Abstract: This study aimed to investigate the process of biofilm formation of Hafnia alvei Ha-01, and to examine the influences of different culture conditions (carbon source, pH, NaCl concentration, and adhesive material) on the number of viable cells in biofilm formed by Hafnia alvei and its growth properties by the ultrasonic plate method and scanning electron microscopy (SEM), and we also assessed the relationship between exogenous N-acyl-homoserine lactone (C6-HSL) as a quorum-sensing (QS) signal molecule and the biofilm formation of Hafnia alvei. The results indicated that the biofilm formation of strain Ha-01 was closely related to incubation time. The biofilm formation ability of Ha-01 varied depending on carbon source, and when xylose was used as carbon source, its biofilm formation ability reached the strongest level of 7.51 (lg (CFU/cm2)), which was increased by 10.28% as compared with that in LB medium. The biofilm formation ability of Ha-01 was stronger under neutral conditions, with the viable cell count reaching 7.77 (lg (CFU/cm2)). At a NaCl concentration of 2%, the biofilm formation was the highest, reaching 7.18 (lg (CFU/cm2)). The biofilm formation ability of Ha-01 on different material surfaces was deceased in the order of Al, Zn, and glass. The numbers of viable cells on these materials were 7.22, 6.48, and 6.11 (lg (CFU/cm2)), respectively. The biofilm formation ability became stronger with the increase of exogenous C6-HSL. In conclusion, culture conditions could affect the biofilm formation of Hafnia alvei, which could be regulated by AHLs.

Key words: Hafnia alvei, biofilm, AHLs, culture conditions