I started culturing algae 14 years ago as an undergraduate at Oklahoma State University. Back then I cultured Synechococcus, Dunaliella and Picochlorum all to be used for experiments. The methods I used were meant to keep the algae uncontaminated by other algae and by bacteria and fungi. I spent lots of time sterilizing media and equipment and all the while working in the laminar flow hood. These are standard laboratory methods when working with algae. Over the years I've become sloppy, out of necessity. The work I have been doing over the past several years has focused on large scale algae production, where these laboratory methods would be difficult to implement.
My new philosophy concerning contamination, for large scale cultivation of algae is a "pest management" approach. Recently, while in Santa Fe for the weekend, the pump which supplies air for my greenhouse algae cultures went off due to a breaker being blown. My algae cultures were not bubbling for at least 24 hrs. After getting the pump going again the Nannochloropsis cultures were soon taken over by a form of cyanobacteria. This was a full takeover. Somehow, the conditions created by not bubbling the bioreactors favored the cyano's and they took off, while the Nanno lagged behind.
This is an example showing the fine line between a healthy algae production system and one on the edge of collapse. I am hoping to investigate in the future some of the mechanisms that send happy unialgal cultures over the cliff.