Differential protein expression in Streptococcus uberis under planktonic and biofilm growth conditions

Abstract

The bovine pathogen Streptococcus uberis was assessed for biofilm growth. The transition from planktonic to biofilm growth in strain 0140J correlated with an upregulation of several gene products that have been shown to be important for pathogenesis, including a glutamine ABC transporter (SUB1152) and a lactoferrin binding protein (gene lbp; protein SUB0145).

FIG. 1.

Biofilm formation by S. uberis clinical isolates. Quantitative biofilm formation of S. uberis isolates after 24 h in TSBM. Strains 0140J, EF20, Y38, C197C, and C221 were isolated from diseased cows and form significantly more biofilm biomass than strain C198, isolated from a healthy cow. The asterisk denotes the statistical significance of biofilm formation between 0140J and C198 (P ≤ 0.05).

FIG. 2.

Transcriptional analysis in 0140J planktonic and biofilm cells. (a) Difference in C_T values across all planktonic and biofilm cDNAs from reference gene candidates ddlA, glnA, gyrA, and recA. (b) Example of raw qRT-PCR data showing amplification curves of ddlA in 8-h planktonic, 8-h biofilm, and 36-h biofilm cDNA. (c) Relative fold change in expression of scpA, ccpA, gcaD, glyC, lacR, lbp, and mtsB in 8-h biofilm cells. The gray bars represent expression in early biofilm cells, in comparison to planktonic cells. The striped bars represent expression in early biofilm cells, in comparison to late biofilm cells. glyC and lbp show significant fold change between 8 h of planktonic growth and 8 h of biofilm growth (>9.06- and 2.72-fold change, respectively). lbp shows the only significant fold change in expression between 8-h and 36-h biofilm growth (>2.96-fold change). Asterisks denote statistical significance in difference in expression, as normalized by the reference gene ddlA (P ≤ 0.05).