PathogenDx DetectX Combined Demonstrates Equivalent Performance in Comparison to Four AOAC Certified Methods for the Detection of Aspergillus Species, Salmonella Species, and STEC in Dried Hemp Flower.

BACKGROUND: The PathogenDx DetectX Combined method is a certified Performance Tested MethodSM (012201) that is enrichment-free and utilizes a DNA microarray-based end point PCR method for the simultaneous detection of Aspergillus (A. flavus, A. fumigatus, A. niger, and A. terreus), Salmonella spp., and a broad range of Shiga toxin-producing Esherichia coli (STEC) from hemp and cannabis flower, edibles, and concentrates. OBJECTIVE: This study aimed to compare the PathogenDx DetectX Combined enrichment-free method to four AOAC INTERNATIONAL certified molecular methods that utilize enrichment prior to quantitative PCR (qPCR) amplification in hemp flower for the detection of Aspergillus (A. flavus), S. enterica, and Escherichia coli 026. METHODS: In this method comparison study, each method was evaluated according to the AOAC validated instructions for use (IFU) and the AOAC Appendix J validation guidelines. A total of 16 samples at three levels of contamination (0, 0.7, and 2 CFU/10g test portion) were analyzed by each method. The results for all methods were evaluated by using the probability of detection statistical model (POD). RESULTS: Results of the validation study demonstrate that the PathogenDx DetectX Combined enrichment-free method is equivalent in performance to the three proprietary methods evaluated in this study. CONCLUSION: The method comparison study indicated that the PathogenDx DetectX Combined enrichment-free method provides equivalent detection of the target analytes (A. flavus, Salmonella, and a broad range of STEC) in hemp flower. HIGHLIGHTS: The performance of The PathogenDx DetectX Combined method is significantly faster and possesses a higher or equivalent degree of sensitivity and specificity. Implementation of this method for routine microbial pathogen analysis in laboratories would save significant time and resources.

Legacies of precipitation influence primary production in Panicum virgatum.

Precipitation is a key driver of primary production worldwide, but primary production does not always track year-to-year variation in precipitation linearly. Instead, plant responses to changes in precipitation may exhibit time lags, or legacies of past precipitation. Legacies can be driven by multiple mechanisms, including persistent changes in plant physiological and morphological traits and changes to the physical environment, such as plant access to soil water. We used three precipitation manipulation experiments in central Texas, USA to evaluate the magnitude, duration, and potential mechanisms driving precipitation legacies on aboveground primary production of the perennial C4 grass, Panicum virgatum. Specifically, we performed a rainout shelter study, where eight genotypes grew under different precipitation regimes; a transplant study, where plants that had previously grown in a rainout shelter under different precipitation regimes were moved to a common environment; and a mesocosm study, where the effect of swapping precipitation regime was examined with a single genotype. Across these experiments, plants previously grown under wet conditions generally performed better than expected when exposed to drought. Panicum virgatum exhibited stronger productivity legacies of past wet years on current-year responses to drought than of past dry years on current-year responses to wet conditions. Additionally, previous year tiller counts, a proxy for meristem availability, were important in determining legacy effects on aboveground production. As climate changes and precipitation extremes-both dry and wet-become more common, these results suggest that populations of P. virgatum may become less resilient.