We are working with photo-sensitive surfactants that can induce surface flows when irradiated by a focused laser. These surface flows stop when we add salt to the solution. We need surfactant solutions of about 1mM for these flows to develop. We would like to know how bacteria or other organisms from sizes 2 to 10 microns act on these surface flows. We tried some bacteria and cells but they barely survive di-ionized water. When we add surfactant they all die. Where can we find bacteria or other organisms that survive these deadly environments?
Bacteria are killed after the addition of the cationic surfactant. Experience the surfactant without charge, ie, nonionic surfactants.Use the Gram-positive bacteria.
Best regards.
Use organisms having cell walls (e.g. algae), they will withstand higher surfactant concentrations
Hello David,
Your problem is not explicit enough to understand everything. What I know is that many microorganisms survive better (or even good) to surfactants when embedded in a biofilm or a floc. Can it be useful to you?
Jacques
Thanks for your answers!
For induced surface flows we use simple cleaned glass slides. Our surfactant has an ammonium bromide head group where a spacer of 6 methyl groups is connected which is followed by an azobenzene group with 4 methyl groups making the end. The surfactant is hydrophobic in the trans state. When switched to cis conformation it becomes more hydrophilic and the critical micelle concentration rises from 0.5mM to more then 4mM. Usually, we use concentrations around 1mM, which induces surface flows. It is not possible to use buffer solution (because the flow stops), however, we tried to add glucose to somehow decrease osmotic pressure. It stops dictostylium discoideum from exploding when surfactant is added, but they do not survive surfactant exposure. We haven't tried non-ionic photo-sensitive surfactant yet.
What kind of algae do you have in mind Omar? Like Chlamydomonas reinhardtii?
Yuri, do you think gram-positive bacteria like bacillus subtilis might work? Do you think only with non-ionic surfactant?
As far as I understand you, Jacques, a higher density of bacteria that form flocs? I think biofilms cover the whole surface. The surfactant acts on the surface, so it would not work.
Hi David,
Biofilm is generally not a continuous surface and it spontaneously leaves its foundation surface, moreover, there exists metabolites able to "dissolve" the biofilm "slime". It may perhaps be added to your product?
Have you tried Bacillus spores? They may be too small for your purposes. Yeast spores may also be more resistant and give you many species to choose from. Saccharomyces may be the easiest to work with.
Nov. 10, 2016
Dear David,
Bacillus subtilis (or related species) should work for you. B. subtilis and other members of this genus produce their own surfactants. They are lipo-peptides consisting of a long chain fatty acid joined via an amide linkage to one or more amino acids. One of the better known Bacillus surfactants is surfactin. You can find its structure w/ a google search. With surfactin, the fatty acid is joined to a cyclic heptapeptide. It has 2 glutamic acid residues, each w/ a free -COOH group, so it is anionic. The bacilli make this material, so it is not toxic to the cells, so Bacillus cells may tolerate exposure to your surfactant. You can check this reference for more information on surfactin and lipopeptide biosurfactants: Biochemical Engineering Journal 95:48-55 (2015).
I hope this information helps you.
Bill Colonna
Center for Crops Utilization Research, Iowa State University, Ames, IA USA
you may think on to adapt a microbial community by slowly increasing surfactant concentration to desired level, starting from very low ones.
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