Relationship of biofilm-forming ability of with swimming motility, twitching motility and virulence gene distribution / 浙江大学学报·医学版

To investigate the relationship of biofilm-forming ability of (PA) with swimming motility, twitching motility and virulence gene distribution. A total of 192 clinical isolates of PA were collected consecutively. Microtiter plate method was used to evaluate the ability to form biofilm. The swimming and twitching motilities were detected by plate method. Polymerase chain reaction (PCR) was used to detect virulence genes. Of the 192 PA clinical isolates, 186 (96.9%) showed biofilm-forming ability. Among them, 36 isolates showed weak biofilm-forming ability, 84 exhibited moderate biofilm-forming ability and 66 showed strong biofilm-forming ability. The diameters of the swimming ring for PA with none biofilm-forming ability, weak biofilm-forming ability, moderate biofilm-forming ability, strong biofilm-forming ability were (9.12±6.76), (18.42±7.51), (19.10±4.77) and respectively. The diameters of the twitching ring for PA in above groups were (8.38±1.50), (17.21±7.42), (18.49±5.62) and respectively. The swimming motility and twitching motility of none biofilm-forming ability group were weaker than biofilm-forming ability groups (all <0.05). Among 192 PA strains, 163 were positive (84.9%), 40 were positive (20.8%), 183 were positive (95.3%), and 189 were positive (98.4%). The positive rate of PA virulence gene , and were different in strains with different biofilm-forming abilities (<0.05). The rate of in the strong biofilm-forming ability group was lower than that in the moderate biofilm-forming ability group (=9.293, <0.01) and the weak biofilm-forming ability group (=9.997, <0.01). The rate of in the strong biofilm-forming ability group was higher than that in the weak biofilm-forming ability group (=10.803, <0.01). Most clinical isolates of PA can form biofilm. Swimming and twitching motilities are related to the formation of biofilm, but not significantly related to strength of biofilm-forming ability. The virulence genes of type Ⅲ secretion system for PA may be related to the biofilm-forming ability.

Regulation of swimming motility by H-NS in Vibrio parahaemolyticus / 军事医学

Objective To investigate the regulation of swimming motility by H-NS in Vibrio parahaemolyticus(VP). Methods VP was inoculated into the semi-solid swimming agar plate containing 1% Oxoid tryptone, 2% NaCl, 0.5%Difco Noble Agar, and 0.1% arabinose followed by incubation at 37℃ for 4.5 h before the diameters of bacterial lawns were measured.Total RNAs were extracted from the wild-type (WT) strains and the hns null mutant (Δhns), and the quantitative real-time( RT)-PCR( qRT-PCR) was carried out to calculate the transcriptional variation of flaA between WT andΔhns strains.The entire promoter DNA region of flaA was amplified and cloned into the lacZ fusion vector pHRP309 containing a promoterless lacZ gene. The recombinant lacZ reporter plasmid was transformed into WT and Δhns, respectively, to measure the β-galactosidase activities in cellular extracts using the β-galactosidase enzyme assay system. Results and Conclusion The phenotype results showed that swimming motility of VP was enhanced by H-NS.The qRT-PCR and LacZ fusion results indicated that the transcription of flaA was positively regulated by H-NS.Collectively, H-NS promotes the swimming motility of VP, at least partly, by activating the transcription of flaA.