Hi Fred, Here is an explanation in plain English but your best bet is to contact Loka at the NIO who I am sure will explain to you very articulately her reasons for studying sulfur reducing bacteria along the west coast of India. This is the thrid time that I have tried to post this message! --Helga
Sulfur-reducing bacteria (SRB) are one kind of bacteria that live in oxygen-deficient environments such as deep wells, plumbing systems, water softeners and water heaters. Unlike commonly found bacteria they do not need oxygen but use sulfate as their oxidizing agent. In this process the sulfate compound is reduced (Oxygen is removed and the energy is used by the bacteria just as we do when we eat food) to sulfide which can smell like rotten eggs. When you grow bacteria in the lab you have to make sure you feed them the right stuff and for this there are manuals that prescribe the 'media' or the food for the bacteria. Say you want to grow bacteria that you think breaks down petrol chemicals. Then you had better make sure that you have added some source of hydrocarbon in the right concentration to make sure that only the bacteria that break down hydrocarbons actually grow. There are 2 kinds of SRBs I think - one group grows in a lactate containing medium while the other in acetate. She has a strain that she isolated from the west coast of India. When she says she 'isolated' it means she took some water off the west coast and dumped some drops into a medium that she thought was favorable only to SRBs and that of course has sulfate. So she has practically set the stage for their growth. If there are any SRBs in that water they will thrive while other kinds of bacteria will just die. If the jars where she is growing have been stripped of oxygen (SRBs do not need oxygen) she has eliminated any other oxygen loving bacteria from contaminating her experiment. After probably many trials and errors she finally found one kind of bacteria that she could safely say was a SRB from that region - probably studied it microscopically and made sure it broke down sulphate and produced the odiferous gas hydrogen sulfide. Now why did she study SRBs and make sure that she isolated a west coast of India strain because in fact you do not always need to isolate bacteria - there are many culture collections all over the world that sell bacteria of every kind and they aren't expensive. I think the reason she did so is because she is studying a process called 'bioremediation' and she wants to know if it could be happening off the west coast of India so she needs a strain native to this region. Sometimes one species of bacteria could have different stains which do different things so your best bet is to isolate yourself. Estuarine and marine sediments as well as ground water are contaminated with heavy metals such as lead, mercury and cadmium from industrial effluents- many of these are carcinogenic and can reach us through the fish we eat because these metals can accumulate in the body of the fish or shell fish to very high concentrations. There is really no way to destroy these metals. But SRBs can remove them through complex processes that link microbial metabolism, chemical reactions and transport. Two processes being studied in detail are bioaccumulation and biosorption. In the latter the SRBs take in the metal complexes into their cells and practically isolate and immobilize them. Using some enzymes SRBs reduces the toxic metal complexes to other forms that might not be toxic. In biosorption the odiferous hydrogen sulfide released by the bacteria can react with the soluble heavy metal complexes to form insoluble ones which are not accessible to other marine life. Bioremediation involves a whole suite of chemical reactions but I hope you have got the gist. Regards Helga ########################################################################## # Send submissions for Goanet to [EMAIL PROTECTED] # # PLEASE remember to stay on-topic (related to Goa), and avoid top-posts # # More details on Goanet at http://joingoanet.shorturl.com/ # # Please keep your discussion/tone polite, to reflect respect to others # ##########################################################################
