An altered Pseudomonas diversity is recovered from soil by using nutrient-poor Pseudomonas-selective soil extract media

We designed five Pseudomonas-selective soil extract NAA media containing th e selective properties of trimethoprim and sodium lauroyl sarcosine and 0 t o 100% of the amount of Casamino Acids used in the classical Pseudomonas-se lective Gould's S1 medium. All of the isolates were confirmed to be Pseudom onas by a Pseudomonas-specific OprF antibody and a Pseudomonas-specific PCR targeting 16S ribosomal DNA. The Pseudomonas isolates were characterized b y classical physiological tests, repetitive extragenic palindromic-PCR, Fou rier transform infrared spectroscopy, and carbon source utilization pattern s. Several of these analyses showed that the amount of Casamino Acids signi ficantly influenced the diversity of the recovered Pseudomonas isolates. Fu rthermore, the data suggested that specific Pseudomonas subpopulations were represented on the nutrient-poor media. The NAA 1:100 medium, containing c a. 15 mg of organic carbon per liter, consistently gave significantly highe r Pseudomonas CFU counts than Gould's S1 when tested on four Danish soils. NAA 1:100 may, therefore, be a better medium than Gould's S1 for enumeratio n and isolation of Pseudomonas from the low-nutrient soil environment.