Living Organism Care - Bacteria
Quick Start Information:
- As soon as your shipment arrives, open the shipping package and remove the culture for inspection, but do not open the tube cultures until you are ready to use them.
- Inspect vials to make sure the caps are secure and keep the lids on culture bottles sealed tightly when not in use.
- Cultures can be kept at room temperature, however putting them in the fridge will extend their life by a few weeks.
- Bacteria are the oldest known form of life and have been found in 3.5 billion year old rocks.
- Bacteria do not have a membrane-enclosed nucleus; making them prokaryotes.
- Bacteria can be found almost everywhere on earth; from high in the atmosphere to at least 2 miles underground.
- Bacteria dramatically outnumber all other lifeforms; with an estimated population of 5 million trillion trillion.
- Domain: Eubacteria
- Kingdom: Bacteria
Our bacteria cultures are ready to use when you receive them. Before shipping, they have been incubated and prepared for use.
Some basic tips to follow are:
- Wipe down benches with 70% alcohol or a suitable disinfectant before and after working with cultures
- Wash hands thoroughly before and after working with cultures
- Sterilise the inoculating loop with a Bunsen burner before and after inoculation
- Flame the necks of the culture bottles before and after inoculation
- Avoid leaving agar plates open for any longer than necessary for inoculation
- Avoid placing the lids of the culture bottles on the bench. Instead, hold the lid curled up inside your little finger
- Work within close proximity of the Bunsen burner flame as this area will be sterile within a small radius
- Avoid talking while sub-culturing and work in a closed room to prevent airborne contamination
- Seal culture bottles tightly by securing their caps and ensure petri dishes have their lids in place when not in use
- Sterilise fresh agar by autoclaving, and allow to cool before inoculating
- Before disposal sterilise used agar plates and culture bottles by autoclaving or soaking in 10% bleach solution.
Keep all Bacteria cultures in the vials that they are shipped in, ideally refrigerated to extend life.
Maintaining and Culturing
Our bacteria cultures have been incubated and grown to maturity prior to you receiving them. You do not need to conduct any additional incubation. The majority of our bacterial cultures can be maintained up to 3 weeks at room temperature before the need for transference to fresh media.
Bacteria require transfer to new media when they have exhausted the nutrients in the current media. Many common bacteria, such as Escherichia coli will grow at normal room temperatures of 20 to 22° C, but grow faster when using an incubator. Depending on the bacterium, bacteria will get heavy growth at 48 hours at room temperature and within 24 hours within an incubator.
At the end of a microbiology activity it is important that all equipment be sterilized prior to disposal. Sterilize at 121ºC and a pressure of 15 psi for 20-30 minutes prior to disposal. Verify conditions with a sterile confirmation strip. For safe laboratory handling and disposal, refer to AS/NZS2243 Safety in Laboratory Standards.
All of the bacterial cultures that Southern biological supply are classified in Risk Group 1. Risk Group 1 cultures are unlikely to cause human, plant or animal disease of importance. However preventative laboratory techniques and safety steps, as listed below, should always be used. Follow all established laboratory practices for the handling of microbes.
- Perform work on an open lab bench or table that has been disinfected
- Wear appropriate personal protective equipment (PPE) such as a lab coat, gloves, and eye protection
- Ensure to tie hair back when working with an open flame
- Wash and dry your hands thoroughly before and after handling bacteria.
- Return all cultures to storage areas when you have finished with them for the day.
- Do not use bacteria nearby to locations food is stored, prepared or consumed.
Which agar is best for my bacterial cultures?
Can I pour my own plates if I don’t have an autoclave?
Yes and No. All media should be sterilised before use to ensure contamination does not occur. Southern Biological supply ready pour Nutrient Agar Gels and other prepared media bottles. A bottle containing 100mL of sterilised medium will pour 4 standard 92× 16-mm plates. Watch our video on melting and pouring agar plates for a demonstration of the technique.
Which cultures should I order for antibiotic testing?
For antibiotic testing, we recommend testing against Bacillus Subtilis, which is Gram-positive, and Escherichia coli, which is Gram-negative as Gram-positive and Gram-negative often give different results. Broth cultures are best for this as they are easier to spread over the surface of an agar plate.