Tween is unstable and more likely to break down to oleic acid, which can serve as a fatty acid carbon source for the growth of mycobacteria. Tyloxapol on the other hand has been shown to be more stable and functions more as a detergent. Inclusion of Tween-80 also has been reported to affect other phenotypes such as MIC, response to acidic stress etc.

In acidic pH tween 80 can also give origin to toxic compounds.

Neeraj, do you have a reference for the relative stability of Tween vs Tyloxapol? Or its detergent properties? Tyloxapol is a polymer. Any detailed info would be helpful. THank you!

Pamela, Tween has been shown to degrade and inhibit growth of MTB.

1. Davis BD, Dubos RJ. 1948. The Inhibitory Effect of Lipase on Bacterial Growth in Media Containing Fatty Acid Esters. J Bacteriol 55:11–23.

2. R.J. Dubos, B.D. Davis 1946. Factors affecting the growth of tubercle bacilli in liquid media J. Exp. Med., 83,  409–423

and influence acidic stress response

1. Vandal OH, Pierini LM, Schnappinger D, Nathan CF, Ehrt S. 2008. A membrane protein preserves intrabacterial pH in intraphagosomal Mycobacterium tuberculosis. Nat Med 14:849–854.

Also see

1. Tang YJ, Shui W, Myers S, Feng X, Bertozzi C, Keasling JD. 2009. Central metabolism in Mycobacterium smegmatis during the transition from O2-rich to O2-poor conditions as studied by isotopomer-assisted metabolite analysis. Biotechnology Letters 31:1233–1240.

Hope these help.

Thank you so much! This is a good start.

No one has yet noted that Mtb can use Tween-80 as a carbon source. This is obviously problematic in carbon-restricted/metabolomics experiments but can also modify the transcriptome of the bugs making modified growth phenotypes tricky to dissect. This is not a problem when using tyloxapol as the detergent.

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