Inhibitors of Autoinducer-2 Quorum Sensing and Their Effect on Bacterial Biofilm Formation

Bacteria utilize small signaling molecules, or autoinducers, to regulate their gene expression in tandem by a process termed quorum sensing. The gene encoding the synthase for autoinducer-2 (AI-2), luxS, is conserved in dozens of diverse bacteria. Behaviors controlled by AI-2 include virulence, motility, toxin production, and biofilm formation. The development of therapies that interfere with AI-2 quorum sensing are attractive for targeting biofilms, which exhibit inherent resistance to most antibiotics and biocidal agents. In this study, in vitro synthesized AI-2, LuxS inhibitors, and (5Z)-4-bromo-5-(bromomethylene)-3-butyl-2(5H)-furanone were screened for their effect on biofilm formation in Escherichia coli, Bacillus cereus, and Listeria innocua. The LuxS inhibitors were found to have no influence on biofilm formation in any of the screened species, but reduced exponential phase AI-2 production in Listeria innocua. The brominated furanone significantly inhibited growth in B. cereus and L. innocua, and under certain conditions preferentially inhibited biofilm formation independently from growth

Dimensionamiento y selección del sistema de enfriamiento forzado de mosto por agua en destilería de alcohol de empresa Laredo S.A. para aumentar capacidad de producción

Se presenta el dimensionamiento y selección de un sistema de enfriamiento forzado de mosto por agua en destilería de alcohol de Laredo, para aumentar su capacidad de producción. El principal inconveniente es que no se cuenta con un sistema de enfriamiento adecuado, el sistema actual es del tipo por convección natural, insuficiente para asumir las variaciones de carga. En base al balance de flujo másicos, y de potencia térmica a plena capacidad, resulta que se utiliza 6.38 toneladas de melaza por hora, generando 23.64 ton/h de mosto y 1.4034 ton/h de CO2 por hora. En la preparación de mosto, que es un subproducto de la melaza de caña, el cual sirve a su vez como insumo directo para producir alcohol rectificado, se emplea 6.17 kg/s de agua, se genera 45,548 litros de alcohol/día, a partir de 2870 kg de azúcares fermentezible/h, que es la que determina la productividad de producción de alcohol Se determinó la carga térmica por cuba para el enfriamiento del mosto, de 22000 litros de mosto, el cual se fermenta en 7 horas, en promedio, siendo la carga térmica de 125 kW por cuba de fermentación, en base a este valor se dimensiona la capacidad de enfriamiento del intercambiador de calor, el cual es del tipo de placas, porque es necesario desmontar con bastante frecuencia para su limpieza, pues el mosto es un fluido sucio, que reduce la capacidad de transferencia de calor, se obtiene coeficiente global de intercambio de calor de 5000 w/(m2*°C), diferencia de temperatura entre mosto y agua de enfriamiento de 1.5°C, lo que es muy bueno, y una superficie de intercambio de calor de 5 m2. El sistema de enfriamiento de mosto se diseñó para trabajar en modo automático, PID, para controlar la temperatura del mosto, que debe ser de 30 °C +- 0.5 °C, lo cual es muy importante. En la parte final se hizo el análisis económico: la inversión igual a 213863 soles, el beneficio neto asciende a 25,160.35 soles/mes y el tiempo estimado de retorno de la inversión asciende a 8.5 meses. Se concluye que el proyecto es viable técnico y económico, porque tiene un buen retorno y su vida útil es de 15 años

Genome-wide <i>Escherichia coli </i>stress response and improved tolerance towards industrially relevant chemicals

BACKGROUND: Economically viable biobased production of bulk chemicals and biofuels typically requires high product titers. During microbial bioconversion this often leads to product toxicity, and tolerance is therefore a critical element in the engineering of production strains. RESULTS: Here, a systems biology approach was employed to understand the chemical stress response of Escherichia coli, including a genome-wide screen for mutants with increased fitness during chemical stress. Twelve chemicals with significant production potential were selected, consisting of organic solvent-like chemicals (butanol, hydroxy-γ-butyrolactone, 1,4-butanediol, furfural), organic acids (acetate, itaconic acid, levulinic acid, succinic acid), amino acids (serine, threonine) and membrane-intercalating chemicals (decanoic acid, geraniol). The transcriptional response towards these chemicals revealed large overlaps of transcription changes within and between chemical groups, with functions such as energy metabolism, stress response, membrane modification, transporters and iron metabolism being affected. Regulon enrichment analysis identified key regulators likely mediating the transcriptional response, including CRP, RpoS, OmpR, ArcA, Fur and GadX. These regulators, the genes within their regulons and the above mentioned cellular functions therefore constitute potential targets for increasing E. coli chemical tolerance. Fitness determination of genome-wide transposon mutants (Tn-seq) subjected to the same chemical stress identified 294 enriched and 336 depleted mutants and experimental validation revealed up to 60 % increase in mutant growth rates. Mutants enriched in several conditions contained, among others, insertions in genes of the Mar-Sox-Rob regulon as well as transcription and translation related gene functions. CONCLUSIONS: The combination of the transcriptional response and mutant screening provides general targets that can increase tolerance towards not only single, but multiple chemicals. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12934-016-0577-5) contains supplementary material, which is available to authorized users

Selecting the Best: Evolutionary Engineering of Chemical Production in Microbes

Microbial cell factories have proven to be an economical means of production for many bulk, specialty, and fine chemical products. However, we still lack both a holistic understanding of organism physiology and the ability to predictively tune enzyme activities in vivo, thus slowing down rational engineering of industrially relevant strains. An alternative concept to rational engineering is to use evolution as the driving force to select for desired changes, an approach often described as evolutionary engineering. In evolutionary engineering, in vivo selections for a desired phenotype are combined with either generation of spontaneous mutations or some form of targeted or random mutagenesis. Evolutionary engineering has been used to successfully engineer easily selectable phenotypes, such as utilization of a suboptimal nutrient source or tolerance to inhibitory substrates or products. In this review, we focus primarily on a more challenging problem—the use of evolutionary engineering for improving the production of chemicals in microbes directly. We describe recent developments in evolutionary engineering strategies, in general, and discuss, in detail, case studies where production of a chemical has been successfully achieved through evolutionary engineering by coupling production to cellular growth

The cellular uptake and cytotoxic effect of curcuminoids on breast cancer cells

AbstractObjectiveCurcuminoids (including curcumin) are natural antioxidants demonstrating potent chemopreventive properties against several forms of cancer. This study investigated the antiproliferative and induced apoptotic effects of curcuminoids on three cell lines isolated from human breast adenocarcinoma and ductal carcinoma (MDA-MB-231, MDA-MB-435S, and MCF-7).Materials and MethodsThis study developed a highly sensitive, reproducible assay method using high-pressure liquid chromatography to quantify the cellular uptake of curcuminoids by breast cancer cells and quantitate its effect on inhibition of proliferation and activation of apoptosis in breast cancer cells.ResultsResults indicate that curcuminoids inhibited cell proliferation and activation of apoptosis in the cell lines in this study. Both effects were observed to increase in proportion to the cellular uptake of curcuminoids; cellular uptake increased following an increase in the dosage of curcuminoids.ConclusionThe inhibition of proliferation and increased apoptosis of breast cancer cells appears to be associated with the uptake of curcuminoids by cancer cells