Treatment by shaking time 12 and 24 hours of crude oil solubility showed an increasing result, but 36 hours of treatment showed a lower result than both 12 and 24 hours. Is there any scientific explanation for this? Or was it just an error procedure?
nb: the biosurfactant was produced by Acinetobacter sp.
thank you, David
I have already analyzed the biosurfactant production in my culture by measuring the surface tension and emulsification activity. and it can be concluded that biosurfactant was positively produced.
thank you Mr. Richard
actually i have no idea whether the biosurfactant is biodegradable or not. and what is half time? could you please explain more?
Argus, if you have a way to measure the surfactant, track its disappearance over time (if it degrades). If you natural log transform the data and fit a striaght line equation to it, the half-life (T1/2), or time for half the material to degrade, is 0.693/slope
thank you Mr. Richard
I will do further study to investigate whether it is biodegradable.
If you are talking about biosurfactant production by crude oil as carbon source, then, yes, this is quite possible....Different microorganisms are able to produce biosurfactants at different time intervals. The maximum biosurfactant production by Aspergillus ustus MSF3 was observed after 5 days of incubation while in case of Candida bombicola, the incubation periods were 7, 8 and 11 days.
References
Seghal Kiran G, Hema TA, Gandhimathia R, Selvina J, Anto Thomasa T, Rajeetha Ravji T, Natarajaseenivasan K (2009) Optimization and production of a biosurfactant from the sponge-associated marine fungus Aspergillus ustus MSF3. Colloids Surf B 73: 250-256.
Felse PA, Shah V, Chan J, Rao KJ, Gross RA (2007) Sophorolipid biosynthesis by Candida bombicola from industrial fatty acid residues. Enzyme Microb Technol 40: 316-323
Cavalero DA, Cooper DG (2003) The effect of medium composition on the structure and physical state of sophorolipids produced by Candida bombicola ATCC 22214. J Biotechnol 103: 31-41.
Casas JA, Garcia-Ochoa F (1999) Sophorolipid production by Candida bombicola: medium composition and culture methods. J Biosci Bioeng 88: 488-494.
Bhardwaj G, Cameotra SS, Chopra HK (2013). Biosurfactants from fungi: A review. J Pet Environ Biotechnol 4:1-6.
and if you are talking about the emulsification activity, then this may also decrease after 24 hrs..the reason for this decrease may be the microbe at a particular time produces biosurfactant as secondary metabolite or at another time uses for its own growth..
hello Garima,
I didnt use crude oil as carbon source. The biosurfactants were produced in different medium and nutrients. Then I used the crude products (supernatant without living cells) to investigate the solubility of crude oil.
more over, the microorganisms that i used have been previously reported that the incubation time to produce biosurfactant is 4 days. So, i think there is some other reasons.
and about the emulsification activity, yes it decreased after 24 hours.
thanks you
best, Agus
then may be the environment from where your microbe have been isolated is different from the reported one..
Your culture will show you different result than reported by other as your Acinetobacter strain is different. It is possible that emulsion produced will not remain stable after some incubation time hence you need to check the stability. Which control you have used for this solubility assay? Is control showed you some different result?
dear Trupti,
I used aquadest as control (-) and tweens20 as control (+). they showed me a linear result (increasing from 12, 24, and 36 result)
Then its possibly due alteration in biosurfactant stability after 24h.
Loss of emulsion stability after 24h may be a reason. Handling of sample also a factor and there may be a chance for error. Did you repeat the experiment? that may give you some ideas. Plus, factors such as change in pH, temperature etc in the experiment system also affect the emulsion stability.
dear Mr. Thavasi, I didnt repeat the experiment due to certain reasons. That's why I hope there will be an explanation here. Thank you for you explanation.
regards!
I have done a test of emulsion activity (and surface tension) to characterize the biosurfactant produced by bacteria. The emulsion activity reduced after 24 hours, but no more than 10%. how can I say whether the biosurfactant was stable or not? Is there any standard of how many (%) reduction of emulsion activity to say that it is stable or not?
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