Integrated diversity analysis of the microbial community in a reverse osmosis system from a Brazilian oil refinery.

Oil refineries are known for the large volume of water used in their processes, as well as the amount of wastewater generated at the end of the production chain. Due to strict environmental regulations, the recycling of water has now become a viable alternative for refineries. Among the many methods available to treat wastewater for reuse, the use of membranes in reverse osmosis systems stands out due to several economic and environmental benefits. However, these systems are vulnerable to contamination and deposition of microorganisms, mainly because of the feedwater quality. In this study, the microbial diversity of feedwater and reverse osmosis membranes was investigated using a combination of culture-dependent and culture-independent methods in order to characterize the microorganisms colonizing and deteriorating the membranes. In total, 37 bacterial isolates, 17 filamentous fungi and approximately 400 clones were obtained and analyzed. Among the bacterial genera identified, the most represented were Sphingobium, Acidovorax, Microbacterium, Rhizobium and Shinella. The results revealed genera that acted as candidate key players in initial biofilm formation in membrane systems, and provided important information concerning the microbial ecology of oligotrophic aquatic systems.

Cyanobacteria, microcystins and cylindrospermopsin in public drinking supply reservoirs of Brazil.

Brazil has a history of blooms and contamination of freshwater systems by cyanobacterial toxins. The monitoring relevance of toxins from cyanobacteria in reservoirs for public supply is notorious given its high toxicity to mammals, included humans beings. The most recurrent toxins in Brazilian water bodies are microcystins (MC). However, the recent record of cylindrospermopsin (CYN) in northeastern Brazil, Pernambuco state, alerts us to the possibility that this could be escalating. This study reports occurrence of MC and CYN, quantified with ELISA, in 10 reservoirs, devoted to public drinking supply in northeastern Brazil. The composition and quantification of the cyanobacteria community associated with these water bodies is also presented. From 23 samples investigated for the presence of MC, and CYN, 22 and 8 out were positive, respectively. Considering the similarity of the cyanobacteria communities found in reservoirs from Pernambuco, including toxin-producing species associated to MC and CYN, we suggest that geographic spreading can be favored by these factors. These issues emphasize the need for increased monitoring of MC and CYN in drinking supply reservoirs in Brazil.

Phylogenetic study of Geitlerinema and Microcystis (Cyanobacteria) using PC-IGS and 16S-23S ITS as markers: investigation of horizontal gene transfer.

Selection of genes that have not been horizontally transferred for prokaryote phylogenetic inferences is regarded as a challenging task. The markers internal transcribed spacer of ribosomal genes (16S-23S ITS) and phycocyanin intergenic spacer (PC-IGS), based on the operons of ribosomal and phycocyanin genes respectively, are among the most used markers in cyanobacteria. The region of the ribosomal genes has been considered stable, whereas the phycocyanin operon may have undergone horizontal transfer. To investigate the occurrence of horizontal transfer of PC-IGS, phylogenetic trees of Geitlerinema and Microcystis strains were generated using PC-IGS and 16S-23S ITS and compared. Phylogenetic trees based on the two markers were mostly congruent for Geitlerinema and Microcystis, indicating a common evolutionary history among ribosomal and phycocyanin genes with no evidence for horizontal transfer of PC-IGS. Thus, PC-IGS is a suitable marker, along with 16S-23S ITS for phylogenetic studies of cyanobacteria.

Microcystin-producing genotypes from cyanobacteria in Brazilian reservoirs.

The aim of this study was to evaluate the use of new oligonucleotide primers (mcyB-F/R, mcyB-F/R-A, and mcyB-F/R-B) designed from Brazilian cyanobacteria for the detection of microcystin-producing genotypes in 27 environmental samples from water reservoirs and 11 strains of Microcystis. Microcystins were found using HPLC in all 11 strains and 19 of the environmental samples. The new oligonucleotide primers amplified fragments of microcystin-producing genes, including the eight environmental samples in which no microcystins were detected by HPLC, but which presented amplified fragments, thereby demonstrating the existence of microcystin-producing genes. The new oligonucleotide primers exhibited better specificity when used with environmental samples and were more reliable in comparison with those described in the literature (mcyB-FAA/RAA and mcyA-Cd/FR), which generate false-negative results. The better performance of these new oligonucleotide primers underline the need for designing molecular markers that are well fitted to the regional biological diversity. As this is a fast predictive technique for determining the presence or absence of microcystins, it could be used either alone or in conjunction with other techniques, such as the screening of samples to be sent for quantitative toxicological analysis using HPLC, thereby reducing monitoring cost and time. © 2010 Wiley Periodicals, Inc. Environ Toxicol, 2012.