Environmental Screening of a Cannabis Production and Processing Facility: A Comparison of an Environmental DNA Microarray and Traditional Microbiological Plating Methods

December 18, 2019
Abstract / Synopsis: 

As the cannabis industry continues to expand and become more heavily regulated, the need for screening tools that detect microbial contamination increases. While screening has primarily focused on the raw product, there has been little emphasis on the actual facilities in which that product is processed, which has the potential to be a contaminating source for the cannabis product. The following case study was performed to demonstrate the utility and necessity of environmental screening in a cannabis production and processing facility. Samples were collected for assessment of microbial contamination across 11 locations throughout the facility. Each sample was assessed by traditional microbiological plating and an environmental DNA microarray to compare the effectiveness of both methods.

Environmental surveillance is increasingly appreciated for its utility in public health efforts, including those related to agriculture and quality control (1). The presence of pathogenic organisms in production facilities is concerning because it indicates that there may be a reservoir of the contaminating organisms within the facility (2). Importantly, these pathogenic organisms may be capable of posing a significant risk to both human health and agricultural products. More specifically, the presence of agricultural pathogens in horticultural operations may increase the risk of agricultural disease, thereby increasing the likelihood of agricultural losses and rejected batches of product. These concerns persist not only in agricultural operations, but also in food and drug production.

Provided the potential ramifications of microbial contamination in such a facility, it is important that practices in risk reduction are diligently followed and maintained. An important component of risk reduction is the continuous screening and monitoring of a facility for microbial contamination. Importantly, while an initial investigation may be able to detect and identify contaminating organisms present within a facility, subsequent screening and surveillance is necessary to confirm the effectiveness of decontamination methods, verify sources of contamination, and validate the cleanliness of a facility, as well as identifying any new instances of contamination that may occur.

Currently, the golden standard for the screening, detection, and assessment of microbial contamination has been through culturing on agar plates (3). While traditional plating methods offer a visual confirmation of microbial presence and viability, and do not require sophisticated equipment, this method does pose several disadvantages. For instance, plating is incredibly time-consuming, can be laborious, and requires the expertise of a skilled microbiologist. Additionally, a comprehensive microbiological analysis, which encompasses the detection of multiple types of organisms, often requires the use of multiple plates and media types, increasing material and labor costs; even so, species-level identifications require secondary methods of confirmatory testing.

Though their use has not yet become standard in the industry, the use of microarrays for broad-spectrum microbial detection and identification has been well-studied for its many applications in clinical and agricultural settings (4). Microarray technology is able to identify microorganisms at the family, genus, and species-level of classification. Multiplexed in design, microarrays are capable of simultaneously detecting a multitude of microbial isolates within a single sample in a matter of a few hours, making the array more cost-effective and less labor-intensive than traditional plating methods. While microarrays do require specialized equipment and training in molecular techniques, the mechanism of recognition of specific DNA sequences imparts a high degree of both specificity and sensitivity in microbial detection.

This study was conducted in an effort to highlight the utility and necessity of environmental screening of an agricultural production and processing facility. The study also compares the proficiency of traditional microbiological plating and the environmental DNA microarray used in this screening.

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About the Authors

Chelsea Adamson is a microbiologist and Benjamin A. Katchman is a principal scientist at PathogenDX in Tucson, Arizona. Direct correspondence to: [email protected]

How to Cite this Article

C. Adamson and B.A. Katchman, Cannabis Science and Technology 2(6), 54-61 (2019).