Letheen Broth Base, modified

Letheen Broth Base Modified

EMD Cat. No. 1.10405.0500

500 g

Letheen Agar and Letheen Broth are special formulations for the determination of bacterial activity of quaternary ammonium compounds.

The media formulations comply with the recommendations of FDA/BAM (1995).

Mode of Action	Preparation
Experimental Procedure and Evaluation	Quality Control
Typical Composition (g/liter)	Literature

Mode of Action
Letheen media are highly nutritious containing Lecithin and Tween® 80 for neutralizing quaternary ammonium compounds. These media are modifications of the AOAC formulae.

Letheen Broth Base is used for determining the phenol coefficient of quaternary compounds.

Typical Composition (g/liter)
Letheen Broth Base:
Peptone from meat 20.0; peptone from casein 5.0; meat extract 5.0; yeast extract 2.0; sodium chloride 5.0; lecithin 0.7; sodium bisulfite 0.1.

Preparation of Letheen Broth
Suspend 37.8 g and 5 ml of Tween^® 80 in 1 liter of distilled or purified water until evenly dispersed. Heat, if necessary, with repeated stirring to dissolve completely and autoclave at 121 °C for 15 min.
pH: 7.2 ± 0.2 at 25 °C.
The prepared broth is turbid and yellowish-brown.

Incubation: 18 - 48 hours at 35 - 37 °C.

Experimental Procedure
Depending on the purpose for which the media are used.

Quality control

Test strains	Growth

Escherichia coli ATCC 25922	good / very good
Enterococcus faecalis ATCC 29212	good / very good
Pseudomonas aeruginosa ATCC 27853	good / very good
Staphylococcus aureus ATCC 25923	good / very good
Staphylococcus epidermidis ATCC 12228	good / very good
Salmonella typhimurium ATCC 14028	good / very good

Literature

FDA Bacteriological Analytical Manual (BAM), 8th ed. (1995), chapter 23: Microbiological Methods for Cosmetics, Letheen Agar (modified) = M 78, Letheen Broth (modified) = M 79.

Additives

EMD Cat. No.	Product	Pack Size
PX1291-1	Tween^® 80	500 ml