The use of phenol-converting organisms has been demonstrated in fixed beds and in stirred tanks. However, the residence times are rather long, up to days in some cases, and undesirable. Preliminary results with fluid beds indicate that the advantages of phenol scavenging by microorganisms can be appended to fluid-bed operation with a considerable decrease in residence time, according to Scott. The system being developed at Oak Ridge involves the use of various types of Pseudomonas bacteria immobilized on particles of anthracite. The particles are fluidized by the wastewater in a vertical tapered tube. The most efficient organism found to date is a mutant strain of Pseudomonas bacteria sold under the trade-name Phenobac. The system employing this bacterial strain was found capable of reducing phenol levels to less than 25 ppb with residence time of a few minutes. During treatment, biomass (organism) concentration builds up but can be continuously controlled in the normal course of bed operation by bleeding off the organisms. Similarly, new organisms can be introduced while the bed is operating. Even though bacterial degradation of the phenols generates carbon dioxide, presence of the gas does not adversely affect bed operation. Likewise, introduction of oxygen at the narrow base of the bed to maintain bacteria viability causes no upset in the quantities that are used. The principal virtue of the tapered bed is that it permits considerable variation in flow rate without particle spillover. So far the system has been demonstrated in a bench-scale apparatus with a bed 3 inches in diameter. Scaleup by a factor of 10 is believed possible with present knowledge. •
Microbes can live suspended in air Prospects of an "Andromeda Strain"—a microorganism brought back to earth by a space probe and that proliferates and endangers life on earth—have so far been confined to science fiction. And contamination of other planets with terrestrial microbes hitchhiking on spacecraft also has been considered unlikely. However, tightening and redefining of contamination controls for future space missions may become necessary in light of findings by three California scientists. And at least simple forms of life on a gaseous planet such as Jupiter seem somewhat more possible. 8
C&EN June 21, 1976
Dr. Robert L. Dimmick, Mark Chatigny, and Dr. Hyman Wolochow of the Naval Biosciences Laboratory—a research center run by the University of California, Berkeley, for the Office of Naval Research—have obtained the first direct evidence that microorganisms can live and propagate while suspended in air. Until now, it has been thought that organisms can propagate only on solid surfaces or in liquids, and will die in a suspended state. Dimmick told a meeting of the international Committee on Space Research in Philadelphia last week that he and his colleagues suspended a bacterium, Serratia marcescens, in air inside a 6-foot rotating drum and exposed it to a mist of radioactive sugar molecules. To their surprise, the bacterium metabolized the sugar (as shown by production of radiolabeled carbon dioxide), synthesized new DNA, and divided—doubling its initial population and even showing evidence of a third generation. Dimmick notes that many scientists have dismissed the possibility that life exists on Jupiter because its surface is not solid, but instead is
composed mainly of dense helium and hydrogen gas. The new Berkeley findings indicate that bacteria can live and multiply in such a gas phase. To be sure, emphasizes Dr. Robert Heckly, associate director of the Naval Biosciences Laboratory, these experiments are far from proving that organisms can live on Jupiter. To deal with that question, experiments with gas mixtures and conditions more closely simulating Jupiter's atmosphere are necessary. In any case, Heckly says of the "Andromeda Strain" concept, "the chances of bringing back an organism from Jupiter are slim." The possibility of contaminating Jupiter with terrestrial microorganisms is also small, but of more concern. "Even if the bacteria survived the hazards of space travel, they would still be faced with numerous adaptation problems on Jupiter," Dimmick notes. Nevertheless, now that it has been shown that bacteria can live while suspended in a gas, Dimmick believes that contamination controls for spacecraft must be re-examined. E
Chemistry freshmen \ei > well prepared Freshmen who plan to study chemistry in college are increasingly less well prepared in high school science and mathematics, according to a sixyear study conducted at Washington State University. Dr. Glenn A. Crosby and Dr. Jane L. Crosby of the university's chemistry department told the Northwest Regional Meeting of the American Chemical Society in Reno, Nev., last week that test scores on a placement examination given each year to 1500 to 2100 entering freshmen who plan to take chemistry courses show a steady decline in average scores in both these areas. The decline ranges from a 10% drop in scores on the chemical knowledge section to a 16% drop in scores in the section testing knowledge of basic arithmetic skills. According to the Crosbys, "The evidence indicates that about 15% of the students entering Washington State University who plan to take chemistry are so seriously deficient in basic arithmetic skills and knowledge of elementary physical principles that success in any physical science or mathematics course is improbable." The Washington State test is administered by the chemistry department and is entirely separate from the school's entrance requirements. It is used to determine which of three chemistry sequences open to freshmen best suits a student's high school
preparation. The test has three parts, one testing knowledge of high school chemistry and some general science, another testing basic arithmetic required for most college courses, and a third testing advanced mathematics to identify unusually well-prepared students. The mechanics of the exam, including the recommendation for course selection, are handled by computer. The same test is given each year, and analysis of past test scores, according to the Crosbys, shows that it is a useful tool in predicting how students will do in university chemistry, mathematics, and physics courses. The emphasis in high schools appears to be on earning good grades rather than on mastering basic skills, the Crosbys say, repeating a complaint voiced by other educators. The Crosbys note that the average high school grade point average for entering freshmen at Washington State has risen 5% during the six years the test has been given. The two Washington chemists call for basic skills examinations in reading, writing, arithmetic, and logical thinking in the eighth, 10th, and 12th grades. They believe that passage of these examinations should be an additional requirement both for high school graduation and entrance into a university. •
