Monday, March 01, 2010

What are you reading?

Effects of plant and influent C:N:P ratio on microbial diversity in pilot-scale constructed wetlands (pdf, 9 pages)

Abstract
Microbial processes within the rhizosphere of constructed wetlands are crucial to wastewater treatment, but the relation between microbial community diversity in rhizosphere, plant growth and water quality are unclear at present. The effects of plant growth, water C:N:P ratio and their interaction on microbial diversity in the rhizosphere were studied in synthetic wastewater in planted and unplanted wetlands during three different seasons. The physiological profile of microbial community-level in each wetland was assessed using substrate utilization patterns gathered via BIOLOGTM ECOplates. Plant had a significant effect on AWCD parameter, since the planted wetlands usually had a higher the total microbial activity than the unplanted over the study period. The Shannon, Simpson and McIntosh indices in the planted wetlands were apparently higher than those in the unplanted wetlands under any C:N:P ratio influent condition especially in summer. It was also shown that the unplanted wetlands have a greater shift of the interstitial microbial community than the planted at different seasons, since plant rhizospheres produce a more ecologically stable system in order to resist against shifts in microbial community composition in response to C:N:P ratio change in wastewater. Principal component analysis and clustering analysis indicated that influent C:N:P ratio would induce similar microbial species in the planted wetlands and detach them from the unplanted wetlands.

5 comments:

soil mama said...

so Tom, how do you feel about Biolog? do you use it in your lab? I've heard that some of the "newer generation" plates are better, but I'm not sure if they are really being sold or used yet...

this is one I've read recently. It's an interesting way to view community structure and to think of model communities. I'd be interested in seeing how approach would work in another model community, and wonder what other kind of microbes could count as a "model community"...
http://www.nature.com/ismej/journal/v4/n3/abs/ismej2009122a.html

Thomas Joseph said...

I think Biolog may be a way to quickly screen for community diversity. As a matter of fact, I am thinking about employing it for some metagenomic studies we're about to perform. Here's how:

We use Biolog to determine what carbon sources are being used by the bacterial communities in a particular sample (i.e., soils). That will allow us to use that carbon source (Carbon13 labeled) in an incorporation study. We can then separate out the DNA based on weight (that which and which did not incorporate the Carbon13) and perform metagenomics. This will give us the active and non-active communities.

Yes, one carbon source will bias the results, but at least it'll tell you what effect that relevant carbon source is having on your communities. So in this case, the Biolog comes in real handy.

Anonymous said...

what? I thought you had no interest in doing SIP work. It sounds so cool, but can be so messy when you get to mass balancing and really figuring out what's going on, especially with soils. There are only a few labs that I really think do it well.

we can talk about this "privately" if you would like. I've put a lot of thought into a similar study and have spoke with several folks who have done it.

As for the Biolog, I can see where you're coming from, but I still think there are some pretty big setbacks with the approach, especially the fact that you are essentially only looking at the culturable organisms. I have heard that some labs (I can get you in touch with them) are using an approach that is similar to biolog, but gets around some of those issues (although I've only heard them mention the techniques and don't know the details).

Thomas Joseph said...

I didn't, until a potential collaborator started talking to me about it, and I found out that I can pharm out most of the work. ;)

Anonymous said...

oh I see how it is! ;)
I'd love to hear more about it at some point. I wish we could catch up over a beer... but I don't think I'll make it to any meetings this year so it might be a while.

I think we're really on the brink of so many super cool possibilities, I just hope the data quality can keep up with the sexy techniques.