Agar-filled QTrays are used for large scale culture and screening of bacterial colonies. With the addition of a 48-well divider, multiple bacteria samples can be separately cultured on the same QTray (Figure 1 left). Typically plating on the QPix 460 is easily performed using QTrays with dividers. However, it is possible to culture multiple bacteria samples on QTrays without dividers as well, but concerns regarding cross-contamination must be overcome. In this note we demonstrate how the QPix™ 460 with customized plating can be used to plate QTrays without dividers while minimizing potential for cross-contamination between samples.
The QPix 460 automated microbial colony picker has the ability to plate samples on to agar-filled QTrays. 96 samples can be plated in 30 minutes. The default QPix 460 plating patterns are designed for plating agar-filled QTrays with dividers. However, the Plating Pattern Editor process in the QPix 460 software allows users to have the flexibility to create custom plating patterns. This makes it possible to create smaller plating patterns which will result in sufficient spacing between samples to prevent contamination when plating on to agar-filled QTrays without dividers.
Creating custom plating patterns
The Plating Pattern Editor is located under Plating Processes in the QPix 460 software (Figure 2). Once in the Plating Editor window, a custom plating pattern can be created and added (Figure 3).
Plating E.coli on to QTray
After creating the partial spiral plating pattern (Figure 4B), we used the Plating process on the QPix 460 along with the spreading head and pins to plate out E.coli diluted out at various concentrations on to a LB agar QTray without dividers. The QPix 460 was programmed to pipet 40µl of each E.coli sample and to use the partial spiral plating pattern.
After plating, the QTray was incubated overnight at 37°C. The next day the entire QTray was imaged in white light on the QPix 460 (Figure 5B and 6B).
Using the partial spiral plating pattern, there is plenty of space between each sample so that the samples remain separate with no colony growth observed in between them. This demonstrates that the QPix 460 is capable of not only plating multiple samples on to QTrays with dividers, but also on to QTrays with no dividers without any cross-contamination. The same partial plating pattern method can be adapted for Nunc™ OmniTrays™ as well.
|QPix 460||High-throughput screening and objective selection system for microbial colonies||Contact Us|
|Vented QTray with cover, polystyrene, 240 x 240 x 20 mm||20 per case||X6023|
|Vented Qtray with cover & 48 Well Divider, polystyrene, 242 x 240 x 20 mm||20 per case||X6029|
|Replacement pin for streaking head||Each||X4330|
|Streaking head||8 pins – 3.0 mm diameter||X4345|
|130 µL ART pipette tips||Pack of 10 boxes||T0130|