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Mycopathologia et mycologia applicata

, Volume 50, Issue 2, pp 151–161 | Cite as

Efficiency of various selective media in determining Pythium population in soil

  • Srecko M. Mircetich
  • J. M. Kraft
Article
  • 314 Downloads

Abstract

Of 15 selective media recommended for isolation and enumeration ofPythium spp. directly from soil, corn meal agar (CMA) supplemented with agar, sucrose, minor elements, thiamine, rose bengal, pimaricin, pentachloronitrobenzene and vancomycin (MPVM) was the most efficient. Streptomycin (30–50 ppm) and rose bengal (33–60 ppm) as used in certain tested media effectively suppressed development of bacteria and actinomycetes. However, these chemicals adversely affected germination of spores and mycelial growth and thereby the recovery ofPythium spp. from soil. Media containing pimaricin (5 to 100 ppm) were more effective than those with nystatin (40 ppm) in suppressing development of nonphycomycetous fungi on isolation plate. MPVM with pimaricin at 5 ppm was more efficient than that with 10 ppm of the antibiotic in recoveryingPythium from soil. However, there was no difference in recovery ofPythium by this medium containing rose bengal at 5 ppm or at 10 ppm, butPythium colonies were more dense and better delineated when the medium contained 10 ppm of rose bengal. CMA containing pimaricin (5–100 ppm) and vancomycin (200 ppm) permitted occasionally development of a large number ofMortierella and bacterial colonies from certain soils, that interfered with accurate determination of colonies of certainPythium spp. on the plates. Vancomycin at 300 ppm, as used in MPVM, substantially reduced development of bacterial colonies compared to 200 ppm of the antibiotic. Surface-soil dilution-plate was more effective than the soil-dilution-plate method in reducing bacteria andMortierella colonies on isolation plates without affecting recovery ofPythium. The importance of basal medium, complement of antimicrobial agents, and isolation methods for efficiency of selective medium in recovery ofPythium spp. directly from soil is discussed.

Keywords

Sucrose Vancomycin Antimicrobial Agent Basal Medium Thiamine 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Dr. W. Junk B.V. 1973

Authors and Affiliations

  • Srecko M. Mircetich
  • J. M. Kraft
    • 1
    • 2
  1. 1.Plant Science Research DivisionARS, USDABeltsville
  2. 2.Prosser

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