Silver Nanocomposite Biosynthesis: Antibacterial Activity against Multidrug-Resistant Strains of Pseudomonas aeruginosa and Acinetobacter baumannii.

Bacterial resistance is an emerging public health issue that is disseminated worldwide. Silver nanocomposite can be an alternative strategy to avoid Gram-positive and Gram-negative bacteria growth, including multidrug-resistant strains. In the present study a silver nanocomposite was synthesized, using a new green chemistry process, by the addition of silver nitrate (1.10-3 mol·L-1) into a fermentative medium of Xanthomonas spp. to produce a xanthan gum polymer. Transmission electron microscopy (TEM) was used to evaluate the shape and size of the silver nanoparticles obtained. The silver ions in the nanocomposite were quantified by flame atomic absorption spectrometry (FAAS). The antibacterial activity of the nanomaterial against Escherichia coli (ATCC 22652), Enterococcus faecalis (ATCC 29282), Pseudomonas aeruginosa (ATCC 27853) and Staphylococcus aureus (ATCC 25923) was carried out using 500 mg of silver nanocomposite. Pseudomonas aeruginosa and Acinetobacter baumannii multidrug-resistant strains, isolated from hospitalized patients were also included in the study. The biosynthesized silver nanocomposite showed spherical nanoparticles with sizes smaller than 10 nm; 1 g of nanocomposite contained 49.24 µg of silver. Multidrug-resistant strains of Pseudomonas aeruginosa and Acinetobacter baumannii, and the other Gram-positive and Gram-negative bacteria tested, were sensitive to the silver nanocomposite (10-12.9 mm of inhibition zone). The biosynthesized silver nanocomposite seems to be a promising antibacterial agent for different applications, namely biomedical devices or topical wound coatings.

Chemical Composition and Antimicrobial Activity of a New Olive Pomace Functional Ingredient.

Olive pomace, an olive oil processing byproduct, can be upcycled and meet the current demand for natural and sustainable food ingredients. In this work, a patented process was used to obtain a functional ingredient from different olive pomaces. The nutritional, chemical and antioxidant profiles, as well as the antimicrobial activity against S. aureus, E. coli and C. albicans, were investigated for the first time. The amount of phenolics ranged between 3.1 and 3.8 g gallic acid eq./100 g in all samples and flavonoids between 2.0 and 3.2 g catechin eq/100 g. No significant differences were found regarding the antioxidant activity. The total fat varied between 5 and 11%, α-tocopherol being the major vitamer and oleic acid the main fatty acid. The protein and ash contents were 1-4% and 10-17%, respectively. The functional ingredient with a higher hydroxytyrosol content (220 mg/100 g) also presented the best minimal inhibitory concentration against the tested bacteria. No activity against C. albicans was verified. This new functional ingredient presents the potential to be used as a natural preservative or as a nutritional profile enhancer. Moreover, it can be an advantageous ingredient in food products, since it comprises specific lipid and hydrophilic bioactive compounds usually not present in other plant extracts.

Analysis of polycyclic aromatic hydrocarbons in fish: evaluation of a quick, easy, cheap, effective, rugged, and safe extraction method.

QuEChERS method was evaluated for extraction of 16 PAHs from fish samples. For a selective measurement of the compounds, extracts were analysed by LC with fluorescence detection. The overall analytical procedure was validated by systematic recovery experiments at three levels and by using the standard reference material SRM 2977 (mussel tissue). The targeted contaminants, except naphthalene and acenaphthene, were successfully extracted from SRM 2977 with recoveries ranging from 63.5-110.0% with variation coefficients not exceeding 8%. The optimum QuEChERS conditions were the following: 5 g of homogenised fish sample, 10 mL of ACN, agitation performed by vortex during 3 min. Quantification limits ranging from 0.12-1.90 ng/g wet weight (0.30-4.70 microg/L) were obtained. The optimized methodology was applied to assess the safety concerning PAHs contents of horse mackerel (Trachurus trachurus), chub mackerel (Scomber japonicus), sardine (Sardina pilchardus) and farmed seabass (Dicentrarchus labrax). Although benzo(a)pyrene, the marker used for evaluating the carcinogenic risk of PAHs in food, was not detected in the analysed samples (89 individuals corresponding to 27 homogenized samples), the overall mean concentration ranged from 2.52 +/- 1.20 ng/g in horse mackerel to 14.6 +/- 2.8 ng/g in farmed seabass. Significant differences were found between the mean PAHs concentrations of the four groups.

Valorization of crude glycerol based on biological processes for accumulation of lipophilic compounds.

Bacteria that are capable of accumulating lipids in their cells as storage compounds can also produce polyhydroxyalkanoates of high technological value, depending on the specific culture conditions. The objective of this study was to utilize crude glycerol from biodiesel (CGB) as a substrate, which is a major byproduct from biodiesel production, to produce lipophilic compounds. Bacillus megaterium INCQS 425 was cultivated and evaluated for the production of lipophilic compounds and the properties of these compounds were investigated. Cultivation of the bacteria in a medium with a C:N ratio of 0.60:1 favored the accumulation of lipids by (17.5%) comprising mainly palmitic acid (13.08%), palmitoleic (39.48%), and especially oleic acid (37.02%), which imparts good characteristics to biodiesel. Meanwhile, cultivation of the bacteria in a medium with a C:N ratio of 4:1 favored the accumulation of polyhydroxyalkanoates (PHA) (3.31gL-1) mainly comprising medium and long chain PHA. Low crystallinity (<30%) and excellent thermal properties make them suitable for processes that demand high temperatures, such as extrusion. The lipids produced in the present study had satisfactory oxidative stability for the production of quality biodiesel. The polyhydroxyalkanoates produced in the study are of low cost and have promising thermal properties that justify its technological potential, thereby configuring highly competitive bioproducts.

Investigation of cellular fatty acid composition of Xanthomonas spp. as chemical markers of productivity and quality of xanthan gum.

In this study, we investigated the cellular fatty acid profiles of different Xanthomonas pathovars producing xanthan gum and explored the fatty acid composition to identify chemical markers of xanthan gum productivity and quality. Three Xanthomonas pathovars were studied. The fermentation was conducted for 168 h. Samples from the fermented medium were collected for extraction, quantification, and characterization of xanthan. The unsaturated/saturated (U/S) fatty acid ratio in Xanthomonas cells during fermentation was correlated with production, viscosity, and molecular weight of the gum obtained at each 24 h. The Xanthomonas axonopodis pv manihotis 290 strain showed a higher U/S ratio for major cell fatty acids (C16:1ω7/C16:0) as compared with the other two strains; this high ratio was directly associated with xanthan production. No correlation was observed between cellular fatty acid composition and characteristics of xanthan synthesized. Thus, it was possible to determine a production chemical marker for xanthan gum in Xanthomonas strains.

Xanthan Gum Production by Xanthomonas campestris pv. campestris IBSBF 1866 and 1867 from Lignocellulosic Agroindustrial Wastes.

This study aimed to evaluate the properties of xanthan gum produced by Xanthomonas campestris pv. campestris 1866 and 1867 from lignocellulosic agroindustrial wastes. XG was produced using an orbital shaker in a culture medium containing coconut shell (CS), cocoa husks (CH), or sucrose (S) minimally supplemented with urea and potassium. The XG production results varied between the CS, CH, and S means, and it was higher with the CH in strains 1866 (4.48 g L-1) and 1867 (3.89 g L-1). However, there was more apparent viscosity in the S gum (181.88 mPas) and the CS gum (112.06 mPas) for both 1866 and 1867, respectively. The ability of XGCS and XGCH to emulsify different vegetable oils was similar to the ability of XGS. All gums exhibited good thermal stability and marked groups in the elucidation of compounds and particles with rough surfaces.

Efeito da germinação e da desidratação no valor nutritivo, compostos bioativos e atividade antioxidante de farinhas de leguminosas / Germination and dehydration effects on nutritional value, bioactive compounds and antioxidant activity of legume flours / Efectos de la germinación y la deshidratación sobre el valor nutritivo, los compuestos bioactivos y la actividad antioxidante de harinas de leguminosas

Os objetivos deste trabalho foram avaliar o efeito da germinação no teor de macronutrientes e da desidratação em compostos bioativos, nutrientes e atividade antioxidante de farinhas das leguminosas Phaseolus lunatus L. e Cajanus cajan (L. Millsp.) germinadas. As condições de germinação foram controladas em laboratório e as amostras foram submetidas à desidratação térmica (55°C) e liofilização. Foram realizadas as análises de composição centesimal, fenólicos totais flavonoides, atividade antioxidante (DPPH, FRAP), perfil de ácidos graxos (CG-FID) e de vitâmeros de tocoferol (HPLC- DAD). A germinação das leguminosas promoveu aumento de proteínas, lipídios e carboidratos. O processamento térmico para desidratação contribuiu para perdas de proteínas, lipídios, cinzas, e maior atividade antioxidantes em ambas as espécies. O perfil de ácidos graxos e vitâmeros de tocoferol mostraram-se com variações que dependem do tipo de leguminosa e condições de processamento, podendo ser positivas ou negativas. Farinhas de leguminosas germinadas pode ser uma alternativa para a inserção na dieta ou em formulações alimentícias e as condições de processamento devem ser monitoradas com intuito de otimiza propriedades nutritivas e funcionais.

The objectives of this work were to evaluate the effect of germination on macronutrient content and dehydration on bioactive compounds, nutrients and antioxidant activity of flours from germinated Phaseolus lunatus L. and Cajanus cajan (L. Millsp.) legumes. The germination conditions were controlled in the laboratory and the samples were submitted to thermal dehydration (55°C) and lyophilization. Analyses were carried out for centesimal composition, total phenolic flavonoids, antioxidant activity (DPPH, FRAP), fatty acid profile (GC-FID) and tocopherol vitamers (HPLC-DAD). Germination of the legumes promoted an increase in proteins, lipids and carbohydrates. Thermal processing for dehydration contributed to losses of proteins, lipids, ash, and higher antioxidant activity in both species. The profile of fatty acids and tocopherol vitamers showed variations that depend on the type of legume and processing conditions, and can be positive or negative. Sprouted legume flours can be an alternative for insertion in the diet or in food formulations and the processing conditions must be monitored in order to optimize nutritional and functional properties.

Los objetivos de este trabajo fueron evaluar el efecto de la germinación sobre el contenido en macronutrientes y de la deshidratación sobre los compuestos bioactivos, los nutrientes y la actividad antioxidante de harinas de leguminosas germinadas de Phaseolus lunatus L. y Cajanus cajan (L. Millsp.). Las condiciones de germinación se controlaron en el laboratorio y las muestras se sometieron a deshidratación térmica (55°C) y liofilización. Se realizaron análisis de composición centesimal, flavonoides fenólicos totales, actividad antioxidante (DPPH, FRAP), perfil de ácidos grasos (GC-FID) y vitaminas tocoferol (HPLC-DAD). La germinación de las leguminosas promovió un aumento de proteínas, lípidos y carbohidratos. El procesado térmico para la deshidratación contribuyó a pérdidas de proteínas, lípidos, cenizas y a una mayor actividad antioxidante en ambas especies. El perfil de ácidos grasos y vitaminas tocoferol mostró variaciones que dependen del tipo de legumbre y de las condiciones de procesado, pudiendo ser positivas o negativas. Las harinas de leguminosas germinadas pueden ser una alternativa para su inserción en la dieta o en formulaciones alimentarias y las condiciones de procesado deben ser monitorizadas para optimizar las propiedades nutricionales y funcionales.

Nutraceutical Potential of New Alfalfa (Medicago sativa) Ingredients for Beverage Preparations.

Alfalfa (Medicago sativa) has been extensively used as animal feed, due to its fiber, protein, minerals, and vitamins, being also a useful source of phenolic compounds with potential therapeutic benefits. Nevertheless, its potential use as human ingredient is scarce. The aim of this work was to assess the nutritional composition, amino acid profile, and antioxidant capacity (AOC) of freeze-dried juice (FDJ) and fibrous residual material (RM), two new alfalfa-derived products (Adps) recently launched as ingredients for beverage preparations. Results demonstrated a high content of proteins (23-30 g/100 g FDJ and 13-17 g/100 g RM), crude fiber (29 g/100 g RM), and minerals (such as sodium, calcium, iron, and zinc). No significant difference was found in caloric content (4 kcal/g). Essential and nonessential amino acids were quantified in both Adps being leucine and lysine the most abundant. Total phenolic and total flavonoid contents (TPC and TFC, respectively) and their changes along the different harvesting periods of the year were also examined. FDJ presented the highest TPC in May (19 mg gallic acid equivalents/g dry weight [dw]), while in October TFC had the maximum value (4 mg catechin equivalents/g dw). Both products exhibited an interesting AOC by 1,1-diphenyl-2-picrylhydrazyl (DPPH) and ferric reducing antioxidant power assays. This study reports the nutraceutical potential of two new types of Adps.

Simple laccase-based biosensor for formetanate hydrochloride quantification in fruits.

This work describes the development of an electrochemical enzymatic biosensor for quantification of the pesticide formetanate hydrochloride (FMT). It is based on a gold electrode modified with electrodeposited gold nanoparticles and laccase. The principle behind its development relies on FMT's capacity to inhibit the laccase catalytic reaction that occurs in the presence of phenolic substrates. The optimum values for the relevant experimental variables such as gold nanoparticles electrochemical deposition (at -0.2V for 100s), laccase immobilization (via glutaraldehyde cross-linking), laccase concentration (12.4mg/mL), substrate selection and concentration (5.83×10(-5)M of aminophenol), pH (5.0), buffer (Britton-Robinson), and square-wave voltammetric parameters were determined. The developed biosensor was successfully applied to FMT determination in mango and grapes. The attained limit of detection was 9.5×10(-8)±9.5×10(-10)M (0.02±2.6×10(-4)mg/kg on a fresh fruit weight basis). Recoveries for the five tested spiking levels ranged from 95.5±2.9 (grapes) to 108.6±2.5% (mango). The results indicated that the proposed device presents suitable characteristics in terms of sensitivity (20.58±0.49A/µM), linearity (9.43×10(-7) to 1.13×10(-5)M), accuracy, repeatability (RSD of 1.4%), reproducibility (RSD of 1.8%) and stability (19days) for testing of compliance with established maximum residue limits of FMT in fruits and vegetables.

Polycyclic aromatic hydrocarbon levels in three pelagic fish species from Atlantic Ocean: inter-specific and inter-season comparisons and assessment of potential public health risks.

The concentrations of 18 polycyclic aromatic hydrocarbons (PAHs) were determined in three commercially valuable fish species (sardine, Sardina pilchardus; chub mackerel, Scomber japonicus; and horse mackerel, Trachurus trachurus) from the Atlantic Ocean. Specimens were collected seasonally during 2007-2009. Only low molecular weight PAHs were detected, namely, naphthalene, acenaphthene, fluorene and phenanthrene. Chub mackerel (1.80-19.90µg/kgww) revealed to be significantly more contaminated than horse mackerel (2.73-10.0µg/kgww) and sardine (2.29-14.18µg/kgww). Inter-specific and inter-season comparisons of PAHs bioaccumulation were statistically assessed. The more relevant statistical correlations were observed between PAH amounts and total fat content (significant positive relationships, p⩽0.05), and season (sardine displayed higher amounts in autumn-winter while the mackerel species showed globally the inverse behavior). The health risks by consumption of these species were assessed and shown to present no threat to public health concerning PAH intakes.