Cultivating members of the microbial majority

It is with great excitement that I get to post that our manuscript on cultivating members of the microbial majority using an artificial seawater medium is finally out! This manuscript represents the hard work of not just myself, but Dr. Thrash, our undergraduates (past and present), and Austen Webber. Over the last two years, I have traveled to sites along the Gulf of Mexico collecting water for cultivation experiments (> 2000 miles traveled, > 4500 well inoculated). From the sites along the coasts of Louisiana, we have cultivated organisms from the Gulf of Mexico representing many important marine clades: SAR11, SAR116, OM43, OM252, Roseobacter, and many more. While isolating these organisms is important, it is also important to isolate organisms that represent abundant taxa within your source water. We compared OTUs from community sequencing of the source water  to our  isolate sequences to demonstrate that our method frequently captured some of the most abundant organisms in the system.

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This work also represents the first instance where many of these clades were isolated from the Gulf of Mexico, and importantly, on an artificial seawater medium. While high throughput, dilution-to-extinction culturing using natural seawater has been highly successful, we hope that this new approach using artificial seawater media will help more researchers cultivate important microorganisms without the hassle of collecting large volumes of natural seawater and needing a boat.

If you have any questions, please feel free to contact us! We are more than willing to answer any questions you may have. You can check out our list of organisms isolated so far HERE!

Henson, Michael W., David M. Pitre, Jessica Lee Weckhorst, V. Celeste Lanclos, Austen T. Webber, and J. Cameron Thrash. (2016). Artificial seawater media facilitates cultivating members of the microbial majority from the Gulf of Mexico. mSphere 1(2). doi: 10.1128/mSphere.00028-16. (Undergraduate authors) Supplementary Information.

Some associated press became available on May 1st. Check out Becoming Acculturated, by Jeffrey M. Perkel.

Emily and Celeste present at LSU Discover Day

IMG_7074Emily presented her LA Sea Grant-funded work to characterize one of our coastal isolates from the OM252 clade, LSUCC0096. She showed this organism has remarkable salinity tolerance, and can grow under chemolithoautotrophic conditions, a feature that was predicted from genome analysis.





IMG_7071Celeste presented results of her experiment to enrich for microorganisms that could utilize fulvic acids as their sole carbon source. She compared her work to that of former lab member Jessica Weckhorst who performed a similar experiment with humic acids. These are both extremely important fractions of the marine DOC pool.

Sampling the Mississippi River Delta

Mike and I went on a sampling trip Tuesday (1/12/16) to the Mississippi Delta (“The Birdfoot”) near Buras, LA. This was my first sampling trip ever with the Thrash lab, and I must say that it was a great experience! We headed out loaded up with our equipment and coffee, and ended up with a fantastic view of  the sunrise at the edge of Lake Pontchartrain. Sadly, the picture does not come close to the beauty of  our actual view.

Sunrise at the edge of Lake Pontchartrain

At the site, Mike waded out into the water to collect the sample while I got to hang back and enjoy the scenery. It was a great day to be outdoors with cool air and the sun shining.

Our view from the dock


Some pelicans that didn't seem to mind us
Some pelicans that didn’t seem to mind us


Mike taking YSI readings
Mike taking YSI readings


Mike filtering a water sample
Mike filtering a water sample

Overall, I really enjoyed my sampling adventure with Mike. This trip was a part of our 3 year study of the coastline to characterize the microbial population of the Louisiana coast in conjunction with adding microbes to our Louisiana State culture collection (LSUCC) from the Gulf of Mexico. I’m hopeful that we will isolate some novel organisms from this and future trips. Not all undergraduates are lucky enough to be a part of a lab that allows us to be out in the field for data collection, so I’m grateful to Dr. Thrash and Mike for the opportunity!


Sampling Lake Borgne

Last week David and I got up early enough to duck a series of storms coming through the region for some sunny sampling on Lake Borgne. This also saw the maiden voyage of a new Thrash Lab capital acquisition, the R/V Schipperke. We put in at Campo’s Marina, toodled out to a site past the old fort (these are commonplace in this region), and took measurements and water collections. The water was almost fresh, with a salinity ~5. David used these to inoculate the latest high throughput cultivation experiment since Mike Henson is currently at the C-MORE summer course. Here are some photos.

On the way through the cut
David taking YSI readings


Our Trip to the Atchafalaya River Delta for sampling

Well it was that time again, time to go acquire another water sample as part of the LSU Culture Collection and surveying of the microbial communities of Southern Louisiana coastline grant. For this site, because we had a prospective student with us, we decided to pick somewhere to see the beauty of Southern Louisiana. Though I find myself spoiled having lived near Pictured Rocks National Lakeshore and Sleeping Bear Dunes in Michigan, there is nothing like driving along a road with over hanging Oak tree branches that are covered in Spanish Moss with the sun just peaking through. So we picked a site near the Atchafalaya River mouth, the site was Burns Point Recreational Park in Franklin, La.

The “adventures” have become less dramatic as we have become more acquainted with how to properly get our act together, but this time instead of a change in site like the last time, it was just cold. Okay… for most of you not from the South, it wasn’t that cold. It was roughly 32-40F when we were driving and sampling and for someone from the North after the last winter this weather is getting close to shorts weather.

Burn's Recreational Park, Franklin, LA
Burn’s Recreational Park, Franklin, LA
The cool transition zone between the Bay and the swamp area. This was to the right of where we sampled.

With the help of some friendly Duck Hunters of Louisiana, we were able to have a sample taken just off the launch site away from the shoreline and boat channel.

Looking out towards Marshall Island and where our sample was taken.

Once we had our water sample, we followed our previously demonstrated protocol (see of filtering 100mL of water through a 2.7um prefilter followed by a 0.2um sterivex filter. We also collect water for nutrients and cell culturing. To compliment the nutrient data and to provide ever more information, we also took our handy YSI reader with us to get real time data from the site.

Don’t say that as a Graduate student you don’t get to live dangerously, because I will have you know that those rocks were slippery when I took the YSI readings!

Once all the data was collected and filtration done, it was back to the lab to prep the sample and inoculate dilution plates for cultures.
So cheers to another round of successful sampling and here is to hoping we “Catch ’em all”.
–Michael Henson