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

Soils in Urban Agriculture: Testing, Remediation, and Best Management Practices

Soils are an important consideration for individuals, community groups, and local governments becoming involved in urban agriculture. In many situations, urban soil has been contaminated and degraded by past industrial, dumping, construction or other activity, and adjacent buildings where lead-based paint has been applied. Elevated levels of lead are fairly common in urban soils and pose health risks, especially to young children who can ingest soil while playing or helping in gardens

Soils in Urban Agriculture: Testing, Remediation, and Best Management Practices

Soils are an important consideration for individuals, community groups, and local governments becoming involved in urban agriculture. In many situations, urban soil has been contaminated and degraded by past industrial, dumping, construction or other activity, and adjacent buildings where lead-based paint has been applied. Elevated levels of lead are fairly common in urban soils and pose health risks, especially to young children who can ingest soil while playing or helping in gardens

Evaluating Correlations and Development of Meteorology Based Yield Forecasting Model for Strawberry

California state is among the leading producers of strawberries in the world. The value of the California strawberry crop is approximately $2.6 billion, which makes it one of the most valuable fruit crops for the state and nation’s economy. California’s weather provides ideal conditions for strawberry production and changes in weather pattern could have a significant impact on strawberry fruit production. Evaluating relationships between meteorological parameters and strawberry yield can provide valuable information and early indications of yield forecasts that growers can utilize to their advantage. Objectives of this paper were to evaluate correlations of meteorological parameters on strawberry yield for Santa Maria region and to develop meteorology based empirical yield forecasting models for strawberries. Results showed significant correlation between meteorological parameters and strawberry yield and provided a basis for yield forecasting with lead time. Results from empirical models showed that cross-validated yields were closely associated with observed yield with lead time of 2 to 5 months. Overall, this study showed great potential in developing meteorology based yield forecast using principal components. This study only looked at meteorology based yield forecasts. Skills of these models can be further improved by adding physiological parameters of strawberry to existing models for strawberry

California Urban Agriculture Food Safety Guide: Laws and Standard Operating Procedures for Farming Safely in the City

This guide provides urban food producers in California with an overview of Federal and California food safety laws and regulations that may impact their operations

California Urban Agriculture Food Safety Guide: Laws and Standard Operating Procedures for Farming Safely in the City

This guide provides urban food producers in California with an overview of Federal and California food safety laws and regulations that may impact their operations

Fresh-Market Bulb Onion Production in California

Basic information for commercial fresh-market bulb onion producers, including information on crop climatic requirements, varieties, planting, fertilization, harvest, and marketing channels