For example, take Proterro’s cyanobacteria, which naturally detects an increase in the salt concentration in water – such as those evolutionary moments when the shallow, life-teeming, brackish pond is drying up – and responds by making sucrose as a form of osmotic protection – basically a biohazard suit made of sugar.
What is Proterro doing? Locating that trigger in the genome, swapping it for a trigger that Proterro can control, and amping up the sucrose producing response. Voila, a sugar producing cell without all the inconvenience of encasing the sugars in a bunch of cellulose and lignin. Then, developing a solid-phase bioreactor that hosts those cyanobacteria. Proven at scale? Not yet. Game changing? If its viable and scalable, for sure.
Elsewhere in the Digest article was a comment to the effect the ideas themselves have been around:
Kef Kasdin, Proterro’s CEO, pooh-poohed the idea that there is a sudden revolution in feedstock technologies. “If you have been going to some of the more technical conferences, you’ll know that these ideas have been worked on for quite some time by a lot of talented people.
Of salt, Proterro wrote in paragraph 5 of PCT/US2009/030162 :
It is known that some cyanobacteria produce sucrose through the action of sucrose phosphate synthase and sucrose phosphate phosphatase, where it has been studied exclusively as an osmoprotectant. With respect to salt tolerance, cyanobacteria can be divided into three groups. Strains having low tolerance (less than 700 rnM) synthesize either sucrose, as is the case with Synechococcus elongatus PCC 7942, or another dissaccharide known as trehalose [Blumwald et al, Proc Natl Acd Sci USA (1983) 80:2599-2602 and Reed et al, FEMS Microbiol Rev (1986) 39:51-56]. Glucosylglycerol is produced by strains having moderate halotolerance (0.7-1.8 mM), such as Synechocystis sp. PCC 6803. High salt tolerance (up to 2.5 M) results from the accumulation of either glycine betaine or glutamate betaine. Miao et al. [FEMS Microbiol Lett (2003) 218:71-77] determined that when glucosylglycerol biosynthesis is blocked by deletion of the agp gene, however, Synechocystis sp. PCC 6803 produces sucrose as its osmoprotectant. Desiccation tolerant cyanobacteria also produce sucrose and trehalose in response to matric water stress [Hershkovitz et al., Appl Environ Microbiol (1991) 57:645-648].
The PCT claims priority to US provisional application 61/018,798, filed January 3, 2008 and to 61/085,797. An "international search report" was mailed May 22, 2009. Note also US application 20090181434, published on July 16, 2009 . Curiously, the preliminary amendment thereto references PCT/US08/69659, an entirely different case of the law firm Sonnenschein Nath & Rosenthal LLP.