Can you use a solvent for your 'crude', pour it on the plate and let it evaporate? Might have to account for the presence of the solvent but you could also analyze for its presence. I did look over your papers, is there agar in the plates shown?

Hi Cory, will try solvent next time. For now, even with the uneven distribution, it seems to be working. Attached a pic

Think you'd do better with broth enrichment than direct plating.

Please don't presume that growth indicates "crude" degrading microbes.

Cheers Phil Geis , we didn't do enrichment so far.

@ Phil Geis

With crude oil as sole carbon source, could growth on the Agar still means utilization of inorganic ions for growth? Please I need some clarification.

Thank you

Haruna Yahaya Ismail I would believe the ones growing in minimal media using oil as a sole C source are not chemolithotrophs, and are taking both carbon and energy from the Oil supplied.

@Daniel Menezes-Blackburn

That's exactly what I know so far. However, the comment of @Phil Geis seems contrary, that's why I wanted him to shed more light. Because even in chemolithotrophy, carbon is necessary for growth.

Haruna Yahaya Ismail

Bacteria will grow on the agar with out without the crude oil smear. Bacteria can grow in distilled water. Either technique can potentially find bugs able to metabolize some component of "crude oil". Broth based enrichment eliminates on confounding variable - agar.

Agree, it's not chemolithotrophy.

Why not have your student also inoculate a "crude oil'-free control?

Phil Geis, all possible control plates were used: no-oil, no-oil general media, general media + oil, and uninoculated plates for contamination checks. In minimal media, they only show low growth from undiluted water samples when oil is added (no enrichment used so far), and even for the general media, there are higher colony counts when oil is added.

Thanks! You could have told us. So what's next with this?

Thanks Phil Geis. Fatema (one of my MSc Students) is characterising the microbial diversity of oil-degrading bacteria in a recently installed produced water treatment using a wetland in Rima (Oman), a project engineered and administrated by Veolia. It's my first time working with oil-degrading microbes, hence the question. We were not sure if those plates were right at the start, but they seem to be working now.

Daniel Menezes-Blackburn I have been into similar research in the last 10 years and the methods you stated earlier are mostly routine in this aspect. However, the comments made by Phil Geis on bacterial growth even in distilled water made me speculate on better approaches. Nevertheless, your protocols are on track. best wishes

In my experience, liquid enrichment the protocol. Looks like the plates are working. The difference might be liquid broth enrichment offers the most active, competitive in that context.

Is Veolia experiencing micro problems with the system? Although bacteria degrading components of crude oil may not be so novel for publication, the impact on applied systems sure can be.

Haruna Yahaya Ismail thanks!

Phil Geis No issues in the system, oil degradation is verified. They are supporting an MSc student to foster research and to establish cooperation with local universities.

Daniel Menezes-Blackburn

Kudos to those guys. Still - keep an eye out - maybe something in the system generates a unique phenomenon.