Sequentially aerated membrane biofilm reactors for autotrophic nitrogen removal: microbial community composition and dynamics

Membrane-aerated biofilm reactors performing autotrophic nitrogen removal can be successfully applied to treat concentrated nitrogen streams. However, their process performance is seriously hampered by the growth of nitrite oxidizing bacteria (NOB). In this work we document how sequential aeration can bring the rapid and long-term suppression of NOB and the onset of the activity of anaerobic ammonium oxidizing bacteria (AnAOB). Real-time quantitative polymerase chain reaction analyses confirmed that such shift in performance was mirrored by a change in population densities, with a very drastic reduction of the NOB Nitrospira and Nitrobacter and a 10-fold increase in AnAOB numbers. The study of biofilm sections with relevant 16S rRNA fluorescent probes revealed strongly stratified biofilm structures fostering aerobic ammonium oxidizing bacteria (AOB) in biofilm areas close to the membrane surface (rich in oxygen) and AnAOB in regions neighbouring the liquid phase. Both communities were separated by a transition region potentially populated by denitrifying heterotrophic bacteria. AOB and AnAOB bacterial groups were more abundant and diverse than NOB, and dominated by the r-strategists Nitrosomonas europaea and Ca. Brocadia anammoxidans, respectively. Taken together, the present work presents tools to better engineer, monitor and control the microbial communities that support robust, sustainable and efficient nitrogen removal

Época apropriada para a poda apical do algodoeiro para o controle de pragas

O objetivo deste trabalho foi determinar a época apropriada para a realização da poda apical em algodoeiro. O trabalho foi realizado durante as safras de 2008 e 2009 (maio a novembro) em delineamento de blocos ao acaso, em dois ambientes, com as variedades: BRS 201, de fibra branca, e BRS Rubi, BRS Safira e BRS Verde, de fibra colorida, em Paudalho, PE; e BRS 201 e BRS Rubi, em Surubim, PE. A poda apical consistiu na retirada dos ápices das plantas com estruturas vegetativas e reprodutivas, em duas idades fenológicas: com 50% das maçãs maduras (poda I) e no surgimento dos primeiros capulhos (poda II). A poda I resultou em maior retirada de botões florais do que a poda II. Em ambas as podas, houve a retirada de cinco nós dos ponteiros. A produção e a qualidade de fibra não diferiram entre plantas podadas ou não. Um número significativo de estruturas atacadas foi eliminado pela poda. A poda apical é recomendada para reduzir o número de estruturas não produtivas, ao final da safra, que são utilizadas como hospedeiras de pragas

Sputum containing zinc enhances carbapenem resistance, biofilm formation and virulence of Pseudomonas aeruginosa.

Pseudomonas aeruginosa chronic lung infections are the leading cause of mortality in cystic fibrosis patients, a serious problem which is notably due to the numerous P. aeruginosa virulence factors, to its ability to form biofilms and to resist the effects of most antibiotics. Production of virulence factors and biofilm formation by P. aeruginosa is highly coordinated through complex regulatory systems. We recently found that CzcRS, the zinc and cadmium-specific two-component system is not only involved in metal resistance, but also in virulence and carbapenem antibiotic resistance in P. aeruginosa. Interestingly, zinc has been shown to be enriched in the lung secretions of cystic fibrosis patients. In this study, we investigated whether zinc might favor P. aeruginosa pathogenicity using an artificial sputum medium to mimic the cystic fibrosis lung environment. Our results show that zinc supplementation triggers a dual P. aeruginosa response: (i) it exacerbates pathogenicity by a CzcRS two-component system-dependent mechanism and (ii) it stimulates biofilm formation by a CzcRS-independent mechanism. Furthermore, P. aeruginosa cells embedded in these biofilms exhibited increased resistance to carbapenems. We identified a novel Zn-sensitive regulatory circuit controlling the expression of the OprD porin and modifying the carbapenem resistance profile. Altogether our data demonstrated that zinc levels in the sputum of cystic fibrosis patients might aggravate P. aeruginosa infection. Targeting zinc levels in sputum would be a valuable strategy to curb the increasing burden of P. aeruginosa infections in cystic fibrosis patients.

Correlação entre a capacidade proliferativa in vitro e a dominância apical in vivo da bananeira cvs. Grand naine e Nanicão

No presente trabalho, buscou-se correlacionar diferentes graus de dominância apical in vivo com a capacidade proliferativa in vitro da bananeira, através da relação existente entre a fonte de explante e o seu posterior comportamento in vitro. Brotos laterais de Musa acuminata Colla: Nanicão (AAA) e Grand Naine (AAA), oriundos de plantas-matrizes mostrando diferentes graus de dominância apical in vivo (elevada, média e baixa) foram cultivados in vitro, no Laboratório de Cultura de Tecidos Vegetais da EEI/ EPAGRI-SC, por cinco subcultivos, em intervalos de 30 dias, em meio MS suplementado com BAP (11,1 mmol/l), sacarose (30 g/l), ágar (7 g/l), vitaminas MS e pH 5,8. O grau de dominância apical in vivo influenciou diretamente o comportamento in vitro dos explantes, no que diz respeito à capacidade proliferativa. Brotos laterais oriundos de plantas-matrizes, com grau de dominância apical in vivo baixa, proporcionaram a maior taxa média proliferativa (7,5 brotos/explante) para a cv. Grand Naine, enquanto brotos laterais oriundos de plantas-matrizes com grau de dominância apical média proporcionaram a maior taxa média proliferativa (10,96 brotos/explante) para a cv. Nanicão.

Indução de brotações em gema apical e axilar do porta-enxerto de macieira 'EM-9' cultivadas in vitro

O trabalho objetivou comparar dois tipos de explantes (gema apical e gema axilar) do porta-enxerto de macieira 'EM-9' e o tempo de permanência destes explantes no meio de cultura de indução (20, 30 e 40 dias), na capacidade de regeneração in vitro de brotações. O meio de cultura de indução de regeneração constituiu-se dos sais de MS, suplementado com mio-inositol (100 mg.L-1), sacarose (30 g.L-1), ágar (6,0 g.L-1), BAP (4,44 µM) e ANA (0,54 µM). Transcorrido o tempo de permanência no meio de cultura de indução de regeneração, os explantes foram transferidos para meio de cultura de multiplicação, de constituição semelhante ao meio de indução, porém sem a presença de auxina. A partir dos resultados obtidos, concluiu-se que as gemas apicais e axilares do porta-enxerto de macieira 'EM-9', não diferem quanto à capacidade de regeneração in vitro de brotações e, o tempo de permanência das gemas no meio de indução de regeneração, apenas mostrou diferenças para o comprimento médio das brotações, obtendo-se o maior valor com 30 dias.

Effects of biofilm and refrigeration on acerola postharvest conservation

The objective of this work was to compare the effects of four different concentrations of cassava starch film and storage temperature on shelf life and the quality of a genotype of acerola from the Germplasm Active Bank (GAB) of Federal Rural University of Pernambuco, Brazil. Sound orange-reddish acerola fruits were washed with a chlorine solution (100 mg.L-1 active chlorine) and randomly distributed into different lots. The fruits were dipped for 3 min in a cassava starch suspension with concentrations of 1, 2, 3 and 4% (w/v) and the control without coating, stored at 10ºC (85% RH) and 22ºC (85% RH). The total soluble solids (TSS), pH, titratable acidity (TA) and ascorbic acid (AA) were determined at harvest and regular interval during storage. The use of cassava biofilm at 1% on acerola fruits maintained the highest ascorbic acid content and the temperature of 10ºC extended storage life. The fruits coated with 1 and 2% biofilm could be stored for a period up to 15 days at 10ºC, with acceptable quality characteristics.

Reguladores vegetais na quebra da dominância apical de mamoeiro (Carica papaya L.)

O trabalho avaliou os efeitos de reguladores vegetais sobre a quebra da dominância apical de mamoeiro (Carica papaya L. cv. Improved Sunrise Solo). A aplicação dos reguladores vegetais foi iniciada quando as plantas tinham seis meses de idade, totalizando três aplicações, a intervalos de sete dias, constando dos seguintes tratamentos: T1- água (testemunha); T2- GA3 250 mg L-1; T3- GA3 500 mg L-1; T4- benziladenina (BA) 250 mg L-1; T5- BA 500 mg L-1; T6- GA3 125 mg L-1 + BA 125 mg L-1; T7- GA3 250 mg L-1 + BA 250 mg L-1. Esses tratamentos foram acompanhados da remoção ou não da gema apical. Os resultados mostraram que plantas tratadas com GA3 + BA a 125 e 250 mg L-1, com e sem a remoção da gema apical, apresentaram maior número de brotações que a testemunha, a qual não apresentou nenhuma brotação das gemas laterais.

Quorum-sensing regulates biofilm formation in Vibrio scophthalmi

Background: In a previous study, we demonstrated that Vibrio scophthalmi, the most abundant Vibrio species among the marine aerobic or facultatively anaerobic bacteria inhabiting the intestinal tract of healthy cultured turbot (Scophthalmus maximus), contains at least two quorum-sensing circuits involving two types of signal molecules (a 3-hydroxy-dodecanoyl-homoserine lactone and the universal autoinducer 2 encoded by luxS). The purpose of this study was to investigate the functions regulated by these quorum sensing circuits in this vibrio by constructing mutants for the genes involved in these circuits. Results. The presence of a homologue to the Vibrio harveyi luxR gene encoding a main transcriptional regulator, whose expression is modulated by quorumsensing signal molecules in other vibrios, was detected and sequenced. The V. scophthalmi LuxR protein displayed a maximum amino acid identity of 82% with SmcR, the LuxR homologue found in Vibrio vulnificus. luxR and luxS null mutants were constructed and their phenotype analysed. Both mutants displayed reduced biofilm formation in vitro as well as differences in membrane protein expression by mass-spectrometry analysis. Additionally, a recombinant strain of V. scophthalmi carrying the lactonase AiiA from Bacillus cereus, which causes hydrolysis of acyl homoserine lactones, was included in the study. Conclusions: V. scophthalmi shares two quorum sensing circuits, including the main transcriptional regulator luxR, with some pathogenic vibrios such as V. harveyi and V. anguillarum. However, contrary to these pathogenic vibrios no virulence factors (such as protease production) were found to be quorum sensing regulated in this bacterium. Noteworthy, biofilm formation was altered in luxS and luxR mutants. In these mutants a different expression profile of membrane proteins were observed with respect to the wild type strain suggesting that quorum sensing could play a role in the regulation of the adhesion mechanisms of this bacterium.

Comparison between Radiographic (2-dimensional and 3-dimensional) and Histologic Findings of Periapical Lesions Treated with Apical Surgery.

INTRODUCTION: The aim of this study was to evaluate the concordance of 2- and 3-dimensional radiography and histopathology in the diagnosis of periapical lesions. METHODS: Patients were consecutively enrolled in this study provided that preoperative periapical radiography (PR) and cone-beam computed tomographic imaging of the tooth to be treated with apical surgery were performed. The periapical lesional tissue was histologically analyzed by 2 blinded examiners. The final histologic diagnosis was compared with the radiographic assessments of 4 blinded observers. The initial study material included 62 teeth in the same number of patients. RESULTS: Four lesions had to be excluded during processing, resulting in a final number of 58 evaluated cases (31 women and 27 men, mean age = 55 years). The final histologic diagnosis of the periapical lesions included 55 granulomas (94.8%) and 3 cysts (5.2%). Histologic analysis of the tissue samples from the apical lesions exhibited an almost perfect agreement between the 2 experienced investigators with an overall agreement of 94.83% (kappa = 0.8011). Radiographic assessment overestimated cysts by 28.4% (cone-beam computed tomographic imaging) and 20.7% (periapical radiography), respectively. Comparing the correlation of the radiographic diagnosis of 4 observers with the final histologic diagnosis, 2-dimensional (kappa = 0.104) and 3-dimensional imaging (kappa = 0.111) provided only minimum agreement. CONCLUSIONS: To establish a final diagnosis of an apical radiolucency, the tissue specimen should be evaluated histologically and specified as a granuloma (with/without epithelium) or a cyst. Analysis of 2-dimensional and 3-dimensional radiographic images alike results only in a tentative diagnosis that should be confirmed with biopsy.

SEM evidence for existence of an apical disc on the scolex of Clestobothrium crassiceps (Rudolphi, 1819): comparative results of various fixation techniques

The scolex of the bothriocephalidean cestode Clestobothrium crassiceps was studied by means of scanning electron microscopy (SEM). The comparative results of various fixation procedures and techniques are presented. The scolex of C. crassiceps is oval to globular and exhibits two deep bothria which appear in the form of two lobes separated by a longitudinal groove. At the apex of the scolex, resembling a beret, an apical disc is present (oval, flattened and with a sinuous edge). Our results are compared with those previously reported in other species of Clestobothrium. This study represents the first report which highlights the presence of an apical disc in the scolex of C. crassiceps. It describes the effects of different procedures applied to our material during preparation and a comparative analysis results obtained using these various methods.

SEM evidence for existence of an apical disc on the scolex of Clestobothrium crassiceps (Rudolphi, 1819): comparative results of various fixation techniques

The scolex of the bothriocephalidean cestode Clestobothrium crassiceps was studied by means of scanning electron microscopy (SEM). The comparative results of various fixation procedures and techniques are presented. The scolex of C. crassiceps is oval to globular and exhibits two deep bothria which appear in the form of two lobes separated by a longitudinal groove. At the apex of the scolex, resembling a beret, an apical disc is present (oval, flattened and with a sinuous edge). Our results are compared with those previously reported in other species of Clestobothrium. This study represents the first report which highlights the presence of an apical disc in the scolex of C. crassiceps. It describes the effects of different procedures applied to our material during preparation and a comparative analysis results obtained using these various methods.

Occurrence and new mutations involved in rifampicin-resistant Propionibacterium acnes strains isolated from biofilm or device-related infections.

We described for the first time the amino acid substitutions conferring rifampicin resistance in eight Propionibacterium acnes strains isolated from patients with biofilm or device-related infections. We identified different mutations in cluster I and one mutation, never reported, in cluster II of the rpoB gene (I480V) associated with the most frequent one in cluster I (S442L). Half of the patients previously received treatment with rifampicin.

Apical closure device for transapical valve procedures?.

OBJECTIVES: Transapical transcatheter valve procedures are performed through a left minithoracotomy and require apical sutures to seal the apical access site. The use of large-calibre devices compromises any attempt to fully perform the procedure with a thoracoscopic approach or percutaneously. We report our preliminary experience in animals with a new sutureless self-expandable apical occluder, engineered to perform transapical access site closure in a minimally invasive setting with large-size introducer sheaths. METHODS: The apical occluder with extendable waist was implanted in six young pigs during an acute animal study. Under general anaesthesia, animals (mean weight: 62 ± 8 kg) received full heparinization (heparin: 100 UI/kg; activated clotting time above 250 s). Through a median sternotomy, a 21-Fr Certitude? introducer sheath (outer diameter: 25 Fr) was placed over the wire into the cardiac apex. The delivery catheter carrying the constrained apical plug was inserted into the sheath and deployed under fluoroscopic control, whereas the Certitude? was retrieved. After protamine infusion, we observed and recorded the 1-h bleeding with standard haemodynamic parameters. Animals were sacrificed, and hearts analysed. RESULTS: Six apical closure devices were successfully introduced and deployed in six pig hearts through large-size apical sheaths at first attempt. In all animals, the plugs guaranteed immediate apical sealing and traces of blood were collected in the pericardium during the 1-h observational period (mean of 16 ± 3.4 ml of blood loss per animal). Haemodynamic parameters remained stable during the entire study period and no plug dislodgement was detected with normal systemic blood pressure (mean arterial mean blood pressure: 65 ± 7 mmHg). Post-mortem analysis confirmed the full deployment and good fixation of all plugs, without macroscopic damages to the surrounding myocardium. CONCLUSIONS: This sutureless self-expandable apical occluder is a simple device capable of sealing large-size apical access sites (20-35 Fr) in an acute animal study. This approach is a step further towards less invasive transapical valve procedures in the clinical setting, and further animal tests will be performed to confirm the long-term efficacy and safety of this device.

Use of a ventricular septal defect occluder for apical closure in transapical aortic valve replacement.

During transapical transcatheter aortic valve replacement (TA-TAVR), the apical closure remains a challenge for the surgeon, having the risk for ventricular tear and massive bleeding. Apical closure devices are already under clinical evaluation, but only a few can lead to a full percutaneous TA-TAVR. We describe the successful use of a 9-mm myocardial occluder (ventricular septal defect occluder) that was used to seal the apex after a standard TA-TAVR (using the Sapien XT 23-mm transcatheter valve and the Ascendra + delivery system). The placement of the nonmodified myocardial occluder was performed through the Ascendra + delivery system, with a very small amount of blood loss and an acceptable sealing of the apical tear. This approach is feasible and represents a further step toward true-percutaneous transapical heart valve procedures. Modified apical occluders are under evaluation in animal models.