Cyanobacteria, as primary producers, once opened up the way for life as it is today, altering earth’s atmosphere deeply due to their photosynthetic consumption of CO2, leading to the production of oxygen gas.7 Once again, they could play a role in helping to reduce the impact of CO2 on earth´s climate. However, from an economic point of view, they have two major drawbacks: (1) their native PHA content is low, almost always below 10 % of cell biomass, in most cases even below 2 % and (2) genetic modification to achieve an essentially increased productivity has rarely been successful.
The following paragraphs give an overview of several aspects of PHA production with photo-autotrophic microorganisms, with special focus on cyanobacteria.