Pilot-scale crossflow-microfiltration and pasteurization to remove spores of Bacillus anthracis (Sterne) from milk

High-temperature, short-time pasteurization of milk is ineffective against spore-forming bacteria such as Bacillus anthracis (BA), but is lethal to its vegetative cells. Crossflow microfiltration (MF) using ceramic membranes with a pore size of 1.4 μm has been shown to reject most microorganisms from skim milk; and, in combination with pasteurization, has been shown to extend its shelf life. The objectives of this study were to evaluate MF for its efficiency in removing spores of the attenuated Sterne strain of BA from milk; to evaluate the combined efficiency of MF using a 0.8-μm ceramic membrane, followed by pasteurization (72°C, 18.6 s); and to monitor any residual BA in the permeates when stored at temperatures of 4, 10, and 25°C for up to 28 d. In each trial, 95 L of raw skim milk was inoculated with about 6.5 log10 BA spores/mL of milk. It was then microfiltered in total recycle mode at 50°C using ceramic membranes with pore sizes of either 0.8 μm or 1.4 μm, at crossflow velocity of 6.2 m/s and transmembrane pressure of 127.6 kPa, conditions selected to exploit the selectivity of the membrane. Microfiltration using the 0.8-μm membrane removed 5.91 ± 0.05 log10 BA spores/mL of milk and the 1.4- μm membrane removed 4.50 ± 0.35 log10 BA spores/ mL of milk. The 0.8-μm membrane showed efficient removal of the native microflora and both membranes showed near complete transmission of the casein proteins. Spore germination was evident in the permeates obtained at 10, 30, and 120 min of MF time (0.8-μm membrane) but when stored at 4 or 10°C, spore levels were decreased to below detection levels (≤0.3 log10 spores/mL) by d 7 or 3 of storage, respectively. Permeates stored at 25°C showed coagulation and were not evaluated further. Pasteurization of the permeate samples immediately after MF resulted in additional spore germination that was related to the length of MF time. Pasteurized permeates obtained at 10 min of MF and stored at 4 or 10°C showed no growth of BA by d 7 and 3, respectively. Pasteurization of permeates obtained at 30 and 120 min of MF resulted in spore germination of up to 2.42 log10 BA spores/mL. Spore levels decreased over the length of the storage period at 4 or 10°C for the samples obtained at 30 min of MF but not for the samples obtained at 120 min of MF. This study confirms that MF using a 0.8-μm membrane before high-temperature, short-time pasteurization may improve the safety and quality of the fluid milk supply; however, the duration of MF should be limited to prevent spore germination following pasteurization

Prevalence, distribution, and molecular characterization of Salmonella recovered from swine finishing herds and a slaughter facility in Santa Catarina, Brazil.

Projeto: 04.10.06.001

Isolation of Escherichia coli O157:H7 from Intact Colon Fecal Samples of Swine1

Escherichia coli O157:H7 was recovered from colon fecal samples of pigs. Polymerase chain reaction confirmed two genotypes: isolates harboring the eaeA, stx1, and stx2 genes and isolates harboring the eaeA, stx1, and hly933 genes. We demonstrate that swine in the United States can harbor potentially pathogenic E. coli O157:H7

From DNA sequence to application: possibilities and complications

The development of sophisticated genetic tools during the past 15 years have facilitated a tremendous increase of fundamental and application-oriented knowledge of lactic acid bacteria (LAB) and their bacteriophages. This knowledge relates both to the assignments of open reading frames (ORF’s) and the function of non-coding DNA sequences. Comparison of the complete nucleotide sequences of several LAB bacteriophages has revealed that their chromosomes have a fixed, modular structure, each module having a set of genes involved in a specific phase of the bacteriophage life cycle. LAB bacteriophage genes and DNA sequences have been used for the construction of temperature-inducible gene expression systems, gene-integration systems, and bacteriophage defence systems. The function of several LAB open reading frames and transcriptional units have been identified and characterized in detail. Many of these could find practical applications, such as induced lysis of LAB to enhance cheese ripening and re-routing of carbon fluxes for the production of a specific amino acid enantiomer. More knowledge has also become available concerning the function and structure of non-coding DNA positioned at or in the vicinity of promoters. In several cases the mRNA produced from this DNA contains a transcriptional terminator-antiterminator pair, in which the antiterminator can be stabilized either by uncharged tRNA or by interaction with a regulatory protein, thus preventing formation of the terminator so that mRNA elongation can proceed. Evidence has accumulated showing that also in LAB carbon catabolite repression in LAB is mediated by specific DNA elements in the vicinity of promoters governing the transcription of catabolic operons. Although some biological barriers have yet to be solved, the vast body of scientific information presently available allows the construction of tailor-made genetically modified LAB. Today, it appears that societal constraints rather than biological hurdles impede the use of genetically modified LAB.

Real-time observation of antigen¿antibody association using a low-cost biosensing system based on photonic bandgap structures

This paper was published in OPTICS LETTERS and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://dx.doi.org/10.1364/OL.37.003684. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law[EN] In this letter, we present experimental results of antibody detection using a biosensor based on photonic bandgap structures, which are interrogated using a power-based readout technique. This interrogation method allows a realtime monitoring of the association process between the antigen probes and the target antibodies, allowing the instantaneous observation of any interaction event between molecules. because etunable lasers and optical spectrum analyzers are avoided for the readout, a drastic reduction of the final cost of the platform is obtained. Furthermore, the performance of the biosensing system is significantly enhanced due to the large number of data values obtained per second.This work was partially funded by the European Commission under contract FP7-295043-BELERA, from the Spanish Ministerio de Ciencia e Innovacion (MICINN) under contracts TEC2008-06333 and CTQ2010-15943 (subprogram BQU), and from Generalitat Valenciana through the PROMETEO grants 2010-008 and 2012-087.García Castelló, J.; Toccafondo, V.; Escorihuela Fuentes, J.; Bañuls Polo, MJ.; Maquieira Catala, Á.; García-Rupérez, J. (2012). Real-time observation of antigen¿antibody association using a low-cost biosensing system based on photonic bandgap structures. Optics Letters. 37(17):3684-3686. https://doi.org/10.1364/OL.37.003684S368436863717Luchansky, M. S., & Bailey, R. C. (2011). High-Q Optical Sensors for Chemical and Biological Analysis. Analytical Chemistry, 84(2), 793-821. doi:10.1021/ac2029024Qavi, A. J., & Bailey, R. C. (2010). Multiplexed Detection and Label-Free Quantitation of MicroRNAs Using Arrays of Silicon Photonic Microring Resonators. Angewandte Chemie International Edition, 49(27), 4608-4611. doi:10.1002/anie.201001712García-Rupérez, J., Toccafondo, V., Bañuls, M. J., Castelló, J. G., Griol, A., Peransi-Llopis, S., & Maquieira, Á. (2010). Label-free antibody detection using band edge fringes in SOI planar photonic crystal waveguides in the slow-light regime. Optics Express, 18(23), 24276. doi:10.1364/oe.18.024276Toccafondo, V., García-Rupérez, J., Bañuls, M. J., Griol, A., Castelló, J. G., Peransi-Llopis, S., & Maquieira, A. (2010). Single-strand DNA detection using a planar photonic-crystal-waveguide-based sensor. Optics Letters, 35(21), 3673. doi:10.1364/ol.35.003673Claes, T., Molera, J. G., De Vos, K., Schacht, E., Baets, R., & Bienstman, P. (2009). Label-Free Biosensing With a Slot-Waveguide-Based Ring Resonator in Silicon on Insulator. IEEE Photonics Journal, 1(3), 197-204. doi:10.1109/jphot.2009.2031596Scullion, M. G., Di Falco, A., & Krauss, T. F. (2011). Slotted photonic crystal cavities with integrated microfluidics for biosensing applications. Biosensors and Bioelectronics, 27(1), 101-105. doi:10.1016/j.bios.2011.06.023Zlatanovic, S., Mirkarimi, L. W., Sigalas, M. M., Bynum, M. A., Chow, E., Robotti, K. M., … Grot, A. (2009). Photonic crystal microcavity sensor for ultracompact monitoring of reaction kinetics and protein concentration. Sensors and Actuators B: Chemical, 141(1), 13-19. doi:10.1016/j.snb.2009.06.007Sepúlveda, B., Río, J. S. del, Moreno, M., Blanco, F. J., Mayora, K., Domínguez, C., & Lechuga, L. M. (2006). Optical biosensor microsystems based on the integration of highly sensitive Mach–Zehnder interferometer devices. Journal of Optics A: Pure and Applied Optics, 8(7), S561-S566. doi:10.1088/1464-4258/8/7/s41Claes, T., Bogaerts, W., & Bienstman, P. (2011). Vernier-cascade label-free biosensor with integrated arrayed waveguide grating for wavelength interrogation with low-cost broadband source. Optics Letters, 36(17), 3320. doi:10.1364/ol.36.003320Zinoviev, K. E., Gonzalez-Guerrero, A. B., Dominguez, C., & Lechuga, L. M. (2011). Integrated Bimodal Waveguide Interferometric Biosensor for Label-Free Analysis. Journal of Lightwave Technology, 29(13), 1926-1930. doi:10.1109/jlt.2011.2150734Densmore, A., Vachon, M., Xu, D.-X., Janz, S., Ma, R., Li, Y.-H., … Schmid, J. H. (2009). Silicon photonic wire biosensor array for multiplexed real-time and label-free molecular detection. Optics Letters, 34(23), 3598. doi:10.1364/ol.34.003598Castelló, J. G., Toccafondo, V., Pérez-Millán, P., Losilla, N. S., Cruz, J. L., Andrés, M. V., & García-Rupérez, J. (2011). Real-time and low-cost sensing technique based on photonic bandgap structures. Optics Letters, 36(14), 2707. doi:10.1364/ol.36.002707Krishnamoorthy, G., Bianca Beusink, J., & Schasfoort, R. B. M. (2010). High-throughput surface plasmon resonance imaging-based biomolecular kinetic screening analysis. Analytical Methods, 2(8), 1020. doi:10.1039/c0ay00112

Employment Services Utilization and Outcomes among Substance Abusing Offenders Participating in California’s Proposition 36 Drug Treatment Initiative

California drug treatment programs may use funds to address barriers to work faced by Proposition 36 offenders, most of whom are not working at treatment entry, but employment services utilization and related behavioral outcomes have never been studied. This study examined primary data collected on 1,453 offenders by 30 programs during 2004 to explore the characteristics, employment services utilization, and outcomes of those who did and did not receive employment services while in drug treatment. One-year outcomes were mostly similar across groups, however, increases in the proportion of offenders employed, receiving income from employment and family or friends, and being paid for work were significantly greater among the received-employment-services group, and a greater proportion of this group also completed drug treatment. Employment services utilization was less likely for persons recruited from outpatient settings and more likely with greater severity of family/social problems and desire for services. Odds of employment one-year post-treatment entry were higher for those of Hispanic race/ethnicity (vs. White) and for those with treatment completion/longer retention but lower for those who were older, lived in specific counties, had greater employment problem severity at intake, and received other income-related services. Strategies for improving employment services utilization and outcomes among Proposition 36 offenders are discussed