Denise Mara Soares Bazzolli

Enrichment of mushrooms: An interesting strategy for the acquisition of lithium

The capability of Pleurotus ostreatus mushroom to accumulate lithium (Li) and the accessibility of this Li compared with lithium carbonate (Li(2)CO(3)), often used as psychiatric medicine, were investigated. Mushrooms were produced on a substrate-based on coffee husk, with different added concentrations of lithium chloride (LiCl). Biological efficiency (BE), the crude protein content, the concentration of Li and other elements present in mushrooms were determined. The sequential extraction and in vitro test were used to verify the accessibility and the degree of solubility of this element. Li concentration in mushrooms was directly influenced by increasing LiCl concentration in the substrate (P<0.05). The BE was not affected by different concentrations of LiCl. Li present in enriched mushrooms showed greater accessibility than in Li(2)CO(3). Therefore, P. ostreatus mushrooms, enriched with lithium can be an alternative source of Li, as well as being a food with high nutritional value.

In vivo bioavailability of selenium in enriched Pleurotus ostreatus mushrooms

The in vivo bioavailability of Se was investigated in enriched Pleurotus ostreatus mushrooms. A bioavailability study was performed using 64 Wistar male rats separated in 8 groups and fed with different diets: without Se, with mushrooms without Se, with enriched mushrooms containing 0.15, 0.30 or 0.45 mg kg(-1) Se and a normal diet containing 0.15 mg kg(-1) of Se using sodium selenate. The experiment was performed in two periods: depletion (14 days) and repletion (21 days), according to the Association of Official Analytical Chemists. After five weeks, the rats were sacrificed under carbon dioxide, and blood was drawn by heart puncture. Blood plasma was separated by centrifugation. The total Se concentration in the plasma of rats fed with enriched mushrooms was higher than in rats fed with a normal diet containing sodium selenate. The plasma protein profiles were obtained using size exclusion chromatography (SEC) and UV detectors. Aliquots of effluents (0.5 mL per minute) were collected throughout in the end of the chromatographic column. However, Se was determined by graphite furnace atomic absorption spectrometry (GF AAS) only in the aliquots where proteins were detected by SEC-UV. The plasma protein profile of rats fed with different diets was similar. The highest Se concentration was observed in a peptide presenting 8 kDa. Furthermore, the higher Se concentration in this peptide was obtained for rats fed with a diet using enriched mushrooms (7 μg L(-1) Se) compared to other diets (2-5 μg L(-1) Se). These results showed that Se-enriched mushrooms can be considered as an alternative Se food source for humans, due to their high bioavailability.

Galleria mellonella is an effective model to study Actinobacillus pleuropneumoniae infection

Actinobacillus pleuropneumoniae is responsible for swine pleuropneumonia, a respiratory disease that causes significant global economic loss. Its virulence depends on many factors, such as capsular polysaccharides, RTX toxins and iron-acquisition systems. Analysis of virulence may require easy-to-use models that approximate mammalian infection and avoid ethical issues. Here, we investigate the potential use of the wax moth Galleria mellonella as an informative model for A. pleuropneumoniae infection. Genotypically distinct A. pleuropneumoniae clinical isolates were able to kill larvae at 37 °C but had different LD50 values, ranging from 10(4) to 10(7) c.f.u. per larva. The most virulent isolate (1022) was able to persist and replicate within the insect, while the least virulent (780) was rapidly cleared. We observed a decrease in haemocyte concentration, aggregation and DNA damage post-infection with isolate 1022. Melanization points around bacterial cells were observed in the fat body and pericardial tissues of infected G. mellonella, indicating vigorous cell and humoral immune responses close to the larval dorsal vessel. As found in pigs, an A. pleuropneumoniae hfq mutant was significantly attenuated for infection in the G. mellonella model. Additionally, the model could be used to assess the effectiveness of several antimicrobial agents against A. pleuropneumoniae in vivo. G. mellonella is a suitable inexpensive alternative infection model that can be used to study the virulence of A. pleuropneumoniae, as well as assess the effectiveness of antimicrobial agents against this pathogen.

Pseudomonas spp. and Serratia liquefaciens as Predominant Spoilers in Cold Raw Milk.

The storage of fresh raw milk at low temperature does not prevent proliferation of psychrotrophic bacteria that can produce heat-resistant proteolytic enzymes contributing to the reduced shelf life of dairy products. This study aimed to identify the dominant psychrotrophic proteolytic enzyme-producing population of raw milk from Brazil. Raw milk samples collected in 3 different cooling tanks in Brazil were stored at optimal (45 h at 4 °C followed by 3 h at 7 °C) and suboptimal (45 h at 7 °C followed by 3 h at 10 °C) conditions to simulate farm storage and transportation allowed by Brazilian laws. The highly proteolytic enzyme-producing strains isolated from stored cold raw milk were characterized by repetitive sequence-based Polymerase Chain Reaction (PCR) analysis. This clustering resulted in 8 different clusters and 4 solitary fingerprints. The most proteolytic isolates from each rep-cluster were selected for identification using miniaturized kit, 16S rDNA and rpoB gene sequencing. Serratia liquefaciens (73.9%) and Pseudomonas spp. (26.1%) were identified as the dominant psychrotrophic microorganisms with high spoilage potential. The knowledge of milk spoilage microbiota will contribute to improved quality of milk and dairy products.

Complete Genome Sequence of MIDG2331, a Genetically Tractable Serovar 8 Clinical Isolate of Actinobacillus pleuropneumoniae

ABSTRACT We report here the complete annotated genome sequence of a clinical serovar 8 isolate Actinobacillus pleuropneumoniae MIDG2331. Unlike the serovar 8 reference strain 405, MIDG2331 is amenable to genetic manipulation via natural transformation as well as conjugation, making it ideal for studies of gene function.

Quorum sensing regulated phenotypes in Aeromonas hydrophila ATCC 7966 deficient in AHL production

The virulence of Aeromonas hydrophila is positively regulated by a quorum sensing (QS) system based on the ahyRI genes. The aim of this study was to evaluate the phenotypic characteristics related to virulence in the A. hydrophila strain ATCC 7966 in order to check if virulence traits are still functioning, despite the absence of a well characterized QS system. As expected, we were not able to detect quorum signaling AHL molecules in A. hydrophila ATCC 7966 by cross-streaking or thin layer chromatography with AHL biosensor strains. Although A. hydrophila ATCC 7966 did not produce AHLs, transcription of the ahyI and ahyR genes was observed by RT-PCR. Phenotypes generally recognized as QS-regulated in A. hydrophila were maintained in ATCC 7966; these phenotypes included proteolytic activity on casein and gelatin and amylolytic, lipolytic, and β-hemolytic activities, as well as the ability to adhere to surfaces and to form biofilms. Moreover, the addition of exogenous AHLs did not induce changes in the evaluated phenotypes. The results suggest that although this strain does not produce AHL as evaluated in this study, it maintains the phenotypes commonly associated with QS in this species indicating that other regulatory mechanisms independent of ahyRI may be in place.

Nitrogen-fixing bacteria in Eucalyptus globulus plantations.

Eucalypt cultivation is an important economic activity worldwide. In Portugal, Eucalyptus globulus plantations account for one-third of the total forested area. The nutritional requirements of this crop have been well studied, and nitrogen (N) is one of the most important elements required for vegetal growth. N dynamics in soils are influenced by microorganisms, such as diazotrophic bacteria (DB) that are responsible for biological nitrogen fixation (BNF), so the aim of this study was to evaluate and identity the main groups of DB in E. globulus plantations. Samples of soil and root systems were collected in winter and summer from three different Portuguese regions (Penafiel, Gavião and Odemira). We observed that DB communities were affected by season, N fertilization and moisture. Furthermore Bradyrhizobium and Burkholderia were the most prevalent genera in these three regions. This is the first study describing the dynamic of these bacteria in E. globulus plantations, and these data will likely contribute to a better understanding of the nutritional requirements of eucalypt cultivation and associated organic matter turnover.

Abiotic and biotic degradation of oxo-biodegradable plastic bags by Pleurotus ostreatus.

In this study, we evaluated the growth of Pleurotus ostreatus PLO6 using oxo-biodegradable plastics as a carbon and energy source. Oxo-biodegradable polymers contain pro-oxidants that accelerate their physical and biological degradation. These polymers were developed to decrease the accumulation of plastic waste in landfills. To study the degradation of the plastic polymers, oxo-biodegradable plastic bags were exposed to sunlight for up to 120 days, and fragments of these bags were used as substrates for P. ostreatus. We observed that physical treatment alone was not sufficient to initiate degradation. Instead, mechanical modifications and reduced titanium oxide (TiO2) concentrations caused by sunlight exposure triggered microbial degradation. The low specificity of lignocellulolytic enzymes and presence of endomycotic nitrogen-fixing microorganisms were also contributing factors in this process.

Differential expression of plg genes from Penicillium griseoroseum: plg1 a pectinolytic gene is expressed in sucrose and yeast extract.

Aims:  To study the regulation of the plg1 and plg2 genes of Penicillium griseoroseum, in order to identify the industrial potential of their products in alternative carbon sources that are cheaper and widely available in Brazil.

p518, a small floR plasmid from a South American isolate of Actinobacillus pleuropneumoniae

Highlights • Smallest floR plasmid in the Pasteurellaceae.• Unique arrangement with complete strA, but partial strB and sul2 sequences.• Loss of mobilisation genes indicated by partial mobC; no other mob genes.• Not transferrable by conjugation or natural transformation.