Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

OBTENCIÓN DE ACEITE DE SEMILLA DE MANGO MANILA (Mangifera indica L.) COMO UNA ALTERNATIVA PARA APROVECHAR SUBPRODUCTOS AGROINDUSTRIALES EN REGIONES TROPICALES

The use of agricultural waste products in Mexico, and specifically in tropical regions is an area with great economic potential. In some tropical regions in Mexico it is necessary to generate new products with added value to increase regional development. In this work, two different solvents were evaluated (petroleum ether and ethyl ether) and two different size sample (3 and 6 g) using a factorial design 22 in order to optimize the extraction of fat from the mango. Additionally the chemical characterization of fat obtained was carried out. The results showed significant difference in the type of solvents used, ethyl ether showed better results; however in the size of sample no significant differences were appeared (= 0.01), extraction percent on average of samples were of 5.5%. Chemical characteristics of mango seed kernel oil were found to have a higher ratio of unsaturated fats (53.7%) than saturated fats (45.2%). Oleic acid had the highest proportion (45.6%). The oil obtained showed less than 0.2% moisture and free fatty acid concentration of 2%