Microbial biomass based feed products
Aquafeed, animal feed, and other food products, as well as nutritional and pharmaceutical compounds, chemicals and biomaterials are important commodities that can be produced at commercial scale by fermentation of microorganisms. The present invention provides a method for producing these valuable multi-carbon compounds from simple gas feedstocks, such as carbon dioxide, hydrogen and oxygen, by cultivating a consortium of microbial cells specially selected for this purpose in an aqueous culture medium. In addition to exploiting inexpensive feedstocks, such as waste industrial gas for this cultivation, the platform described herein also provides the advantage of removing carbon dioxide and other waste gases from industrial emissions, which would otherwise contribute to global climate change. Furthermore, the cultivation of a microbial consortium can provide highly nutritious components to a feed blend that might not be available from a monoculture.
1. A method comprising:
providing a consortium of chemoautotrophic and photoautotrophic bacteria and heterotrophic microbes within a system, the system including a fermentation vessel filled with an aqueous medium comprising the consortium, the fermentation vessel having an input port into which gaseous substrates are introduced into the aqueous medium, the fermentation vessel further having an exhaust port through which gases exit the fermentation vessel, wherein the aqueous medium comprises inorganic anions and inorganic cations, and wherein the aqueous medium contains a concentration of no more than 0.05% of each of added sugars, yeast extract, tryptone, and organic carbon compounds, the consortium including
chemoautotrophic bacteria from the genera Cupriavidus, Rhodococcus , or Methylococcus,
photoautotrophic bacteria from the genera Rhodobacter, Rhodospirillum, Rhodopseudomonas , or Arthrospira , and
heterotrophic microbes from the genera of Bacillus, Bacteroides, Bifidobacterium, Lactobacillus, Lactococcus, Leuconostoc, Acidilactici, Pediococcus, Propionibacterium , or Streptococcus;
introducing a first gaseous substrate into the input port, the first gaseous substrate including carbon dioxide;
introducing a second gaseous substrate into the aqueous medium, the second gaseous substrate including predominantly hydrogen gas (H 2 ), wherein either of the first or second substrates additionally includes oxygen gas (O 2 ), wherein a volume ratio of H 2 in the second gaseous substrate to CO 2 in the first gaseous substrate is in the range of 1:1 to 8:1; and
harvesting cells of the bacteria from the system to generate a biomass product that has enhanced nutritional value compared to the biomass that the same chemoautotrophic bacteria would produce if grown alone.