Search

Summary. Tomato-infecting begomoviruses have been reported throughout Brazil since the introduction of the B biotype of Bemisia tabaci. Here, we report a large scale survey on the distribution and genetic diversity of tomato-infecting begomoviruses. Tomato samples with typical begomovirus symptoms were collected in seven different states, comprising the major tomato growing areas of the country. Viruses were detected by polymerase chain reaction (PCR) using universal primers for the genus Begomovirus. PCR-amplified fragments were cloned and sequenced. Based on sequence comparisons and phylogenetic analyses, at least seven previously undescribed species of begomoviruses were found. Four of the new viruses were found exclusively in the Southeastern states, two exclusively in the Northeastern states, and one was found in both regions. Sequence comparisons reveal strong evidence of recombination among the Brazilian begomoviruses. Together, the results indicate the existence of a high degree of pre-existing genetic diversity among tomato-infecting begomoviruses in Brazil and suggest that these viruses have emerged after being transferred from natural hosts to tomatoes, due to the introduction into Brazil of a novel polyfagous biotype of the whitefly vector. [ABSTRACT FROM AUTHOR]

The emergency of diseases caused by begomoviruses and phytoplasmas continues increasing. In Cuba, «Candidatus Phytoplasma asteris» affect diverse hosts and the begomoviruses have emerged among the principal pathogens limiting the production of solanaceous and bean crops. Nowadays, studies for their individual identification are leading. However, there are unknown aspects such as their coexistence, the indicators of their presence, as well as the molecular identity of the possible agent associated with the symptom complex. In the last years, the observation of diverse symptoms in the field, along with the incidence of whiteflies and high populations of leafhoppers, suggests the presence of mixed infections by these pathogens. Samples from symptomatic plants were analyzed. In bean crops, samples with predominant symptoms of golden yellow mosaic from the eastern and western regions of Cuba were collected. In soybean crops, samples showing diverse symptoms from the eastern region were evaluated. Technologies of nested PCR allowed detecting Candidatus Phytoplasma asteris in these plants. The RCA/RFLP's methodology made possible the characterization of complete genomes of begomoviruses present in these crops. High indexes of infection by both pathogens were observed in individual detection and in mixed infections. The statistical analysis showed a high probability of co-infection occurrence when the presence of phytoplamas was detected in first instance. The high indexes in the coexistence of both entities suggest to detail into interaction studies among these that allow the design of major efficiency measures for the fabaceous crops management. [ABSTRACT FROM AUTHOR]

This paper evaluates the performance of a simplified bench-scale UV-photoreactor used to inactivate Escherchia coli and eggs of Ascaris lumbricoides. The photoreactor consisted of a tubular unit constructed with PVC tube, 100 mm diameter and 45 cm total height, with a low-pressure mercury lamp adapted in the centre of the tube. The reactor was tested to disinfect the effluent from a trickling filter and from an UASB reactor, both fed with domestic sewage. The results showed an excellent performance of the photoreactor, with very high E. coli inactivation efficiencies being observed for the aerobic effluent (in the range of 4 to 5 log-units, for doses varying from 50.7 to 13.6 mW x s x cm(-2)) and also for the effluent from the UASB reactor (usually above 4 log-units, for doses of 20.3 and 13.6 mW x s x cm(-2)). In relation to the inactivation of helminth eggs, it was observed that UV radiation significantly affected the development of eggs of Ascaris lumbricoides, with the better results being obtained for radiation times of 40 and 60 seconds (doses of 13.6 and 20.3 mW x s x cm(-2), respectively), when approximately 65% of the eggs remained in the stage of single cell and only 9 to 10% were able to fully develop to the stage of motile larva.

The paper evaluates and models helminth eggs removal in a combined UASB (Upflow Anaerobic Sludge Blanket) reactor-maturation pond system (one baffled and one unbaffled pond in parallel). The system is comprised of demonstration-scale units, treating actual domestic sewage from Itabira city, Brazil. The paper addresses the following points: (i) removal of helminth eggs from the wastewater in the system; (ii) comparison of the observed removal efficiency with the predictions using the Ayres et al. model; (iii) accumulation of helminth eggs in the sludge; (iv) viability of eggs in the sludge; (v) distribution of helminth species in the sludge. The removal efficiency of helminth eggs from the wastewater in both ponds was 100% for most of the time (0 counts in the final effluent). The predictions of helminth eggs removal according to the Ayres et al. model can be considered reasonable. After one year of operation, 88% of the eggs in the sludge remained viable. Helminth eggs counts in the sludge tended to decrease along the baffled pond length (from first to last compartment). The prevailing helminth species found in the sludge from both ponds was Ascaris lumbricoides.

The paper presents the monitoring results of a pilot UASB reactor followed by a baffled polishing pond treating domestic sewage in Brazil. Longitudinal profiles of E coli and helminth eggs along the baffled pond have been undertaken. The experimental results have been compared with von Sperling's model for coliform removal and Ayres' model for helminth eggs removal, and the fitting was considered satisfactory in both cases. The distribution of the helminth species along the system is also presented.

This research aimed at the investigation of an overland flow system applied to the post-treatment of anaerobic effluents. The system treated domestic sewage in Itabira City (Brazil), being composed by an anaerobic reactor and an overland flow system, the latter working as a post-treatment unit. A portion of the reactor's effluent was directed to a group of three overland flow slopes (demonstration scale), that were operated with different application rates. During Phase 1 of the research the overland flow system was fed under a permanent hydraulic regime (constant flows), having as inflow the effluent from an UASB reactor (full-scale, volume of 477 m3). During Phase 2, the overland system was fed under a hydraulic transient pattern (variable flows with hourly variations), having as inflow the effluent from a partitioned UASB reactor (demonstration-scale, volume of 9 m3). In general, the performance of the overland flow system as a polishing step was very good, mainly because of the low solids and organic matter concentration in the final effluent (average values of BOD from 48 to 62 mg/L; COD from 98 to 119 mg/L and SS from 17 to 57 mg/L). Regarding nutrients and coliforms, the system also reached satisfactory efficiency levels. Based on the experience obtained with this study, it is suggested that overland flow systems, working as post-treatment step of UASB reactors, can work with application rates in the range of 0.4 to 0.5 m3/m.h, which are higher than those normally applied.