Antibiotic resistance and tolerance to simulated gastrointestinal conditions of eight hemolytic Bacillus pumilus isolated from pulque,a traditional Mexican beverage

Food Science and Biotechnology - Traditional fermented sap beverages from two provinces of Mexico were studied for the isolation of pathogenic bacteria from these beverages. Eight strains of...     

Nanobiosensors based on individual olfactory receptors

The animal olfactory system represents the gold standard of biosensors, due to its ability to identify and discriminate thousands of odorant compounds with very low thresholds. Using olfactory receptors (ORs) as sensing elements instead of chemical sensors, biosensors would benefit the naturally optimized molecular recognition of odorants to develop a new generation of bioelectronic noses. The purpose of SPOT-NOSED European project was the development of nanobiosensors based on single ORs anchored between nanoelectrodes, to mimic the performances of natural olfactory system. Nanobiosensors arrays could then increase odorant sensitivity or widen the odorant detection spectrum. ORs were expressed in yeasts plasmic membrane, and their functionality tested in whole yeasts. Then, nanosomes bearing the ORs were prepared from S. cerevisiae, and Surface Plasmon Resonance was performed on nanosomes for quantitative evaluation of OR response to odorant stimulation. ORs retain full activity and discrimination power in immobilized nanosomes, thus allowing their use in the fabrication of the nanobiosensors. Nanoelectrodes were fabricated using conventional photolithography and focused ion beam milling, with sizes in adequation with the nanosomes. ORs borne by nanosomes were specifically immobilized onto conducting substrates via mixed Self Assembled Monolayers, neutravidin and specific antibody to the ORs. The process was optimized by microcontact printing, and the anchored nanovesicles visualized by Atomic Force Microscopy. A transimpedance preamplifier suited for low-noise wide-bandwidth measurements was designed to be directly connected to the nanoelectrodes. Electrochemical Impedancemetric Spectroscopy detected significant changes upon electrodes functionalization, grafting of ORs carried by nanosomes, and ORs conformational change induced by odorant binding.     

Experimental Determination of the Liquidus in the High-Basicity Region in the Al2O3(25?mass?pct)-CaO-MgO-SiO2 and Al2O3(35?mass?pct)-CaO-MgO-SiO2 Systems

Liquidus in the Al₂O₃(25 mass pct)-CaO-MgO-SiO₂(<20 mass pct) and Al₂O₃(35 mass pct)-CaO-MgO-SiO₂(<20 mass pct) systems were determined experimentally in the high-CaO-containing region at 1873 K (1600 °C). For the Al₂O₃(35 mass pct)-CaO-MgO-SiO₂(<20 mass pct) system, liquidus data were also determined for 1773 K (1500 °C). The equilibrating and quenching technique with subsequent electron probe microanalyzer (EPMA) microanalysis were employed. Based on the data, liquidus lines were constructed for the 25 and 35 mass pct alumina planes at silica contents generally below 20 mass pct. The current results showed a slightly lower solubility of CaO and a higher solubility of MgO at 1873 K (1600 °C) for the 25 mass pct Al₂O₃ section compared with the existing phase diagram. At 1773 K (1500 °C), the result showed a slightly lower solubility of both CaO and MgO in the 35 mass pct Al₂O₃ section compared with the existing phase diagram. In addition, the activities of MgO, CaO, and Al₂O₃ were estimated at 1773 K and 1873 K (1500 °C and 1600 °C) using the phase diagram information.     

Multi-robot olfactory search in structured environments

This paper presents a cooperative distributed approach for searching odor sources in unknown structured environments with multiple mobile robots. While searching and exploring the environment, the robots independently generate on-line local topological maps and by sharing them with each other they construct a global map. The proposed method is a decentralized frontier based algorithm enhanced by a cost/utility evaluation function that considers the odor concentration and airflow at each frontier. Therefore, frontiers with higher probability of containing an odor source will be searched and explored first. The method also improves path planning of the robots for the exploration process by presenting a priority policy. Since there is no global positioning system and each robot has its own coordinate reference system for its localization, this paper uses topological graph matching techniques for map merging. The proposed method was tested in both simulation and real world environments with different number of robots and different scenarios. The search time, exploration time, complexity of the environment and number of double-visited map nodes were investigated in the tests. The experimental results validate the functionality of the method in different configurations.     

Chemical characterisation of Nephrops norvegicus from Portuguese coast

BACKGROUND: Among seafood products, crustaceans are an important group owing to their nutritional benefits and high market value. The aim of this study was to evaluate the proximate composition as well as essential and non‐essential elements in the edible muscle of Nephrops norvegicus (Norway lobster). RESULTS: The studied crustacean showed a high protein level of about 210 g kg^?1 and a mineral level of about 24 g kg^?1. The pattern for the elements studied was Cl > Na > K > P > S > Ca > Mg > Br > Fe > Sr ≈ Zn > Cu > Mn > Rb > Se > Ni > Cr. Regarding non‐essential elements, the average total Hg content was 0.40 mg kg^?1, but two samples exceeded the legal limit set by the European Union (EU) for Hg in crustaceans (0.50 mg kg^?1). The levels of Pb and Cd found in all samples were below the EU limits (0.50 mg kg^?1 for both metals). CONCLUSION: Nephrops norvegicus is a good source of protein and contains most minerals at levels sufficient to satisfy the dietary reference intake. The amounts of Pb and Cd are not a concern. Hg levels indicate some contamination; however, taking into account the type of consumption of this species, it can be concluded that this does not represent a risk in terms of the human diet. Copyright © 2009 Society of Chemical Industry     

Cover Image,Volume 97, Issue 13

The cover image, by Márcia Carvalho et al., is based on the Review Cowpea: a legume crop for a challenging environment, DOI: 10.1002/jsfa.8250 . Photo Credit: Eduardo Rosa.