Plant sap were squeezed and filter before autoclave.
Fermentation media are consist of sap liquid only (no additional commercial media)
Fermentation of plant sap by S. cerevisiae at 30C to produce bioethanol.
Glucose level increase in first 10 hrs of incubation before decrease.
Hi Siti,
Autoclaving affects the medium composition noticeably if not considerably. If you have got the plant sap filtered through 0.45 micron filter, you should not need autoclaving for the plant sap. A simple addition of this filtered sap to a pre-autoclaved culture should work fine.
Autoclaving at 121 C for 16--30 minutes hydrolyses the sugars. Depending on the nature of sugar in plant sap and in growth medium, this will be either partial or complete. This increases the total glucose level count in the medium considerably. I have attached one of my early papers which hopefully will help you. If not, then go the references I have used for that paper. A number of other people have worked on this aspect which will certainly help you to address this issue.
A good practice for you should be measure the sugars (1) Before autoclaving, (2) after autoclaving and (3) as usual during fermentation.
Best wishes,
Avinash
Hi Siti,
It is true that autoclave have effects on the composition of the substrate, and technically, after autoclave you might have more sugars available. for effect of autoclaving you may look through literature. However, based on your explanation, I believe you have counted that, at the beginning of the experiment or the very first hours. I mean if it was the sole effect of the autoclave, you must still see a decreasing trend. Which is not true based on the fig.
What I think which may explain the phenomenon you see:
1-Autoclaving resulted in partial degradation of some more complex compounds in the sample, yet not sugars.
2- during the first 10 hours, the yeast is not active, therefore, no sugar consumption.
3- Hydrolyzing of the derivatives by water, where compounds are simpler because of the initial autoclave process, released sugar.
4-after 10 hours, sugar consumption by yeasts, supersedes the release of sugar, because of both the increasing population of the yeast as well as depletion of the available compounds for the hydrolysis. this results in a continuous reduction in the sugars consumption.
Hope it helps.
The sap containing glucose increase in the early 10 hrs could be due to evaporation of water during autoclaving and incubation at 300C before the yeast growth takes up and start decreasing as soon as the fermentation starts & it gets converting to ethanol.
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