I guess you could try to acquire some of those blue green algae. They're basically plant-bacteria, so they do photosynthesis. This means that you could try to grow them. I guess, if you take the bacteria and a bucket of the water they seem to grow well in, and raise the temperature to 35 degrees celsius or something, they'll grow pretty hard. Don't grow them in sunlight, VFDF degrades under UV. first dry the bacteria before you eat them, it's unstable in water.
…maybe it's easier to just gather a bunch of the stuff, dry it, then eat it, instead of growing it. Would you mind posting it if you are going to do it? Or otherwise stream it or something? So we know it works?