Evidence that the stress hormone cortisol regulates biofilm formation differently among Flavobacterium columnare isolates

AbstractThe impact of cortisol onFlavobacterium columnare biofilm formation was explored. Firstly, the dynamics of biofilm formation by one highly (HV) and one low virulent (LV)F. columnare isolate with and without the stress hormone cortisol under microfluidic flow conditions was characterized. This to confirm thatF. columnare cells could form biofilm under cortisol supplementation, and to compare the temporal and structural differences between different treatment groups. One trial revealed that in both isolates cell aggregates resembling biofilms occurred within 7-h post-inoculation. Consequently, cell clusters were sloughed away, followed by a rebuilding of bacterial cell aggregates, suggestive for a high spreading capacity. While the HV isolate revealed cell aggregates formed upstream at all time-points, for the LV isolate this was only seen upon cortisol supplementation. Secondly, the transcriptional effect of genes (gldK, gldL, gldM,gldN,sprA,sprE,sprT, andporV) belonging to the Type IX secretion system involved in gliding motility was investigated in planktonic and biofilm cells of a HV and LV isolate to which no, a low (LD) or high (HD) dose of cortisol was added. Significantly lower expression of gliding genesgldK,gldL, gldM andgldN, and of protein secretion regulatorporV was seen in the LV isolate planktonic cells supplemented with a HD-cortisol. The LV isolate biofilm cells treated with the HD-cortisol showed a significant upregulation ofsprT, encoding mobile surfa...
Source: Veterinary Research - Category: Veterinary Research Source Type: research