Word: bacterias
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...Breeding Grounds. Doctors disagree on the answer. The common technique for measuring pollution is counting the number of coliform, or intestinal bacteria in samples of water. These organisms are easily detected. Although they are usually harmless, they often coexist with more menacing microorganisms and viruses that cannot be discovered without more extensive testing. Hence the count provides a useful index of pollution. Yet levels that are regarded as safe by some public officials are rejected as dangerous by others...
...bulges, which often but not always signal the presence of botulinum toxin, one of the most deadly poisons known to man. (One ounce of the poison is enough to kill the entire population of the U.S.) The toxin is produced by the hard-shelled spores of the Clostridium botulinum bacteria, which lie dormant in !he soil but flourish in the airless environment of canned foods when they are improperly processed. Heating at 212° for five hours or at 240° for 30 minutes is sufficient to kill the bacteria during the canning process. But occasionally food is unsufficiently heated...
Building on the hypothesis that bac-teria use chemotaxis to locate food, Fogel, Chet and Mitchell investigated the effects of chemical pollutants on bacterial sensing mechanisms. They found that many of the bacteria tested could not detect food when small, non-lethal amounts of organic chemicals such as alcohol's were added to the seawater...
...concentration of pollutants needed to inhibit the chemotaxis of bacteria may reasonably be found in nature. Fogel concluded, Chet and Mitchell speculate that pollutants might concentrate in small areas of the ocean and prevent bacteria from finding food or purifying the water...
Although the research team only studied marine bacteria, Mitchell said wouldn't get exactly the same results there was "no reason to believe that we with ... any other bacteria." Thus, the cleansing action of bacteria in fresh water may also be affected by the pollutants...