Molecular and Biochemical Identification of the Bacterial Isolates Used in Common Biofertilizers in Iran

The benefits of biofertilizers in agriculture depend on the use of effective strains with desirable motivating plant growth characteristics. The quality control of the biofertilizers, especially in terms of investigating and proving the genus and species of the bacteria used in them is one of the most important criteria. Therefore, in this study, isolates of the four types of common nitrogen and phosphate biofertilizers in Iran, including Barvar2 (Ba1 and Ba2), Biosuperphosphate (Bio1, Bio2, Bio3 and Bio4), Supernitroplus (Sn1 and Sn2) and Nitroxin (N1, N2, N3, N4 and N5) were studied for the correctness at the genus and species levels. The molecular identification method was applied based on amplifying the 16S rDNA genes using universal primers 27F and 1492R. Also, the bacterial genus and species used in the biofertilizers were determined by proper biochemical tests. The results showed that the isolates N1, N5, Sn2 and Bio3 had a similar phenotype and all of them belonged to the Pseudomonas genus. Also, the Sn1 and Bio4 isolates had morphological and molecular similarities belonging to the Bacillus genus. The results of identification for the isolates Ba1, Ba2, Bio2, N2, N3 and N4 showed that they were Pantoea, Pseudomonas, Acinetobacter, Pseudomonas, Citrobacter and Pseudomonas, respectively. Among the isolates, the presence of Citrobacter (N3) and Acinetobacter (Bio2) in the Nitroxin and Biosuperphosphate biofertilizers were noticeable, because they had not been reported by manufacturers in ingredient of the mentioned biofertilizers. However, contrary to the Nitroxin and Supernitroplus biofertilizers manufacturers’ claim about using two isolates Azotobacter and Azospirillum, the present study indicated the lack of these bacteria in these biofertilizers.