In these SEM image is shown biofilm from bacteria vibrio harveyi which were grown for 24h, then a fixation was made using formaldehyde. Biofilm were grown on a small glass.
When checking on SEM i found these weird structures which are made mostly of Carbons (meanings organic), any idea what it could be?
Hi, based on your sole micrograph I would guess the 'weird structures' were microbial flocs made up of V. harveyi cells and exopolymeric substances (EPS). If you look closely (perhaps you have a more magnified version focused on these structures?), the cells were clumped together and the 'frays' were dehydrated EPS (your drying and dehydration prep for SEM most likely accounted for this) that held the cells together to create microbial 'balls'.
Nur's explanation is exactly the one I would give, but I wouldn't be due the groups ("balls") are an artefact of drying. I can't see a size marked on the photo. If these cells are too small for Vibrio, then I would suggest you have contamination.
the cells showing are most likely to be vibrio, dont think its a contamination, been working with vibrio from the my stock in sterile conditions, also you can see they are rod shaped (just like in the literature), and i have confirmed a few times in the past that i have no contamination using PCR
Yes, Muhammad is correct. Usually after fixation and gentle rinse in aqueous medium (such as DDW), the sample would undergo a series of graded ethanol dehydration, followed by a drying method. These steps ensure your sample is more properly (or more gently, so to speak) dehydrated and dried as opposed to letting water evaporated straight off of it. The latter may likely cause your cells to shrink and create artefacts which of course you do not want.
There are a number of options for drying (the step after ethanol dehydration), e.g. critical point drying (CPD) and hexamethyldisilizane (HMDS). If you're interested you could take a look at my paper describing a method on using HMDS as a drying agent for SEM prep of bacterial cells (however there's a corrigendum to that paper- please have a look at it too). I find the method easy and effective. Hope it'll be of help for you too. Best of luck!
I have seen such structures in P.aeruginosa biofilm. During biofilm maturation mushroom like structures will be formed made up of cells and EPS. And it will be visible as balls when we look from above. All the best
Yes, but the structures in P. aeruginosa biofilms do not look shrunk.
Dear Liat fr
The SEM image for Vibrio biofilm share by you reflects following two possibilities:-
1. As biofilm formation start with the formation of micro colonies, which gets enlarges, merged and form a film. Those globular structures are probably microcolonies., which are rich in EPS. The growth of microcolonies is not always even through out biofilm. If you grow the biofilm for longer time you will for sure get a complete bacterial film/mat structure.
2. If its an older biofilm, those structures might represents fruiting body, which generally forms at the later stages (during disintegration) of biofilm.
It donot looks like carbon.. These are small biofilm; maybe not matured biofilm because you can even see the single cells around the big objects. It may happens EPS or filaments agglomerated upon drying process. You can find some SEM images of biofilm, http://pubs.acs.org/doi/suppl/10.1021/acs.nanolett.6b01998/suppl_file/nl6b01998_si_001.pdf
Mature biofilm often covered completely with EPS matrix- we can not see individual bacterial within a biofilm matrix.
http://www.nature.com/article-assets/npg/srep/2015/150413/srep09856/extref/srep09856-s5.pdf
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