Screening and Identification of p-Hydroxybenzoic Acid-Degrading Strain ZL22 from Wuyi Tea Continuous Cropping Soil

The p-hydroxybenzoic acid (HBA) released by the plant itself has becoming the main autotoxin for tea ratoon continuous cropping, which had influenced the recycling land/natural resources and economic benefits of the crop. In this study, continuous cropping of Wuyi rock tea at the same area for 32 years' soil was collected to obtain an effective HBA degrading strain. Pseudomonas fluorescens strain ZL22 was isolated and subject to morphological identification and phylogenetic analysis. Biodegradation experiments showed that it could tolerate a high (5 g/L) HBA concentration and under optimal conditions degraded it within 7 days. The enzyme optimization of p-hydroxybenzoate hydroxylase was 30°C, pH 6 and maintained at least 90% residual activity enzyme activity within 25 min. This result indicated that ZL22 possessed an HBA degradation pathway and not only rapidly degraded the autotoxic substance, but also helped strain ZL22 to colonize the rhizosphere soil by using HBA as a carbon source. P. fluorescens ZL22 has a great potential for relieving continuous cropping obstacles and has wild application for rhizosphere soil.