**5. Conclusions**

The *KLa* of the biofilm bioreactor showed high oxygen transfer in both liquid and gaseous phases. The designed bioreactor ensured the development of SmF and SSF at the same time and the production of both aerial conidia and oosporein by *Beauveria bassiana* PQ2. The CO2 production dynamic allowed determining the fungal growth in the whole process. To our knowledge, this is the first report on the biomass estimation of *B*. *bassiana* through respirometry and the production of oosporein in a biofilm bioreactor. It represents a viable alternative for obtaining value-added products from filamentous fungi.

**Supplementary Materials:** The following are available online at https://www.mdpi.com/article/10 .3390/jof7080582/s1, Figure S1: Evolution of oxygen solubility at different air flow-rates quantified by titration of liquid media with thiosulfate. Values of slope were used in Equation (1) for calculating Volumetric oxygen transfer coefficients (*KLa*) values, Figure S2: Invasion of metal solid support with mycelia and aerial conidia.

**Author Contributions:** H.R.L.-J. and J.G.Á.-H., conceptualization, methodology, and writing; L.V.R.- D., writing, data curation, and formal analysis; M.R.M., writing and editing; J.E.W.-P., D.B.M.-M., and F.V., methodology and formal analysis; M.A.-Z., writing and review; J.A.A.-V., investigation and formal analysis; P.A.-Z., visualization, supervision, and funding acquisition. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by TECNOLÓGICO NACIONAL DE MÉXICO, granted to CVU IT17A895-2021.

**Conflicts of Interest:** The authors declare no conflict of interest.
