US Patent 8,993,290 with Tony Melis as first inventor, titled Continuous diffusion based method of cultivating photosynthetic microorganisms in a sealed photobioreactor to obtain volatile hydrocarbons

The first claim of US 8,993,290 :




A continous method of cultivating photosynthetic microorganisms in a sealed photobioreactor to obtain a volatile hydrocarbon product of photosynthesis generated by the microorganisms, the method comprising (i) culturing a photosynthetic microorganism in light in a sealed photobioreactor, wherein the photobioreactor contains a lower aqueous phase comprising the photosynthetic microorganism, and an upper gaseous phase, wherein the upper gaseous phase comprises CO.sub.2 that is introduced from outside of the photobioreactor through a port into the photobioreactor as a source of carbon for the photosynthetic microorganisms, wherein the CO.sub.2 is introduced to provide a concentration in the upper gaseous phase of at least 10%; (ii) collecting from the gaseous phase the volatile hydrocarbon produced by the microorganism that diffuses into the gaseous phase; (iii) introducing additional CO.sub.2 from outside of the photobioreactor into the upper gaseous phase to replace CO.sub.2 that is consumed by the photosynthetic microorganisms, wherein the additional CO.sub.2 is introduced to provide a concentration of at least 10%.




From the specification



Thus, in one aspect, the invention provides a method of cultivating photosynthetic microorganisms in a sealed photobioreactor to obtain a volatile product of photosynthesis generated by the microorganisms, the method comprising culturing a photosynthetic microorganism in a sealed photobioreactor, wherein the photobioreactor contains a lower aqueous phase comprising the photosynthetic microorganism, and an upper gaseous phase, wherein the upper gaseous phase has a CO.sub.2 concentration of at least 10%; introducing additional CO2 into the upper gaseous phase when the CO.sub.2 concentration drops below 10%; and collecting the volatile product that is sequestered into the gaseous phase and displaced by the additional CO.sub.2. In some embodiments, the photosynthetic microorganism is a recombinant organism that expresses at least one heterologous gene that produces the volatile hydrocarbon, such as isoprene. In some embodiments, the microorganism expresses an isoprene synthase gene. In some embodiments, the microorganism is a cyanobacteria or a green microalgae. In some embodiments, the volatile compound is an alcohol, such as ethanol, butanol or isobutanol. In some embodiments, the volatile compound is an aldehyde such as acetaldehyde, butyraldehyde, or isobutyraldehyde.

In some embodiments, the volume ratio of the gaseous phase to the aqueous phase is in the range of from about 1:9 to about 9:1. In some embodiments, the volume ratio of the gaseous phase to the aqueous phase is in the range of from about 4:6 to about 6:4.

In some embodiments, the step of introducing additional CO.sub.2 into the upper gaseous phase occurs when the CO2 concentration is below 50%.