Investigation of Plant Growth Promoting Traits of Microflora Isolated from Periphyton in Paddy Field of Gilan province

To date, no research has been done on the role of periphyton in paddy fields, especially on phosphate solubilizing ability of bacteria and fungi isolated from the biofilm. The aim of this study was to investigate the phosphate solubilizing ability and some other plant growth promoting (PGP) traits of bacteria and fungi isolated from the periphyton sampled from 20 paddy fields in Guilan province. In this study, 44 bacterial isolates and 32 fungal isolates capable of solubilizing phosphate were isolated. Among the microbial isolates, effective 10 bacterial isolates and 5 fungal isolates were selected for additional tests. The results showed that bacterial isolates 13B25 and 6B11, with the highest phosphate solubilization, solubilized 354 and 327.3 mg P l-1, respectively. The ability to produce siderophore (based on HD / CD index) by isolate 13B25 and 6B11 was equal to 3.2 and 3.4, respectively, with a significant increase (p < 0.001) compared to other isolates. The production of indole-3-acetic acid by the isolates 13B25 and 6B11 was 175.3 and 205.7 μg ml-1, respectively. Among the fungal isolates, two isolates, 6F11 and 8F12, were the best in PGP traits. The solubilization content of phosphorus by these two fungal isolates was 742 and 818 mg l-1, respectively. The results of molecular identification of effective bacterial isolates showed that 13B25 and 6B11 were most similar to Bacillus cereus and Acinetobacter calcoaceticus, respectively. In addition, fungal isolates 6F9 and 8F12 were most similar to Talaromyces minioluteu and Talaromyces stipitatus, respectively.