Gonzalez-Garcia, D. | bioRxiv Science

bioRxiv2026

Integrating Fungal-Bacterial Synergy to Enhance Circular MFC-Hydroponic Performance

Microbial fuel cells (MFCs) represent a promising technology for the simultaneous treatment of wastewater and bioelectricity generation. In this study, the MFCs are conceived as functional modules to be integrated into hydroponic cultivation systems, acting as a prosthetic rhizosphere capable of coupling wastewater treatment and bioelectrochemical activity with plant nutrition improvement. We compared the electrochemical performance of different microbial consortia comprising the electroactive bacterium Shewanella oneidensis, the plant growth promoting rhizobacterium (PGPR) Pseudomonas putida, and the plant biomass-degrading fungus Ophiostoma piceae, along with the supplementation with the quorum sensing (QS) analogue molecule 1{square} dodecanol. These microbial consortia are tested in MFCs fed with wastewater and root exudates to analyze enhanced feedstock assimilation, electricity production, and the generation of plant growth-promoting substances (PGPS). From an electrochemical perspective, we evaluated planktonic growth, anode adhesion, substrate consumption, and the production of redox-active molecules and PGPS such as flavins and siderophores respectively alongside key electrical production parameters, including current output and power. Among the different microbial configurations tested, the consortium combining S. oneidensis, P. putida, and O. piceae exhibited the highest electrical production potential. Moreover, within this framework, we detected the extracellular production of siderophores in MFCs containing P. putida, suggesting a potential role supporting hydroponic crop growth. Furthermore, the addition of 1-dodecanol led to an improvement of the bioelectrochemical parameters. These results highlight the potential of synthetic microbial consortia in MFC-based systems not only to enhance electricity generation from wastewater but also to provide added value in integrated hydroponic applications through rhizosphere-like functions.

microbiology↗

bioRxiv2025

Synthetic Yarrowia lipolytica consortium for efficient conversion of lignocellulosic oligosaccharides into lipids

Lignocellulosic biomass (LCB) is an abundant and renewable feedstock for the sustainable production of bioproducts; however, its industrial exploitation is limited by its complex composition and by the lack of microbial platforms capable of simultaneously degrading and assimilating cellulose- and hemicellulose-derived oligosaccharides. Yarrowia lipolytica lacks the native enzymatic machinery required for this process. In this study, we engineered a multifunctional strain (YBXT-XR-BGL3) able to secrete fungal {beta}-glucosidase (BGL3 or BGL1) and {beta}-xylosidase (BxTw1) from Talaromyces amestolkiae, enabling the hydrolysis of cellobiose and xylooligosaccharides, respectively. In addition, a xylose reductase pathway was introduced to confer xylose assimilation. Because the construction of a single multifunctional strain may impose a significant metabolic burden and reduce fitness, we benchmarked this strain against a division-of-labor strategy. To this end, we also developed a cellobiose-specialized strain (YBGL3 or YBGL1) and a xylooligosaccharide-specialized strain (YBXT-XR). Functional characterization revealed efficient saccharification of cello- and xylooligosaccharides under acidic conditions, with BGL3 outperforming BGL1 in glucose release and BxTw1 exhibiting broad pH tolerance. Under nitrogen-limited conditions, this enabled lipid accumulation of up to 20% from cellobiose in YBGL3 and YBXT-XR-BGL3, and up to 15% from xylooligosaccharides in YBXT and YBXT-XR-BGL3. In co-culture experiments using a mixed substrate (glucose, cellobiose, and xylooligosaccharides), both the multifunctional strain and the consortium produced up to 0.67 g L{square}{superscript 1} of lipids. However, the division-of-labor approach led to higher lipid accumulation (34% versus 26.3% in the monoculture), driven by a rapid population shift: following cellobiose depletion (after 72 h), YBXT-XR became predominant and utilized the remaining xylooligosaccharides almost exclusively for lipid synthesis. Overall, this study provides the first demonstration of a Y. lipolytica system capable of simultaneously utilizing cellulose- and hemicellulose-derived oligosaccharides. Moreover, benchmarking a division-of-labor consortium against a multifunctional monoculture highlights a robust strategy to enhance lipid biosynthesis and improve process resilience for LCB valorization.

synthetic biology↗