Automatic Colony Counter

What is the Automatic Colony Counter?

An automatic colony counter captures a digital image of a plate and uses software segmentation to detect, count and size colonies without operator guessing. It suits laboratories that process many plates and need consistent, documented counts.

Overview

An automatic colony counter replaces visual judgement with controlled illumination and image analysis. The plate sits on a backlit or dark-field stage and a fixed camera captures an image at defined brightness and contrast. Software sets a threshold that separates colonies from the agar background, then applies size, circularity and color filters to reject dust, bubbles and plate artefacts. Detected colonies are counted, measured and optionally classified, and the result is reported as CFU with the dilution applied. Algorithms estimate the number of merged colonies, and plates outside the statistical counting range are flagged. Images and results are stored for review and export, and many instruments add inhibition-zone or spiral-plate modules. Performance depends on medium and colony color, so plates are validated against manual counts.

How does it work?

Automated colony counting replaces the naked-eye tally with a sensor and software. A plate is placed on a backlit or dark-field stage and a camera captures a high-resolution image. Software applies thresholding and brightness or color segmentation to separate colonies from the agar background, and size and circularity filters remove bubbles, dust and cracks. Counts are reported as colony-forming units and converted to CFU per millilitre or gram using the dilution. Laser counters scan with a moving beam and detect colonies by light attenuation, which avoids ambiguity from similar-colored growth, while fluorescence counters excite labeled or fluorogenic targets and read the emitted light. Many instruments estimate the number of merged colonies, flag plates outside the statistical counting range, and export images and results for review.

What are the key features?

• Fixed camera and controlled LED illumination for reproducible images
• Size, circularity and color filters reject artefacts and bubbles
• Handles merged colonies and flags out-of-range plates
• Automatic CFU calculation with dilution factor input
• Image and result storage with LIMS or spreadsheet export

What are the technical specifications?

A typical automatic colony counter configuration offers detection principle of Digital image analysis, camera resolution of 5–12 MP, illumination of Adjustable LED ring, bright-field or dark-field, plate formats of 55 mm, 90 mm, 150 mm, minimum detectable colony of 0.1 mm and counting range of 1–10,000 CFU per plate (configurable). Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Automatic Colony Counter is used in food and beverage microbiological testing, pharmaceutical environmental monitoring, water and wastewater analysis, cosmetics and personal care testing and contract microbiology laboratories. Across the wider Colony Counters class, laboratories also deploy it for food and beverage microbiological testing, pharmaceutical environmental monitoring and water and wastewater analysis.

Which standards and certifications apply?

Relevant standards and methods include ISO 7218, ISO 4833-1, ISO 4833-2, ISO 11133, FDA BAM Chapter 3 and IEC 61010-1. Certification candidates for this model are CE, ISO 9001 manufacturing and ISO 13485 manufacturing; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Install the counter on a stable bench away from direct sunlight, which changes illumination and thresholds. Keep the stage and optics clean, and follow the manufacturer interval for lamp or LED output checks. Verify performance with reference plates or a printed counting template and record results, because a drifting camera or dirty lens shifts counts. Before routine use, compare automated results with manual counts on typical media and organisms. For regulated laboratories, define who reviews flagged images, retain original images with the reported count, and place software updates under change control. Electrical safety follows IEC 61010-1.

How do I select the right Automatic Colony Counter?

Choose an automatic counter for medium to high plate volumes where consistency and documentation matter. In an RFQ specify plate sizes, minimum colony size, media types, required statistics and data export, and ask the supplier to demonstrate agreement with manual counts on your own plates.

How does it compare with other Colony Counters variants?

Match the counter to your plate types and throughput before comparing prices. Low-volume work with standard 90 mm dishes is well served by an illuminated manual counter, while routine high volume justifies an automated system. Confirm the plate formats accepted, including 55 mm contact plates, 90 mm and 150 mm dishes, and any compact dry or film plates you use. Check the detection principle, because color-based imaging is fast while laser scanning better separates colonies of similar hue, and fluorescence is needed for chromogenic or fluorogenic media. Look for statistics that follow ISO 7218 and recognized compendial guidance, including counting-range limits and treatment of spreading growth. Consider image retention, LIMS export and validation against manual counts on your own plates.