title: Effect of polymyxin B nonapeptide and polymyxin B sulphate on trichothecene mycotoxin sensitivity of yeasts using a conductimetric instrument.
abstract: The addition of polymyxin B sulphate (PBS), or an inactive by-product, polymyxin B nonapeptide (PBN) to a yeast bioassay system, increased its sensitivity to various toxic agents. The nil effect level (NEL) of T-2 toxin was reduced from 0.1 to 0.01 microgram/ml for Kluyveromyces fragilis GK 1005 in the presence of these agents when using a Malthus AT 192 conductimetric instrument. Other synergistic agents (DMSO, ethanol, cetyl trimethyl ammonium bromide and Triton X-100) gave poor results in the conductimetric system. PBN also increased sensitivity of K. fragilis GK 1005 towards cycloheximide in the Malthus system, and PBS reduced the NEL of T-2 toxin for K. fragilis GK 1005 in a disc diffusion assay from 0.2 to 0.04 microgram per disc. No yeasts were found sensitive to the trichothecene deoxynivalenol (DON) even at a DON concentration of 10 micrograms/ml, except in the presence of PBN and PBS. The minimal inhibitory concentration (mic) of DON in the presence of PBS was 2 micrograms/ml for K. fragilis GK 1005.
authors.affiliation: Food Science Division, Ministry of Agriculture, London, U.K.
authors.forename: P
authors.initials: P
authors.lastname: Connolly
authors.forename: J E
authors.initials: JE
authors.lastname: Corry
mesh_terms: D000891:Anti-Infective Agents, Local / Q000494:pharmacology; D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000494:pharmacology; D003513:Cycloheximide / Q000494:pharmacology; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D000431:Ethanol / Q000494:pharmacology; D007716:Kluyveromyces / Q000187:drug effects; D017830:Octoxynol; D011092:Polyethylene Glycols / Q000494:pharmacology; D011112:Polymyxin B / Q000031:analogs & derivatives / Q000494:pharmacology*; D011113:Polymyxins / Q000494:pharmacology*; D012441:Saccharomyces cerevisiae / Q000187:drug effects; D012717:Sesquiterpenes / Q000494:pharmacology*; D013605:T-2 Toxin / Q000494:pharmacology; D014255:Trichothecenes / Q000494:pharmacology*; D015003:Yeasts / Q000187:drug effects*
chemical_list: D000891:Anti-Infective Agents, Local; D002593:Cetrimonium Compounds; D011113:Polymyxins; D012717:Sesquiterpenes; D014255:Trichothecenes; D000431:Ethanol; D011092:Polyethylene Glycols; C038934:polymyxin B nonapeptide; D017830:Octoxynol; D003513:Cycloheximide; D013605:T-2 Toxin; D011112:Polymyxin B; C007262:deoxynivalenol; D004121:Dimethyl Sulfoxide; D000077286:Cetrimonium