Isolation, identification and degradation characteristics of apple rhizosphere autotoxicitic compounds-degrading bacteria

Abstract:

[Objective] The aim of this study was to screen autotoxicitic compounds degradation bacteria from apple rhizosphere soil, and investigate the capacity of degradating phloridzin, phthalic acid, P-hydroxybenzoic acid and pyrogallic acid of the bacteria. [Methods] Bacteria were enriched and isolated by the sole carbon source Phthalic acid, Then，the strains were identified by the determination of physiological and biochemical characteristics, as well as 16S rRNA gene sequence analysis. Additionally, the ability of degradating phthalic acid, pyrogallic acid, P-hydroxybenzoic acid and phloridzin using the ultraviolet spectrophotometry and high-performance liquid chromatography. [Results] A total of five bacteria were isolated and named as BL1, BL2, BL3, BJ1 and BJ2, respectively. All of them degraded phthalic acid, pyrogallic acid, P-hydroxybenzoic acid and phloridzin. The five strains BL1, BL2, BL3, BJ1 and BJ2 were identified as Cupriavidus necator, Azospirillum lipoferum, Microbacterium hydrocarbonoxydans, Paenibacillus phyllosphaerae and Ochrobactrum cytisi respectively. The degration rates to phthalic acid, pyrogallic acid, P-hydroxybenzoic acid and phloridzin of BL1, BL2 and BL3 were all more than 50%. The degradation rate to phthalic acid, pyrogallic acid, P-hydroxybenzoic acid and phloridzin of BL2 was highest, and the degradation rate was 91%, 72%, 84% and 84% respectively. [Conclusion] We firstly discovered that Cupriavidus necator, Azospirillum lipoferum and Microbacterium hydrocarbonoxydans had the ability to degrade those four autotoxictic compounds, and they were expected to be applied in continuous cropping obstacle caused by autotoxicitic compounds in apple.