The chemical compositions of the surface conditioning layers formed by different types of solutions (from isolated EPS to whole culture media), involving different bacterial strains relevant for biocorrosion were compared, as they may influence the initial step in biofilm formation. Different substrata (polystyrene, glass, steel) were conditioned and analyzed by X-ray photoelectron spectroscopy. Peak decomposition and assignment were validated by correlations between independent spectral data and the ubiquitous presence of organic contaminants on inorganic substrata was taken into account. Proteins or peptides were found to be a major constituent of all conditioning layers and polysaccharides were not present in appreciable concentrations; the proportion of nitrogen which may be due to DNA was lower than 15%. There was no significant difference between the compositions of the adlayers formed from different conditioning solutions, except for the adlayers produced with tightly bound EPS extracted from D. alaskensis.

The primary source of biodiesel obtainment in Brazil is concentrated in oleaginous vegetables, especially soy. However, there is a great hold-up caused by competition with the food industry, which makes the search for alternative pathways that do not compete with other industries needed. The goal of this study was to investigate the biotechnological potential of cyanobacteria, which were grown in two different culture media, as an alternative approach for obtaining biodiesel. For this purpose, Microcystis aeruginosa CACIAM03, CACIAM08, Synechocystis sp. CACIAM05, Lyngbya sp. CACIAM07, Cyanobium sp. CACIAM14, Leptolyngbya sp. CACIAM18, Limnothrix redekei CACIAM25 and Planktothrix pseudoagardhii CACIAM27 were evaluated. Fatty acid composition was determined using gas chromatography. Fatty acids found in all strains were identified as palmitic acid (C16:0) (7.43–38.37% content), stearic acid (C18:0) (1.44–13.82%), caproic acid (C6:0) (0.82–78.84%) and oleic acid (C18:1) (1.13–46.76%). The biodiesel quality parameters were calculated based on the fatty acid profile. Strains that showed the best values and provided better biodiesel quality were Synechocystis sp. CACIAM05 and Microcystis aeruginosa CACIAM03 that were grown in BG-11 medium. This study showed us a promising source of biodiesel production from cyanobacterial lipids based on empirical calculations of the parameters of biodiesel quality that met the fuel standards. Furthermore, our results suggest the production of fatty acids through a metabolic route, due to the change in the profile of fatty acids in both culture media, providing valuable information for future engineering to increase the percentage of fatty acids that give better biodiesel quality.

The genus Synechococcus is widespread in aquatic environments and is known to be abundant in the Tucuruí Hydroelectric Power Station (HPS) reservoir, in eastern Brazilian Amazonia. However, little is known about this man-made water body's planktonic community. The diversity and phylogeny of the Synechococcus group present in the Tucuruí HPS reservoir were analysed using a culture-independent approach, by amplifying three different loci: the rpoC1 gene, the 16S-23S rRNA-internal transcribed spacer (ITS) and the cpcBA-IGS operon and comparing them to the 16S rRNA gene. The phenograms inferred independently using the three markers indicate the presence of at least six Synechococcus groups in the reservoir. The results also demonstrate a high level of microdiversity in the reservoir. The rpoC1 gene was unable to resolve the most recent branches and is therefore not suggested for studies at the Cyanobacteria genus level. The ITS sequences obtained permitted the modelling of the secondary structure of the RNA of the segment containing the two transfer RNAs and a variable stem region, which was a useful complementary tool in diversity studies of the group. The cpcBA genes have good phylogenetic signal and resolution throughout several taxonomic levels, allowing for correlation between the sequence and pigmentation physiology. However, the choice of molecular markers for phylogenetic analysis of cyanobacteria should be made carefully to maximize the phylogenetic signal.

The present study intended to characterize the phenotypic and genetic diversity of Brazilian isolates of Chromobacterium violaceum from aquatic environments within the Amazon region. Nineteen isolates showed morphological properties of C. violaceum and the majority grew at 44°C. Low temperatures, in contrast, showed to be inhibitory to their growth, as eleven isolates did not grow at 10ºC and nine did not produce pigmentation, clearly indicating an inhibition of their metabolism. The largest variation among isolates was observed in the citrate test (Simmons), in which 12 isolates were positive, and in the oxidation/fermentation of sucrose, with six positives isolates. Chloramphenicol, gentamicin and sulfonamides efficiently inhibited bacterial growth. Amplified products of the recA gene were digested with HindII or PstI, which produced three or four restriction fragments patterns, respectively. The combined analysis arranged the isolates into six genospecies. The higher diversity observed in Belém (genotypes C, D, E and F) may be a consequence of intense human occupation, pollution of the aquatic environment or due to the higher diversity of the environments sampled in that region. In conclusion, a high level of genetic and phenotypic diversity was observed, and four new genospecies were described.

Babesiosis is an infectious hemolytic disease that occurs worldwide, and is caused by a protozoan of the Babesia genus (Apicomplexa). Little is known about this genus; therefore, this study conducted a molecular characterization of Babesia spp in naturally infected dogs in northern Brazil. Blood samples were collected from 172 dogs from metropolitan Belém, and screened for Babesia spp using semi-nested polymerase chain reactions. Subsequently, 18S rDNA gene fragments were amplified and sequenced. Alignments of the 27 nucleotide sequences returned fragments measuring 1023 bp in size, which did not include any polymorphic sites (100% identity). This genotype was very similar to the 18S rDNA gene in B. vogeli. This study provides an important molecular characterization of the parasite responsible for canine babesiosis in naturally infected dogs in metropolitan Belém. In addition, the 18S rDNA gene in B. vogeli may represent the most common genotype occurring in South America.