Guide frame system to adapt a 96-well plate assay to solid media

Authors: Lewis, Micah; McMillan, Elizabeth; Adams, Eric

Submitted to: Invention Report
Publication Type: Other
Publication Acceptance Date: 6/24/2025
Publication Date: 6/25/2025
Citation: Lewis, M.A., Mcmillan, E.A., Adams, E.S. 2025. Guide frame system to adapt a 96-well plate assay to solid media. Invention Report. https://doi.org/10.60705/3DPX/22732.1.
DOI: https://doi.org/10.60705/3DPX/22732.1

Interpretive Summary: ARS scientists designed an inexpensive, 3D printed guide tool that can be used to accurately replicate the contents of microtiter plates onto petri-dishes. This simple device enhances the throughput of microbiology labs that work on bacteria not well suited to microtiter plate assays. The 3D plans for making this device are being made available in an online repository for bioscientific and medical 3D models and builds.

Technical Abstract: Within industrial, regulatory, and research microbiology laboratories, many experiments or tests require high-throughput assessment of small-volume inoculation. Such assessments can be performed in 96-well microtiter plates. The 96 wells are normally filled with broth that identifies the presence of certain bacteria by either changing color or becoming cloudy. This method is effective for testing the phenotypic responses of many bacteria. However, there are other bacteria with responses that are hard to interpret using this testing method. For instance, the presence of Campylobacter in the wells causes no color change or cloudiness which can be detected visually. While such bacteria are cumbersome to test in applications utilizing 96-well plates filled with broth, better accuracy of interpreting results is observed when the same bacteria are tested on a plate culture with agar. A large-volume, 150 x 15 mm petri dish was observed to be large enough to accommodate a 96-well replicator for plate culture. Thus, a 96-well repeater was utilized to transfer broth culture from all 96 wells simultaneously to the larger petri dish filled with agar to confirm growth. The applicator has 96 pins that correspond to the positioning of the wells on the microtiter plate. However, simply transferring the growth to the larger petri dish using the replicator was not accurate enough to determine which wells had growth and which did not. Therefore, out of need for a better solution, the 96-Well Microtiter Plate Replicator Guide System for Petri-dish Applications was developed within USDA ARS. The system boosts efficiency of a 10-replicate study by reducing time from 4 hours to 30 minutes and reducing the accumulated cost of supplies from $220 to $20. The system consists of 5 parts, all of which can be created with a 3D printer for less than $3. This system allows you to adapt a 96-well plate assay to solid media for whatever application you would need.