Toxi-Lab™ Testing Educational Kit

toxi lab bacterial toxicity educational kit

 

Acute Toxicity Test for the Classroom

 

Timeline: 2 to 3 Classroom Periods

About the Toxi-Lab™: The Toxi-Lab™ determines environmental toxicity and can be used for a variety of toxic substances such as heavy metals, as well as organic and inorganic pollutants. The test determines the relative toxicity of different samples at varying concentrations.  The Toxi-Lab™ uses a non-pathogenic, harmless, mutated strain of E. coli specifically engineered to be highly sensitive to toxic substances. In microplate wells, the bacteria are exposed to different concentrations of a test chemical for a period of time, and the chemical’s effect on the health and survival of the bacteria is measured.

Figure 1 shows typical results for the bacterial based Toxi-Lab with red chromogen. Figure 2 shows typical results with blue chromogen. Clear gradations in colour illustrate the effect of concentration on toxicity. Each column allows students to quantify the toxic effects of various test samples.

red High School Toxicity TestFigure 1: With Red Chromogen

Toxi Lab Bacterial Lab ResultsFigure 2: With Blue Chromogen

 Reaction: The Toxi-Lab™ takes advantage of E.coli’s natural ability to produce an enzyme called β-galactosidase which is used by bacteria to metabolize the food source lactose. The E.coli bacteria was exposed to stressing conditions and need to first recover, before they will actively produce β-galactosidase. The bacteria was incubated in a cocktail containing essential factors required for the recovery of the bacteria, a specific inducer of β-galactosidase, and the test chemical. This bioassay is based on the knowledge that a biologically active toxicant or chemical can interfere with the bacteria’s recovery process, diminishing β-galactosidase’s action or preventing its production, effectively slowing down or even stopping the digestion of lactose. We provide a synthetic sugar (a chromogen called X-gal) to emulate the lactose. β-galactosidase recognizes this imposter molecule as “lactose” and cleaves (hydrolyzes) the X-gal, producing a blue colour in the well with the bacteria. The amount of blue chromogen released reveals the extent to which the chemical is harmful to this living cell.

 

EDUCATIONAL LAB HANDOUT 

 

toxi lab bacterial toxicity educational kit logo.jpg

 

Download the Handout which includes Educator Resources, Student Handout, Preparation, and Lab Procedure

Learning Goals (see About Us for Details):  LG 1, LG 2, LG 3, LG 4, LG 7, LG 8, LG 9

Toxi-LabTM Information for the Educator

The Toxi-LabTM is offered in a format that will meet the needs of most class sizes and schedules.
Each kit contains sufficient components for one lab experiment. The bottles and vials in the Toxi-LabTM 
are labelled with clear, bold letters that are coded.  The Toxi-LabTM is designed for students to work in
8 groups of three to four students with one microplate for each group.  We also provide resources to complete the lab experiment along with a lab booklet. Each booklet contains information on concepts, preparation, the procedure, observing and recording results, further analysis, and a student lab
report for assessment and evaluation. EBPI can supply further supplies and equipment as needed.
See our supplies and equipment section for further information.

If you have further inquiries or concerns, please contact us.