N-fertiliser application or legume integration enhances N cycling in tropical pastures

Understanding the effects of N application or the introduction of a legume on N cycling is critical for achieving productive and sustainable grassland systems. This 2-year study assessed the N cycling of three pasture treatments: (1) mixed Marandu palisadegrass (Brachiaria brizantha) and forage peanut (Arachis pintoi) without N fertiliser (GRASS?+?LEGUME); (2) monoculture Marandu palisadegrass fertilised with 150 kg N ha^?1 year^?1 (GRASS?+?N); and (3) monoculture Marandu palisadegrass without N fertiliser (GRASS). Continuous stocking was used with a target canopy height of 0.20 to 0.25 m. Litter responses, forage and N intake, N livestock excretion and N cycling were measured. Existing litter and litter deposition rate were greatest in GRASS pasture (3030 and 84.3 vs. 2140 kg ha^?1 and 64.8 kg OM ha^?1 d^?1; average of GRASS?+?N and GRASS?+?LEGUME pastures, respectively; P?<?0.10). Litter decomposition rate in GRASS pasture was smaller 30.4 and 36.0% compared to GRASS?+?N and GRASS?+?LEGUME pastures, respectively (P?<?0.10). The GRASS?+?N obtained greatest (P?<?0.10) faecal N excretion (21.7 vs. 13.8 kg N ha^?1 season^?1), and urinary N excretion (32.0 vs. 14.2 kg N ha^?1 season^?1). In the GRASS?+?N and GRASS?+?LEGUME pastures, there was a positive overall change of N in the soil–plant–animal system of 13 and 33 kg N ha^?1 year^?1, respectively. In the GRASS pasture, there was an overall negative change of N in the soil–plant–animal system of ??41 kg N ha^?1 year^?1. Nitrogen application or the integration of forage peanut in a grass pasture increased the conservation of soil N reserves.

     

Prediction via Neural Networks of the Residual Hydrogen Peroxide used in Photo‐Fenton Processes for Effluent Treatment

This communication proposes the use of neural networks in the prediction of residual concentrations of hydrogen peroxide from the treatment of effluents through Advanced Oxidative Processes (AOP's), in particular, the photo‐Fenton process. To verify the efficiency of the oxidative process, the Chemical Oxygen Demand (COD) parameter, the values of which may be modified by the presence of oxidizing agents such as residual hydrogen peroxide, is frequently taken in account. The analysis of the H₂O₂ interference was performed by spectrophotometry at 450 nm wavelength, via the monitoring of the reaction of ammonia with metavanadate. The results of the hydrogen peroxide residual concentration were modeled via a feedforward neural network, with the correlation coefficients between actual and predicted values above 0.96, indicating good prediction capacity.     

Development of method for monitoring of chloride release in the oil refining processes

During oil refining, equipments are constantly exposed to the action of compounds such as salts, leading corrosion problems and to decrease in equipment service life. Soon, the growing search for productivity increasingly demand more strategies to monitor the processes and minimize costs. This article contributes to the methodology development to study the chlorides released during the oil distillation, in a similar process that occurs in refineries, enabling predict and minimize damage. Oils were evaluated with respect to chloride release during each stage of oil heating. Salinity mass balance were obtained as well as their respective chloride release percentage to each oil.     

Brazil’s growing production of scientific articles—how are we doing with review articles and other qualitative indicators?

This article identifies scientific fields in Brazil that have been generating new knowledge, their evolution, tendencies and the relationship between scientific production and the National Postgraduate Program (Programa Nacional de Pós-Graduação—PNPG). It works with review articles and assesses: (a) articles published as reviews by international databases; (b) the growth of Brazilian participation in that context; (c) institutional participation; (d) the predominant fields of knowledge; (e) the most productive authors, and (f) periodicals that published the greatest number of review articles by Brazilian authors. The 5,348 review articles published between 2000 and 2009 were made available in 1,309 scientific publications, and the fields that published the most reviews were Pharmacology, Chemistry, Neurosciences, Biochemistry and Molecular Biology, Psychiatry, Neurology, Endocrinology and Internal Medicine. The reviews were produced by 27,096 authors under the auspices of 20 institutions which, together, answer for 95 % of the Brazilian production, and are public, excepting for the Pontifícia Universidade Católica do Rio Grande do Sul (PUC-RS). In the international scenario, we find that 31 countries are responsible for 90.11 % of the total scientific production and 94.08 % of the review articles. To establish a comparison between Brazil and its closest competitors, these countries can be classified arbitrarily in three groups: (1) countries with a large number of review articles (>3100), an average number of citations above 18, and an h-index greater than 95; (2) countries with a significant production of articles (between 2,000 and 3,000), average number of citations between 12 and 17, and an h-index below 95. Brazil is in the third group, (3) formed by countries with a lower level of production and the two qualitative indicators at opposite poles: the average of citations on a par with the first group (>18) and h-indexes like those of the second group (<95).     

Antifungal effect of organic acids from lactic acid bacteria on Penicillium nordicum

The control of fungal contamination is particularly important to avoid both spoilage of food and feed products and the occurrence of toxic compounds, known as mycotoxins. Some lactic acid bacteria (LAB) strains have shown the capacity to inhibit fungal growth and the production of mycotoxins. In this work, cell-free supernatants (CFS) of Lactobacillus plantarum UM55 and Lactobacillus buchneri UTAD104 were tested against Penicillium nordicum radial growth and OTA production. When CFS of these strains were used, the radial growth of the fungus was inhibited by less than 20%, but the production of OTA was reduced by approx. 60%. These antifungal effects resulted from organic acids produced by LAB. The CFS of L. plantarum UM55 contained lactic acid, phenyllactic acid (PLA), hydroxyphenyllactic acid (OH-PLA) and indole lactic acid (ILA), while L. buchneri UTAD104 CFS contained acetic acid, lactic acid and PLA. These organic acids were further tested individually for their inhibitory capacity. Calculation of the inhibitory concentrations (ICs) showed that acetic acid, ILA and PLA were the most effective in inhibiting P. nordicum growth and OTA production. When the inhibitory activity of LAB cells incorporated into the culture medium was tested, L. buchneri UTAD104 inhibited the production of OTA entirely in all conditions tested, but fungal growth was only inhibited completely by the highest concentrations of cells. Acetic acid production was primarily responsible for this effect. In conclusion, the ability of LAB to inhibit mycotoxigenic fungi depends on strain capability to produce specific organic acids, and those acids may differ from strain to strain. Also, the use of LAB cells, especially from L. buchneri, in food products prone to contamination with P. nordicum (e.g. dry-cured meats and cheeses) may be an alternative solution to control fungal growth and OTA production.     

Characterization of an extracellular β‐d‐fructofuranosidase produced by Aspergillus niveus during solid‐state fermentation (SSF) of cassava husk

β‐d ‐Fructofuranosidases are biotechnologically important enzymes produced by various organisms. Here, Aspergillus niveus produced an extracellular β‐d ‐fructofuranosidase during SSF of cassava husk. This enzyme was purified 8.5‐fold (recovery of 5.2%). A 37‐kDa protein band was observed after 8% SDS‐PAGE. Native molecular mass is 91.2 kDa. Optimal temperature and pH of activity were 55°C and 4.5, respectively. The enzyme was stable at 50°C for 1 hr, and 80% of its activity was retained after 1 hr at pH 8.0. The enzymatic activity was improved by Mn²⁺, was resistant to most solvents, and was inhibited by Triton X‐100 and Tween 20. K_m and V_max with sucrose were 22.98 mM and 120.48 U/mg of protein, respectively. With Mn²⁺, these values were 16.31 mM and 0.30 U/mg of protein. The enzyme did not hydrolyze inulin and for this reason can be considered a true invertase. Thus, A. niveus β‐d ‐fructofuranosidase holds promise for invert sugar production.

Practical applications

β‐d ‐Fructofuranosidase is an enzyme that can be applied to different industrial sectors, especially food and beverage industries. It is responsible for the hydrolysis of sucrose and yields an equimolar mixture of D‐glucose and D‐fructose, named as inverted sugar syrup, with broad applications in the confectionery industry. The Aspergillus niveus enzyme hydrolyzed only sucrose here and can be considered a true invertase, showing its potential for application to invert sugar production. Besides, the use of cassava husk for enzyme production means an interesting utilization route of this agroindustrial residue. Thus, characterization of this enzyme is an important step for identification of its potential for practical applications.     

Toxigenic status of Staphylococcus aureus isolated from bovine raw milk and Minas frescal cheese in Brazil

A group of 291 Staphylococcus aureus isolates from mastitic cow's milk (n = 125), bulk tank milk (n = 96), and Minas frescal cheese (n = 70) were screened for staphylococcal enterotoxin (SE) genes (sea, seb, sec, sed, see, seg, seh, sei, selj, and sell) and for the tst-1 gene encoding staphylococcal toxic shock syndrome toxin 1 by PCR assay. A total of 109 (37.5%) of the isolates were positive for at least one of these 11 genes, and 23 distinct genotypes of toxin genes were observed. Of the S. aureus isolates bearing SE genes, 17 (13.6%) were from mastitic cow's milk, 41 (41.7%) were from bulk tank milk, and 51 (72.9%) were from Minas frescal cheese. The occurrence of exclusively more recently described SE genes (seg through sell) was considerably higher (87 of 109 PCR-positive strains) than that of classical SE genes (sea through see, 15 strains). The SE genes most commonly detected were seg and sei; they were found alone or in different combinations with other toxin genes, but in 60.8% of the cases they were codetected. No strain possessed see. The tst-1 gene was found in eight isolates but none from mastitic cow's milk. Macrorestriction analysis of chromosomal DNA from 89 S. aureus isolates positive for SE gene(s) was conducted with the enzyme SmaI. Fifty-five distinct pulsed-field gel electrophoresis patterns were found, demonstrating a lack of predominance of any specific clone. A second enzyme, Apa I, used for some isolates was less discriminating than Sma I. The high genotype diversity of potential toxigenic S. aureus strains found in this study, especially from Minas frescal cheese, suggests various sources of contamination. Efforts from the entire production chain are required to improve consumer safety.     

RE-PCR variability and toxigenic profile of food poisoning, foodborne and soil-associated Bacillus cereus isolates from Brazil

Twenty-three Bacillus cereus isolates from food poisoning outbreaks associated with a diarrheal-type syndrome, fourteen foodborne isolates not associated with food poisoning and fifteen isolates from Brazilian soil samples were analyzed for the presence and genetic diversity (by RE-PCR) of the virulence genes ces (emetic toxin, cereulide), plcR-papR (pleiotropic regulator PlcR and peptide PapR), nheA (a component of the NHE complex), bceT (diarrheal enterotoxin bc-D-ENT), gyrB (B subunit of DNA gyrase), cytK-2 (necrotic enterotoxin cytotoxin K-2), and plcA (phosphatidylcholine-specific phospholipase C). Additionally, these isolates were phenotypically characterized for motility, hemolytic and lecithinase activities, as well as HBL enterotoxin production. The group of isolates associated with food poisoning had the highest occurrence of the phenotypically analyzed factors and the most frequent occurrence and highest genetic diversity of the plcR-papR, nheA, bceT, cytK-2, plcA, and gyrB genes. An analysis of molecular variance (AMOVA), in which all loci were analyzed, demonstrated that the genetic variation intragroup of isolates (92%) was significantly higher than that intergroup (8%) (P < 0.05). These results were corroborated by an analysis of the genetic differentiation between the groups, which was low/moderate, the result of a high degree of allele sharing. Our results suggest that B. cereus isolates with the potential to cause food poisoning outbreaks do not have a specific genetic profile characterized by the presence of a particular gene or allele among the genes assessed. On the contrary, different combinations of genes encoding virulence factors may be present in different isolates of B. cereus that potentially cause food poisoning outbreaks.