Trophic regulation of autoaggregation in Pseudomonas taiwanensis VLB120

Abstract

Five mutants of Pseudomonas taiwanensis VLB120ΔCeGFP showed significant autoaggregation when growing on defined carbohydrates or gluconate, while they grew as suspended cells on complex medium and on organic acids like citrate and succinate. Surprisingly, the respective mutations affected very different genes, although all five strains exhibited the same behaviour of aggregate formation. To elucidate the mechanism of the aggregative behaviour, the microbial adhesion to hydrocarbons (MATH) assay and contact angle measurements were performed that pointed to an increased cell surface hydrophobicity. Moreover, investigations of the outer layer of the cell membrane revealed a reduced amount of O-specific polysaccharides in the lipopolysaccharide of the mutant cells. To determine the regulation of the aggregation, reverse transcription quantitative real-time PCR was performed and, irrespective of the mutation, the transcription of a gene encoding a putative phosphodiesterase, which is degrading the global second messenger cyclic diguanylate, was decreased or even deactivated in all mutants. In summary, it appears that the trophic autoaggregation was regulated via cyclic diguanylate and a link between the cellular cyclic diguanylate concentration and the lipopolysaccharide composition of P. taiwanensis VLB120ΔCeGFP is suggested.

Removal of Nitrate in Simulated Water at Low Temperature by a Novel Psychrotrophic and Aerobic Bacterium, Pseudomonas taiwanensis Strain J

“…This difference identification results between PLFAs and 16S rRNA gene sequence might be that the version 6.0 of Sherlock Microbial identification system did not contain the species of Pseudomonas taiwanensis . Although the species of Pseudomonas taiwanensis has been reported by Volmer et al [ 32 ] and Schmutzler et al [ 33 ], whether the strain of Pseudomonas taiwanensis could conduct aerobic denitrification has not been researched. The accession number of strain J in GenBank nucleotide sequence databases is KY927411.…”

Hyperadherence of Pseudomonas taiwanensis VLB120ΔC increases productivity of (S)‐styrene oxide formation

“…Our previous study showed that P. taiwanensis VLB120ΔCeGFP Δ04710 forms cell aggregates (Fig. A) containing considerable amounts of EPS, when grown in M9 (0.5% (wt/vol) glucose) medium (Schmutzler et al ., , ). These cell autoaggregates were observed to adhere strongly to polymeric and glass surfaces (Fig.…”

“…On the other hand it was speculated that the secretion of EPS increases the attachment forces of the cells which finally allows the cells to overcome the interfacial forces generated by the segmented flow and form a biofilm. These suggestions are in good agreement to our findings since the aggregates of P. taiwanensis VLB120ΔCeGFP Δ04710 were shown via confocal laser‐scanning microscopy and scanning electron microscopy to excrete considerable amounts of EPS material (Schmutzler et al ., , ). Therefore, it can be concluded that P. taiwanensis VLB120ΔCeGFP Δ04710 aggregates probably gained additional binding forces due to the presence of EPS as compared with the planktonic cells of the parent strain.…”

“…In this work, the problem of weak initial attachment forces was addressed by applying a hyperadherent mutant of the ( S )‐styrene oxide production strain P. taiwanensis VLB120ΔCeGFP. The variant P. taiwanensis VLB120ΔCeGFP Δ04710 possessing a genetically engineered cyclic diguanylate (c‐di‐GMP) metabolism (Schmutzler et al ., , ) carried a deletion of a phosphodiesterase highly similar to BifA of other pseudomonads (Kuchma et al ., , ; Jiménez‐Fernández et al ., ). This mutant developed macroscopic aggregates in dependency of the supplied carbon source.…”

“…This mutant developed macroscopic aggregates in dependency of the supplied carbon source. In minimal medium supplemented with carbohydrates or gluconate the variant showed heavy autoaggregation with enhanced adhesiveness of the cells due to excreted EPS material and/or enhanced cell surface hydrophobicity compared with the parent strain (Schmutzler et al ., , ). The attachment behaviour of the autoaggregates to silicone rubber and the biofilm formation of P. taiwanensis VLB120ΔCeGFP Δ04710 were studied in detail.…”