Microbial Diversity and Functional Profiles of Three Commercial Biofertilizers and Impacts on the Bacterial Communities of Avocado’s Soil Rhizosphere

Abstract

Chilean avocado (Persea americana Mill.) exports have accounted for 60 % of the total production and are recognized for their high quality worldwide. However, avocado production has significantly decreased in recent years, which is mainly attributed to abiotic and biotic factors, among which are high and low temperatures, intense and sudden rains, unavailability of water resources, and agricultural salinity. Secondary factors include pests and diseases. Applying plant growth promoting microorganisms (PGPM)-based commercial biofertilizers is a potential practice to increase avocado production and resistance to edaphoclimatic factors. In this study, to determine the functionality of microbial communities present in three commercial biofertilizers (Biofert A, Biofert B, and Biofert C) and thus offer a structure of associated microbial communities, the rhizospheric soil of avocado was analysed using the Biolog EcoPlate™ technique, providing information on the community level physiologic profiles (CLPP) and biodiversity indices by denaturing gradient gel electrophoresis (DGGE). The findings revealed that the microbial diversity in the three commercial biofertilizers is highly different, showing a SIMPER overall dissimilarity of 83.9 % in the catabolic capacity. Concerning the impact on avocados’ rhizosphere soil bacterial communities, the results demonstrated significant changes in their composition, particularly with Biofert A and C. In contrast, Biofert B did not show significant changes, especially on days 15 and 30. Long-term studies are recommended to develop sustainable agricultural practices for Chilean avocados.