Biosafety Cabinet
What are they and why do we use them? What types are there?
Biosafety cabinets are used to create a Sterile Workspace for performing Sterile Technique, replacing the traditional Bunsen burner. Incoming air passes through a HEPA filter and is blown in two curtains towards the bottom of the cabinet. Suction at the bottom of the cabinet rapidly pulls the air out of the cabinet.
The net result is a zone of negative pressure, protecting the work from the researcher and researcher from the work.
There are numerous types and classes of Biosafety Cabinet, however this level of sterility is already overkill for most projects you should be considering. High classes of biosafety cabinets are recommended for work with pathogens, something that you should avoid in synthetic biology. You can learn more about the distinctions between biosafety cabinet classes here.
When do you use?
A Biosafety Cabinet is an excellent piece of technology for ensuring you have a sterile workspace for all of your work. Some researchers choose to do all of their work in a Cabinet.
However, access to the Biosafety Cabinet in any lab may be a bottleneck, so it can be important to know which protocols need priority access to the space. If possible, you should always use a Laminar Flow space or Biosafety Cabinet for the production of Competent Cells and Plate Pouring.
It is possible to perform both of these protocols under a simple Bunsen burner, or preferably a Laminar flow hood.
How do you use?
Use of a Biosafety Cabinet requires a proper understanding of the airflow within the cabinet. You will always want to have your project closer to the air outlet than you - ensuring bacteria/enzymes aren’t blown off your skin and into your project.
Start-up Protocol:
Place the metal cover over the hood opening and turn on the UV light. The glass should be UV resistant, but don’t tempt fate by staring.
After 10 minutes, turn off the UV light, and turn on the Laminar flow fans. As the suction begins, pull off the metal front panel.
Don’t leave the panel on for too long as it may be damaged by the air pressure.
Put on your gloves and spray them with 70% ethanol.
Spray the inside of the Biosafety Cabinet with 70% ethanol and wipe it down with paper towel.
The Laminar flow hood is now sterile.
As you move your work into the Biosafety Cabinet, spray the outside of each bottle/tube with 70% ethanol and wipe them down with paper towel.
As a general rule, always move an object backwards and to one side after use.
If you need to sterilise an inoculating loop in the cabinet while using a Bunsen burner, keep in mind that the stronger air flow of the cabinet will override the traditional cone of protection. The heat will still sterilise, but the air flow will blow the bacteria on the loop back towards you. Set up your workspace with this in mind.