D B Steele

Auburn University, Auburn, Alabama, United States

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Publications (5)23.19 Total impact

  • D B Steele, M D Stowers
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    ABSTRACT: The screening of microorganisms for the production of useful products continues to be an important aspect of biotechnology. Although advances in instrumentation, genetics, and microbial physiology are having an impact, screening programs are still primarily based on so-called classical techniques of enrichment and mutagenesis. One area that needs strengthening is the advancement of knowledge in microbial physiology. Recent surveys indicate that industry leaders see trained microbial physiologists as being the limiting factor in development of biotechnology in the coming decade. The largest impediment to development of new screening techniques is the ironic lack of programs specifically directed at developing new techniques. Too much emphasis is placed on using available techniques and relying on sheer labor and screening of vast numbers of organisms to produce novel products. In this respect, the Japanese are the exception and have proven that the establishment of new programs is worth the cost and effort. They are undoubtedly the world leaders in development of screening techniques and consequently the discovery of novel products. The isolation of microbes from novel and extreme environments holds tremendous promise in two areas. First, as Omura (46) and others (9, 48, 65) state, novel organisms will yield novel products. Second, such organisms serve as models for the understanding of structure and function that will facilitate the genetic manipulation of organisms and advance our ability to engineer novel enzymes. Hopefully such advances will enable genetic and protein engineering to have a greater impact on screening programs and techniques in the future. The earth holds a vast amount of varied and unique environments, from natural extremes such as high-altitude deserts and thermal springs, to manmade environments such as industrial-waste-treatment facilities, from which, with the appropriate methods and techniques, we may isolate and evaluate new potential products.
    Annual Review of Microbiology 02/1991; 45:89-106. · 12.90 Impact Factor
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    ABSTRACT: A pure culture of an Agrobacterium sp. (deposited as ATCC 55002) that mineralizes the ferric chelate of EDTA (ferric-EDTA) was isolated by selective enrichment from a treatment facility receiving industrial waste containing ferric-EDTA. The isolate grew on ferric-EDTA as the sole carbon source at concentrations exceeding 100 mM. As the degradation proceeded, carbon dioxide, ammonia, and an unidentified metabolite(s) were produced; the pH increased, and iron was precipitated from solution. The maximum rate of degradation observed with sodium ferric-EDTA as the substrate was 24 mM/day. At a substrate concentration of 35 mM, 90% of the substrate was degraded in 3 days and 70% of the associated chemical oxygen demand was removed from solution. Less than 15% of the carbon initially present was incorporated into the cell mass. Significant growth of this strain was not observed with uncomplexed EDTA as the sole carbon source at comparable concentrations; however, the ferric chelate of propylenediaminetetraacetic acid (ferric-PDTA) did support growth.
    Applied and Environmental Microbiology 12/1990; 56(11):3346-53. · 3.95 Impact Factor
  • D. Bernie Steele, K. Ramirez, M. D. Stowers
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    ABSTRACT: Optimum growth conditions and inoculation regimes were determined for severalFrankia strains isolated from both Alnus and Casuarina host plants. Growth conditions were estabilished that allowed a reduction in generation time to less than 15 hours for certain Alnus derivedFrankia. Differences in plant growth response were observed with differing inoculum levels and soil mixtures. Elite strains of Alnus derivedFrankia were isolated that elicited similar growth reponses in allAlnus species tested; however, differences were observed betweenFrankia strains and plant growth response of variousCasuarina species tested.
    Plant and Soil 08/1989; 118(1):139-143. · 3.24 Impact Factor
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    ABSTRACT: A clinical isolate and a soil isolate of Chromobacterium violaceum were compared to determine differences in virulence-related characteristics. Purified lipopolysaccharide (endotoxin) from the virulent, clinical strain was more reactive than that from the avirulent soil strain as determined by the Limulus amebocyte lysate assay. There were no differences in hemolysin or cyanide production between the two strains. The virulent strain was more resistant to phagocytosis and intracellular killing by human polymorphonucleocytes. The clinical strain showed a superoxide dismutase activity 30% higher and a catalase activity fivefold higher than the activities of the soil-isolated strain. The clinical strain also was capable of producing approximately twice as much hydrogen peroxide during growth as compared with the soil isolate. This study suggests that virulence of C. violaceum may be, at least in part, associated with endotoxin, and some protection of the virulent, clinical strain from phagocytic attack is afforded by elevated levels of superoxide dismutase and catalase.
    Canadian Journal of Microbiology 04/1988; 34(3):249-55. · 1.20 Impact Factor
  • M. D. Stowers, R. K. Kulkarni, D. B. Steele
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    ABSTRACT: Frankia isolate NPI 0136010 was able to use only propionate and acetate as sole carbon sources and was unable to use hexoses, pentoses, disaccharides, and trisaccharides. Cell free extracts were surveyed for key enzymes of intermediary carbon metabolism. Enzymes of the Embden-Meyerhof-Parnas (EMP) pathway, the tricarboxylic acid (TCA) cycle and glyoxylate shunt were detected while enzymes of the pentose phosphate (PP) and Entner-Doudoroff (ED) pathways were absent. Malic enzyme was present allowing for the conversion of malate to pyruvate and gluconeogenesis. Radiorespirometric analysis confirmed the operation of the TCA cycle and established the methylmalonyl pathway as the route of propionate metabolism. The uptake of propionate was active and mediated by sulfhydryl groups.
    Archives of Microbiology 12/1985; 143(4):319-324. · 1.91 Impact Factor

Publication Stats

75 Citations
23.19 Total Impact Points

Institutions

  • 1988–1991
    • Auburn University
      • College of Sciences and Mathematics
      Auburn, Alabama, United States
  • 1989
    • The University of Tennessee Medical Center at Knoxville
      Knoxville, Tennessee, United States
  • 1985
    • Park University
      Parkville, Missouri, United States