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Poster: Biology & Disease Mgmt: Bacteriology


Effect of biofertilizer applications on bacterial communities in the rhizosphere of citrus affected by huanglongbing
J. LI (1), Y. Zhang (2), L. Li (3), U. Handique (2), N. Wang (3) (1) University of Florida, U.S.A.; (2) University of Florida, U.S.A.; (3) University of Florida, U.S.A.

Biofertilizer is increasingly used to maintain the health and productivity of citrus trees affected by huanglongbing (HLB) in Florida. Although the practice is of controversy regarding effectiveness, little is known about its non-target effects in the environment. We investigated the impact of soil application of bacterial biofertilizer agents (BFA) on rhizosphere microbial communities of HLB diseased citrus trees. Soil samples were collected at one week before applying BFA and 14 months after the first application respectively. Bacterial communities were profiled by high-throughput sequencing of 16S rDNA V3-V4 hypervariable region. Comparison of taxonomic communities only revealed marginal changes after application of BFA. The phyla Proteobacteria, Bacteroidetes Firmicutes, Actinobacteria, and Acidobacteria were most abundant in all samples, representing 95.0 to 97.0% of all assigned sequences. Analysis of the most prominent genera revealed that Pseudomonas, Chitinophaga, Bacillus, Pedobacter, Flavobacterium, Bradyrhizobium, and Rhizobium represented between 5% and 25% of the microbial communities in all the samples that where either treated or not treated. A general shift within the composition of the microbial communities that was independent of the application of BFA was observed after application. The results indicate that BFA application has limited effect on citrus rhizosphere bacterial communities; however, its lasting effects need to be determined.