Fig 1.
POLIR architecture, positional accuracy, and resolution.
A3 imaging size of POLIR filled with 2160 individual capillaries and a 96 well plate. The area was imaged using a Canon EOS 1300D with ES-F f/2.8 Macro Lens (a) or individual images using the POLIR (b). Scale bar indicates 48 pixels. Histogram of the deviation of repeated measurements from the mean for the x-axis (a) and y-axis (b). Scatter diagrams showing the x and y positions in relation to the mean when there is no homing (c) and with homing every 13 image acquisitions (d). (e) line pairs/mm in relation to the z-height of the camera axis for objects flat on the white light LED board and on agar plates. (f) Image of POLIR from front view and top view. All files needed to build the POLIR have been deposited on GitLAb licenced under the MIT license. (g) Number of line pairs/mm from USAF 1915 resolution target seen at increasing z-height. (h) Photograph showing the front and top view of the POLIR.
Fig 2.
Demonstration of different experimental formats performed using POLIR using agar plates, microtitre plates and microcapillary film.
(a) Motility assay using motile E. coli 25922 and non-motile S. aureus 12600. (b) Detection of E. coli colonies on LB agar supplemented with 0.1 mg/mL TTC showing both the raw and binary images. (c) Effect of milk concentration on E. coli growth and detection within MCF, error bars indicate ± SD of 3 replicate wells for MTP or 10 capillaries for MCF. (d) Images of MTP wells at start and endpoint of data shown in Fig 2C. (e) Images of MCF at start and endpoint of data shown in Fig 2C.
Fig 3.
POLIR can be used to screen antibiotic resistance of bacteria.
Growth curves of E.coli 25922 grown in MH broth or 10, 50 and 90% sterilised milk diluted in MH broth without and with 5 μg/mL gentamicin in MTP. Error bars indicate ± SD of triplicate wells in microtitre plate.
Fig 4.
Adaptation of POLIR for fluorescence measurements.
Growth curves of E. coli 25922 detected by fluorescence increase in resazurin metabolism measured in microtitre plates (a) and micro capillary film (b) Error bars indicate ± SD of duplicate wells in microtitre plates or 10 capillaries in microcapillary film. (c) Images captured from POLIR of microtitre plate and (d) microcapillary film.
Table 1.
Doubling time and resistance/susceptibility profile of bacteria isolated from bovine mastitis samples.
Table 2.
Summary of POLIR benefits over microplate reader or static camera.