available data indicate that contrasts between aquatic and terrestrial food webs are driven primarily by the growth rate, size and nutritional quality of autotrophs. Differences in food-web architecture (food chain length, the prevalence of omnivory, specialization or anti-predator defences) may arise as a consequence of systematic variation in the character of the producer community.

Animals↗
PubMedDate not supplied

[Bacterial communities of brown and red algae from Peter the Great Bay, the Sea of Japan].

The structure of microbial communities of brown algae, red algae, and of the red alga Gracilaria verrucosa, healthy and affected with rotten thallus, were comparatively investigated; 61 strains of heterotrophic bacteria were isolated and characterized. Most of them were identified to the genus level, some Vibrio spp., to the species level according to their phenotypic properties and the fatty acid composition of cellular lipids. The composition of the microflora of two species of brown algae was different. In Chordaria flagelliformis, Pseudomonas spp. prevailed, and in Desmarestia viridis, Bacillus spp. The composition of the microflora of two red algae, G. verrucosa and Camphylaephora hyphaeoides, differed mainly in the ratio of prevailing groups of bacteria. The most abundant were bacteria of the CFB cluster and pseudoalteromonads. In addition, the following bacteria were found on the surface of the algae: Sulfitobacter spp., Halomonas spp., Acinetobacter sp., Planococcus sp., Arthrobacter sp., and Agromyces sp. From tissues of the affected G. verrucosa, only vibrios were isolated, both agarolytic and nonagarolytic. The existence of specific bacterial communities characteristic of different species of algae is suggested and the relation of Vibrio sp. to the pathological process in the tissues of G. verrucosa is supposed.

Agar↗
PubMed2005

A model for the interaction between plant GAPN and 14-3-3zeta using protein-protein docking calculations, electrostatic potentials and kinetics.

Phosphorylated non-phosphorylating glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.9; GAPN) found in heterotrophic cells of wheat is activated by MgCl(2). The divalent cation disrupts the interaction between GAPN and a 14-3-3 regulatory protein. This effect is quite remarkable, since it has previously been shown that 14-3-3 binding to a target protein requires divalent cations as Mg(2+) or Ca(2+). Binding of the divalent cation to 14-3-3 causes an increase in surface hydrophobicity. Crystal structure of a 14-3-3-target protein complex has been only determined for serotinin N-acetyltransferase. We utilized a model of a subunit of plant GAPN and the crystallographic structure of human 14-3-3zeta to shape the complex between theses two proteins. Initial dockings were performed with the BiGGER program, which allows an exhaustive search of translational and rotational space. A filtering procedure was then applied to reduce the number of complexes to a manageable number. We predict the structural characteristics of GAPN-14-3-3zeta binding process, proposing that the main attractive force in this complex derives from electrostatic interactions. The predicted model was corroborated by analysis of kinetic behavior of GAPN and its relationship with pH and ionic strength conditions. This study provides a variant on the interaction of 14-3-3 with target proteins, thus affording a wider scenario to establish possible structural models for this remarkable family of regulatory proteins.

14-3-3 Proteins↗
PubMed2006

Quantification of ammonia-oxidizing bacteria populations in full-scale sewage activated sludge systems and assessment of system variables affecting their performance.

This study carried out quantification of ammonia-oxidizing bacteria (AOB) populations in 12 full-scale sewage activated sludge systems that were different in ammonia removals and treatment processes during three different seasons. Experiment was divided into 3 parts: 1) analysis of AOB communities by PCR-DGGE-cloning-sequencing of 16S rRNA genes; 2) development of four real-time PCR primer sets for quantification of the particular AOB of interest; and 3) quantification of AOB populations by using the newly developed real-time PCR primer sets. The results suggested that all the primer sets gave good reproducibility and specificity for PCR amplification with the detection limits of 10(2) copies/PCR reaction. Although the 12 systems were different in several aspects, one of the identified sequence types of Nitrosomonas oligotropha cluster was the dominant AOB in every system and every season studied. However, the other sequence type of this cluster was not significantly involved in ammonia removals in the systems. The occurrence of N. communis cluster in the systems seemed to depend on the remaining oxygen concentrations in the sludge floc and thus the activity of aerobic heterotrophs in the aeration tanks. N. europaea-Nitrosococcus. mobilis solely existed in one A20 system of which the influent contained twice the chloride concentrations than those of other systems.

Ammonia↗
PubMed2005

Aerobic nitrification-denitrification by heterotrophic Bacillus strains.

Twenty-four Bacillus strains predominantly outgrown in a night soil treatment system were isolated and characterized. Under various culture conditions, cell interactions took place among them and cell population changed. Maximum removal of NH4+-N and cell production by the isolates occurred under the conditions of 30% DO and C/N ratio of 8. Five dominant isolates were identified to be species of Bacillus cereus, Bacillus subtilis and Bacillus licheniformis with similarities of 78-94%. Additions of 0.8% peptone and 0.3% yeast extract to a basal medium influenced the growth of isolates and the removal of NH4+-N in flask culture. Metal ions such as Ca2+, Fe2+ and Mg2+ had a similar effect. The specific growth rates of the five isolates were found to be in a range of 0.43-0.55 h(-1). During the flask experiment of nitrogen removal under aerobic growth conditions, active nitrification by the isolates occurred largely in 1h with a decrease of COD and alkalinity reduced to only 74.6% of theoretical value. From the nitrogen balance, the percentage of nitrogen lost in the flask culture was estimated to be 33.0%, which was presumed to convert to N2 gas. This conversion of ammonia to N2 without formation of nitrous oxide under aerobic growth conditions was confirmed by GC analysis. From all the results, it has been found that the Bacillus strains were able to occur simultaneously aerobic nitrification/denitrification and the B3 process using the Bacillus strains seemed to possess some economic advantages.

Aerobiosis↗
PubMed1997

Algae or protozoa: phylogenetic position of euglenophytes and dinoflagellates as inferred from mitochondrial sequences.

The chloroplasts of euglenophytes and dinoflagellates have been suggested to be the vestiges of endosymbiotic algae acquired during the process of evolution. However, the evolutionary positions of these organisms are still inconclusive, and they have been tentatively classified as both algae and protozoa. A representative gene of the mitochondrial genome, cytochrome oxidase subunit I (coxI), was chosen and sequenced to clarify the phylogenetic positions of four dinoflagellates, two euglenophytes and one apicomplexan protist. This is the first report of mitochondrial DNA sequences for dinoflagellates and euglenophytes. Our COXI tree shows clearly that dinoflagellates are closely linked to apicomplexan parasites but not with algae. Euglenophytes and algae appear to be only remotely related, with euglenophytes sharing a possible evolutionary link with kinetoplastids. The COXI tree is in general agreement with the tree based on the nuclear encoded small subunit of ribosomal RNA (SSU rRNA) genes, but conflicts with that based on plastid genes. These results support the interpretation that chloroplasts present in euglenophytes and dinoflagellates were captured from algae through endosymbioses, while their mitochondria were inherited from the host cell. We suggest that dinoflagellates and euglenophytes were originally heterotrophic protists and that their chloroplasts are remnants of endosymbiotic algae.

Animals↗
PubMed1998

Genome evolution within the alpha Proteobacteria: why do some bacteria not possess plasmids and others exhibit more than one different chromosome?

Animal intracellular Proteobacteria of the alpha subclass without plasmids and containing one or more chromosomes are phylogenetically entwined with opportunistic, plant-associated, chemoautotrophic and photosynthetic alpha Proteobacteria possessing one or more chromosomes and plasmids. Local variations in open environments, such as soil, water, manure, gut systems and the external surfaces of plants and animals, may have selected alpha Proteobacteria with extensive metabolic alternatives, broad genetic diversity, and more flexible and larger genomes with ability for horizontal gene flux. On the contrary, the constant and isolated animal cellular milieu selected heterotrophic alpha Proteobacteria with smaller genomes without plasmids and reduced genetic diversity as compared to their plant-associated and phototrophic relatives. The characteristics and genome sizes in the extant species suggest that a second chromosome could have evolved from megaplasmids which acquired housekeeping genes. Consequently, the genomes of the animal cell-associated Proteobacteria evolved through reductions of the larger genomes of chemoautotrophic ancestors and became rich in adenosine and thymidine, as compared to the genomes of their ancestors. Genome organisation and phylogenetic ancestor-descendent relationships between extant bacteria of closely related genera and within the same monophyletic genus and species suggest that some strains have undergone transition from two chromosomes to a single replicon. It is proposed that as long as the essential information is correctly expressed, the presence of one or more chromosomes within the same genus or species is the result of contingency. Genetic drift in clonal bacteria, such as animal cell-associated alpha Proteobacteria, would depend almost exclusively on mutation and internal genetic rearrangement processes. Alternatively, genomic variations in reticulate bacteria, such as many intestinal and plant cell-associated Proteobacteria, will depend not only on these processes, but also on their genetic interactions with other bacterial strains. Common pathogenic domains necessary for the invasion and survival in association with cells have been preserved in the chromosomes of the animal and plant-associated alpha Proteobacteria. These pathogenic domains have been maintained by vertical inherence, extensively ameliorated to match the chromosome G + C content and evolved within chromosomes of alpha Proteobacteria.

Animals↗
PubMed2006

Improving the start-up of an EBPR system using OUR to control the aerobic phase length: a simulation study.

The enhanced biological phosphorus removal (EBPR) process is based on enriching the sludge with polyphosphate accumulating organisms (PAO) which are scarce in conventional non-EBPR wastewater treatment plant sludge. Hence, the start-up of EBPR systems (i.e. enriching the sludge with PAO) can be very slow and complex. A simulation study of a possible improvement of the start-up of an EBPR system in a sequencing batch reactor is presented in this work. The improvement is based on reducing the length of the aerobic phase so that it coincides with the depletion of orthophosphate from the medium. This improvement, though verified by simulation to be very successful, requires a good on-line orthophosphate sensor. To avoid this technical limitation, a link between oxygen uptake rate (OUR) measurements and orthophosphate presence is proposed. This link allows the control of the aerobic phase length with OUR as a measured variable and, consequently, a considerable improvement with respect to the conventional fixed aerobic phase length operation. An improvement of 95% in the ratio of PAO to heterotrophs and an increase of 30% in the final amount of PAO in sludge is achieved with this control strategy. The kinetic mod for simulations was a modification of the Activated Sludge Model 2d.

Aerobiosis↗
PubMed1993

[Do soluble organic nitrogen compounds cause unusual algal blooms in seawater?].

Up to now the nature and importance of the macromolecular forms of organic nitrogen in the marine environment is poorly understood. There is no doubt on the capacity of phytoplankton to utilize low molecule weight dissolved organic nitrogen compounds competitively with bacteria. In marine ecosystems the members of the plankton community show a complex close coupling with biological substances. In spite of trace concentrations the high dynamics in uptake and release processes cause strong fluxes of these compounds. In the case of inorganic nutrient deprivation or reduced photosynthesis under light deficiency algal utilization of organic nitrogen becomes noteworthy. Even under high nitrate supply an algal development occurred which was mainly triggered by amino acid uptake as was demonstrated during field experiments in the German Bight. The consumption of amino acids is controlled by several uptake systems, which are specified for transportation of different groups of amino acids through the cell wall. Since the uptake systems can also differ among species, the amino acid composition of the environment could preferentially enhance the growth of some selected species in comparison with other components of natural phytoplankton assembles. In the scope of increasing water pollution and the resulting shift in nutrient distribution one may expect the development of phytoplankton species, which had not been supported so far. In estuaries and costal zones photosynthesis is effected by light absorbance from particulate material. This phenomenon additionally will sustain algae, which are able to compensate a photosynthesis deficit by heterotrophic uptake. Though interrelationships are not clear up to now, it becomes evident that increasing impact of dissolved organic substances cause strong changes in species composition of marine ecosystems.

Amines↗
PubMed2006

Marine cyanophages and light.

In contrast to the phages of heterotrophic hosts, light can play a key role in all aspects of the life cycle of phages infecting ecologically important marine unicellular cyanobacteria of the genera Synechococcus and Prochlorococcus. Phage adsorption, replication, modulation of the host cell metabolism, and survival in the environment following lysis, all exhibit light-dependent components. The analysis of cyanophage genomes has revealed the acquisition of key photosynthetic genes during the course of evolution, such as those encoding central components of the light harvesting apparatus. These discoveries are beginning to reveal novel features of the interactions between parasite and host that shape the biology of both.

Bacteriophages↗
PubMed2003

Oxygen flux implications of observed nitrogen removal rates in subsurface-flow treatment wetlands.

Nitrification, an oxygen-requiring microbial process, is generally considered the rate-limiting step for N removal in subsurface-flow constructed wetlands treating organic wastewaters. We used a simplified model of sequential N transformations and sinks to infer required rates of oxygen supply at 5 stages along experimental wetland mesocosms supplied with four different organic wastewaters with contrasting ratios of COD: N and forms of N. Mass balances of water-borne organic, ammoniacal and nitrate N, and plant and sediment N uptake showed average net rates of N mineralisation ranging from 0.22-0.53 g m(-2) d(-1), nitrification 0.56-2.15 g m(-2) d(-1), denitrification 0.47-1.99 g m(-2) d(-1) (60-84% of measured N removal) and plant assimilation 0.28-0.47 g m(-2) d(-1). The nitrogenous oxygen demand (NOD) required to support the observed nitrification rates alone was high compared to expected fluxes from surficial and plant-mediated oxygen transfer. In the presence of high levels of degradable organic matter (COD removal rates up to 66 g m(-2) d(-1)), heterotrophs with significantly higher oxygen affinities and energy yields are expected to outcompete nitrifiers for available oxygen. Problems with commonly held assumptions on the nature of coupled nitrification-denitrification in treatment wetlands are discussed.

Biodegradation, Environmental↗
PubMed2007

Complementary limiting factors of astaxanthin synthesis during photoautotrophic induction of Haematococcus pluvialis: C/N ratio and light intensity.

We investigated the effect of carbon/nitrogen (C/N) ratio on astaxanthin synthesis in Haematococcus pluvialis during photoautotrophic induction by continuous input of both CO(2)-air mixture and intense light. When H. pluvialis was induced by constant irradiance induction at 200 micromol photon m(-2) s(-1), there was a positive correlation with astaxanthin content and C/N ratio, which was similar to the case for heterotrophic induction. Lower C/N ratios did not retard Haematococcus encystment, but did increase culture biomass, resulting in a decrease in astaxanthin production because of light limitation. However, induction using variable irradiance showed that reduction of astaxanthin production at low C/N ratios was successfully overcome by simply increasing the light intensity from 200 to 300 micromol photon m(-2) s(-1) to overcome the light limitation. This resulted in a greatly enhanced astaxanthin synthesis in proportion to cell density in cultures with low C/N ratios. Our results indicate that light intensity is more critical than C/N ratio in astaxanthin production by H. pluvialis during photoautotrophic induction.

Autotrophic Processes↗
PubMed2005

A novel membrane bioreactor enhanced by effective microorganisms for the treatment of domestic wastewater.

The activated sludge membrane bioreactor (MBR) has been shown to have some advantages for the processing and reclamation of domestic wastewater. We hypothesized that certain microorganisms, chosen for their abilities to decompose the chemical components of raw sewage, would, when coupled with the MBR, significantly improve the stability and efficiency of this system. We selected environmental bacterial strains which oxidize ammonia and nitrites and produce protease, amylase, and cellulase for the development and testing of a novel biologically enhanced MBR (eMBR). We compared the eMBR with the activated sludge MBR. With the eMBR, the average values of effluent quality were: chemical oxygen demand (COD), 40 mg/l(average efficiency of removal 90.0%); and NH(4) (+)-N, 0.66 mg/l(average efficiency of removal 99.4%). Effluent qualities met the standard and were stable during the entire 90 days of this study. For the activated sludge MBR, the COD removal rate was 91.7%, and the NH(4) (+)-N removal (94.8%) was less than that of the eMBR. Start-up time for the eMBR was only 24-48 h, much shorter than the 7-8 days required to initiate function of the standard MBR. The biomass concentrations of total heterotrophic bacteria and autotrophic bacteria in the eMBR did not fluctuate significantly during the course of the study. Various kinds of microorganisms will establish an ecological balance in the reactor. Compared with the activated sludge MBR, the eMBR not only produced an excellent and stable quality of effluent but also resulted in a shorter time to start-up and significantly improved the efficiency of NH(4) (+)-N removal.

Bacteria↗