Análisis y caracterización de poblaciones bacterianas solubilizadoras de P en un ensayo de larga duración con diferentes secuencias de cultivo

Abstract

It is well known that different soil use and management systems affect the abundance, activity and composition of the soil microbial community. In this work, the behavior of cultivable bacterial populations and, in particular, P (PSB) solubilizing bacteria in soil samples from a long-term trial with different culture sequences was studied. The results obtained show that the clearing and subsequent agricultural use after 11 years generated a decrease in the population of cultivable bacteria in general, and of P-solubilizing bacteria in particular, with respect to the pristine soil. Isolates with high P solubilization efficiency were obtained from the soils from the different rotations. These efficient isolates were taxonomically classified by 16S RNA analysis as belonging to the genera Bacillus, Paenibacillus, Pseudomonas and Xanthomonas. In particular, the characterization of the culture supernatants of the isolates Pseudomonas koreensis and Paenibacillus pabuli showed they are producers of organic acids. The combined inoculation tests of these two strains on maize plants in a culture chamber revealed a synergistic effect on the growth promotion of this species. The results presented here suggest that although PSB populations are more numerous in pristine soils, certain long-term crop rotations favor the increase of more efficient solubilizing bacteria, an aspect that should be considered when designing future search strategies for potential bioinoculants.