Transducer, which senses pressure buildup, is easy to assemble and use, and rate of gas produced can be measured automatically and accurately. Method can be used in research, in clinical laboratories, and for environmental pollution studies because of its ability to detect and quantify rapidly the number of gas-producing microorganisms in water, beverages, and clinical samples

Mills, S. M.

Pearson, A. O.

Wilkins, J. R.

English

NASA Technical Reports Server

August 1973	 B73-10241 
•	 NASA TECH BRIEF 
Langley Research Center 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Measuring Micro-Organism Gas Production 
.
A simple method has been devised to measure 
micro-organism gas production. It uses a pressure 
transducer to sense pressure buildup. The transducer is 
easy to assemble and use, and the rate of gas produced 
can be measured automatically and accurately. 
This method can be used ih research and in clinical 
laboratories, and for environmental pollution studies, 
because of its ability to detect and quantify rapidly 
the number of gas-producing micro-organisms in water, 
beverages, and clinical samples. 
A 5.0-psi (35 x -10 3 -N/m 2) differential pressure 
transducer and a 20-gauge needle are fitted to a metal 
cap which is machined to fit a 20- by 150-mm test tube. 
The inlet tube of the transducer and the needle are 
inserted through the cap and soldered into place. A 
silicone rubber gasket is positioned inside the cap to 
form a gastight seal. The needle, with an on-off valve 
attached, is used to equalize pressure inside the test 
tube with ambient pressure after the cap is positioned 
in place. 
The culture tube and transducer assembly are placed 
inside an incubator, with the electrical output of the 
transducer connected to a strip chart recorder. A dc 
power supply is used to energize the transducer. 
Measurements on the recorder are made on the 50-mV 
scale, and, in addition, an ac-dc digital voltmeter is used 
to read millivolt responses directly. The linear relation-
ships between inoculum size and time-to-pressure build-
up permit quantification of the number of micro-
organisms in a sample. 
The pressure transducer technique can be used 
effectively to determine the number of coliforms, in one 
sample of water, more accurately and faster than the 
presently used MPN (Most Probable Number) procedure.
Gas-producing micro-organisms of the Enterobac-
teriaceae are responsible for the majority of urinary 
tract infections. As counts must exceed 100,000 cells/ml 
before a urinary infection is established, it is possible 
to determine within five hours or less, with the trans-
ducer method, the number of micro-organisms in a 
sample. The conventional plate-counting method requires 
24 hours. 
This technique has potential application in the 
alcoholic beverage industry (beer, wine, whiskey, etc.), 
where the transducer method could be used to check on 
the fermentation capabilities of yeast cultures and also 
as an aid in monitoring various stages of!production. 
Note: 
Requests for further information may be directed to: 
Technology Utilization Officer 
Langley Research Center 
Mail Stop 139-A 
Hampton, Virginia 23665 
- Reference: B73-10241 
Patent status; 
Inquiries concerning rights for the commercial use of 
this invention should be addressed to: 
Patent Counsel 
Langley Research Center 
Code 456 
Hampton, Virginia 23665 
Source: Judd R. Wilkins, Albin 0. Pearson,
and Stacey M. Mills
Langley Research Center 
(LAR-1 1326) 
Category 05 
This document was prepared under the sponsorship of the National 	 Government assumes any liability resulting from the use of the' —
Aeronautics and Space Administration. Neither the United States 	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States 	 will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19730000241 2020-03-17T07:15:29+00:00Z


Measuring micro-organism gas production

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server