The 98-picogram weakling: Crop Defense and Algae

February 18, 2015 |

algae-atlasWe now can grow algae, dewater it, harvest it, and process it on an industrial scale into dozens of useful everyday fuels, chemicals, food ingredients and materials.

But can we keep it alive?

What have we learned about keeping algae safe from predators, competitors, parasites and disease?

Poor algae. It’s been programmed by Nature, likes some sports teams we know, to be on the losing side of almost every competition. It’s the bottom of the food chain, like the bunny served up in a fixed boxing match who was always destined to be defeated. Algae is the 98-pound weakling of the evolutionary beach — someone is always kicking sand in its face.

Until now, that’s been a good thing. Nature’s way of keeping algae weak has been good news for the plankton that graze on it, and good in turn for all the animals farther up the food chain, the critters who eat plankton, the fish who eat the critters, the birds who eat the fish, and all the way up to humans at the top of the predatory pyramid.

In the end, we’ve all been provided with an indirect way to consume food made from the abundant CO2, water and sunlight around us, without the inefficient limitations placed on our size by the pesky requirement to do the conversion ourselves. We omnivores just munch all the fats, carbs and proteins that are densely stored up in plants and animals — and much of the credit for the menu ought to begin with algae.

Lately, though, in our never-ending quest for higher energy efficiencies, cheaper foods, and land intensification — more and more attention has come back to algae. After all, they are a productivity monster — in some cases a population can double its mass in under one day. Plus, it uses just about the three most abundant materials here on Planet Dearth — free sunlight, (in most cases) saltwater or non-potables, and the dread atmospheric CO2.

It should hardly surprise that in a time of widespread concern about too much CO2, not enough fresh water, not enough land, not enough energy and not enough food — enterprising researchers might point out: “Er…well, there’s algae.”

And so the research dollars have poured in, and begun to solve many of the technical challenges that pertain to industrial algae but rarely bother plankton. Such as how to get the water out of the algae or the algae out of the water. Or how to modify algae so that we can “milk” them for valuable molecules for fuels or nutraceuticals. Or how to harvest algae like a crop and fraction out the carbs, the proteins and the fats, for different appplications.

But one big challenge remains. And it remains big.

And that’s reversing Nature’s command that the vast genetic array known as algae should collectively be the lowest form of life in the food chain, the easiest to hunt, knock over, catch, make sick or kill.

You might wonder, for example, if all that algae need are CO2, sunlight and water to double their population mass in under a day, why aren’t the oceans completely covered all the time with algae. Turns out that what’s required slightly more complicated set of ingredients — for example, algae have DNA just like you do and every strand is built on a backbone of phosphorus, which isn’t found in abundance in  a whole lot of places. And algae need a range of vitamins just like you do to maintain a healthy body.

But if the lack of nutrients prevent some algae blooms from happening, why do they disappear in those places where they have formed. That’s where you enter into a world of microscopic predators, competitors, parasites, and viruses.

After all, a two-celled creature may look very threatening under the microscope. But to algae, they look like Godzilla.

In the world of terrestrial plants, we’ve seen over the past century a similar set of problems. Romans were fanous for their crop productivities in ancient times, it was one source of the Roman Empire’s strength, but in those days 10 bushels of grain per acre would have been a pretty good haul.

These days, the productivities for corn grain grown in the United States are in the 170 bushel per acre range. Some of that is die to fertilizer, and breeding programs that allow us to crowd more stalks onto an acre because they stand up straighter and have larger ears compared to their predecessors. But a lot of credit goes to warding off the evils posed by weeds and pests. That is, the relatively obscure science of Crop defense.

Crop Protection. What can be done to help out in the world of algae?

To date, there have been three basic strategies for protecting algae.

First, the Fortress Strategy, usually involving growing algae in a controlled environment using photobioreactors or fermenters. Predators are reduced by controlling the gates — basically, Elvis has left the building. But the costs are high — capex almost ruinously so, and no one has yet been able to make a controlled environment produce fuel-grade algae economics. Only Algenol remains on this track.

Then, there’s the Green Horde Strategy, usually involving raising a batch of super-dense algae in a controlled environment such as a PBR, then inoculating an open pond with enough robust and healthy algae that they simply outcompete the other organisms and grow faster than the competitors can knock them off. It’s been tried and there’s been some success. But the trouble is, when you try and raise the productivity to improve the economics — well, whoops, that usually involves harvesting more algae, which thins the pond community and makes it toughter for them to stay ahead of the predators. Pond production can slow or the pond system can completely crash.

celebrity hot tubFinally, there’s the James Brown celebrity Hot Tub Party strategy (if you’ll remember Eddie Murphy’s version from Saturday Night Live — it was a case of Huh! Whoa! Too Hot to Hot Tub. In this strategy, the science team finds an extremophile strain of algae that can survive exotic conditions, such as super high temperatures or salinities, that kill off the competition, leaving the pond safely to our target algae.

Problem here is no one has yet found an extremophile that can produce target materials at sufficient productivity levels. So they have the pond to themselves, but are as sluggish as people who spend too much time in the hot tub.

New directions

There’s one strategy that, to date, has been the road less travelled in the world of algae. And that’s the Rattlesnake Strategy. 

Think of it this way, you’re hungry, the 7-Eleven is a four-mile walk down the road, and here’s a tasty rattlesnake just waiting to be caught, lying outside in a sort of stupor in the sun. Most people pick the 7-Eleven. In fact, most people beat a hasty retreat, turn and run like heck, and head for the 7-Eleven.

That’s because of snake bite venom, which is to say, a chemical defense. And, if algae conjure up a whole bunch of useful nutraceuticals, some of them also produce some nasty toxins — at least, nasty at microscoptiv scale. Sometimes, algae secrete a toxin into the water around them — to create a sort of “don’t come any closer” halo of toxic death around them. Other algae contain a whole bunch of toxin built up in them, sort of like blowfish, so that predators keel over long before they have helped themselves to a full algae meal.

In an article of a couple of years back, a group of UCSD scientists led by Steve Mayfield suggested that another option was the development of algae insecticide, by expressing insecticidal proteins that have been successfully introduced in plants and cyanobactera.

They also suggest what here in Digestville we call the Enemy of my Enemy is my Friend strategy. They write:

“Some aquatic invertebrates might be beneficial for algae, and could be used as a biological control strategy. Certain species have strict preference for prey other than algae, such as the heterotrophic protists. For example, copepods have been shown to directly contribute to the blooming of the alga Phaeocystis (Haptophyceae) by selectively eating its protozoan predators.

Pond Crash Forensics

In 2013, Sandia National Laboratories developed a toolkit to address the RapTOR (Rapid Threat Organism Recognition) challenge — with a goal of 24 hour turnaround in characterizing new threats. . It was designed to serve as a tool to rapidly characterize a biological organism with no pre-existing knowledge.

Using pathogen detection and characterization technologies developed under the RapTOR Grand Challenge, they are comparing the environmental conditions and metagenomes of algal samples taken from normal ponds to those taken from ponds that have undergone collapse.

“Pathogens and viruses fall into these ponds and can crash a pond overnight,” says develop Todd Lane. “No one has identified many of the agents that are causing these pond crashes. You can’t develop countermeasures without understanding why something is happening. This is a complex problem with a lot of factors at play.”

Sandia’s Tom Reichardt said that the instrument package analyzes the algae concentration levels, examining its photosynthesis and performing other diagnostics.

“In real-time, it will tell you if things are going well with the growth of your algae or whether it’s beginning to show signs of trouble,” said Reichardt.  However, he cautioned, while this real-time monitoring will warn pond operators when the ponds have been attacked, it may not be able to identify the attacker.

To help pinpoint the problems, a Sandia team led by researcher Todd Lane have developed a process to quickly and accurately identify pond crash agents through ultra-high-throughput sequencing using RapTOR.

Lane’s team also created a method for creating a field-ready assay for those agents, something that works quickly and is relatively inexpensive. They are applying SpinDx, a device developed by other Sandia/California researchers that can (among other features) analyze important protein markers and process up to 64 assays from a single sample, all in a matter of minutes.

 

The Bottom Line

As the New England Patriots might have observed earlier this month, defense really does win the Super Bowl.

Without effective crop defense, it may well be possible to make algae economical simply by following the strategies already in use around the world — such as the Fortress, the Green Horde or the James Brown Hot Tub Party.

But we suspect that algae will never find its potential until the Rattlesnake Strategy, or the Enemy of My Enemy, is better employed. After all, triangulation has been a proven winning strategy in board games and diplomacy for a long, long time, and California ranchers have been friends to owls for a long, long time because they take down the mice and close the restaurant for the rattlers.

And, venom has a pretty amazing track record too. Even humans, at the top of the food chain, are wary of animals using that strategy. Might be just the ticket for our friend algae — they might just waeve us a web of industrial product magic if we help give them a nasty microscopic bite.

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