The architecture of a mixed fungal–bacterial biofilm is modulated by quorum‐sensing signals

Abstract

Summary Interkingdom communication is of particular relevance in polymicrobial biofilms. In this work, the ability of the fungus Ophiostoma piceae to form biofilms individually and in consortium with the bacterium Pseudomonas putida, as well as the effect of fungal and bacterial signal molecules on the architecture of the biofilms was evaluated. Pseudomonas putida KT2440 is able to form biofilms through the secretion of exopolysaccharides and two large extracellular adhesion proteins, LapA and LapF. It has two intercellular signalling systems, one mediated by dodecanoic acid and an orphan LuxR receptor that could participate in the response to AHL‐type quorum sensing molecules (QSMs). Furthermore, the dimorphic fungus O. piceae uses farnesol as QSM to control its yeast to hyphae morphological transition. Results show for the first time the ability of this fungus to form biofilms alone and in mixed cultures with the bacterium. Biofilms were induced by bacterial and fungal QSMs. The essential role of LapA‐LapF proteins in the architecture of biofilms was corroborated, LapA was induced by farnesol and dodecanol, while LapF by 3‐oxo‐C6‐HSL and 3‐oxo‐C12‐HSL. Our results indicate that fungal signals can induce a transient rise in the levels of the secondary messenger c‐di‐GMP, which control biofilm formation and architecture.

Fungal–Lactobacteria Consortia and Enzymatic Catalysis for Polylactic Acid Production

“…Firstly, bacterium–fungus combinations were tested in liquid medium: GPP (Glucose-Proline-Phosphate) minimal medium [ 21 ], Czapek’s Dox [ 29 ], CDM (chemical defined medium) [ 30 ] and plantarum minimal medium (PMM5) [ 27 ], all with glucose as a carbon source. In subsequent experiments, we used MRS broth (Condalab) with glucose as a control medium and MRS broth without dextrose and beef extract (Condalab) with 1% ( w / v ) starch as the carbon source.…”

“…Recently, it has been shown that some Gram-positive organisms such as Lactobacillus plantarum also respond to these molecules [ 19 ]. Furthermore, farnesol (a terpene) and dodecanol (an alcohol) induce different responses among fungi [ 20 ] and affect biofilm formation differently in consortia of Ophiostoma piceae and Pseudomonas putida [ 21 ]. Biofilms allow microorganisms to adhere and form a resistant new ecological niche [ 22 ]; the regulation of biofilm formation by QS in bacteria and fungi has already been demonstrated [ 21 ].…”

“…Furthermore, farnesol (a terpene) and dodecanol (an alcohol) induce different responses among fungi [ 20 ] and affect biofilm formation differently in consortia of Ophiostoma piceae and Pseudomonas putida [ 21 ]. Biofilms allow microorganisms to adhere and form a resistant new ecological niche [ 22 ]; the regulation of biofilm formation by QS in bacteria and fungi has already been demonstrated [ 21 ]. These types of structures, which are common in nature, can be very interesting for the development of consortia for industrial biotransformations.…”

Dynamic flux regulation for high-titer anthranilate production by plasmid-free, conditionally-auxotrophic strains of Pseudomonas putida

“…cross-talk) with the synthetic Esa QS circuit. It has been previously described that P. putida KT2440 does not produce any of the common signal molecules typically involved in QS systems described in other bacteria (Fernández-Piñar et al, 2011;Ruiz et al, 2021;Subramoni and Venturi, 2009). The genome of this strain appears to display a single open reading frame (PP_4647) that encodes an unpaired transcriptional regulator belonging to the LuxR protein family-i.e.…”

Quorum sensing in synthetic biology: A review

“…Very few studies currently look at inter-kingdom communication [20]. However, as we learn more about fungal communication systems we can envision to see more studies programming population level behaviours in yeast and fungi as well as in inter-kingdom contexts [21,22,23,24,25].…”