Effect of the Mode of Fermentation on the Behavior of Penicillium bilaiae in Conditions of Abiotic Stress Vassileva, Maria Hristova Martos Núñez, María Vanesa García Del Moral Garrido, Luis F. Vassilev, Nikolay Bojkov Penicillium bilaiae Stress abiotic factors Different modes of fermentation P-solubilisation activity This research was funded from the European Union’s Horizon 2020 Research and Innova- tion Program under grant agreement No. 817946 and partly by the EU project SUSTAINABLE, EU grant agreement no. 101007702. And project P18-HO-4279 Junta de Andalucía-PAIDI 2020, Spain. The ability of a Penicillium bilaiae strain to support acid production and simultaneously solubilize inorganic sources of phosphate in conditions of submerged, solid-state fermentation (SSF) and immobilized cell system was examined in this study. Abiotic stress factors such as NaCl and different values of pH were introduced into the different fermentation process schemes to measure the fungal response. The results showed a higher tolerance of P. bilaiae when the fermentation process was carried out in solid-state and immobilized-cell conditions, which mimics the natural state of the soil microorganisms. The acidic culture conditions were not found to be suitable for fungal growth, which increased at a higher pH, with values of 4.0 and 6.0 being optimal for all types of fermentation. The presence of increasing amounts of NaCl provoked low biomass growth, titratable acidity, and simultaneous phosphate (P) solubilization. These results were, however, less pronounced at pH 4.0 and 6.0, particularly in conditions of SSF. Studying stress-tolerant microbial characteristics, particularly in different conditions and combinations of stress factors, is of great importance for further managing the overall microbial inoculants’ production and formulation process as well as their applications in specific soil–plant systems. 2023-05-25T12:26:03Z 2023-05-25T12:26:03Z 2023-04-19 journal article Vassileva, M.; Martos, V.; del Moral, L.F.G.; Vassilev, N. Effect of the Mode of Fermentation on the Behavior of Penicillium bilaiae in Conditions of Abiotic Stress. Microorganisms 2023, 11, 1064. [https://doi.org/10.3390/ microorganisms11041064] https://hdl.handle.net/10481/81839 10.3390/microorganisms11041064 eng info:eu-repo/grantAgreement/EC/H2020/817946 http://creativecommons.org/licenses/by/4.0/ open access Atribución 4.0 Internacional MDPI