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1.
Huan Jing Ke Xue ; 41(2): 831-838, 2020 Feb 08.
Artigo em Chinês | MEDLINE | ID: mdl-32608744

RESUMO

Because of the massive discharge of nitrogenous wastewater, the eutrophication of a water body is becoming increasingly serious, and how to effectively remove nitrogen from this wastewater remains an urgent problem to be solved. In this study, due to disadvantages in the traditional biological nitrogen removal process, such as complex and long procedures, high energy consumption, weak impact resistance, and N2O release, the nitrogen removal theory by heterotrophic nitrification was further analyzed by discussing the physiological-biochemical, heterotrophic nitrification-aerobic denitrification, and N2O production characteristics of a high-efficiency heterotrophic nitrifying bacteria Pseudomonas aeruginosa YL. Results show that the strain YL had an eminent heterotrophic nitrification and aerobic denitrification ability, and NH4+-N, NO2--N, and NO3--N with concentration of 100 mg·L-1 could be completely removed during the 24-hour incubation period. There was almost no intermediate product in the process of heterotrophic nitrification, however when NO3--N was used as nitrogen source, the accumulation of NO2--N reached 25.55 mg·L-1. Meanwhile, the successful expression of denitrification genes napA, nirK, and nosZ further confirmed the aerobic denitrification ability of strain YL. Gaseous nitrogen products accounted for about 30%-40% of removed TN in the heterotrophic nitrification-aerobic denitrification process by strain YL, and N2 was the main denitrification product. When NH4+-N, NO2--N, and NO3--N were used as the sole nitrogen source, N2 production amounted to 3.46, 3.49, and 3.36 mg, respectively. In contrast, only small amounts of N2O were produced in the denitrification process by strain YL, and the total amount was 6.63 µg when NH4+-N was the nitrogen source, which was much lower than in the cases of NO2--N and NO3--N as the sole nitrogen source. In addition, high C/N, low pH, high temperature, high NH4+-N, and high NO2--N conditions could result in more N2O generation. Nevertheless, most environmental factors had little effect on N2O production of strain YL, and the maximum N2O production was significantly lower than that of short-cut nitrification system and autotrophic nitrification system. These results demonstrated that strain YL exhibited excellent abilities of nitrogen removal, N2O emission control, and tolerance to environmental conditions, and could be an effective candidate for treating wastewater without secondary air pollution.


Assuntos
Desnitrificação , Processos Heterotróficos , Nitritos/metabolismo , Pseudomonas aeruginosa/fisiologia , Aerobiose , Genes Bacterianos , Nitrificação , Nitrogênio/metabolismo
2.
Bioresour Technol ; 312: 123593, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32526666

RESUMO

Heterotrophic nitrification and aerobic denitrification (HN-AD), which is primarily performed by bacteria rather than fungi, is an attractive approach for nitrogen removal. In this study, a red yeast, Sporidiobolus pararoseus Y1, was isolated and shown to exhibit optimal growth and nitrogen removal efficiency on glucose, followed by citrate, sucrose, acetate and starch. The nitrogen removal efficiency increased with increasing initial concentrations of NH4+-N, NO2--N and NO3--N from 14 to 140 mg·L-1. At an initial nitrogen concentration of 140 mg·L-1, the maximum removal efficiencies of NH4+-N, NO2--N and NO3--N were 98.67%, 97.13% and 83.51% after 72 h incubation, while those of corresponding total nitrogen were 88.89%, 81.31% and 70.18%, respectively. The nitrification (amoA) and denitrification genes (nirK and napA) were amplified from Y1. These results suggest that yeast are also capable of HN-AD, which can be used to remove nitrogen in wastewater systems.


Assuntos
Compostos de Amônio , Basidiomycota , Produtos Biológicos , Aerobiose , Carbono , Desnitrificação , Processos Heterotróficos , Nitrificação , Nitritos , Nitrogênio
3.
Bioresour Technol ; 312: 123633, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32531738

RESUMO

A novel phosphate-accumulating organism (PAO), Arthrobacter sp. HHEP5 was isolated from mariculture effluents. It produced no hemolysin and was susceptible to most antibiotics. It had removal efficiencies of above 99% for 1-10 mg/L phosphorus at 18-28 °C, pH 5.5-8.5, salinities 0-3%, C/N ratios 5-20, P/N ratios 0.1-0.2 and 20-260 rpm. It exhibited simultaneous aerobic phosphorus removal, nitrification and denitrification with the highest ammonium, nitrite, nitrate removal efficiencies of 99.87%, 100%, 99.37%. Phosphorus removal was accomplished by assimilating phosphate with the existence of polyphosphate kinase completely under aerobic condition. Genes involved in nitrogen removal were amplified. 99% of phosphorus and 95% of nitrogen in both mariculture and domestic wastewater were removed by HHEP5. This study provided sound methods for future screening of PAOs and new perspectives for renewed cognition of phosphorus removal process. Wide adaptation and remarkably aerobic phosphorus, nitrogen removal performances would make HHEP5 a promising candidate in wastewater treatment.


Assuntos
Arthrobacter , Nitrificação , Aerobiose , Desnitrificação , Processos Heterotróficos , Nitritos , Nitrogênio , Fosfatos , Fósforo , Águas Residuárias
4.
Chemosphere ; 257: 127272, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32534299

RESUMO

A hybrid biofilter was established on Fe-C supported carriers aimed to enhance nitrogen removal from polluted water of low Carbon/Nitrogen (C/N) ratio. Effects of organic loadings, hydraulic retention time (HRT), additional electron donor (Fe2+) supplementation and operation mode on the performance of the biofilter were investigated. Results showed that up-flow operation mode was better than down-flow mode in terms of nitrate and total nitrogen (TN) removal at low COD/N. The average removal of NO3--N, NH4+ -N and TN attained 83.1%, 84.7% and 81.2%, respectively, under the conditions of influent COD/NO3--N = 1.5-3.6, HRT = 10 h and up-flow operation. When the biofilter was operated under autotrophic conditions without organic compounds in influent as electron donors, the biofilter achieved a NO3--N removal of 46% and TN removal of 56% depending on the innate electron donors provided by the Fe-C carriers. Supplementation of Fe2+ in influent further promoted autotrophic denitrifying process, and the removal of NO3--N and TN increased to 96.3% and 84.7%, respectively, at the mol ratio of Fe2+/NO3- = 10 and HRT = 10 h. The microbial community was analyzed for the biofilm samples enriched under heterotrophic and autotrophic conditions. The Fe-C biofilter boosted the growth of a large population of mixotrophic denitrifying bacteria including Gallionella, heterotrophic denitrifying bacteria Denitratisoma, and autotrophic denitrifying bacteria Thiobacillus and Thioalkalispira. On the whole, the biofilter coupled with Fe-C micro-electrolysis provides a novel strategy to treat polluted water of low C/N under both heterotrophic and autotrophic conditions.


Assuntos
Reatores Biológicos/microbiologia , Nitrogênio/metabolismo , Processos Autotróficos , Bactérias , Carbono , Desnitrificação , Poluentes Ambientais , Processos Heterotróficos , Nitratos , Águas Residuárias , Água
5.
Chemosphere ; 253: 126693, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32464770

RESUMO

Nitrate pollution presents a serious threat to the environment and public health. As an excellent heterotrophic denitrification carbon source, banana peel (a kind of agricultural waste) provides a feasible alternative to deal with the persistent high concentrations of nitrate pollution. Although the feasibility and economy of banana peel for denitrification have already been reported, the long-term stability and mechanism were still unclear. The coupling mechanism of organic matters and microorganism in the denitrification process was systematically investigated through a 17-cycle experiment. The results showed that significant NO3--N removal load and rate of 164.42 mg/g and 4.69 mg/(L·h) after long-term tests could be obtained. Organic matter analysis and 16S rRNA sequencing showed that the evolution of organic matter was dominated by Anaerolineaceae (fermenting bacteria), and, in the final step, the humification of organic matter was realized. Moreover, the presence of Lentimicrobium (denitrifying bacteria) was indispensable for the continuous removal of high concentrations of nitrate. The main functional gene of nitrogen transformation in this reaction system was NirS (haem-containing). This lab-scale heterotrophic denitrification process could contribute to a better understanding of the carbon and nitrogen cycles in the biogeochemical cycles to some extent, and it also provides a reference for the construction of highly efficient nitrate degradation reactors, based on agricultural wastes.


Assuntos
Reatores Biológicos/microbiologia , Desnitrificação , Musa , Bactérias/metabolismo , Carbono/metabolismo , Desnitrificação/genética , Processos Heterotróficos , Nitratos/metabolismo , Nitrogênio/metabolismo , Ciclo do Nitrogênio , RNA Ribossômico 16S/genética , Águas Residuárias/química
6.
Int J Syst Evol Microbiol ; 70(5): 3348-3354, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32375942

RESUMO

A novel acidophilic member of the phylum Actinobacteria was isolated from an acidic, metal-contaminated stream draining from an abandoned underground coal mine (Trongol mine), situated close to Curanilahue, Biobío Region, Chile. The isolate (USS-CCA1T) was demonstrated to be a heterotroph that catalysed under aerobic conditions the oxidation of ferrous iron and the reduction of ferric iron under anaerobic conditions, but not the oxidation of sulfur nor hydrogen. USS-CCA1T is a Gram-positive, motile, short rod-shaped, mesophilic bacterium with a temperature growth optimum at 30 °C (range 20-39 °C). It was categorized as an extreme acidophile growing between 1.7 and 4.5 and optimally at pH 3.0. The G+C content of the chromosomal DNA of the isolate was 74.1 mol%, which is highly related to Aciditerrimonas ferrireducens IC-180T , (the most closely related genus; 94.4 % 16S rRNA gene identity), and higher than other acidophilic actinobacteria. The isolate (USS-CCA1T) was shown to form a distinct 16S rRNA clade from characterized acidophilic actinobacteria, well separated from the genera Acidimicrobium, Ferrimicrobium, Ferrithrix, 'Acidithrix' and Aciditerrimonas. Genomic indexes (ANIb, DDH, AAI, POCP) derived from the USS-CCA1T draft genome sequence (deposited at DDBJ/ENA/GenBank under the accession WJHE00000000) support assignment of the isolate to a new species and a new genus within the Acidimicrobiaceae family. Isolate USS-CCA1T is the designated type strain of the novel species Acidiferrimicrobium australe (=DSM 106828T,=RGM 2506T).


Assuntos
Actinobacteria/classificação , Processos Heterotróficos , Ferro/metabolismo , Mineração , Filogenia , Microbiologia da Água , Ácidos , Actinobacteria/isolamento & purificação , Técnicas de Tipagem Bacteriana , Composição de Bases , Chile , DNA Bacteriano/genética , Ácidos Graxos/química , Concentração de Íons de Hidrogênio , Oxirredução , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
7.
Sci Total Environ ; 732: 139268, 2020 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-32402929

RESUMO

The rapid expansion of aquaculture industry brings about significant environmental concerns, especially nitrogen pollution. Compared to nitrogen bioconversion implemented by the conventional autotrophic nitrifiers and anaerobic denitrifiers, bacteria capable of heterotrophic nitrification-aerobic denitrification (HNAD) in mariculture environments have yet to be well understood. In this study, twenty-five species of new halophilic HNAD bacteria were isolated and identified from mariculture water. By these strains co-cultured in the synthetic mariculture water (ammonia: 5 mg/L, C/N: 5, salinity: 30‰), microbial dynamic analysis showed that ammonia were mainly removed by dominant genera of Marinomonas, Marinobacterium, Halomonas, and Cobetia which simultaneously had positive correlations to total nitrogen removal. Metagenomic annotations revealed that inorganic-N was converted into gaseous-N and organic-N by these HNAD bacteria through nitrogen metabolism pathways of assimilation, partial nitrification, nitroalkane oxidation, nitrate/nitrite dissimilation reduction, and denitrification. Among them, due to the interspecific coexistence and cooperation, Marinomonas communis &Halomonas titanicae, Marinomonas communis &Cobetia marina, Marinomonas aquimarina &Halomonas titanicae, and Marinomonas aquimarina &Cobetia marina exhibited significantly better inorganic-N removal efficiency and stability. The four novel bacterial consortia could transform approximately 60% of initial ammonia into intracellular organic-N (18-20%) and gaseous-N (36-38%), which were significantly higher than those of their single strains. These findings will contribute to understanding and developing the culturable HNAD bacteria as promising candidates for nitrogen pollution control and water bioremediation in mariculture or other saline environments.


Assuntos
Desnitrificação , Nitrificação , Aerobiose , Bactérias , Processos Heterotróficos , Metagenômica , Nitrogênio , Águas Residuárias , Água
8.
Bioresour Technol ; 307: 123242, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32248065

RESUMO

Consortia of aerobic heterotrophic bacteria (AHB) have potential as sustainable microbial protein (MP) source in animal feed. A systematic screening of the nutritional value and safety of AHB biomass from full-scale activated sludge plants from 25 companies in the food sector was performed. The variable protein content (21-49%) was positively correlated with biomass-specific nitrogen loading rate and negatively with sludge retention time (SRT). Compared to the essential amino acid profile of soybean meal protein, AHB displayed an overall surplus of threonine and valine, and deficits in cysteine, histidine, lysine and phenylalanine. Histidine was positively correlated with bCOD/PO43- in the influent and valine, isoleucine and threonine with SRT. Most AHB samples were safe apropos heavy metals, polycyclic aromatic hydrocarbons and antibiotics. Some pesticides exceeded regulatory limits, necessitating mitigation. This work highlighted that the food sector can provide high-quality MP, while retrofitting existing activated sludge plants towards high-rate processes can increase AHB quality and productivity.


Assuntos
Reatores Biológicos , Esgotos , Animais , Bactérias Aeróbias , Bebidas , Processos Heterotróficos , Eliminação de Resíduos Líquidos
9.
Sheng Wu Gong Cheng Xue Bao ; 36(4): 652-665, 2020 Apr 25.
Artigo em Chinês | MEDLINE | ID: mdl-32347060

RESUMO

Co-culture systems consisted of photosynthetic microorganisms and others heterotrophic microbes have attracted great attention in recent years. These systems show many advantages when compared with single culture grown under autotrophic conditions, such as less vulnerable to pollution and more stability, thus have been applied to wastewater treatment, soil remediation, biodegradable harmful substances, and production of high value-added products. In order to explore basic theory and further applications, we summarize here recent progresses in artificial co-culture systems of using photosynthetic microorganisms, to provide a current scientific understanding for the rational design of the co-culture system based on photosynthetic microorganisms using synthetic biology.


Assuntos
Técnicas de Cocultura , Microbiota , Fotossíntese , Biologia Sintética , Processos Heterotróficos , Técnicas Microbiológicas/tendências , Microbiota/fisiologia , Fotossíntese/fisiologia , Biologia Sintética/tendências
10.
Bioresour Technol ; 310: 123309, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32344242

RESUMO

Nitrogenous wastewater is difficult to treat using conventional microorganisms in high salinity and acidic/alkaline environments. Two halotolerant bacteria, heterotrophic nitrifying Stenotrophomonas sp. MSNA-1 and aerobic denitrifying Pseudomonas sp. MSD4, were isolated, and the amplification of functional genes provided the evidences of nitrogen removal performance. The results regarding salinity and pH resistance showed that strain MSNA-1 is robust at salinities of 0-15% and pH of 3-10. It can remove 51.2% of NH4+-N (180 mg/L) at salinity of 10% (pH: 7) and 49.2% of NH4+-N under pH 4 (salinity: 3%). For strain MSD4, it is robust at salinities of 0-10% and pH of 5-11. It can remove 62.4% of TN (100 mg/L) at salinity of 7% (pH: 7) and 72.2% of TN under pH 9 (salinity: 3%). Their excellent salinity and pH resistances make them promising candidates for treating nitrogenous wastewaters under extreme conditions with low operational cost.


Assuntos
Desnitrificação , Nitrogênio , Aerobiose , Processos Heterotróficos , Concentração de Íons de Hidrogênio , Nitrificação , Nitritos , Salinidade , Águas Residuárias
11.
Chemosphere ; 252: 126378, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32199161

RESUMO

Biofilm based systems and the hybrid between activated sludge and biofilms have been popularly applied for wastewater treatment. Unlike the suspended biomass, the biofilm concentration and kinetics on the media cannot be easily measured. In this study, a novel and easy-to-use approach has been developed based on pulse-flow respirometer to characterize the biofilm stoichiometry and kinetics in situ. With the new designed breathing reactor, the mutual interference between the magnetic stirring and biofilm media that happened in the conventional breathing reactor was solved. Moreover, Microsoft Excel based programs had been developed to fit the oxygen uptake rate curves with dynamic nonlinear regression. With this new approach, the yield coefficient, maximum oxidation capacity, and half-saturation constant of substrate for the heterotrophic biofilms in a fix bed reactor were determined to be 0.46 g-VSS/g-COD, 67.0 mg-COD/(h·L-media), and 4.4 mg-COD/L, respectively. Those parameters for biofilm ammonia oxidizers from a moving bed biofilm reactor were determined to be 0.17 g-VSS/g-N, 18.6 mg-N/(h·L-media), and 1.2 mg-N/L, respectively, and they were 0.11 g-VSS/g-N, 20.9 mg-N/(h·L-media), and 0.98 mg-N/L for nitrite oxidizers in the same biofilms. This study also found that the maximum specific substrate utilization rate for detached biofilms increased by 3.2 times, indicating that maintaining biofilm integrity was very important in the kinetic tests. Using this approach, the biofilm kinetics on the media can be regularly measured for treatment optimization.


Assuntos
Biofilmes , Reatores Biológicos , Eliminação de Resíduos Líquidos/métodos , Biomassa , Processos Heterotróficos , Cinética , Esgotos/química , Águas Residuárias
12.
Chemosphere ; 252: 126482, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32222520

RESUMO

This study investigated the feasibility of using photoheterotrophic microalga, Desmodesmus armatus SCK, for removal of cesium (Cs+) followed by recovery process using magnetic nanoparticles. The comparison of three microalgae results indicated that D. armatus SCK removed the most Cs+ at both 25 °C and 10 °C. The results also revealed that the use of microalga grown in potassium (K+)-starved condition improves the accumulation of Cs+. Heterotrophic mode with addition of volatile fatty acids (VFAs), especially acetic acids (HAc), also enhanced removal of Cs+ by K+-starved D. armatus SCK; maximum removal efficiency of Cs+ was almost 2-fold higher than that of cells grown without organic carbon source. The Cs+ taken up by this microalga was efficiently harvested using magnetic nanoparticles, polydiallyldimethylammonium (PDDA)-FeO3. Finally, this strain eliminated more than 99% of radioactive 137Cs from solutions of 10, 100, and 1000 Bq mL-1. Therefore, use of K+-starved microalga, D. armatus SCK, with VFAs could be promising means to remove the Cs from the liquid wastes.


Assuntos
Césio/metabolismo , Microalgas/metabolismo , Poluentes Químicos da Água/metabolismo , Césio/análise , Radioisótopos de Césio , Ácidos Graxos Voláteis , Processos Heterotróficos , Fenômenos Magnéticos , Potássio , Poluentes Químicos da Água/análise
13.
Aquat Toxicol ; 222: 105463, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32172181

RESUMO

Massive use of glyphosate-based herbicides in agricultural activities has led to the appearance of this herbicide in freshwater systems, which represents a potential threat to these systems and their communities. These herbicides can affect autotrophic and heterotrophic picoplankton abundance. However, little is known about glyphosate impact on the whole structure of these assemblages. Herein, we used an 8-day long microcosm approach under indoor controlled conditions to analyze changes in the structure of picoplankton exposed to a single pulse of glyphosate. The analyzed picoplankton correspond to two outdoor ponds with contrasting states: "clear" (chlorophyll-a = 3.48 µg L-1± 1.15; nephelometric turbidity, NTU = 1) and "turbid" (chlorophyll-a = 105.96 µg L-1 ± 15.3; NTU = 48). We evaluated herbicide impact on different picoplankton cytometric populations and further explored changes in bacterial dominant operational taxonomic units (OTUs) fingerprinting. We observed that glyphosate induced a drastic decrease in the abundance of phycocyanin-rich picocyanobacteria. Particularly, in the turbid system this effect resulted in an 85 % decrease in the abundance of the whole autotrophic picoplankton. Glyphosate also changed the structure of the heterotrophic fraction by means of changing bacterial dominant OTUs fingerprinting patterns in both systems and by shifting the relative abundances of cytometric groups in the clear scenario. These results demonstrate that upon glyphosate exposure picoplanktonic fractions face not only the already reported changes in abundance, but also alterations in the composition of cytometric groups and of bacterial dominant operational taxonomic units. This research provides suitable and still little explored tools to analyze agrochemical effects on picoplanktonic communities.


Assuntos
Processos Autotróficos/efeitos dos fármacos , Glicina/análogos & derivados , Herbicidas/toxicidade , Processos Heterotróficos/efeitos dos fármacos , Plâncton/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Agricultura , Clorofila A/metabolismo , Cianobactérias/efeitos dos fármacos , Cianobactérias/crescimento & desenvolvimento , Cianobactérias/metabolismo , Água Doce/química , Glicina/toxicidade , Plâncton/crescimento & desenvolvimento , Plâncton/metabolismo
14.
Proc Natl Acad Sci U S A ; 117(7): 3656-3662, 2020 02 18.
Artigo em Inglês | MEDLINE | ID: mdl-32015111

RESUMO

In the nutrient-rich region surrounding marine phytoplankton cells, heterotrophic bacterioplankton transform a major fraction of recently fixed carbon through the uptake and catabolism of phytoplankton metabolites. We sought to understand the rules by which marine bacterial communities assemble in these nutrient-enhanced phycospheres, specifically addressing the role of host resources in driving community coalescence. Synthetic systems with varying combinations of known exometabolites of marine phytoplankton were inoculated with seawater bacterial assemblages, and communities were transferred daily to mimic the average duration of natural phycospheres. We found that bacterial community assembly was predictable from linear combinations of the taxa maintained on each individual metabolite in the mixture, weighted for the growth each supported. Deviations from this simple additive resource model were observed but also attributed to resource-based factors via enhanced bacterial growth when host metabolites were available concurrently. The ability of photosynthetic hosts to shape bacterial associates through excreted metabolites represents a mechanism by which microbiomes with beneficial effects on host growth could be recruited. In the surface ocean, resource-based assembly of host-associated communities may underpin the evolution and maintenance of microbial interactions and determine the fate of a substantial portion of Earth's primary production.


Assuntos
Bactérias/metabolismo , Ecossistema , Microbiota , Bactérias/classificação , Bactérias/genética , Bactérias/isolamento & purificação , Processos Heterotróficos , Filogenia , Fitoplâncton/crescimento & desenvolvimento , Fitoplâncton/microbiologia , Água do Mar/microbiologia
15.
Syst Appl Microbiol ; 43(2): 126066, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32019686

RESUMO

On-going studies of phytoplankton-bacterioplankton interactions at the long-term ecological research site Helgoland Roads have indicated that many of the heterotrophic bacterial taxa have not yet been cultivated. A high-throughput approach combining whole cell matrix-assisted laser desorption ionization - time of flight mass spectroscopy with 16S rRNA gene sequencing was applied to the spring bloom of 2016. Aiming at an assessment of cultivability during a spring bloom, cultivation on solid marine media had to be used since dilution to extinction would not have been feasible for a high-throughput approach, as performed in this study. A total of 5023 isolates were obtained from nine weekly samples on eight different solid media between the early-bloom and post-bloom periods. Most of the 4136 strains identified affiliated with Bacteroidetes (13.3%), Gammaproteobacteria (26.9%), Alphaproteobacteria (40.6%) and Actinobacteria (6.7%). Of the 271 operational phylogenetic units (OPUs) identified, 13 are likely to represent novel genera and 143 novel species. A comparison with 16S rRNA gene tag data indicated that most of the isolates were rather rare in surface waters, with the exception of five OPUs affiliating with Rhodobacteraceae, Polaribacter, Psychromonas and Pseudoalteromonas. The effort yielded many novel isolates, yet most of the abundant heterotrophic bacteria still remained elusive. The large strain collection obtained will not only provide insights into the succession of the cultivable fraction of the bacterioplankton, but also enable fine-tuned taxonomic and physiological follow-up studies for improving our knowledge on heterotrophic bacteria in North Sea waters.


Assuntos
Bactérias/crescimento & desenvolvimento , Bactérias/metabolismo , Fitoplâncton/crescimento & desenvolvimento , Fitoplâncton/metabolismo , Água do Mar/microbiologia , Bactérias/classificação , Bactérias/genética , Meios de Cultura , DNA Bacteriano/genética , Eutrofização , Processos Heterotróficos , Mar do Norte , Filogenia , Fitoplâncton/classificação , Fitoplâncton/genética , RNA Ribossômico 16S/genética , Estações do Ano , Água do Mar/química , Análise de Sequência de DNA
16.
Sci Total Environ ; 717: 136981, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-32092802

RESUMO

Total nitrogen (TN) removal is the major technical challenge for wastewater treatment plants to meet the more stringent discharge standard. In this study, lab- (0.05 m3/d), pilot- (1000 m3/d) and full-scale (10,000 m3/d) combined heterotrophic and autotrophic denitrification reactors (HARs) were designed and operated to treat municipal secondary effluent. During the 110-day stable operation, the effluent TN was reduced below 2.5 mg/L without secondary pollution causing by the excessive addition of organics, close to Class IV of Environmental Quality Standards for Surface Water. The bacterial richness and diversity increased with the expansion of reactor scale. Denitrifying bacteria (DB) dominated in all reactors, however, Thiomonas (12.42%), Methylotenera (6.35%), Thiobacillus (20.62%), Methyloverstatilis (5.44%) and Thauera (8.21%) were the main genera in lab-, pilot- and full-scale reactors respectively. The denitrification efficiency temporarily deteriorated at the later stage, and redundancy analysis (RDA) indicated the obviously increased sulfate reducing bacteria (SRB) and sulfide were main contributors. Sludge supplement rapidly recovered the reactors performance in five days. This study suggests that HARs could be a promising technique for advanced denitrification of the municipal secondary effluent.


Assuntos
Processos Autotróficos , Desnitrificação , Processos Heterotróficos , Bactérias , Reatores Biológicos , Nitratos , Nitrogênio , Águas Residuárias
17.
PLoS One ; 15(2): e0225677, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32084664

RESUMO

Heterotrophic growth mode is among the most promising strategies put forth to overcome the low biomass and secondary metabolites productivity challenge. To shedding light on the underlying molecular mechanisms, transcriptome meta-analysis was integrated with weighted gene co-expression network analysis (WGCNA), connectivity analysis, functional enrichment, and hubs identification. Meta-analysis and Functional enrichment analysis demonstrated that most of the biological processes are up-regulated at heterotrophic growth condition, which leads to change of genetic architectures and phenotypic outcomes. WGNCA analysis of meta-genes also resulted four significant functional modules across logarithmic (LG), transition (TR), and production peak (PR) phases. The expression pattern and connectivity characteristics of the brown module as a non-preserved module vary across LG, TR, and PR phases. Functional analysis identified Carotenoid biosynthesis, Fatty acid metabolism and Methane metabolism as enriched pathways in the non-preserved module. Our integrated approach was applied here, identified some hubs, such as a serine hydroxymethyltransferase (SHMT1), which is the best candidate for development of metabolites accumulating strains in microalgae. Current study provided a new insight into underlying metabolite accumulation mechanisms and opens new avenue for the future applied studies in the microalgae field.


Assuntos
Processos Autotróficos/genética , Processos Heterotróficos/genética , Microalgas/metabolismo , Metabolismo Secundário/fisiologia , Biologia de Sistemas/métodos , Ciclo do Carbono/fisiologia , Carotenoides/metabolismo , Ácidos Graxos/metabolismo , Perfilação da Expressão Gênica , Redes Reguladoras de Genes , Glicina Hidroximetiltransferase/metabolismo , Metano/metabolismo , Microalgas/crescimento & desenvolvimento , Transcriptoma
18.
Bioresour Technol ; 303: 122948, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32058906

RESUMO

A heterotrophic nitrifying and aerobic denitrifying fungus was isolated from lake water and identified as Penicillium tropicum strain IS0293. The strain exhibited efficient heterotrophic nitrification-aerobic denitrification ability and could utilize ammonium, nitrite and nitrate as a sole nitrogen source. Batch tests demonstrated that strain IS0293 can remove nitrate using variety of organic carbon compounds as carbon sources. The effect of woodchip leachate collected at different degradation times on denitrification performance of the strain was also investigated. Furthermore, two denitrifying woodchip bioreactors were constructed to assess the bioaugmention of strain IS0293 for nitrate removal from surface water. Results demonstrated that the incubation of strain IS0293 enhanced the nitrate removal efficiency of the bioreactor. In addition, the average effluent TOC content of the bioaugmention bioreactor was 38.22% lower than the control bioreactor. This study would be valuable to develop an effective technology for nitrate-laden surface water under aerobic conditions.


Assuntos
Processos Heterotróficos , Água , Aerobiose , Reatores Biológicos , Desnitrificação , Fungos , Nitratos , Nitrificação , Nitritos , Nitrogênio
19.
Bioresour Technol ; 302: 122840, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32014729

RESUMO

Herein, a two-stage cultivation process was devised to overcome low pigment content of algal biomass grown in heterotrophy. Post-treatment conditions (i.e., light intensity, temperature, pH and salinity) were initially tested for dense heterotrophically-grown Chlorella sp. HS2 cultures in a multi-channel photobioreactor (mcPBR), and the results clearly indicated the influence of each abiotic factor on algal pigment production. Subsequently, the optimal post-treatment conditions (i.e., 455 µmol m-2 s-1, 34.8℃, pH 8.23 and 0.7% (w/v) salinity), in which highest accumulation of algal pigments is expected, were identified using Response Surface Methodology (RSM). Compared to the control cultures grown in mixotrophy for the same duration of entire two-stage process, the results indicated a significantly higher pigment productivity (i.e., 167.5 mg L-1 day-1) in a 5-L fermenter following the post-treatment at optimal conditions. Collectively, these results suggest that the post-treatment of heterotrophic cultures can be successfully deployed to harness the nascent algae-based bioeconomy.


Assuntos
Chlorella , Processos Heterotróficos , Biomassa , Fotobiorreatores , Salinidade
20.
Environ Sci Pollut Res Int ; 27(9): 9307-9317, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31916165

RESUMO

Nitrogen (N) loss is generally caused by denitrification under anaerobic conditions and the N loss in the heterotrophic nitrification_aerobic denitrification (HN_AD) system is of recent research interest. However, previous studies are generally focused on pure cultures-based system and the information on HN_AD in the complex aquatic ecosystem is limited. In this study, HN-AD system was established in the mixed cultures of the sediments and the performances of HN-AD were evaluated under different conditions. Further, the N loss mechanism in HN_AD system was explored. The study found that the N was lost in the sediment cultures with ammonium-N (NH4+_N) (or) and nitrate-N (NO3-_N) as N source under aerobic conditions. The highest N loss rate was achieved under the TOC/TN mass ratio of 10 with citrate as the carbon source. Under this condition, the N loss percentages of NH4+_N (201.91 mg/L) and NO3-_N (130.00 mg/L) reached 99.61% and 100.00%, respectively, which were higher than those in the pure HN_AD strains reported in the literature. High NH4+_N removal efficiencies were also achieved at low C/N mass ratio and high NH4+_N concentration (493.12 mg L-1). The N loss pathway in the system was investigated by adding Na2WO4 as the nitrate reductase inhibitor. The study found that the N was not lost via partial nitrification/denitrification pathway, i.e., NH4+ → NH2OH → NO2- → N2O (N2), instead via full nitrification/denitrification pathway, i.e., NH4+ → NH2OH → NO2- → NO3- → NO2- → N2O (N2), since nitrate was a key intermediate. The variation in NH4+_N, NO3-_N, and NO2-_N concentrations in the HN_AD processes further confirmed the N transformation pathway. Therefore, HN_AD may occur and cause N loss in natural aquatic ecosystems. The results of this study demonstrate that N was lost through HN-AD and that the well-cultured HN-AD sediments could be useful biological tool to remediate eutrophic water bodies.


Assuntos
Desnitrificação , Nitrificação , Nitrogênio/análise , Aerobiose , Ecossistema , Processos Heterotróficos , Nitrogênio/química
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