关键词: 海氏肠球菌, 分离, 鉴定, 生物学特性, 天鹅

Abstract: [Objective] To isolate probiotic bacteria from swan feces and identify candidate strains for probiotic development and application. [Methods] Eight swan fecal samples were collected from Korla City, Xinjiang Uygur Autonomous Region. Probiotic bacteria were isolated and identified through morphological, biochemical, and sequencing analyses. The biological characteristics of the isolate, including growth curve, acid production capacity, tolerance, antibacterial activity, antibiotic susceptibility, auto-aggregation ability, and surface hydrophobicity, were evaluated. [Results] Bacteriological culture of the eight fecal samples yielded one potential lactic acid bacterium, identified as a Gram-positive, catalase-negative strain. Sequence alignment revealed 100% similarity with Enterococcus hirae from a Philippine bat source, confirming the isolate as E. hirae, designated as strain Hl4. As determined, the isolate exhibited a logarithmic growth phase between 4 and 14 hours; the pH of the bacterial culture stabilized at 4.10, indicating strong acid production capacity; the survival rate exceeded 20.00% after exposure to pH 2.00 and 0.40% bile salts, demonstrating robust tolerance; the auto-aggregation rate was 54.34%, and surface hydrophobicity was 67.07%. Antibacterial assays showed that the cell-free supernatant of the isolate significantly inhibited Escherichia coli and Staphylococcus aureus. Antibiotic susceptibility testing indicated moderate sensitivity to rifampicin and cefoxitin, and sensitivity to ciprofloxacin, tetracycline, erythromycin, penicillin, ampicillin, and chloramphenicol. [Conclusion] The isolated swan-derived E. hirae strain Hl4 exhibits favorable biological characteristics, making it a promising candidate for development as a functional lactic acid bacterium.

Key words: Enterococcus hirae, isolation, identification, biological characteristics, swans