pH effects on 10 Streptomyces spp. growth and sporulation depend on nutrients

Aims:  Streptomycetes are regarded to prefer neutral to alkaline environmental pH, although they commonly occur at remarkably variable pH and nutritional conditions. Therefore, the dependence of 10 Streptomyces spp. pH tolerance on nutrients was determined. Methods and Results:  Ten environmental Streptomyces spp. were grown and sporulated between pH 4·0 and 11·5, at the interval of 1·5, on starch-casein-KNO3, tryptone-yeast extract-glucose, glycerol-arginine and tryptone-soy agars, and three their modifications. On media with starch and casein; glucose, tryptone and yeast extract; tryptone and soy peptone; and glycerol-arginine and yeast extract strains grew over a broad pH range between 4·0–5·5 and 10·0–11·5. On glycerol-arginine and on medium with Na-propionate, NH4NO3 and yeast extract, streptomycetes grew optimally at pH 7·0 and above. The high organic load enabled the growth over a wide pH range. The sporulation pH ranges followed those for growth. Conclusions:  The high organic load enabled the growth over a wide pH range. The strain-specific differences in sporulation were greater than those caused by pH. The best medium for sporulation contained glucose and tryptone with minerals of glycerol-arginine agar at pH 5.5. Significance and Impact of the Study:  The growth pH ranges, pH ranges for the optimal growth, and sporulation were strongly dependent on nutrients.