Evaluation of different selective media for enumeration of probiotic micro-organisms in combination with yogurt starter cultures in fermented milk

The aim of this study was to assess selective plating methodologies for the enumeration and identification of Streptococcus thermophilus, Lactobacillus delbrueckii ssp. bulgaricus, Lactobacillus acidophilus, Lactobacillus rhamnosus and Bifidobacterium animalis ssp. lactis in fermented milks. Seven agar media (MRS with added sorbitol, clindamycin or vancomycin, acidified MRS, RCA with added aniline blue and dicloxacilin, M17 and ST) were evaluated. The results showed that RCA dicloxacilin agar was suitable for the selective enumeration of B. animalis ssp. lactis in fermented milk. Either MRS (acidified) or M17 agar could be used for enumeration of L. delbrueckii ssp. bulgaricus and S. thermophilus, respectively. MRS media containing antibiotics were effective for the enumeration of the probiotic organisms (L. rhamnosus and L. acidophilus) inoculated in fermented milks.

New Isomers in the Full Seniority Scheme of Neutron-Rich Lead Isotopes: The Role of Effective Three-Body Forces

The neutron-rich lead isotopes, up to Pb-216, have been studied for the first time, exploiting the fragmentation of a primary uranium beam at the FRS-RISING setup at GSI. The observed isomeric states exhibit electromagnetic transition strengths which deviate from state-of-the-art shell-model calculations. It is shown that their complete description demands the introduction of effective three-body interactions and two-body transition operators in the conventional neutron valence space beyond Pb-208.

Exploring the coordination chemistry of isomerizable terpyridine derivatives for successful analyses of cis and trans isomers by travelling wave ion mobility mass spectrometry

The photochemical cis-trans isomerization of the 4-{4-[2-(pyridin-4-yl)ethenyl]phenyl}-2,2': 6',2''-terpyridine ligand (vpytpy) was investigated by UV-vis, NMR and TWIM-MS. Ion mobility mass spectrometry was performed pursuing the quantification of the isomeric composition during photolysis, however an in-source trans-to-cis isomerization process was observed. In order to overcome this inherent phenomenon, the isomerization of the vpytpy species was suppressed by complexation, reacting with iron(II) ions, and forming the [Fe(vpytpy)(2)](2+) complex. The strategy of "freezing" the cis-trans isomerizable ligand at a given geometric conformation was effective, preventing further isomerization, thus allowing the distinction of each one of the isomers in the photolysed mixture. In addition, the experimental drift times were related to the calculated surface areas of the three possible cis-cis, cis-trans and trans-trans iron(II) complex isomers. The stabilization of the ligand in a given conformation also allows us to obtain the cis-cis and cis-trans complexes exhibiting the ligand in the metastable cis-conformation, as well as in the thermodynamically stable trans-conformation.

Gas-phase reactivity of protonated 2-oxazoline derivatives: mass spectrometry and computational studies

RATIONALE: Oxazolines have attracted the attention of researchers worldwide due to their versatility as carboxylic acid protecting groups, chiral auxiliaries, and ligands for asymmetric catalysis. Electrospray ionization tandem mass spectrometric (ESI-MS/MS) analysis of five 2-oxazoline derivatives has been conducted, in order to understand the influence of the side chain on the gas-phase dissociation of these protonated compounds under collision-induced dissociation (CID) conditions. METHODS: Mass spectrometric analyses were conducted in a quadrupole time-of-flight (Q-TOF) spectrometer fitted with electrospray ionization source. Protonation sites have been proposed on the basis of the gas-phase basicity, proton affinity, atomic charges, and a molecular electrostatic potential map obtained on the basis of the quantum chemistry calculations at the B3LYP/6-31 + G(d, p) and G2(MP2) levels. RESULTS: Analysis of the atomic charges, gas-phase basicity and proton affinities values indicates that the nitrogen atom is a possible proton acceptor site. On the basis of these results, two main fragmentation processes have been suggested: one taking place via neutral elimination of the oxazoline moiety (99 u) and another occurring by sequential elimination of neutral fragments with 72 u and 27 u. These processes should lead to formation of R+. CONCLUSIONS: The ESI-MS/MS experiments have shown that the side chain could affect the dissociation mechanism of protonated 2-oxazoline derivatives. For the compound that exhibits a hydroxyl at the lateral chain, water loss has been suggested to happen through an E2-type elimination, in an exothermic step. Copyright (C) 2012 John Wiley & Sons, Ltd.

Resolution of isomeric multi-ruthenated porphyrins by travelling wave ion mobility mass spectrometry

The ability of travelling wave ion mobility mass spectrometry (TWIM-MS) to resolve cationic meta/para and cis/trans isomers of mono-, di-, tri- and tetra-ruthenated supramolecular porphyrins was investigated. All meta isomers were found to be more compact than the para isomers and therefore mixtures of all isomeric pairs could be properly resolved with baseline or close to baseline peak-to-peak resolution (Rp-p). Di-substituted cis/trans isomers were found, however, to present very similar drift times and could not be resolved. N-2 and CO2 were tested as the drift gas, and similar a but considerably better values of R-p and Rp-p were always observed for CO2. Copyright (C) 2012 John Wiley & Sons, Ltd.

Mixed colonies of two species of congeneric stingless bees (Hymenoptera: Apinae, Meliponini) display environmentally-acquired and endogenously-produced recognition signals

Nestmate recognition is fundamental for the maintenance of social organization in insect nests. It is becoming well recognized that cuticle hydrocarbons mediate the recognition process, although the origin of recognition cues in stingless bees remains poorly explored. The present study investigates the effects of endogenously-produced and environmentally-acquired components in cuticular hydrocarbons in stingless bees. The tests are conducted using colonies of Plebeia droryana Friese and Plebeia remota Holmberg. Recognition tests are performed with four different groups: conspecific nestmates, conspecific non-nestmates, heterospecifics and conspecific, genetically-related individuals that emerge in a heterospecific nest. This last group is produced by introducing brood cells of P. droryana into a P. remota colony, and the resulting adult bees are tested for acceptance 10 days after emergence. For all groups, 15 individuals are sampled for chemical analysis. The results show the acceptance of all conspecific nestmates, and the rejection of almost every conspecific non-nestmate and every heterospecific bee. Genetically-related individuals emerging from heterospecific nests present intermediate rejection (66.7% rejection). Chemical analysis shows that P. droryana individuals emerging in a P. remota nest have small amounts of alkene and diene isomers found in P. remota cuticle that are not found in workers from the natal nest. The data clearly show that the majority of the compounds present in P. droryana cuticle are endogenously produced, although a few unsaturated compounds are acquired from the environment, increasing the chemical differences and, consequently, the rejection percentages.

Hybrid density functional study of small Rh-n (n=2-15) clusters

The physical properties of small rhodium clusters, Rh-n, have been in debate due to the shortcomings of density functional theory (DFT). To help in the solution of those problems, we obtained a set of putative lowest energy structures for small Rh-n (n = 2-15) clusters employing hybrid-DFT and the generalized gradient approximation (GGA). For n = 2-6, both hybrid and GGA functionals yield similar ground-state structures (compact), however, hybrid favors compact structures for n = 7-15, while GGA favors open structures based on simple cubic motifs. Thus, experimental results are crucial to indicate the correct ground-state structures, however, we found that a unique set of structures (compact or open) is unable to explain all available experimental data. For example, the GGA structures (open) yield total magnetic moments in excellent agreement with experimental data, while hybrid structures (compact) have larger magnetic moments compared with experiments due to the increased localization of the 4d states. Thus, we would conclude that GGA provides a better description of the Rh-n clusters, however, a recent experimental-theoretical study [ Harding et al., J. Chem. Phys. 133, 214304 (2010)] found that only compact structures are able to explain experimental vibrational data, while open structures cannot. Therefore, it indicates that the study of Rh-n clusters is a challenging problem and further experimental studies are required to help in the solution of this conundrum, as well as a better description of the exchange and correlation effects on the Rh n clusters using theoretical methods such as the quantum Monte Carlo method.

Administration of a murine diet supplemented with conjugated linoleic acid increases the expression and activity of hepatic uncoupling proteins

Daily intake of conjugated linoleic acid (CLA) has been shown to reduce body fat accumulation and to increase body metabolism; this latter effect has been often associated with the up-regulation of uncoupling proteins (UCPs). Here we addressed the effects of a CLA-supplemented murine diet (similar to 2 % CLA mixture, cis-9, trans-10 and trans-10, cis-12 isomers; 45 % of each isomer on alternating days) on mitochondrial energetics, UCP2 expression/activity in the liver and other associated morphological and functional parameters, in C57BL/6 mice. Diet supplementation with CLA reduced both lipid accumulation in adipose tissues and triacylglycerol plasma levels, but did not augment hepatic lipid storage. Livers of mice fed a diet supplemented with CLA showed high UCP2 mRNA levels and the isolated hepatic mitochondria showed indications of UCP activity: in the presence of guanosine diphosphate, the higher stimulation of respiration promoted by linoleic acid in mitochondria from the CLA mice was almost completely reduced to the level of the stimulation from the control mice. Despite the increased generation of reactive oxygen species through oxi-reduction reactions involving NAD(+)/NADH in the Krebs cycle, no oxidative stress was observed in the liver. In addition, in the absence of free fatty acids, basal respiration rates and the phosphorylating efficiency of mitochondria were preserved. These results indicate a beneficial and secure dose of CLA for diet supplementation in mice, which induces UCP2 overexpression and UCP activity in mitochondria while preserving the lipid composition and redox state of the liver.

Corrole isomers: intrinsic gas-phase shapes via traveling wave ion mobility mass spectrometry and dissociation chemistries via tandem mass spectrometry

Corrole and four of its isomers with subtle structural changes promoted by exchange of nitrogen and carbon atoms in the corrole ring have been studied by traveling wave ion mobility mass spectrometry and collision induced dissociation experiments. Significant differences in shapes and charge distributions for their protonated molecules were found to lead to contrasting gas phase mobilities, most particularly for corrorin, the most "confused" isomer. Accordingly, corrorin was predicted by B3LYP/6-31g(d,p) and collisional cross section calculations to display the most compact tri-dimensional structure, whereas NCC4 and corrole were found to be the most planar isomers. Better resolution between the corrole isomers was achieved using the more polarizable and massive CO2 as the drift gas. Sequential losses of HF molecules were found to dominate the dissociation chemistry of the protonated molecules of these corrole isomers, but their unique structures caused contrasting labilities towards CID, whereas NCC4 showed a peculiar and structurally diagnostic loss of NH3, allowing its prompt differentiation from the other isomers.

Preparation, characterization and structure of ruthenium phosphine complexes containing non-innocent ligands

Phosphine ruthenate complexes containing the non-innocent ligands 4-chloro-1,2-phenylenediamine (opda-CI) and 3,3',4,4'-tetraamminebiphenyl (diopda) were synthesized and characterized by means of X-ray diffraction, electrochemistry, P-31{H-1} NMR and electronic spectroscopies. Crystals of cis-[RuCl2 (dppb)(bqdi-CI)] complex were isolated as a mixture of two conformational isomers due to different positions of the chlorine atoms of the o-phenylene ligand in relation to the P1 atom of the phosphine moiety. (C) 2011 Elsevier Ltd. All rights reserved.

N-glycome profiling of Bothrops jararaca newborn and adult venoms

Glycosylation is an important post-translational modification of snake venom proteins and contributes to venom proteome complexity. Many snake venom components are known to be glycosylated, however, very little is known about the carbohydrate structures present in venom glycoproteins. Previous studies showed that the ontogenetic shift in diet, from ectothermic prey in early life to endothermic prey in adulthood, and shift in animal size are associated with changes in the venom proteome of the snake Bothrops jararaca. In this study we explored the composition of the N-glycome released from newborn and adult B. jararaca venom proteins. We used an ion trap mass spectrometer (IT-MS) to disassemble glycan structures based on the use of several pathways of MS (MSn) and demonstrate the presence of some structural isomers in both newborn and adult venom B. jararaca N-glycans. The main N-glycans identified in both venoms are of the hybrid/complex type however some mannose-rich type structures were also detected. The N-glycan composition of newborn and adult venoms did not vary indicating that differences in the utilization of the N-glycosylation motif could be the explanation for the differences in the glycosylation levels indicated by the differential electrophoretic profiles previously reported for B. jararaca newborn and adult venoms. (C) 2011 Elsevier B.V. All rights reserved.

Effect of inulin on the growth and metabolism of a probiotic strain of Lactobacillus rhamnosus in co-culture with Streptococcus thermophilus

Metabolic studies are very important to improve quality of functional dairy products. For this purpose, the behaviors of pure cultures of Streptococcus thermophilus (St) and Lactobacillus rhamnosus (Lr) as well a co-culture of them (St-Lr) were investigated during skim milk fermentation, and the inulin effect as prebiotic was assessed. Lr was able to metabolize 6 g/100 g more galactose than St and St-Lr. Final lactic acid production by Lr was higher (9.8 g/L) compared to St (9.1 g/L) and St-Lr (9.1 g/L). Acetic acid concentration varied from 0.8 g/L (St-Lr) to 1.5 g/L (Lr) and that of ethanol from only 0.2 g/L (St-Lr) to 0.4 g/L (Lr), which suggests the occurrence in Lr of a NADH oxidase activity and citrate co-metabolization via pyruvate, both dissipating a part of the reducing power. Diacetyl and acetoin accumulated at the highest levels (18.4 and 0.8 mg/L, respectively) with St-Lr, which suggests possible synergistic interactions between these microorganisms as well as the Lr capability of co-metabolizing citrate in the presence of lactose. Inulin stimulated both biomass growth and levels of all end-products, as the likely result of fructose release from its partial hydrolysis and subsequent metabolization as an additional carbon and energy source. Crown Copyright (C) 2012 Published by Elsevier Ltd. All rights reserved.

Co-metabolic models of Streptococcus thermophilus in co-culture with Lactobacillus bulgaricus or Lactobacillus acidophilus

To shed light on the interactions occurring in fermented milks when using co-cultures of Streptococcus thermophilus with Lactobacillus bulgaricus (StLb) or Lactobacillus acidophilus (StLa), a new co-metabolic model was proposed and checked either in the presence of Inulin as a prebiotic or not. For this purpose, the experimental data of concentrations of substrates and fermented products were utilized in balances of carbon, reduction degree and ATP. S. thermophilus exhibited always quicker growth compared to the other two microorganisms, while the percentage of lactose fermented to lactic acid, that of galactose metabolized, and the levels of diacetyl and acetoin formed strongly depended on the type of co-culture and the presence of inulin. The StLb co-culture led to higher acetoin and lower diacetyl levels compared to StLa, probably because of more reducing conditions or limited acetoin dehydrogenation. Inulin addition to StLa suppressed acetoin accumulation and hindered that of diacetyl, suggesting catabolite repression of alpha-acetolactate synthase expression in S. thermophilus. Both co-cultures showed the highest ATP requirements for biomass growth and maintenance at the beginning of fermentation, consistently with the high energy demand of enzyme induction during lag phase. Inulin reduced these requirements making biomass synthesis and maintenance less energy-consuming. Only a fraction of galactose was released from lactose, consistently with the galactose-positive phenotype of most dairy strains. The galactose fraction metabolized without inulin was about twice that in its presence, which suggests inhibition of the galactose transport system of S. thermophilus by fructose released from partial inulin hydrolysis. (C) 2012 Elsevier B.V. All rights reserved.

Multi-molecular markers and metals as tracers of organic matter inputs and contamination status from an Environmental Protection Area in the SW Atlantic (Laranjeiras Bay, Brazil)

The sources and concentrations of aliphatic hydrocarbons (AHs) and polycyclic aromatic hydrocarbons (PAHs), faecal and biogenic sterols, and trace metals at 10 sampling sites located in Laranjeiras Bay, a large Environmental Protection Area in the southern Atlantic region of Brazil, were determined to assess the sources of organic matter and the contamination status of estuarine sediments. Organic compounds were determined by GC-FID and GC-MS, and ICP-OES was used to evaluate trace metals. The total AHs concentration ranged from 0.28 to 8.19 mu g g(-1), and n-C-29 and n-C-31 alkanes were predominant, indicating significant inputs from higher terrestrial plants. Unresolved complex mixtures (UCM) were not detected at any site, suggesting that the study area was not significantly contaminated by fossil fuels. The total PAH concentration varied from 3.85 to 89.2 ng g(-1). The ratio between selected PAH isomers showed that combustion of biomass, coal, and petroleum is the rnain source of PAHs in the study area. The concentrations of the faecal sterols coprostanol and epicoprostanol were below the detection limits, suggesting that sewage was not a significant contributor to sedimentary organic matter. The concentrations of the trace metals (As, Cr, Cu, Ni, Pb and Zn) were low, except near sites located at the mouths of rivers that discharge into the study area and near urbanised regions (Paranagua city and the adjoining harbour). In general, the concentrations of PAHs were below the threshold effect concentrations (TEL) levels. Although the As, Cr and Ni concentrations were above the TEL levels, the study area can be considered as preserved from human activities.

Influence of milk type and addition of passion fruit peel powder on fermentation kinetics, texture profile and bacterial viability in probiotic yoghurts

The effect of the addition of passion fruit peel powder (PFPP) on the fermentation kinetics and texture parameters, post-acidification and bacteria counts of probiotic yoghurts made with two milk types were evaluated during 28 days of storage at 4 degrees C. Milks were fermented by Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus (CY340), and one strain of probiotic bacteria: Lactobacillus acidophilus (L10 and NCFM), Bifidobacterium animalis subsp. lactis (8104 and HN019). The addition of PFPP reduced significantly fermentation time of skim milk co-fermented by the strains L10, NCFM and HN019. At the end of 28-day shelf-life, counts of B. lactis Bl04 were about 1 Log CFU mL(-1) higher in whole yoghurt fermented with PFPP regarding its control but, in general, the addition of PFPP had less influence on counts than the milk type itself. The titratable acidity in yoghurts with PFPP was significantly higher than in their respective controls, and in skim yoghurts higher than in the whole ones. The PFPP increased firmness, consistency (except for the NCFM strain of L acidophilus) and cohesiveness of all skim yoghurts. The results point out the suitability of using passion fruit by-product in the formulation of both skim and whole probiotic yoghurts. (C) 2012 Elsevier Ltd. All rights reserved.