Now showing 1 - 2 of 2
  • Publication
    Characterisitics of Streptomyces griseus biofilms in continuous flow tubular reactors
    The purpose of this study was to investigate the feasibility of cultivating the biotechnologically important bacterium Streptomyces griseus in single-species and mixed- species biofilms using a Tubular Biofilm Reactor (TBR). Streptomyces griseus biofilm development was found to be cyclical, starting with the initial adhesion and subsequent development of a visible biofilm after 24 hours growth, followed by the complete detachment of the biofilm as a single mass, and ending with the re-colonization of the tube. Fluorescence microscopy revealed that the filamentous structure of the biofilm was lost upon treatment with protease, but not DNase or metaperiodate, indicating that the extracellular polymeric substance is predominantly protein. When the biofilm was cultivated in conjunction with Bacillus amyloliquefaciens, no detachment was observed after 96 h, although once subjected to flow detachment occurred. Electron microscopy confirmed the presence of both bacteria in the biofilm and revealed a network of fimbriae-like structures that were much less apparent in single-species biofilm, and are likely to increase mechanical stability when developing in a TBR. This study presents the very first attempt in engineering Streptomyces griseus biofilms for continuous bioprocess applications.
      880ScopusĀ© Citations 15
  • Publication
    Microbial biotransformation of aryl sulfanylpentafluorides
    We report, for the first time, the biotransformation of potential pollutants bearing the pentafluorosulfanyl (SF5-) functional group in a fungus and bacteria. Cunninghamella elegans transformed p-methoxy phenyl SF5 via demethylation; Pseudomonas knackmussii and P. pseudoalcaligenes KF707 transformed amino-, hydroxyamino- and diamino- substituted phenyl SF5, forming the N-acetylated derivatives as the main product. Cell-free extract of Streptomyces griseus transformed 4-amino-3-hydroxy-phenyl SF5 to the N-acetylated derivative in the presence of acetyl CoA, confirming that an N-acetyltransferase is responsible for the bacterial biotransformations. Approximately 25 % of drugs and 30 % of agrochemicals contain fluorine, and the trifluoromethyl group is a prominent feature of many of these since it improves lipophilicity and stability. The pentafluorosulfanyl substituent is seen as an improvement on the trifluoromethyl group and research efforts are underway to develop synthetic methods to incorporate this moiety into biologically active compounds. It is important to determine the potential environmental impact of these compounds, including the potential biotransformation reactions that may occur when they are exposed to microorganisms.
      317ScopusĀ© Citations 9