The bar plate method is a time-tested method widely used in medical, food, veterinary and industrial microbiology to produce isolated colonies of microorganisms. In the article we will consider how this method works, what are its advantages, how to properly perform sowing and what consumables provide the best result.
The essence of the method: how the dashed plate works
The method is based on the sequential application of a sample of microorganisms to the surface of a dense nutrient medium – usually agar in a petri dish. A sterile bacteriological loop or spatula is used to perform successive strokes in several zones. Each subsequent zone contains a smaller number of microbial cells. Due to this, after incubation, clearly isolated colonies grow in the latter zones, from which a pure culture can be isolated.
Stages of sowing
The correct execution of the dashed plate method consists of several mandatory steps:
- Preparation of the environment.
A sterile petri dish filled with nutrient agar is used. A uniform surface without defects is important.
- Sampling
The sterile loop is immersed in a biomaterial (blood, urine, mucus etc.) or in an enriched medium.
- Drawing strokes.
It is carried out in 3-4 sectors:
- The first sector – parallel strokes.
- After sterilization, the loops are strokes in a new direction (perpendicular).
- Next – the third and, if necessary, the fourth sowing zone.
- Incubation.
The plate is placed in a thermostat for 24-48 hours at a temperature of + 35-37 ° C.
- Evaluation of the result.
In the initial zones – dense, often fused colonies; in the final – clearly isolated bacterial colonies.
Advantages for laboratory diagnostics
The method remains unchanged due to its advantages:
- Reliability. High probability of obtaining a pure culture even with a small number of microorganisms.
- Versatility. It is used in bacteriological diagnostics, pharmaceuticals, agro- and food industry.
- Availability. Minimum requirements for equipment and materials.
- Efficiency. Low cost of sowing compared to automated systems.
- Speed. After a day, the specialist receives the result and can begin to identify the pathogen or assess the sensitivity to antibiotics.
The quality of petri dishes matters
For a guaranteed result, it is necessary to use high-quality Petri dishes – transparent, sterile, heat-resistant. The Ukrainian company Vorwarts Diagnostic offers laboratory institutions petri dishes and other consumables of its own production. The products are manufactured on modern equipment with a high degree of automation and go through several stages of quality control.
In the company catalog you will find everything you need for microbiological work:
- Petri dishes
- Eppendorf microtubes
- Tips for dispensers
- Sample tubes and containers
- Pasteur pipettes and other goods
You can view the full range and make an order on the page: vorwartsdiagnostic.com/products
Historical fact: Robert Koch and the emergence of the methodology
The dashed plate method was first proposed by Robert Koch in the second half of the 19th century. His developments in the field of microbiology became the basis for the creation of modern methods for the diagnosis of infectious diseases.
The bar plate method is a simple but powerful microbiologist tool. Its effectiveness in isolating isolated colonies makes it possible to ensure the accuracy of laboratory diagnostics. The further success of the study depends on the quality of the petri dish and the correct execution of the inoculation. That is why more and more laboratories choose Vorwarts Diagnostic as a reliable supplier of laboratory consumables in Ukraine.
