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

Developing a Philippine climate-ocean typology as input to national vulnerability assessments

Remotely-sensed information was utilized to naturally divide the archipelagic waters of the Philippines into distinct clusters of historical air-sea climate exposures. For data, we made use of satellite-derived Sea surface temperature (SST), and sea surface height (SSH), wind data (W), and precipitation (P). Results show that the Philippines naturally divide into 11 exposure clusters. Within each cluster the trends and anomalies of SST, anomalies and future scenarios of precipitation, and trends of sea surface height (SSH) were further calculated. Results were then compared amongst the clusters and against global statistics to gain insight on the behavior in each of the clusters. Analysis shows that the entire Philippines suffer twice to 3-times the magnitude of the global sea level rise. The northwestern (cluster II) and the tip of the northeastern (cluster X) coastal and marine areas of the Philippines are most prone to extreme temperature and precipitation hazards. In comparison the south Sulu Sea (cluster XI) and Sulawesi (cluster VI) are the sites with the lowest magnitude of air-sea hazards. So far, these hazard typologies has serve as input to the Philippine I-C-SEA-Change tool built to guide non-specialists in local and adaptive capacity assessments