Tryptone in Growth Media Enhances Pseudomonas putida Biofilm

Abstract

Extracellular factors and growth conditions can affect the formation and development of bacterial biofilms. The biofilm of Pseudomonas putida has been studied for decades, but so far, little attention has been paid to the components of the medium that may affect the biofilm development in a closed system. It is known that Fis strongly enhances biofilm in complete LB medium. However, this is not the case in the defined M9 medium, which led us to question why the bacterium behaves differently in these two media. Detailed analysis of the individual medium components revealed that tryptone as the LB proteinaceous component maintains biofilm in its older stages. Although the growth parameters of planktonic cells were similar in the media containing tryptone or an equivalent concentration of amino acids, only the tryptone had a positive effect on the mature biofilm of the wild type strain of P. putida. Thus, the peptides in the environment may influence mature biofilm as a structural factor and not only as an energy source. Testing the effect of other biopolymers on biofilm formation showed variable results even for polymers with a similar charge, indicating that biopolymers can affect P. putida biofilm through a number of bacterial factors.

Pseudomonas putida Biofilm Depends on the vWFa-Domain of LapA in Peptides-Containing Growth Medium

“…Knowing the peptide-dependency of P. putida biofilm [ 19 ], we tested whether it is based on LapA or LapF. We previously reported that LapA is a crucial factor in forming P. putida biofilm in LB and that LapF is required for P. putida cell surface hydrophobicity [ 1 , 2 , 20 ].…”

“…Fis-enhanced biofilm appears in P. putida F15 strain when the expression of fis is increased by IPTG compared to the biofilm of F15 without IPTG supplementation (compare biofilms of P. putida F15 in Figure 1 B,C). Peptide-dependent biofilm appears in P. putida strains when the peptides are present in growth media compared to the biofilms formed in growth media without peptides (compare biofilms in Figure 1 A,C) [ 19 ]. If the arithmetic means of the samples are significantly different ( p < 0.05), it is considered a Fis-enhanced or peptide-dependent biofilm.…”

“…We have previously shown that the biofilm of P. putida depends on LapA and the proteinaceous component in the medium [ 1 , 19 ]. Specifically, according to the crystal violet absorption, P. putida forms more biofilm when tryptone or poly-lysine are present in the medium [ 19 ]. In addition, we have ascertained that Fis activates lapA transcription in P. putida [ 20 ].…”

“…We presumed that additional expression of fis from the P tac promoter by IPTG, i.e., an artificial increase in the amount of Fis in the cell (so-called fis -overexpression), has a positive epistatic effect on the P. putida biofilm (Fis-enhanced biofilm). However, we recently ascertained that the positive impact of Fis on the P. putida biofilm depends on the presence of peptides in the medium [ 19 ]. In other words, the overexpression of fis in cells can enhance biofilm by activating lapA transcription only when peptides are present in the medium [ 19 ].…”

“…However, we recently ascertained that the positive impact of Fis on the P. putida biofilm depends on the presence of peptides in the medium [ 19 ]. In other words, the overexpression of fis in cells can enhance biofilm by activating lapA transcription only when peptides are present in the medium [ 19 ].…”