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The prospection of bacteria that are resistant to polyaromatic hydrocarbons (PAH) of activated sludge from a Petrochemical Wastewater Treatment Plant (WWTP) allows investigating potential biodegraders of PAH. For this purpose, sludge samples were cultured with benzo(a)pyrene and/or naphthalene as carbon sources. The recovered isolates were characterized by biochemical methods and identified based on the analysis of the sequence of three genes: 16S, recA and gyrB. The isolated strains were shown to be capable of producing surfactants, which are important for compound degradation. The ability to reduce benzo(a)pyrene in vitro was tested by gas chromatography. After 20 days of experiment, the consortium that was enriched with 1 mg/L of benzo(a)pyrene was able to reduce 30% of the compound when compared to a control without bacteria. The four isolated strains that significantly reduced benzo(a)pyrene belong to the Burkholderia cepacia complex and were identified within the consortium as the species B. cenocepacia IIIa, B. vietnamiensis, B. cepacia, and B. multivorans. This finding demonstrates the biotechnological potential of the B. cepacia complex strains for use in wastewater treatment and bioremediation. Previous studies on hydrocarbon-degrading strains focused mainly on contaminated soil or marine areas. In this work, the strains were prospected from activated sludge in a WWTP and showed the potential of indigenous samples to be used in both improving treatment systems and bioremediation of areas contaminated with petrochemical waste.

Petroleum is the major energy matrix in the world whose refining generates chemical byproducts that may damage the environment. Among such waste, polycyclic aromatic hydrocarbons (PAH) are considered persistent pollutants. Sixteen of these are considered priority for remediation, and among them is benzo(a)pyrene. Amid remediation techniques, bioremediation stands out. The genus Burkholderia is amongst the microorganisms known for being capable of degrading persistent compounds; its strains are used as models to study such ability. High-throughput sequencing allows researchers to reach a wider knowledge about biodegradation by bacteria. Using transcripts and mRNA analysis, the genomic regions involved in this aptitude can be detected. To unravel these processes, we used the model B. vietnamiensis strain G4 in two experimental groups: one was exposed to benzo(a)pyrene and the other one (control) was not. Six transcriptomes were generated from each group aiming to compare gene expression and infer which genes are involved in degradation pathways. One hundred fifty-six genes were differentially expressed in the benzo(a)pyrene exposed group, from which 33% are involved in catalytic activity. Among these, the most significant genomic regions were phenylacetic acid degradation protein paaN, involved in the degradation of organic compounds to obtain energy; oxidoreductase FAD-binding subunit, related to the regulation of electrons within groups of dioxygenase enzymes with potential to cleave benzene rings; and dehydrogenase, described as accountable for phenol degradation. These data provide the basis for understanding the bioremediation of benzo(a)pyrene and the possible applications of this strain in polluted environments.

Polyaromatic Hydrocarbons (PAH) are recalcitrant pollutants that are among the major Petroleum by-products. Among them, benzo(a)pyrene receives special attention as it is carcinogenic and highly insoluble, being really difficult to decompose with conventional treatments. Wastewater treatment plants (WWTP), often use biological techniques such as activated sludge, that rely on microorganisms to degrade organic compounds. Burkholderia genus is known for its biodegradation ability and have been used as study model. Using transcripts and mRNA analyses, one can find out genomic regions and functions involved in this aptitude. In this work we used the model strain B. vietnamiensis G4 aiming to find genes that are differentially expressed in the presence of benzo(a)pyrene. Six transcriptomes where generated from each experimental unit in order to compare gene expression and infer which genes are involved in benzo(a)pyrene degradation pathways. Thirty-six genes were differentially expressed in the group exposed to benzo(a)pyrene, most of them involved in catalytic activity. The most significant genomic regions are: phenylacetic acid degradation protein paaN involved in degradation of organic compounds to obtain energy, oxidoreductase FAD-binding subunit in the regulation of electrons within groups of dioxygenase enzymes, with potential to break benzene rings, and glutamic semialdehyde dehydrogenase, a region described as responsible for the ability of phenol degradation. These candidate genes are now target to new studies aiming optimization of treatment processes.

Secreted phospholipase B1 (CnPlb1) is essential for dissemination of Cryptococcus neoformans to the central nervous system (CNS) yet essential components of its secretion machinery remain to be elucidated. Using gene deletion analysis we demonstrate that CnPlb1 secretion is dependent on the CnSEC14 product, CnSec14-1p. CnSec14-1p is a homologue of the phosphatidylinositol transfer protein ScSec14p, which is essential for secretion and viability in Saccharomyces cerevisiae. In contrast to CnPlb1, neither laccase 1-induced melanization within the cell wall nor capsule induction were negatively impacted in CnSEC14-1 deletion mutants (CnΔsec14-1 and CnΔsec14-1CnΔsfh5). Similar to the CnPLB1 deletion mutant (CnΔplb1), CnΔsec14-1 was hypovirulent in mice and did not disseminate to the CNS by day 14 post infection. Furthermore, macrophage expulsion of live CnΔsec14-1 and CnΔplb1 (vomocytosis) was reduced. Individual deletion of CnSEC14-2, a closely related CnSEC14-1 homologue, and CnSFH5, a distantly related SEC fourteen like homologue, did not abrogate CnPlb1 secretion or virulence. However, reconstitution of CnΔsec14-1 with CnSEC14-1 or CnSEC14-2 restored both phenotypes, consistent with functional genetic redundancy. We conclude that CnPlb1 secretion is SEC14-dependent and that C. neoformans preferentially exports virulence determinants to the cell periphery via distinct pathways. We also demonstrate that CnPlb1 secretion is essential for vomocytosis.

Cryptococcus neoformans is an encapsulated yeast that causes a life-threatening meningoencephalitis in immunocompromised individuals. The ability to survive and proliferate at the human body temperature is an essential virulence attribute of this pathogen. This trait is controlled in part by the Ca 2+ -calcineurin pathway, which senses and utilizes cytosolic calcium for signaling. In the present study, the identification of the C. neoformans gene VCX1 , which encodes a vacuolar calcium exchanger, is reported. The VCX1 knockout results in hypersensitivity to the calcineurin inhibitor cyclosporine A at 35°C, but not at 30°C. Furthermore, high concentrations of CaCl 2 lead to growth inhibition of the vcx1 mutant strain only in the presence of cyclosporine A, indicating that Vcx1 acts in parallel with calcineurin. The loss of VCX1 does not influence cell wall integrity or capsule size but decreases secretion of the major capsular polysaccharide glucuronoxylomannan (GXM) in culture supernatants.Vcx1 also influences C. neoformans phagocytosis by murine macrophages and is required for full virulence in mice. Analysis of cellular distribution by confocal microscopy confirmed the vacuolar localization of Vcx1 in C. neoformans cells.

Cryptococcosis is a major opportunistic mycosis which has meningitis as its most frequent clinical presentation and can be fatal in the absence of antifungal therapy. The aetiological agents are Cryptococcus neoformans, which affects mainly immunocompromised subjects, and C. gattii, the aetiologic agent for cryptococcosis in healthy individuals. A recent outbreak of cryptococcosis on Vancouver Island, Canada, raised the level of concern about the epidemiology of this disease. In Brazil, between 1980 and 2002, six per cent of AIDS patients had cryptococcosis in course at the time of diagnosis. To identify the profile of cryptococcal meningitis patients in Rio Grande do Sul (RS), Brazil, a retroactive study was realized using data from patients registered at Laboratório Central de Saúde Pública IPB-LACEN/RS from 2000 to 2005. Most of the patients were men (77.12%), Caucasian (83.5%), median age between thirty and thirty-nine years old (46.24%) and HIV positive (95%).

Members of the Cryptococcus species complex are encapsulated basidiomycetous yeasts, which can affect the central nervous system (CNS) and if untreated may cause meningitis. Cryptococcus neoformans is an opportunistic pathogen causing infections mainly in immunocompromised individuals. Cryptococcus gattii is a primary pathogen responsible for a high incidence of cryptococcomas in the lung and brain and shows a delayed response to antifungal therapy. The differentiation between the two species is primarily based on their growth on and color change of canavanine - glycine-bromothymol blue agar (CGB). Since this test is not always reliable, a multiplex PCR to identify both Cryptococcus species using more than 130 samples was standardized and the results obtained compared to those with the CGB test, using the Crypto Check serotyping kit as the standard. The multiplex PCR was shown to be more specific than the CGB test, in that results obtained with it were in agreement with those from serotyping all the samples, while the data from the CGB test disagreed with 6 out of 131 samples.

The Cryptococcus species complex contains two sibling taxa, Cryptococcus neoformans and Cryptococcus gattii. Both species are basidiomycetous yeasts and major pathogens of humans and other mammals. Genotyping methods have identified major haploid molecular types of C. neoformans (VNI, VNII, VNB and VNIV) and of C. gattii (VGI, VGII, VGIII and VGIV). To investigate the phylogenetic relationships among these haploid genotypes, we selected 73 strains from 2000 globally collected isolates investigated in our previous typing studies, representing each of these genotypes and carried out multigene sequence analyses using four genetically unlinked nuclear loci, ACT1, IDE, PLB1 and URA5. The separate or combined sequence analyses of all four loci revealed seven clades with significant support for each molecular type. However, three strains of each species revealed some incongruence between the original molecular type and the sequence-based type obtained here. The topology of the individual gene trees was identical for each clade of C. neoformans but incongruent for the clades of C. gattii indicating recent recombination events within C. gattii. There was strong evidence of recombination in the global VGII population. Both parsimony and likelihood analyses supported three major clades of C. neoformans (VNI/VNB, VNII and VNIV) and four major clades of C. gattii (VGI, VGII, VGIII and VGIV). The sequence variation between VGI, VGIII and VGIV was similar to that between VNI/VNB and VNII. MATa was for the first time identified for VGIV. The VNIV and VGII clades are basal to the C. neoformans or the C. gattii clade, respectively. Divergence times among the seven haploid monophyletic lineages in the Cryptococcus species complex were estimated by applying the hypothesis of the molecular clock. The genetic variation found among all of these haploid monophyletic lineages indicates that they warrant varietal status.