Which one of the following is not a biofertilizer?

Explanation

Biofertilizers are organisms that enrich the nutrient quality of the soil. The main sources of biofertilizers are bacteria, fungi, and cyanobacteria. Rhizobium bacteria are found in the nodules on the roots of leguminous plants by symbiotic association. These bacteria fix atmospheric nitrogen into organic forms, which is used by the plants as a nutrient. Fungi are also known to form symbiotic associations with plants called mycorrhiza. Cyanobacteria are autotrophic microbes widely distributed in aquatic and terrestrial environments. Many of these can fix atmospheric nitrogen, e.g., Anabaena, Nostoc, Oscillatoria, etc. But Agrobacterium tumefaciens is a pathogen of several dicot plants. It causes gall tumors in the plants.