Effect of hydrogen peroxide and carbon-to-nitrogen ratio on growth and biochemical profile in oleaginous mucoromycota

In general, all the strains tolerated H₂O₂ at much higher concentrations than those commonly used to improve enzymatic saccharification (1-19 mM vs 1-240 µM). Vibrational spectroscopy (mid-infrared and Raman) was used to analyze the biochemical composition of the fungi. The exposure to sublethal H₂O₂ doses did not increase any metabolite in particular but slightly reduced biomass production at concentrations near the minimal inhibitory concentration (MIC) in some cases. For Lichtheimia corymbifera grown in standard C/N medium, an accumulation of intracellular proteins with oxidative damage was positively correlated to the H₂O₂ concentration. This was not observed for other strains. The biggest changes in the biochemical composition of the fungal biomass were linked to changes in medium C/N ratios. This included different carbon allocation strategies among the tested species, such as accumulation of lipids and polyphosphates, lipids and saccharides, etc. CONCLUSIONS: Our results suggest that the Mucoromycota strains used in this study are compatible with H₂O₂ feeding in lignocellulose-based SSF to enhance efficiency while sustaining minimal risk of oxidative damage.