Non-culture-based identification of mastitis-causing bacteria by MALDI-TOF mass spectrometry

The purpose of this study was to evaluate the detection limit of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for direct identification, without previous microbiological culture, of bovine mastitis-causing bacteria from milk samples. Milk samples (n = 15) were experimentally contaminated with Staphylococcus aureus, Streptococcus uberis, Streptococcus agalactiae, Streptococcus dysgalactiae, and Escherichia coli to have bacterial counts ranging from 10³ to 10⁹ cfu/mL. These contaminated milk samples were subjected to a preparation protocol for bacterial ribosomal protein extraction using the MALDI Sepsityper kit (Bruker Daltonik, Bremen, Germany), which allowed MALDI-TOF MS coupled with Biotyper software (Bruker Daltonik) to identify bacterial fingerprints based on intact ribosomal proteins. The ability of MALDI-TOF MS to correctly identify bacterial strains from experimentally contaminated milk (without previous microbiological culture) depended on the bacterial count of the samples and on the species of the bacteria evaluated. Adequate identification at the bacterial species level (score ≥2.0) directly from milk samples required bacterial counts in the following ranges: ≥10⁶ cfu/mL of Staph. aureus, ≥10⁷ cfu/mL of E. coli, and ≥10⁸ cfu/mL of Strep. agalactiae, Strep. dysgalactiae, and Strep. uberis. We concluded that direct identification of mastitis-causing pathogens is possible for Staph. aureus, E. coli, Strep. agalactiae, Strep. dysgalactiae, and Strep. uberis, but correct identification depended on the bacterial count in the milk samples.     

Development of an Innovative Nutraceutical Fermented Beverage from Herbal Mate (Ilex paraguariensis A.St.-Hil.) Extract

Herbal mate (Ilex paraguariensis A.St.-Hil.) leaves are traditionally used for their stimulant, antioxidant, antimicrobial, and diuretic activity, presenting as principal components polyphenolic compounds. The aim of this work was to develop an innovative, non-dairy, functional, probiotic, fermented beverage using herbal mate extract as a natural ingredient which would also be hypocholesterolemic and hepatoprotective. Among different strains used, Lactobacillus acidophilus was selected as the best for fermentation. The addition of honey positively affected the development of L. acidophilus and the formulated beverage maintained microbial stability during shelf life. Key ingredients in the extract included xanthines, polyphenols and other antioxidants with potential health benefits for the consumer. Caffeine levels and antioxidant activity were also studied. Acceptable levels of caffeine and large antioxidant capacity were observed for the formulation when compared to other antioxidant beverages. An advantage of this product is the compliance to organic claims, while providing caffeine, other phyto-stimulants and antioxidant compounds without the addition of synthetic components or preservatives in the formulation. Sensorial analysis demonstrated that the beverage had good consumer acceptance in comparison to two other similar commercial beverages. Therefore, this beverage could be used as a new, non-dairy vehicle for probiotic consumption, especially by vegetarians and lactose intolerant consumers. It is expected that such a product will have good market potential in an era of functional foods.     

Three‐Step One‐Pot Synthesis of Imidazo[2,1‐b]chalcogenazoles via Intramolecular Cyclization of N‐Alkynylimidazoles

Imidazo‐chalcogenazoles are easily accessible from the corresponding N‐alkynylimidazoles by a three‐step, one‐pot chalcogenation reaction. The generality of this reaction has been established with various substituted N‐alkynylimidazoles as well as elemental chalcogens. By accessing the key intermediate 2‐chalcogenolate‐N‐alkynylimidazole it was also possible to prepare dichalcogenide derivatives.     

Transfer of Salmonella Enteritidis to four types of surfaces after cleaning procedures and cross-contamination to tomatoes

The objectives of the present study were to evaluate the spread of Salmonella Enteritidis to different cutting boards (wood, triclosan-treated plastic, glass, and stainless steel) from contaminated poultry skin (5 log CFU/g) and then to tomatoes and to analyze the effect of different protocols used to clean these surfaces to control contamination. The following procedures were simulated: (1) no cleaning after handling contaminated poultry skin; (2) rinsing in running water; (3) cleaning with dish soap and mechanical scrubbing; and (4) cleaning with dish soap and mechanical scrubbing, followed by disinfection with hypochlorite. The pathogen was recovered from all surfaces following procedure 1, with counts ranging from 1.90 to 2.80 log, as well as from the tomatoes handled on it. Reduced numbers of S. Enteritidis were recovered using the other procedures, both from the surfaces and from the tomatoes. Counts were undetectable after procedure 4. From all surfaces evaluated, wood was the most difficult to clean, and stainless steel was the easiest. The use of hypochlorite as a disinfecting agent helped to reduce cross-contamination.     

Nano and submicrometric fibers of poly(D,L‐lactide) obtained by solution blow spinning: Process and solution variables

Nano and submicrometric fibers of poly(D ,L ‐lactide) (PDLLA or PLA) were spun from solutions using a solution blow spinning (SBS) apparatus. Fiber morphology and diameter were investigated by scanning electron microscopy as a function of polymer concentration, feed rate, and air pressure. A more systematic understanding of the SBS process parameters was obtained, and a quantitative relationship between these parameters and average fiber diameter was established by design of experiments and response surface methodology. It was observed that polymer concentration played an important role in fiber diameter, which ranges from 70 to 2000 nm, and its distribution. Lower polymer concentration tended to increase the formation of bead‐on‐string structures, whereas smooth fibers were formed at higher concentrations. Fiber diameter tended to increase with polymer concentration and decrease with feed rate. Based on these results, optimal conditions could be obtained for solution‐blow spun fibers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Application of Ultrasound for Oil Separation and Recovery of Palm Oil

This work investigated whether ultrasound treatment could improve the oil recovery from the extract obtained from pressed oil palm mesocarp. Oil recoverable after subjecting two process streams from palm oil milling operations to ultrasound were compared to that obtained from corresponding samples without ultrasound treatment. The process streams examined were (i) the ex-screw press feed into the vertical clarification tank and (ii) the underflow sludge from the clarification tank. Oil recoverable was taken as the sum of decantable oil obtained after a gravity settling process at 85 °C for 1 h (skimmed oil) and oil released from the remaining colloidal dispersion after centrifugation at 1,000 g (centrifuged oil). Oil recoverable was dependent on the ultrasound treatment applied, type of transducer used and the feed stream. Increased recoverable oil was obtained by applying low frequency ultrasound (20 kHz) to the ex-screw press feed using a long rod radial sonotrode system but recoverable oil was decreased when a short single step cascade focused sonotrode system was used. High frequency ultrasound (400 + 1,600 kHz) increased recoverable oil from both process streams. Applying sequential low and high frequency ultrasound increased recoverable oil from the ex-screw press feed but decreased that from the underflow sludge. The use of high frequency ultrasound for improving oil recovery is a significant advance for palm oil milling operations.     

Electrothermal model for simulation of bulk-Si and SOI diodes in ESD protection circuits

An electrothermal diode model intended for implementation in a SPICE-like simulator is presented. The model is valid in the high current, forward-bias and reverse-breakdown regimes where diodes operate during ESD events. We also present a procedure for extracting the temperature of an SOI diode from an I–V measurement.     

Accurate wafer-level measurement of ESD protection device turn-onusing a modified very fast transmission-line pulse system

Quantifying the turn-on behavior of electrostatic discharge (ESD) protection devices under subnanosecond transients is critical to achieving robust protection against the Charged Device Model stress. A wafer-level very fast transmission-line pulse system (VFTLP) has been developed and is shown to successfully measure the turn-on time of a common ESD protection device. Both formal analysis and practical details regarding VFTLP system construction and operation are documented