Searching for thermophilic prokaryotes in hydrothermal sediments of Lake Tanganyika, East Africa. Lake Tanganyika hydrothermal system and microbial environment.
In 1991, the multinational (France, Germany, Zaire, Burundi ) TANGANYDRO Expedition investigated sublacustrine hydrothermal seeps at Pemba and Cape Banza sites along the Zaire side of North Tanganyika Trough, in the western branch of the East African Rift System (Refs. 3-6).	Full Map of Africa
Evidence of microbial activity (ref.10) surrounding active hydrothermal vents has been found in Lake Tanganyika . Active vents at the Pemba site (11-46 m depth, fluid temperature in the range 55-88°C) were surrounded by abundant yellow or reddish-brown filamentous microbial colonies resembling Beggiatoa mats similar to those discovered at the Guaymas deep-sea vent site (Gulf of California, Mexico -Ref.8 ). The Cape Banza site (0-6 m depth , fluid temperature ranging 66-103°C) exhibited similar Beggiatoa-like white filamentous bacterial mats, spread among 72 groups of aragonite chimneys.   Subsequent sampling of hot sediments occuring at two hydrothermal patches at Cape Pemba (Ref.11) demonstrated microbial sulfate reduction at up to 80°C after culture enrichment. Organisms thus isolated were morphologically similar to the sporulating Desulfotomaculum spp. and had optimum temperatures for sulfide production of 63 and 80°C. The second TANGANYDRO expedition.   In 1996, the TANGANYDRO '96 Expedition investigated for the second time the Pemba and Cape Banza sites. Evelyne Marguet, from our laboratory, was part of the crew with the aim of finding even more thermophilic organisms than those isolated during the first expedition. Owing to her scuba diving expertise and microbiologist background, she could explore and sample the deeper Pemba site hot vents not examined previously. Hot fluids and sediments samples thus obtained are now in Daniel Prieurs' laboratory, in Roscoff, France, for enrichment and isolation studies. Up to now, most hyperthermophilic archaea have been isolated either from terrestrial hot springs or deep sea vents. The near future will tell us whether new hyperthermophilic microorganisms (ref. 12) also exist in the fresh waters of Lake Tanganyika. Relating the TANGANYDRO '96 expedition. 11 february-6 march 1996.   These pages are a brief and personal account of the TANGANYDRO '96 mission. They are by no means a scientific report or publication. Scientific results will be reported as appropriate in specialized scientific journals after a normal process of peer review.   Moreover, information presented herein only accounts for the microbiological part of the expedition. Other areas of the project, such as geochemistry or geology are completely outside of our competence and responsibility, and material presented here doesn't commit any other member of the project. Evelyne Marguet from our laboratory was kindly invited to take part to the mission, and wishes to express her gratitude to Dr. Daniel Prieur and the members of the team for allowing her to work during the time of the mission.   We present here a few glances at life during a scientific mission. Still photographs and video films of people were taken while they were working. Usually, this kind of information doesn't fit in the normal framework of scientific reports, but we feel that it may be of interest to people willing to know a little bit more about extremophilic organisms and where they live and come from. We are pleased to give such an opportunity, taking into account that pictures and movies presented here are not the work of professional photographers, but of members of the team themselves. About the organization of these pages.   Information presented here don't follow any chronological scheme nor tell a story, but rather allow you to freely browse among the various topics at your convenience: for this use the left side panel to access the desired area. Pictures and movies are spread among the different chapters, but "Still Photos" and "Movies" areas present an index of all the graphics and films at a single glance.   "Refs" area gives additional bibliographic information, essential for a better understanding of the already published background on Tanganyika Lake Hydrothermal system and its microbial environment.   "Tech Infos" area will give you technical informations on the various pictures and movies, as well as a brief explanation on how set up your computer for viewing the movies.   Bon voyage !