According to the text, the main sources of biofertilisers are bacteria, fungi, and cyanobacteria. Specifically, Rhizobium forms symbiotic associations with root nodules of leguminous plants to fix atmospheric nitrogen . Cyanobacteria (like Anabaena, Nostoc) are autotrophic microbes that can fix atmospheric nitrogen and serve as important biofertilisers, especially in paddy fields . In contrast, Aspergillus is noted for producing citric acid and Rhizopus is a bread mould , neither of which are described as biofertilisers in this context.