Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Blood Agar and Vinegar

Name: Luke
status: student
Grade: 6-8
Location: GA
Country: USA
Date: Winter 2011-2012

I am testing hand sanitizer brands on blood agar plates and comparing their antimicrobial activity to distilled vinegar. When I put a couple of drops of vinegar on the innoculated blood agar plate, the blood agar turned brown. Why? NEWTON BBS does not recommend growing/culturing bacteria without the supervision of a microbiologist, and a properly equipped microbiology laboratory. Safety is our main concern! Growing dangerous bacteria species unknowingly is a real possibility and serious illness may occur without proper handling techniques. Furthermore, without proper bacterial disposal procedures such as an autoclave can guarantee, there is a danger to anyone who comes in contact after disposal.

The pH of the blood agar was lowered (made more acidic) by adding vinegar.

Judy Luke

The protein in blood that makes it red is called hemoglobin. Vinegar is an acid with a relatively low pH. Hemoglobin is adapted to working at your body's natural pH which is about 7.3-7.4. Protein denatures at pH's out of the normal range. The vinegar is probably denaturing the hemoglobin in the blood in the agar plates. The evidence of this is turning the blood brown.


Click here to return to the Molecular Biology Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (, or at Argonne's Educational Programs

Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory