Searching for hyperthermophilic prokaryotes in Tanganyika Lake hot vents.

Pemba site 11: the main sampling area.

Hot hydrothermal seep at Pemba site

 Cape Banza hydrothermal aragonite chimney,depth ~-6 meters, temperature range 66-103°C  


Although the Banza site vents are of quite different morphology, and much more interesting from an aesthetic point of view ( see the nice chimneys in the "Vents" page and compare the two vents at the left), our interest was directed towards the deeper Pemba site, as it has not yet been sampled for microorganisms. Depth and temperature of the springs at Pemba makes them good candidates to harbour anaerobic hyperthermophilic procaryotes. The titanium device that can be seen in the picture comes from the "Nautile", IFREMER's submarine which ordinary dives through deep seawaters, and was used by the geologists' team for hot fluid sampling.


Aragonite chimney at shallow Cape Banza site.

Exploration of site 11 begins. Hot water can be easily seen seeping through the bottom, and fluid temperature is measured at 93°C at its outflow by a hand made thermometer (handcrafted by Jean-Jacques Bourrand before our journey). Site depth is 47 meters, which prompts me to start sampling as soon as possible.


 Exploring Pemba site #11  




Sampling the hot springs.

Different methods were used for sampling: hot liquid was collected directly with a syringe equipped with a flexible pipe strengthened by a piece of metal.




Sediments were recovered using a syringe which was cut at one of its extremities. Once the syringe was filled, it was closed with rubber plugs.

 Collecting hot fluid with a flexible tube connected to a serynge  

 Hot sediments are collected with a serynge fitted with rubber plugs. It burns!  



 Another sampling sequence.
Despite my gloves, fingers get rapidly very hot
and handling must be performed quickly.

Temperature of water outflowing from sediments has been measured to be 93°C, which makes it very delicate to work without having my fingers burned by the nearly boiling liquid.





Team work.


Denise was my assistant during all divings and work. Without her help I could not have performed the sampling as our stay at 50 meters depth is limited in time. She helped me in handling the sampling vials, letting me concentrate on the job itself.


 Denise assists me while sampling.We exchange serynges immediately in order to speed up our work  



 Hot fluid sampling.  

As soon as a syringe is filled up with water or sediments, I hand it to Denise who immediately exchanges it with a new one, ready to be filled again.




Before we really started working, our gestures were repeated many times at 4-5 meters depth, because all movements at low depth underwater require much more effort and concentration than normal.

 Serynge exchange between me and Denise.  



 It's time to go back to the surface. Denise tells me to brake, but I don't care !  

Our stay at 50 meters depth is strictly timed as we need extra time to comply with several decompression stages before we can reach the surface. Denise tells me it's time to resurface, but I am so concentrated on my work that I don't realize immediately that I must stop sampling. Denise urges me firmly and eventually we go up, leaving the site 11 tag behind us.



Back to the camp.


My work is not finished yet, and the samples must be conditioned as soon as possible. As we are interested in isolating hyperthermophiles which are mostly anaerobic, I must be sure that samples will remain in a reduced state all the way back to France.


Once back to the camp, I carefully label all the recovered samples: half of them were reduced by addition of sodium sulfide in the presence of resazurine, a redox indicator which is pink in the presence of oxygen and colorless when in anaerobic conditions.

Sitting beside my tent on the sand, I unpack my precious samples.  

 Sony assisting me while I label and condition my samples.  



 Here I'm preparing for injecting sodium sulfide and resazurine into my samples.  


The liquids collected into the syringes were injected into sterilized bottles, previously pressurized with nitrogen. Half of the samples were then reduced to allow the isolation of anaerobic hyperthermophiles.



What's Next ?

Back to France, the mission is over. It finished on the 6th of march 1996, and I returned to Orsay, leaving Zaire behind me. Shortly after my departure, Zaire underwent a tragic and painful upheaval leading to birth of the new Democratic Congo. Many people from Zaire and Burundi that I met during this period became friends, and today their situation is probably very uncertain, some of them are maybe even missing.

What about the samples?

My samples were shipped back to France several days after me, but their final destination was Dr. Daniel Prieur's laboratory at Station Biologique in Roscoff. They were conditioned for long term storage,and waited a few more weeks before microorganism isolation studies really started. Thanks to Jean Louis Birrien and his students, we now have the first isolation results.

 New Thermus species isolated from Tanganyika lake.  

New Thermophilic species from Tanganyika Lake hot vents.

A first round of isolation was carried out in the laboratory of Roscoff, searching for aerobic thermophiles growing in low salinity. New species not yet fully characterized were isolated on solid media, and subsequently enriched for growth in liquid media. Several strains of Thermus and Bacillus thermophilic (~65-80°C) species were thus isolated. Microscope examination of Thermus species showed vesicular (upper part of the micrograph) and "rotund bodies"(lower part) aggregates of cells.


Gerome our cook among    the sampling equipment