ABSTRACT
BACKGROUND AND OBJECTIVES: Phosphorus is one of the low bioavailable macroelements. Use of microorganisms in biofertilizers could release phosphorus from insoluble compounds. Pseudomonas putida P13 and Pantoea agglomerans P5 are well recognized for application as phosphate solubilizing bioinoculants and are used as solid carrier based. Liquid bioinoculants are preferred for economizing production process and longer shelf-life. MATERIALS AND METHODS: Five low cost liquid formulations were examined. Formulations 1, 2 and 3, were phosphate buffer, 0.2% and 0.5% KNO3 dissolved in phosphate buffer, respectively. Formulation 4 was nutrient broth containing 4% glycerol and formulation 5 was diluted nutrient broth containing 4% glycerol. Survival (cfu) and phosphate solubilization index (SI) were evaluated after 3 months. RESULTS: Considering strain P5, increase in KNO3 concentration decreased preserving ability. While using KNO3 at 0.2% was accompanied with reaching maximum SI level. Overall, less nutritious formulations (1 and 5) provided maximum preserving ability without bioactivity loss. In the case of strain P13, maximum survival obtained in formulations 2 and 3, whereas SI level decreased. Preserving ability in formulations 1, 4 and 5 was similar but less nutritious formulations (1 and 5), improved bioactivity. CONCLUSION: The results introduced two formulations of 1 and 5 as economically efficient liquid bioinoculants for Pseudomonas putida and Pantoea agglomerans.
ABSTRACT
BACKGROUND AND OBJECTIVES: Annual incidence of infection with S. Typhi is estimated to be about 17 million cases worldwide. A systematic search among actinomycete isolates from soil of Iran aimed at finding active actinomycetes against the causative agent of typhoid fever, Salmonella Typhi was carried out during this study. MATERIALS AND METHODS: Our anti-Salmonella screening program resulted in nine highly active actinomycete isolates. All nine antibiotic producing strains showed broad-spectrum antibacterial activity, as five strains showed antifungal activity as well. Based on microscopic morphology and cell wall analysis, all nine active actinomycete strains were representatives of the genus Streptomyces. Three of the producing strains including the isolates HG87, HG116 and HG443 with inhibition zone of >20 mm, were selected for further identification and investigation of cytotoxic effects. RESULTS AND CONCLUSION: None of the producing strains showed cytotoxicity on HEK and USSC cell lines, while strain HG116 showed excellent antitumor activity on T47D cancer cell lines. Isolates HG87, HG116 and HG443 can be distinguished from the related species by some phenotypic and biochemical characteristics. Our results demonstrate the broad-range biological activity exhibited by bioactive compounds of soil actinomycetes from Iran.