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journal1 ›› 2019, Vol. 35 ›› Issue (3): 437-448.DOI: 10.16409/j.cnki.2095-039x.2019.03.007

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Identification, Optimization of Fermentation Conditions of Antagonistic Bacterium Pseudomonas extremorientalis against Botrytis cinerea on Pear and Evaluation of Its Biocontrol Efficacy

WANG Yan1, WANG Chunwei1, WANG Lin2, LIU Qianru1, DONG Tian1, HOU Puxing1, ZHANG Xiqian1, WANG Meiqin1, ZHANG Zuogang1, WANG Jianming1   

  1. 1. College of Agriculture, Shanxi Agricultural University, Taigu 030801, China;
    2. Yuncheng Sub-center, Shanxi Entry-Exit Inspection and Quarantine Bureau Technology Center, Yuncheng 044600, China
  • Received:2018-09-25 Online:2019-06-08 Published:2019-06-17

Abstract: Pear gray mold, an important postharvest disease with high incidence, causes serious damage during the storage period. To control this disease efficiently, endophytic bacteria strains were isolated from pear rhizosphere soil by plating dilution method, and screened based on antifungal activity by using agar plate diffusions method. Antagonistic bacterium strain L21 was obtained, and identified as Pseudomonas extremorientalis based on the morphological, physiological and biochemical characteristics, and 16S rRNA and gyrB sequence analysis. The antifungal effects of cell-free fermentation broth of strain L21 on twelve pathogenic fungi were obvious by using mycelial growth rate method. Strain L21 could produce indoleacetic acid (IAA) by Salkowski colorimetric method. Strain L21 could produce extracellular by using casein medium plate. Based on single factor tests, three important factors of pH, temperature and yeast powder were screened by Plackett-Burman experimental design. The optimal fermentation conditions for sucrose 20 g/L, beef extract 20 g/L, manganese sulfate 3.00 g/L, glycerol 1 g/L, K2HPO4 1.50 g/L, inoculation amount 8%, cultural temperature 34℃, pH 7.31, rotational speed 200.66 r/min and cultural time 15 hours were determined by steepest ascent experiment and Box-Behnken experimental design. At 96 hours after application, the control efficacy of strain L21 was 74.23%, and no significant difference compared with that of carbendazim. Strain L21 showed strong inhibition effect and wide antagonistic spectrum, which has the potential to be the novel biocontrol agent for plant fungal diseases control.

Key words: pear, Botrytis cinerea, Pseudomonas extremorientalis, identification, fermentation conditions, control effect

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