A shake flask is a common laboratory vessel, typically made of glass or plastic, designed for cultivating microorganisms or cells. Its purpose is to provide a controlled, agitated environment for uniform growth and optimal conditions for biological cultures.
How Shake Flasks Function
Shake flasks function through continuous orbital shaking motion, imparted by a specialized shaker incubator. This agitation creates a dynamic liquid surface, increasing the interface between the culture medium and headspace air. This increased surface area is important for efficient oxygen transfer into the liquid, a process known as aeration, which often limits aerobic cell growth.
Beyond aeration, constant mixing ensures uniform nutrient distribution throughout the medium. This prevents localized resource depletion and promotes consistent access for all cells. The continuous movement also keeps cells suspended, preventing settling that could lead to nutrient gradients and inefficient growth.
Essential Design Elements
Shake flasks are commonly made from borosilicate glass, known for its chemical resistance and thermal stability, or from disposable plastics. Shapes vary, with Erlenmeyer flasks being common. Specialized baffled flasks have indentations on their inner surface that disrupt liquid flow during shaking, enhancing turbulence and improving oxygen transfer.
The flask opening is sealed with various cap types to maintain sterility and regulate gas exchange. Options include porous foam plugs, which allow passive gas exchange while preventing contamination, or screw caps with integrated sterile filters. These filters permit controlled passage of gases like oxygen and carbon dioxide, balancing aeration with preventing microbial ingress.
Common Uses in Science
Shake flasks are widely used across scientific disciplines for cultivating diverse biological systems. They are routinely used for growing microbial cultures, including bacteria and yeasts, serving as a primary tool for initial cell expansion and maintenance. Many cell cultures, such as insect cells and certain suspension-adapted mammalian cells, also thrive in these agitated environments.
Shake flasks are also used in small-scale fermentation processes. Researchers utilize them for preliminary screening of different culture conditions, such as varying nutrient compositions or pH levels, to identify optimal growth parameters. They also serve as a system for producing small quantities of biomolecules, including recombinant proteins, enzymes, or metabolites, for further research or analysis.
Key Benefits for Research
Shake flasks offer several advantages for research applications. Their simplicity and straightforward operation contribute to their widespread adoption. Compared to more complex bioreactor systems, shake flasks are cost-effective, requiring minimal initial investment and maintenance.
This accessibility makes them versatile for conducting numerous experiments simultaneously, particularly in high-throughput screening. Researchers can easily set up many flasks, each testing a unique condition or microbial strain, in parallel. This enables rapid evaluation of parameters before committing to larger, more resource-intensive bioreactor scales.