Abstract: A method for improving biomass production and/or growth rate of a microorganism in a fermentation process is shown, and includes: (i) providing one or more microorganisms; (ii) providing a fermentation substrate suitable for fermenting the one or more microorganisms; (iii) mixing the one or more microorganisms and the fermentation substrate providing a fermentation broth; (iv) adding the fermentation broth to a fermentation tank; (v) injecting at least one gaseous substrate into the fermentation broth; (vi) running the fermentation process for a fermentation period of at least 1 hour; wherein the at least one gaseous substrate comprises one or more greenhouse gases, such as carbon dioxide (CO2).