The wood decay fungus Cerrena unicolor adjusts its metabolism to grow on various types of wood and light conditions

Abstract

Cerrena unicolor is a wood-degrading basidiomycete with ecological and biotechnological importance. Comprehensive Biolog-based analysis was performed to assess the metabolic capabilities and sensitivity to chemicals of C. unicolor FCL139 growing in various sawdust substrates and light conditions. The metabolic preferences of the fungus towards utilization of specific substrates were shown to be correlated with the sawdust medium applied for fungus growth and the light conditions. The highest catabolic activity of C. unicolor was observed after fungus precultivation on birch and ash sawdust media. The fungus growing in the dark showed the highest metabolic activity which was indicated by capacity to utilize a broad spectrum of compounds and the decomposition of 74/95 of the carbon sources. In all the culture light conditions, p-hydroxyphenylacetic acid was the most readily metabolized compound. The greatest tolerance to chemicals was also observed during C. unicolor growth in darkness. The fungus was the most sensitive to nitrogen compounds and antibiotics, but more resistant to chelators. Comparative analysis of C. unicolor and selected wood-decay fungi from different taxonomic and ecological groups revealed average catabolic activity of the fungus. However, C. unicolor showed outstanding capabilities to catabolize salicin and arbutin. The obtained picture of C. unicolor metabolism showed that the fungus abilities to decompose woody plant material are influenced by various environmental factors.

Fig 1. Comparison of metabolic aptitudes of different wood-rotting fungi.

(A) Phenotype profiles of P. pini FCL3, T. versicolor FCL7, P. radiata FCL99, C. unicolor FCL139, P. chrysosporium FCL236, F. betulina FCL397, A. gallica FCL400, and F. hepatica FCL457 determined by Biolog FF MicroPlates during 192 hours of incubation with respective substrates. The color scale applied into the heat maps indicates the growth of the fungus (mitochondrial activity A_490nm) on a particular substrate. (B) Metabolic diversity (substrate richness) of the fungi representing different rot lifestyles; vertical bars denote 0.95 confidence intervals. (C) Metabolic preferences of fungi towards utilization of a particular group of carbon substrates. (D) Cluster analysis-based dendrogram showing similarity of the FF MicroPlate C-sources utilization profiles of the analyzed strains; P. pini FCL3, T. versicolor FCL7, P. radiata FCL99, C. unicolor FCL139, P. chrysosporium FCL 236, F. betulina FCL397, A. gallica FCL400, and F. hepatica FCL457.

Fig 2. Ratio between normalized values of substrate use (OD 490nm) and biomass production (OD 750nm) defining theoretical metabolic efficiency of different wood-decaying fungi; P. pini FCL3, T. versicolor FCL7, P. radiata FCL99, C. unicolor FCL139, P. chrysosporium FCL 236, F. betulina FCL397, A. gallica FCL400, F. hepatica FCL457.

Fig 3. Utilization profiles of C. unicolor grown on different sawdust substrates.

(A) Phenotype profiles of C. unicolor FCL139 obtained with PM1 and PM2 panels after fungus precultivation on ash, maple, and birch sawdust and LH control medium. The color scale applied into the heat maps indicates the growth of the fungus (OD 750 nm) on a particular substrate. (B) Substrate richness values of C. unicolor FCL139 precultured on ash, maple, and birch sawdust and LH mineral medium; vertical bars denote 0.95 confidence intervals. (C) Metabolic preferences of C. unicolor FCL139 towards particular carbon and energy sources observed after fungus precultivation in media containing different sawdust substrates and LH control medium.

Fig 4. The effect of light on C. unicolor metabolic profiles.

(A) FF MP substrate utilization profile of C. unicolor FCL139 cultured in different light conditions (white, red, blue and, green light, darkness) during 168 hours of incubation. The color scale applied into the heat maps indicates the growth of the fungus (mitochondrial activity A_490nm) on a particular substrate. (B) Substrate richness (R) values of C. unicolor FCL139 cultured in different light conditions (white, red, blue and, green light, darkness); vertical bars denote 0.95 confidence intervals. (C) Metabolic preferences of C. unicolor FCL139 cultured in different light conditions (white, red, blue and, green light, darkness) towards utilization of a particular group of carbon substrates. (D) Cluster analysis-based dendrogram showing similarity of FF MicroPlates C-source utilization profile of C. unicolor FCL139 cultured in different light conditions (white, red, blue and, green light, darkness).

Fig 5. Ratio between normalized values of substrate use (OD 490nm) and biomass production (OD 750nm) defining theoretical metabolic efficiency of C. unicolor cultured in different lightning treatment (white, red, blue and, green light, darkness).

Fig 6. C. unicolor growth in different lighting treatments (white, red, blue and, green light, darkness) in the presence of various groups of potentially toxic chemical compounds.

The scale represents growth values (OD 750 nm) after 10 days of incubation. The horizontal line at a value of 0.2 represents the growth threshold considered positive.

Fig 7

C. unicolor growth in different lighting treatments (white, red, blue and, green light, darkness) in the presence of A–anions, B–cations, C–membrane function-affecting compounds, D–chelators, E–cyclic compounds, F–organic compounds, G–nitrogen compounds, and H–antibiotics. The scales represent growth values (OD 750 nm) after 10 days of incubation. The horizontal line at a value of 0.2 represents the growth threshold considered positive. Vertical bars denote 0.95 confidence intervals.