Abstract: 【Aim】 Gut bacterium Erwinia persicina is one of the dominant bacterial species in the larval gut of the diamondback moth, Plutella xylostella. The aim of the present study is to investigate the phenotypic characteristics of this bacterium. 【Methods】 The cell phenotype of E. persicina was analyzed with BIOLOG Phenotype MicroArray (PM). Totally 950 different metabolic phenotypes were tested using the PM plates 1-10. 【Results】 E. persicina was able to metabolize 39.47% of the tested carbon sources, 89.74% of nitrogen sources, 100% of sulfur sources, and 100% of phosphorus sources. Most informative utilization patterns for carbon sources of E. persicina were organic acids and carbohydrates, and for nitrogen were various amino acids. The bacterium had 261 different nitrogen metabolic pathways and 95 different biosynthetic pathways. It had a wide range of adaptabilities, and could still metabolize in osmolytes with up to 9% sodium chloride, 4% potassium chloride, 5% sodium sulfate, 20% ethylene glycol, 6% sodium formate, 2% urea, 6% sodium lactate, 200 mmol/L sodium phosphate (pH 7.0), 20 mmol/L sodium benzoate (pH 5.2), 100 mmol/L ammonium sulfate (pH 8.0), 100 mmol/L sodium nitrate, and 100 mmol/L sodium nitrite, respectively. It also exhibited active metabolism under pH values between 4.5 and 10, with optimal pH around 7.0. The gut bacterium showed both decarboxylase and deaminase activities in the presence of various amino acids. 【Conclusion】 The phenotypic characterization of E. persicina increased our knowledge of the bacterium, in particular its interactions with insect hosts and the adaptability in gut environments, and showed us some possible approaches to controlling diamondback moth through decreasing E. persicina density.

Key words:  Erwinia persicina, Plutella xylostella, phenotype microarray, metabolic fingerprint, gut bacteria