A NodD-like protein activates transcription of genes involved with naringenin degradation in a flavonoid-dependent manner in Herbaspirillum seropedicae.

Herbaspirillum seropedicae is an associative, endophytic non-nodulating diazotrophic bacterium that colonises several grasses. An ORF encoding a LysR-type transcriptional regulator, very similar to NodD proteins of rhizobia, was identified in its genome. This nodD-like gene, named fdeR, is divergently transcribed from an operon encoding enzymes involved in flavonoid degradation (fde operon). Apigenin, chrysin, luteolin and naringenin strongly induce transcription of the fde operon, but not that of the fdeR, in an FdeR-dependent manner. The intergenic region between fdeR and fdeA contains several generic LysR consensus sequences (T-N11 -A) and we propose a binding site for FdeR, which is conserved in other bacteria. DNase I foot-printing revealed that the interaction with the FdeR binding site is modified by the four flavonoids that stimulate transcription of the fde operon. Moreover, FdeR binds naringenin and chrysin as shown by isothermal titration calorimetry. Interestingly, FdeR also binds in vitro to the nod-box from the nodABC operon of Rhizobium sp. NGR234 and is able to activate its transcription in vivo. These results show that FdeR exhibits two features of rhizobial NodD proteins: nod-box recognition and flavonoid-dependent transcription activation, but its role in H. seropedicae and related organisms seems to have evolved to control flavonoid metabolism.

Molecular characterisation of Salmonella strains isolated from outbreaks and sporadic cases of diarrhoea occurred in Paraná State, South of Brazil.

A total of 46 strains of Salmonella isolated from patients with sporadic diarrhoea or involved in foodborne outbreaks were analysed by PCR for genus identification and serotyping. Subtyping was performed using pulsed-field gel electrophoresis (PFGE) and multiple amplification of phage locus typing (MAPLT) for seven variable loci. Bacteria were identified as belonging to serotype Enteritidis (33 strains; 71·7%) or Typhimurium (13 strains; 28·3%). A high similarity coefficient (94·6%) was observed in the Salmonella Enteritidis group for which were found three related PFGE profiles and only one MAPLT; strains representing profile PA/P1/MI were prevalent (27; 81·8%). Two Salmonella Typhimurium isolates were untypeable by PFGE. The remaining 11 strains had eight PFGE and three MAPLT profiles. The discriminatory power of MAPLT was lower than that of PFGE. Salmonella Enteritidis of clonal nature is predominant in Paraná State, with the most prevalent profile PA/P1/M1 associated with sporadic diarrhoea and with seven of nine reported outbreaks. In conclusion, PFGE shows higher discriminatory power among Salmonella strains.

Development and validation of the first SSR markers for Mimosa scabrella Benth.

Mimosa scabrella Benth., popularly known as ''bracatinga'', is a pioneer and endemic species of Brazil, occurring in Mixed Ombrophilous Forest associated with Brazilian Atlantic Rainforest biomes. It is a fast-growing tree of the Fabaceae family that facilitates the dynamics of ecological succession. SSR development, when there is no genome sequence, is time and labor intensive and there are no molecular markers for M. scabrella. We developed and validated the first microsatellite markers for this tetraploid species, evaluating mother trees and progenies. Using Illumina sequencing, we identified 290 SSR loci and 211 primer pairs. After 31 SSR loci PCR/agarose electrophoresis selection, a subset of 11 primer pairs was synthetized with fluorescence in the forward primer for PCR and capillary electrophoresis validation with leaf DNA of 33 adult and 411 progeny individuals. Polymorphic locus percentage was 36, 4 in 11 loci, 3 chloroplast SSRs, and 1 nuclear SSR. Allele number of polymorphic loci ranged from 2 to 11 alleles considering all sampling. All 11 primer pairs were also tested for cross-species amplification for five Fabaceae-Mimosoideae species, ranging from 2 loci transferred to Calliandra tweedii Benth. and all 11 loci transferred to Mimosa taimbensis Burkart. The assessed and validated SSR markers for M. scabrella are suitable and useful for analysis and population genetic studies.

RNA-seq transcriptional profiling of Herbaspirillum seropedicae colonizing wheat (Triticum aestivum) roots.

Herbaspirillum seropedicae is a diazotrophic and endophytic bacterium that associates with economically important grasses promoting plant growth and increasing productivity. To identify genes related to bacterial ability to colonize plants, wheat seedlings growing hydroponically in Hoagland's medium were inoculated with H. seropedicae and incubated for 3 days. Total mRNA from the bacteria present in the root surface and in the plant medium were purified, depleted from rRNA and used for RNA-seq profiling. RT-qPCR analyses were conducted to confirm regulation of selected genes. Comparison of RNA profile of root attached and planktonic bacteria revealed extensive metabolic adaptations to the epiphytic life style. These adaptations include expression of specific adhesins and cell wall re-modeling to attach to the root. Additionally, the metabolism was adapted to the microxic environment and nitrogen-fixation genes were expressed. Polyhydroxybutyrate (PHB) synthesis was activated, and PHB granules were stored as observed by microscopy. Genes related to plant growth promotion, such as auxin production were expressed. Many ABC transporter genes were regulated in the bacteria attached to the roots. The results provide new insights into the adaptation of H. seropedicae to the interaction with the plant.

Matrix-assisted laser desorption ionization-time of flight mass spectrometry analysis of Escherichia coli categories.

The mass profiles of cell-free extracts of 180 commensal and pathogenic strains of Escherichia coli were determined by MALDI-TOF mass spectrometry (MS). While some peaks were highly conserved in all E. coli, several peaks occurred only in some strains, showing heterogeneity among them. We did not detect strain-specific peaks for any of the E. coli categories tested. However, review of the fully conserved and the variable peaks suggested that MALDI-TOF MS has the potential to distinguish commensal and uropathogenic E. coli strains. Additionally, eight Shigella sonnei isolates were tested and found to be indistinguishable from E. coli by MALDI-TOF MS under the test conditions.

Naringenin degradation by the endophytic diazotroph Herbaspirillum seropedicae SmR1.

Several bacteria are able to degrade flavonoids either to use them as carbon sources or as a detoxification mechanism. Degradation pathways have been proposed for several bacteria, but the genes responsible are not known. We identified in the genome of the endophyte Herbaspirillum seropedicae SmR1 an operon potentially associated with the degradation of aromatic compounds. We show that this operon is involved in naringenin degradation and that its expression is induced by naringenin and chrysin, two closely related flavonoids. Mutation of fdeA, the first gene of the operon, and fdeR, its transcriptional activator, abolished the ability of H. seropedicae to degrade naringenin.

Proteins differentially expressed by Shiga toxin-producing Escherichia coli strain M03 due to the biliar salt sodium deoxycholate.

Shiga toxin-producing Escherichia coli (STEC) can cause conditions ranging from diarrhea to potentially fatal hemolytic uremic syndrome. Enteropathogen adaptation to the intestinal environment is necessary for the development of infection, and response to bile is an essential characteristic. We evaluated the response of STEC strain M03 to the bile salt sodium deoxycholate through proteomic analysis. Cell extracts of strain M03 grown with and without sodium deoxycholate were analyzed by two-dimensional electrophoresis; the differentially expressed proteins were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Three proteins were found to be differentially expressed due to sodium deoxycholate. Glycerol dehydrogenase and phosphate acetyltransferase, which are involved in carbon metabolism and have been associated with virulence in some bacteria, were downregulated. The elongation factor Tu (TufA) was upregulated. This protein participates in the translation process and also has chaperone activities. These findings help us understand strategies for bacterial survival under these conditions.

Comparative proteomic analysis between early developmental stages of the Coffea arabica fruits.

Coffee is one of the most valuable agricultural commodities. There is much agronomic research on coffee, but molecular knowledge of its fruit development and ripening is limited. This study reports a comparative proteomic investigation of immature coffee fruits in two early developmental stages: stage 1, cell division and elongation of the perisperm; and stage 2, early growth of the endosperm progressively replacing the perisperm. Proteins were extracted using a modified SDS-phenol method and two-dimensional electrophoresis gels stained with Coomassie blue revealed about 300 well-resolved polypeptide spots in the pH range of 3 to 10. The differentially expressed polypeptides spots were excised, trypsin-digested, and analyzed by MALDI-TOF mass spectrometry. Peptide MS data were searched against the coffee EST database. Most of the identified protein spots are involved in the glycolytic pathway and energy reserve, and are more highly expressed at stage 2.

Culture-independent analysis of endophytic bacterial communities associated with Brazilian sugarcane.

Sugarcane is an economically important culture in Brazil. Endophytic bacteria live inside plants, and can provide many benefits to the plant host. We analyzed the bacterial diversity of sugarcane cultivar RB-72454 by cultivation-independent techniques. Total DNA from sugarcane stems from a commercial plantation located in Paraná State was extracted. Partial 16S rRNA genes were amplified and sequenced for library construction. Of 152 sequences obtained, 52% were similar to 16S rRNA from Pseudomonas sp, and 35.5% to Enterobacter sp. The genera Pantoea, Serratia, Citrobacter, and Klebsiella were also represented. The endophytic communities in these sugarcane samples were dominated by the families Enterobacteriaceae and Pseudomonadaceae (class Gammaproteobacteria).

Crystallization and preliminary crystallographic analysis of LipC12, a true lipase isolated through a metagenomics approach.

LipC12, a true lipase from family I.1 of bacterial lipases which was previously isolated through a metagenomics approach, contains 293 amino acids. Among lipases of known three-dimensional structure, it has a sequence identity of 47% to the lipase from Pseudomonas aeruginosa PAO1. Recombinant N-terminally His(6)-tagged LipC12 protein was expressed in Escherichia coli, purified in a homogenous form and crystallized in several conditions, with the best crystals being obtained using 2.0 M sodium formate and 0.1 M bis-tris propane pH 7.0. X-ray diffraction data were collected to 2.70 Å resolution. The crystals belonged to the tetragonal space group P4(1)22, with unit-cell parameters a = b = 58.62, c = 192.60 Å.

Polymorphisms of the promoter and exon 3 of the receptor for advanced glycation end products (RAGE) in Euro- and Afro-Brazilians.

The receptor for advanced glycation end products (RAGE or AGER), a member of the immunoglobulin superfamily, is involved in pathologies such as atherosclerosis and diabetes. Over 50 SNPs were reported for RAGE, among which were the promoter region polymorphisms -429T>C (rs1800625), -374T>A (rs1800624) and a 63-bp deletion (-407 to -345 bp), all related to increased RAGE expression. Additionally, in the exon 3, a putative site of binding ligands, the missense variation G82S (rs2070600) was associated with skin disorders in patients with diabetes. We have determined allele, genotype and haplotype frequencies of RAGE polymorphisms -429T>C, -374T>A, 63-bp deletion and G82S in Euro-Brazilians (n = 108) and Afro-Brazilians (n = 91), characterized according to the predominant ancestry of the individuals. The allele frequencies for Euro- and Afro-Brazilians were as follows: -429C, 12.5% vs. 12.1% (P = 0.90); -374A, 31.5% vs. 26.2% (P = 0.25); 63del, 0.0% vs. 3.8% (P = 0.004); and 82S, 1.9% vs. 0.6% (P = 0.24). Absolute linkage disequilibrium was found between the promoter polymorphisms -429T>C and -374T>A plus the 63-bp deletion (D'=1.000; P < 0.0001). The haplotype frequencies differed (P = 0.003) between Euro- and Afro-Brazilians. Our results showed that the frequencies of the 63-bp deletion were higher in Afro-Brazilians, while the other analysed polymorphisms were similarly distributed in the studied populations. The -374T>A plus 63-bp deletion polymorphism captures more than 80% of the haplotypic variation in the studied population.

Low prevalence of glucokinase gene mutations in gestational diabetic patients with good glycemic control.

Glucokinase (GCK) plays a key role in glucose homeostasis. Gestational diabetes mellitus increases the risk of gestational complications in pregnant women and fetuses. We screened for mutations in coding and flanking regions of the GCK gene in pregnant women with or without gestational diabetes in a Brazilian population. A sample of 200 pregnant women classified as healthy (control, N = 100) or with gestational diabetes (N = 100) was analyzed for mutations in the GCK gene. All gestational diabetes mellitus patients had good glycemic control maintained by diet alone and no complications during pregnancy. Mutations were detected by single-strand conformation polymorphism and DNA sequencing. Thirteen of the 200 subjects had GCK gene mutations. The mutations detected were in intron 3 (c.43331A>G, new), intron 6 (c.47702T>C, rs2268574), intron 9 (c.48935C>T, rs2908274), and exon 10 (c.49620G>A, rs13306388). None of these GCK mutations were found to be significantly associated with gestational diabetes mellitus. In summary, we report a low frequency of GCK mutations in a pregnant Brazilian population and describe a new intronic variation (c.43331A>G, intron 3). We conclude that mutations in GCK introns and in non-translatable regions of the GCK gene do not affect glycemic control and are not correlated with gestational diabetes mellitus.

Prokaryotic communities of acidic peatlands from the southern Brazilian Atlantic Forest.

The acidic peatlands of southern Brazil are ecosystems essential for the maintenance of the Atlantic Forest, one of the 25 hot-spots of biodiversity in the world. In this work, we investigated the composition of prokaryotic communities in four histosols of three acidic peatland regions by constructing small-subunit (SSU) rRNA gene libraries and sequencing. SSU rRNA gene sequence analysis showed the prevalence of Acidobacteria (38.8%) and Proteobacteria (27.4%) of the Bacteria domain and Miscellaneous (58%) and Terrestrial (24%) groups of Crenarchaeota of the Archaea domain. As observed in other ecosystems, archaeal communities showed lower richness than bacterial communities. We also found a limited number of Euryarchaeota and of known methanotrophic bacteria in the clone libraries.

Naringenin regulates expression of genes involved in cell wall synthesis in Herbaspirillum seropedicae.

Five thousand mutants of Herbaspirillum seropedicae SmR1 carrying random insertions of transposon pTnMod-OGmKmlacZ were screened for differential expression of LacZ in the presence of naringenin. Among the 16 mutants whose expression was regulated by naringenin were genes predicted to be involved in the synthesis of exopolysaccharides, lipopolysaccharides, and auxin. These loci are probably involved in establishing interactions with host plants.

Virulence characteristics and antimicrobial susceptibility of uropathogenic Escherichia coli strains.

Eight virulence factors associated with uropathogenic Escherichia coli (UPEC) were investigated in 204 clinical isolates of E. coli recovered from urine cultures at counts ≥10(5). The bacteria were classified into two groups according to the number of leukocytes in urine samples from which they were isolated: group I ≤8 leukocytes/hpf, 104 strains; group II >8 leukocytes/hpf, 100 strains. Two multiplex PCR systems were used to detect genes encoding adhesin P (pap), adhesin S (sfa), afimbrial adhesin I (afa), siderophore aerobactin (aer), alpha-hemolysin (hly), cytotoxic necrotizing factor type 1 (cnf1), and traT associated with serum resistance. The PAI marker for the virulence island identified in strains CFT072 and CVD432, a marker of enteroaggregative E. coli, was also investigated using PCR. The susceptibility profile of E. coli strains was determined by disk diffusion method. Ninety percent UPEC showed at least one of the virulence genes, the prevalence being traT (76%), aer (41%), PAI (32%), sfa (26%), pap (25%), cnf1 (18%), afa (6%), and hly (5%). There was no significant difference in the distribution of virulence genes between groups I and II. A significantly higher degree of virulence was detected in UPEC group II. The CVD432 gene was not detected in any of the UPECs. Fifty-nine percent of the strains were resistant to at least one of the antimicrobials that we tested; the most common being resistance to ampicillin (51%) and trimethoprim-sulfamethoxazole (44%).

Influence of soil characteristics on the diversity of bacteria in the Southern Brazilian Atlantic Forest.

The Brazilian Atlantic Forest is one of the 25 biodiversity hot spots in the world. Although the diversity of its fauna and flora has been studied fairly well, little is known of its microbial communities. In this work, we analyzed the Atlantic Forest ecosystem to determine its bacterial biodiversity, using 16S rRNA gene sequencing, and correlated changes in deduced taxonomic profiles with the physicochemical characteristics of the soil. DNAs were purified from soil samples, and the 16S rRNA gene was amplified to construct libraries. Comparison of 754 independent 16S rRNA gene sequences from 10 soil samples collected along a transect in an altitude gradient showed the prevalence of Acidobacteria (63%), followed by Proteobacteria (25.2%), Gemmatimonadetes (1.6%), Actinobacteria (1.2%), Bacteroidetes (1%), Chloroflexi (0.66%), Nitrospira (0.4%), Planctomycetes (0.4%), Firmicutes (0.26%), and OP10 (0.13%). Forty-eight sequences (6.5%) represented unidentified bacteria. The Shannon diversity indices of the samples varied from 4.12 to 3.57, indicating that the soils have a high level of diversity. Statistical analysis showed that the bacterial diversity is influenced by factors such as altitude, Ca(2+)/Mg(2+) ratio, and Al(3+) and phosphorus content, which also affected the diversity within the same lineage. In the samples analyzed, pH had no significant impact on diversity.

Chemical composition of lipopolysaccharides isolated from various endophytic nitrogen-fixing bacteria of the genus Herbaspirillum.

Bacteria from the genus Herbaspirillum are endophytes responsible for nitrogen fixation in gramineous plants of economic importance such as maize, sugarcane, sorghum, rice, and wheat. Some species are known to produce plant growth substances. In contrast, Herbaspirillum rubrisubalbicans strains are known to be mild plant pathogens. The molecular communication between the plant and the microbes might involve lipopolysaccharides present in the outer membrane of these gram-negative bacteria. Phenol-water extraction was used to obtain lipopolysaccharides from 7 strains of Herbaspirillum seropedicae (SmR1, Z67, Z78, ZA95, and M2) and H. rubrisubalbicans (M1 and M4). The electrophoretic profiles and chemical composition of the lipopolysaccharides obtained in the phenol and aqueous extracts were shown herein.

Diversity of endophytic bacteria in Brazilian sugarcane.

Endophytic bacteria live inside plant tissues without causing disease. Studies of endophytes in sugarcane have focused on the isolation of diazotrophic bacteria. We examined the diversity of endophytic bacteria in the internal tissues of sugarcane stems and leaves, using molecular and biochemical methods. Potato-agar medium was used to cultivate the endophytes; 32 isolates were selected for analysis. DNA was extracted and the 16S rRNA gene was partially sequenced and used for molecular identification. Gram staining, catalase and oxidase tests, and the API-20E system were used to characterize the isolates. The strains were divided into five groups, based on the 16S rRNA sequences. Group I comprised 14 representatives of the Enterobacteriaceae; group II was composed of Bacilli; group III contained one representative, Curtobacterium sp; group IV contained representatives of the Pseudomonadaceae family, and group V had one isolate with an uncultured bacterium. Four isolates were able to reduce acetylene to ethylene. Most of the bacteria isolated from the sugarcane stem and leaf tissues belonged to Enterobacteriaceae and Pseudomonaceae, respectively, demonstrating niche specificity. Overall, we found the endophytic bacteria in sugarcane to be more diverse than previously reported.

Isolation of a novel lipase from a metagenomic library derived from mangrove sediment from the south Brazilian coast.

A novel gene coding for a LipA-like lipase with 283 amino acids and a molecular mass of 32 kDa was isolated and characterized from a metagenomic library prepared from mangrove sediment from the south Brazilian coast. LipA was 52% identical to a lipolytic enzyme from an uncultured bacterium and shared only low identities (< or =31%) with lipases/esterases from cultivable microorganisms. Phylogenetic analysis showed that LipA, together with an orthologous protein from an uncultured bacterium, forms a unique branch within family I of true lipases, thereby constituting a new lipase subfamily. Activity determination using crude extracts of Escherichia coli bearing the lipA gene revealed that this new enzyme has a preference for esters with short-chain fatty acids (C < or = 10) and has maximum activity against p-nitrophenyl-caprate (chain length C10, 0.87 U/mg protein). The optimum pH of LipA was 8.0, and the enzyme was active over a temperature range of 20 to 35 degrees C, with optimum activity against p-nitrophenyl-butyrate at 35 degrees C and pH 8.0.

The functional polymorphisms -429T>C and -374T>A of the RAGE gene promoter are not associated with gestational diabetes in Euro-Brazilians.

The receptor for advanced glycation end products (RAGE or AGER) is a multiligand member of the immunoglobulin superfamily. RAGE is expressed in several tissues, including human myometrium, chorionic villi and placenta. Advanced glycation end products are the best studied ligands of RAGE; they have pro-inflammatory actions in human gestational tissues, increasing oxidative stress and the release of cytokines and prostaglandins. We investigated the association of RAGE gene promoter polymorphisms -429T>C (rs1800625) and -374T>A (rs1800624) with gestational diabetes. A sample of 750 unrelated European origin pregnant Brazilian women were classified as nondiabetic (control group, N = 600) or having gestational diabetes (N = 150) according to American Diabetes Association 2009 criteria. Genotyping was performed by PCR-RFLP. The frequencies of the rare alleles -429C (6.3 versus 9.1%) and -374A (26 versus 30%) were not significantly different between the gestational diabetes patients and healthy pregnant women. Also, the -429T>C and -374T>A polymorphisms were not associated with body mass index, lipid profile, fasting glycemia, HbA1C, or insulin requirement. We found that functional promoter polymorphisms of the RAGE gene were not associated with gestational diabetes or its complications in these Euro-Brazilian patients.