Publications by authors named "Sergio S C Dc Rubin"

4 Publications

  • Page 1 of 1

Nitric oxide for anammox recovery in a nitrite-inhibited deammonification system.

Environ Technol 2015 27;36(19):2477-87. Epub 2015 Apr 27.

a Institute of Chemistry, University of Tartu , 14a Ravila St., 50411 Tartu , Estonia.

The anaerobic ammonium oxidation (anammox) process is widely used for N-rich wastewater treatment. In the current research the deammonification reactor in a reverse order (first anammox, then the nitrifying biofilm cultivation) was started up with a high maximum N removal rate (1.4 g N m(-2) d(-1)) in a moving bed biofilm reactor. Cultivated biofilm total nitrogen removal rates were accelerated the most by anammox intermediate - nitric oxide (optimum 58 mg NO-N L(-1)) addition. Furthermore, NO was added in order to eliminate inhibition caused by nitrite concentrations (>50 mg [Formula: see text]) increasing [Formula: see text] (2/1, respectively) along with a higher ratio of [Formula: see text] (0.6/1, respectively) than stoichiometrical for this optimal NO amount added during batch tests. Planctomycetales clone P4 sequences, which was the closest (98% and 99% similarity, respectively) relative to Candidatus Brocadia fulgida sequences quantities increase to 1 × 10(6) anammox gene copies g(-1) total suspended solids to till day 650 were determined by quantitative polymerase chain reaction.
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http://dx.doi.org/10.1080/09593330.2015.1034791DOI Listing
September 2016

Comparison of sulfate-reducing and conventional Anammox upflow anaerobic sludge blanket reactors.

J Biosci Bioeng 2014 Oct 23;118(4):426-33. Epub 2014 May 23.

Institute of Chemistry, University of Tartu, 14a Ravila St., 50411 Tartu, Estonia.

Autotrophic NH4(+) removal has been extensively researched, but few studies have investigated alternative electron acceptors (for example, SO4(2-)) in NH4(+) oxidation. In this study, sulfate-reducing anaerobic ammonium oxidation (SRAO) and conventional Anammox were started up in upflow anaerobic sludge blanket reactors (UASBRs) at 36 (±0.5)°C and 20 (±0.5)°C respectively, using reject water as a source of NH4(+). SO4(2-) or NO2(-), respectively, were applied as electron acceptors. It was assumed that higher temperature could promote the SRAO, partly compensating its thermodynamic disadvantage comparing with the conventional Anammox to achieve comparable total nitrogen (TN) removal rate. Average volumetric NH4(+)-N removal rate in the sulfate-reducing UASBR1 was however 5-6 times less (0.03 kg-N/(m(3) day)) than in the UASBR2 performing conventional nitrite-dependent autotrophic nitrogen removal (0.17 kg-N/(m(3) day)). However, the stoichiometric ratio of NH4(+) removal in UASBR1 was significantly higher than could be expected from the extent of SO4(2-) reduction, possibly due to interactions between the N- and S-compounds and organic matter of the reject water. Injections of N2H4 and NH2OH accelerated the SRAO. Similar effect was observed in batch tests with anthraquinone-2,6-disulfonate (AQDS). For detection of key microorganisms PCR-DGGE was used. From both UASBRs, uncultured bacterium clone ATB-KS-1929 belonging to the order Verrucomicrobiales, Anammox bacteria (uncultured Planctomycete clone Pla_PO55-9) and aerobic ammonium-oxidizing bacteria (uncultured sludge bacterium clone ASB08 "Nitrosomonas") were detected. Nevertheless the SRAO process was shown to be less effective for the treatment of reject water, compared to the conventional Anammox.
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http://dx.doi.org/10.1016/j.jbiosc.2014.03.012DOI Listing
October 2014

Deammonification process start-up after enrichment of anammox microorganisms from reject water in a moving-bed biofilm reactor.

Environ Technol 2013 Nov-Dec;34(21-24):3095-101

Deammonification via intermittent aeration in biofilm process for the treatment of sewage sludge digester supernatant (reject water) was started up using two opposite strategies. Two moving-bed biofilm reactors were operated for 2.5 years at 26 (+/- 0.5 degree C with spiked influent(and hence free ammonia (FA)) addition. In the first start-up strategy, an enrichment of anammox biomass was first established, followed by the development of nitrifying biomass in the system (R1). In contrast, the second strategy aimed at the enrichment of anammox organisms into a nitrifying biofilm (R2). The first strategy was most successful, reaching higher maximum total nitrogen (TN) removal rates over a shorter start-up period. For both reactors, increasing FA spiking frequency and increasing effluent concentrations of the anammox intermediate hydrazine correlated to decreasing aerobic nitrate production (nitritation). The bacterial consortium of aerobic and anaerobic ammonium oxidizing bacteria in the bioreactor was determined via denaturing gel gradient electrophoresis, polymerase chain reaction and pyrosequencing. In addition to a shorter start-up with a better TN removal rate, nitrite oxidizing bacteria (Nitrospira) were outcompeted by spiked ammonium feeding from R1.
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http://dx.doi.org/10.1080/09593330.2013.803134DOI Listing
April 2014

T rypanosoma cruzi trans-sialidase as a multifunctional enzyme in Chagas' disease.

Cell Microbiol 2012 Oct 22;14(10):1522-30. Epub 2012 Jul 22.

Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de São Paulo, UNIFESP, São Paulo, Brasil.

Trypanosoma cruzi trans-sialidase (TS) was identified three decades ago. TS catalyses a trans-glycosylation reaction, transferring SA from sialylated donors to the terminal galactose mucin-glycoconjugates, or non-mucin galactyosyl-glycoconjugates. It is an external surface protein that is also released from the parasite, displaying several binding properties in addition to its enzymatic function. TS structure has been solved and its catalytic properties are well known, providing tools for development of new inhibitors, as potential chemotherapeutic agents against Chagas' disease. However, there are still several unsolved questions regarding TS role in the biology of T. cruzi and in the pathology of Chagas' disease. In this review, we will describe the multifunctional roles of TS regarding the development of Chagas' disease and propose that these multiple functions have to be considered in future investigations aiming to use TS as a drug target.
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http://dx.doi.org/10.1111/j.1462-5822.2012.01831.xDOI Listing
October 2012
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