is BioGlow being realistic?

[Aspen Young]

"Streetlights come in a variety of intensities, but a ballpark figure seems to be about 10,000 lumens. The trees would have the incident sunlight to work with as the source of energy for their glow, and that dwarfs the streetlight, at 100,000 lumens per square meter. Of course, plants can't use most of that energy for a number of reasons: it's the wrong wavelength, it gets reflected, it misses their leaves, etc. Photosynthesis isn't 100 percent efficient, either. By the time all of these factors are accounted for, the typical plant captures somewhere between three and six percent of the incident sunlight. Going with five percent, we're now down to 5,000 lumens

Of course, that's for every square meter, and each streetlight illuminates a lot of square meters. At the same time, the tree won't be able to use all of its energy to make light or it would promptly die. Plants seem to have some energy to spare—they carry around a lot of superfluous DNA and grow excessively ornate flowers—but there are limits to how much energy they can spare and still keep growing. For argument's sake, let's say they can spare about five percent of their total energy for producing light. That takes us down to 250 lumens for each square meter of foliage, or about the equivalent of a 40W bulb.

But most of that energy will never get made into light. Remember, even basic chemicals like cysteine don't come for free; they cost energy. So does making the enzymes that convert them into more complicated chemicals, as well as (typically) the reactions they catalyze. Then you have to make the luciferase enzyme, as well as the recycling enzyme, and power those. Absolutely none of these processes are going to be 100 percent efficient.

You'd be extremely lucky if five percent of the energy being dedicated to producing light ever ends up getting used that way. We're now at 12.5 lumens.

Of course, about half that light would be pointed directly at the sky, and it wouldn't do much good as far as illumination goes. A lot of what's emitted downward will end up being directed back at the tree's branches and trunk, which will absorb some of it. Some other fraction will be absorbed by the cells in which it's emitted (some of it probably by the chlorophyll that powered the process in the first place). That leaves us with under 5 lumens of potential light for every square meter of foliage, and likely much less.

All of which places this on the very edge of being useful directly under a tree. If any of the above estimates turn out to be wrong—or you get too far from the tree—then all bets are off. Streetlights probably have a long career ahead of them.

The project won't work as things stand, and it probably won't even do what's being promised in the future. If those were the only problems with this project, they would be significant ones. But the fact is that the project is largely recreating the wheel; various academic labs already have luciferase working in plants, including in the arabidopsis species that the project plans on sending out to its backers. Even if you wanted to start from scratch, there are cheaper ways of going about making the DNA required than ordering up the DNA online, one base at a time. Plenty of researchers would send the DNA for the luciferase for free." - john timmer

[Yuriy Fazylov]

provide the link back to the original post. 

[Nathan McCorkle]

Does you post title refer to that quoted text? Or are you citing quote
to reinforce that it doesn't seem realistic? I actually thought you
were quoting someone at BioGlow, but from googling it seems the author
is just some tech media writer:
http://arstechnica.com/science/2013/04/why-your-streetlights-wont-be-replaced-by-glowing-trees-anytime-soon/

His analysis seems decent, he notes inefficiencies know and the math
is simple enough.

Certainly with enhancement a few of the points he makes could be
moot... namely the omni-directional character of the light emission
seems like something that could be improved upon, first by moving
expression to some cells on the lower part of the leaves (stomata
maybe), then by controlling the direction the emission complex points
toward. That can all be done in parallel with biochemistry tweaks for
the metabolics.

He also doesn't really go into the 'one-time' costs like enzymes
(these won't actually be one-time costs, but they certainly aren't
quite recurring costs in the same way as the small-molecule energy
transporter is), but somehow determines that only 5% of the energy
involved in luminescense will be photon output, that seems quite low
to me for a system that is based on catalysts (but I really don't
know).

If you assume the machinery is a fixed non-recurring cost, and the
pathway is 15 metabolic steps long (I don't know how many steps it
actually is from common plant molecules), and the assumption is 5%
energy making it to photons, you get an average thermodynamic
efficiency per-metabolic-step of 81%.

I don't honestly know if that is realistic or not. I tried searching
for info on heat/thermal production/waste, or enzyme energy savings,
but I think my search terms were lacking in specificity, as I was
getting more hits enzyme efficiency as related to the speed or
completeness of reaction, rather than % energy to heat. I can't
remember if I want to search for something about Gibbs free energy or
something... I have been bad about memorizing chemistry.


--
-Nathan

[David Wilson]

Well I'm not a biohacker, it would be interesting to be but it's only a fantasy for me. From a marketing standpoint though, the amount of light produced is entirely inefficient. It might be enough if they got a whole lot of them and set them in a row, window on one side, glass on inside on the other, with the plants set up in between with a hydroponic system of sorts. It'd be pretty and that's half the battle. There's no way they could sell it as a streetlight at this point, maybe if you can get it brighter and in vine form guys. That would be a beautiful mix of concrete and plants though, huge vines of glow in the dark plants over the walls... You'd just have to make sure it won't grow horizontally or the maintenance cost would dismiss it. For all that matters, you could sell it to individual businesses to place it over their storefronts, it'd require daily maintenance but would be a statement to their "green" interest, and that would be the point you'd sell it on. If they can make something that forces the plant to stop growing at a certain length or at a certain type of barrier, some kind of emission or light at the bottom of where you want it to stop growing or something I couldn't think of. Feel free to use my idea, no credit of any form necessary, though it would be nice. :) 

[Cathal Garvey]

In Forma we've started growing P.stypticus, the most famous
bioluminescent fungus. In contrast to a plant, a fungus can be easily
fed exogenous sugars or other carbon sources, which lets you concentrate
the energy needed to make bright glowing light.

There's a reason that plants are the only biological group that never
bioluminesces; they're at the bottom of the trophic pile, they can't
afford to waste energy like that. Whereas anything at a higher trophic
level can allocate energy during times of abundance to things like
"glowing".

Insects are most spectacular, glow-bugs and the like. Proportionally,
where light-adapted eyes are assumed, benthic fish are pretty awesome,
too. But on land, for continuous glowing output, fungi are probably the
best bet. We're going to play with P.stypticus for a while and try to
get it glowing efficiently, feeding it cellulose for a long run of
glowing output and spraying with lactose (according to research it can
utilise this very efficiently for glowing, but not at all for growing..)
to get burst output for events or show-cases.

And if we later get into directed evolution or mutagenesis to try and
make it glow even brighter... :)

The downside; Fungal bioluminescence does not have a clear-cut
luciferase, rather the luciferin appears to react with the products of
extracellular metabolites. So, it's not a very transferable system to
other species.

> <http://www.google.com/url?q=http%3A%2F%2Farstechnica.com%2Fscience%2F2013%2F04%2Fwhy-your-streetlights-wont-be-replaced-by-glowing-trees-anytime-soon%2F&sa=D&sntz=1&usg=AFQjCNGjzcejxdqXMIlvj1kYdFIO8rWdjg>

> --
> -- You received this message because you are subscribed to the Google
> Groups DIYbio group. To post to this group, send email to
> diy...@googlegroups.com. To unsubscribe from this group, send email to
> diybio+un...@googlegroups.com. For more options, visit this group
> at https://groups.google.com/d/forum/diybio?hl=en
> Learn more at www.diybio.org
> ---
> You received this message because you are subscribed to the Google
> Groups "DIYbio" group.
> To unsubscribe from this group and stop receiving emails from it, send
> an email to diybio+un...@googlegroups.com
> <mailto:diybio+un...@googlegroups.com>.
> To post to this group, send email to diy...@googlegroups.com
> <mailto:diy...@googlegroups.com>.
> Visit this group at http://groups.google.com/group/diybio.
> To view this discussion on the web visit
> https://groups.google.com/d/msgid/diybio/cd4641f1-056f-4837-bfb1-f25f8291d33e%40googlegroups.com
> <https://groups.google.com/d/msgid/diybio/cd4641f1-056f-4837-bfb1-f25f8291d33e%40googlegroups.com?utm_medium=email&utm_source=footer>.
> For more options, visit https://groups.google.com/d/optout.

[Yuriy Fazylov]

hypothetically speaking, you could transfer the trait to tuber producing plants. such that a system could store sugars and use them when luciferin is present. 

in any case plants are undergoing an update. repairing and less limiting mechanisms will get the current BS into next best thing since sliced bread.

for example the 100% quantum yield efficiency GFP is finally commercially ready