Microbial quality of commercial biofertilizers to increase nutrient use efficiency and crop productivity. O-P18

Commercial agricultural inoculants are increasingly being produced and sold in the market worldwide, and are claimed to have a major impact on increasing crop productivity. The main objective of this research was to characterize and assess the microbial content of biofertilizers obtained from different countries in order to verify whether they fulfill the claims of the manufacturers. The proliferation of the underperforming inoculants can thereafter be prevented, and value can be added to effective products. The microorganisms contained in the commercial inoculants were isolated, purified, and identified by partial sequencing of the 16S rDNA. Results showed that the majority (about 64%) of the products contained one or several strains of contaminants and only 37% of the products could be considered as pure. Forty percent of the tested products did not contain any of the claimed strains but only contaminants and several potential human pathogens were found. Rhizobial products were generally of better quality than the other PGPR-based products. Results highlight the need for better quality control systems to ensure efficacious products reach the end users. (Texte intégral)