RESUMEN
The presence of nontuberculous mycobacteria (NTM) was investigated in forty soil samples belonging to the four physiographic regions (Eastern, Central, Southern and Western) that constitute La Pampa province. The presence of NTM in 67.5 of these soil samples was determined. The density of mycobacteria ranged 25-4,500 mycobacteria g-1 dry soil (mean = 516 CFU g-1). Significant differences were found in relation to both the investigated regions (p < 0.01) and the soil pH (r = 0.44*) (P = 0.02). The mycobacteria represented less than 0.00001 of the total aerobic bacteria found in the soils. Twenty-seven isolated mycobacteria were classified according to the culture, biochemical, enzymatic characteristics and antibiotic sensitivity. Mycobacterium fortitium was the dominant mycobacterium and was detected in 63 of the positive soils. This species showed ability for living in sandy to sandy loam soils, within a wide pH range (6.5-9.7) and organic matter (4.15-83.63 g kg-1). Two other species were M. phlei (range = 50-4,500 CFU g-1) and M. kansasii (range = 50-500 CFU g-1).