Meeting Mario Tredici

Cesare Griffa
A conversation on microalgae with Mario Tredici
Florence, 21 February 2018

Mario Tredici is a biologist. He is full professor at the University of Florence, where he holds courses on Agricultural Microbiology and Microbial Biotechnology. His research topics include photobioreactor design and microalgal biomass production and characterisation.
I first met him in 2013 when I was working on the design for a quite big facade photobioreactor for the Future Food Disctrict at Expo 2015 in Milan. A sort of vertical liquid green facade made with microalgae that would fix CO2 while producing oxygen and valuable biomass. Unfortunately this project didn’t went through. But, since I am still interested in the possibility of integrating algal biotech as a sustainable architectural feature, I have been in contact with Mario since then.
I recorded this discussion when I met him in his office in the research hub of the University of Florence on the 21st of February 2018.



CG: Talking about the relationship between us (humans) and our planet, I would like to have, in general terms, the point of view of the scientist in biology. For that purpose, I have drawn this conceptual map based on your research work on microalgae. As you can see, there are four main islands: the first one is Ithaca, the origins of this Odissey; the second one is Troy, location of the action, the third one is Calypso, in the Gibraltar area, that represents the doors to unknown territories; and the last one that is the island of Circe, the goddess of magic but also the sorceress, it’s about opportunities and threats.

Starting from Ithaca, what I find fascinating about microalgae is to think that they are considered to be the origins of life on planet Earth 3.5 billions years ago, giving also a sense of relativity: on the one hand we are worried that we are destroying the conditions for us to stay on our planet, but on the other hand, we have to be aware that we only are here since a few ten thousands years on a planet that was born 4.5 billions years ago, and has been there for the majority of the time with enormous amounts of CO2 in the atmosphere, and everything was fine with that…

MT: This reminds me a discussion that I had with John Benemann, one of the masters in the world of microalgae that I had the chance to meet some thirty years ago. We became friends and we had great moments together, in the good and in the bad times. We reached together the conclusion that, all considered, algae absolutely don’t care of what we do. They were there before us, and will continue to be there way longer than us. Another interesting concept we discussed is that maybe algae are using us, form an evolutionist approach, because we cultivate them, we isolate them, we study them. So maybe, some algae, smarter than others, are using us for the final goal of reproduction and to conquer more space. Maybe with some algae, it’s not us cultivating them, but it’s them breeding us for their scope.

It’s overwhelming what algae can do. The common idea is that photosynthetic algae grow with light in the oceans and in fresh waters. In reality, they also are in deserts, in rocks, in ice. They are very good in entering in symbiosis. Some algae grow in the fur of some mammals like the sloth. Why do they colonize the fur? Because these mammals have a nutrition lack in proteins. They enter there, find a shelter in this warm environment close to this higher organism, and they pay back by giving back some nitrogen that they fix from atmosphere.

There are also pathogenic algae. It is very hard to say what algae are. A couple of weeks ago, the European Commission contacted us in relation with the new novel food legislation, and the problem of how algae should be treated in the novel food discourse. Something similar to what they are doing with insects. Novel food doesn’t mean the food of the future. It means that you have to go through a complex special procedure to make sure that what is not considered food today, could be considered food in the future. Very few algae are considered food today. Only four in Europe: Spirulina, Chlorella, Aphanizomenon, and some extracts from Haematococcus. These are considered food because they were consumed before 1997. All the others will have to pass through this Novel Food procedure.

The lawyers asked us a question: what can be defined as algae? Since they didn’t know, they contacted me as former president and current vice president of EABA (European Algae Biomass Association), and as a person that have studied algae for the last forty years, asking me to say in a few lines what algae are. I answered that for sure it wouldn’t be a topic to discuss in a few lines. I dedicated a couple of days to think at the answer, and I was in real trouble because one could simply say that they are photosynthetic and oxygenic (they produce oxygen, there are also other photosynthetic organisms that don’t produce oxygen). They use water as an electron-donator, and the byproduct is oxygen. But also plants do that. Are algae inferior plants? Not everybody agrees on that. In our vision, they are not plants because they don’t have certain structures, they don’t do embryos.

If we go to look at them, they are green,and they have chlorophyll. But what do the different kinds of algae have in common? And we get lost, because, for instance, there are algae that don’t do photosynthesis, that don’t have chlorophyll, that are not pigmented. So why are they classified as algae? Because genetically they are so close to other algae, that they cannot be excluded. They are close parents from a phylogenetic point of view. They have very close DNA sequences. But they are not photosynthetic, because they probably lost this capacity during evolution. Others that were not photosynthetic, became photosynthetic because they eat a cyanobacteria. Botanicals used to call cyanobacteria blue green algae, but they are prokaryotic, they are bacteria. They are not eukaryotic algae. They are algae, but they belong to bacteria.
Now, imagine when I go the EU commission and I say: among algae, there is a group called cyanobacteria, and they are bacteria. Disaster! They will say: but if they are bacteria, they are not plants. Sure. They are microorganisms, and so they should go in a totally different place. We should treat them like bacteria or fungi. Yes, and what about all the other algae, like macroalgae, that can reach 30 meters of length? Where should we classify them? And what about algae similar to fungi or protozoa?

So, it was a difficult task. I gave a definition that makes reference to taxonomy, and we have identified eleven phyla (with a phylogenetic approach) and we said: if the organisms to be classified stay in here, they are algae, if not, they are something else. The members of the European Commission didn’t like my answer because they needed something more practical, something like: what the EU identifies as algae? And I said, sorry, but you shouldn’t ask me this question, I should ask it to you! From a normative point of view, we are not well placed. We have problems in defining the object of our study. And you understand that it’s important, because, when somebody says: this product comes from algae, he gives a positive connotation because it’s green, it’s photosynthetic, it’s natural.

There are some PUFA (polyunsaturated fatty acids) like omega 3 DHA that are produced by microbial groups. Somebody says that these organisms are very close parents of algae, and so when they extract the oil, they call it “algal oil”, that is very good for marketing purposes. But others say: these are not algae, they don’t do photosynthesis, they don’t have chlorophyll and they never had it, so you cannot call it algal oil. You should call it, fungal oil, but for marketing purposes this works less. It’s not banal definitions, they go together with laws and with economics. Sometimes it’s very difficult to talk about algae since you don’t even know how to define them.

CG: A fascinating aspect for me is that, in terms of structure, microalgae are among the most simple living organisms around.

MT: Yes. Cyanobacteria are prokaryotic cells with a very simple structure without nucleus membrane. But, when you say simple, or “little evolved”, you have to understand that, first of all, they accomplish all functions of plants in terms of photosynthesis, and they do also nitrogen fixation that plants usually cannot do, unless they have inside nitrogen fixers symbionts, that are all prokaryotic. So, it’s simple organisms that do all the functions, sometimes photosynthesis and respiration at once, in the same membrane. They have an incredible metabolic flexibility. They are little evolved because they are well like that.

And you have also to consider that these simple organisms, like cyanobacteria, gave origin to all lines of microalgae, macroalgae and plants. The chloroplast is a prokaryotic algae, it’s a cyanobacterium, as well as the mitochondrion is a bacterium. How did they gave origin to these superior organisms? Often though endosymbiosis. An eukaryotic organism that eats a prokaryotic microalgae that acts as a chloroplast. Then this microorganism can be eaten by others. Eaten in the sense that, instead of being used as a source of energy, they are not digested, they are embedded, in a form of stable symbiosis.

CG: Two or more organisms that live together?

MT: Yes, but not only for some months and then they split. Sometimes it happens, like in every couple. But often when these symbiosis work, they give origin to other symbiosis.


CG: To me, the magic is here. In this simplicity that brings to an incredible biodiversity, with tens of thousands of species…

MT: Numbers are estimated in 50,000 – 70,000. It’s very difficult to say. What counts is the strains. Coming back to this concept of species, what worries me, is that, for instance Chlorella Vulgaris is classified as food because it was already been eaten before 1997. So if you select a Chlorella Vulgaris from a collection, you know that you can produce some kind of food. The problem is that sometimes there are very remarkable diversities among strains. It’s not the case of Chlorella, but with Diatom for instance, there are some strains that produce toxins. One of the algae classified as food today is the Aphanizomenon flos-aquae, a cyanobacteria harvested in the Lake Klamath in the Unites States that is usually commercialized as a food integrator. It can produce toxins. You have to take care when you cultivate these kind of microorganisms. Sometimes they can create problems, but they are also at the origins of life on Earth as we know it because they produce oxygen.

CG: They are considered responsible of the Oxygen Catastrophe some 3 billion years ago.

MT: It’s been a real catastrophe! Imagine a primordial Earth, not simple, in which everything is reduced. Only a few molecules: water, ammonia, hydrogen, hydrogen sulfide… and a few organic molecules that take nutrition from this primordial soup. At some point, the capacity of using light arises. Some organisms are able to transform light energy into chemical energy using pigments. It’s a big revolution. At the beginning they don’t use water as electron-givers. They use other stuff like hydrogen sulfide, or they do photophosphorylation. I won’t become too technical, but the fact is that they begin to use electrons. Nowadays, we often don’t have the conscience that life is an electron hunting. I always say to my students: when you eat breakfast in the morning, what you are looking for is of course carbon and nutrients, but also electrons. For what? We do redox reactions that generate energy by bringing electrons to oxygen. Somehow, we are like batteries.

What happens in this primordial soup? At some point electrons sources begin to be short. This brings the evolution push to search for new sources of electrons, like water. But water is not a good electron-giver, because oxygen keeps them linked together. So photosynthesis enters the game to facilitate electron donation. Light is used to break down water molecules in a photolytic reaction, and the result is the liberation of electrons, good for energy, and a by-product that is oxygen. And so oxygen begins to accumulate. The first oxygenic photosynthetic organisms obtained their goal of finding an inexhaustible source of electrons with the result of producing oxygen, that was not there.

Atmosphere became oxygenated. But the oxygen is toxic. Because it’s the best acceptor of electrons and creates intermediate products: the free radicals that begin to kill all species that didn’t have a capacity of self-defence. During evolution, a number of self-defence mechanisms appeared. But, still today, free radicals are the ones that create damage. A lot of organisms cannot adapt, they die in presence of oxygen (like for instance methanogens). We too suffer from this toxicity: oxygen free radicals make us sick, they are responsible of some forms of cancer and aging.

CG: There is a science fiction novel by Michel Houellebeck from 2006 “The Possibility of an Island” in which he imagines genetically modified photosynthetic humans that don’t need food but only water and mineral salts.

MT: Yes, it could be. I wouldn’t exclude this possibility. It could happen, maybe through an evolutionary symbiosis, or through something artificial. But there is no need of going so far. Humans are in a certain way already photosynthetic. We depend on photosynthesis. If we imagine a worlds without photosynthesis, certainly we wouldn’t be here. If we were to eliminate all photosynthetic organisms, including plants and micro-algae, there would be no oxygen. Algae in the oceans produce an amount of oxygen equal to the one produced by plants on land. Ocean surface is larger than land on our planet. On lands, plants are more active than algae in the oceans, that are somehow more diluted. But the oxygen produced is substantially the same.

CG: Microalgae, the simplest organisms that do very complex things such as photosynthesis, and maybe other things that we complex organisms are not able to do.

MT: Microalgae have been at the origins of evolution of all plants. They give us oxygen, and are also at the base of the food chain. Let’s not forget that. If in the oceans there would be no algae, more precisely phytoplankton, there would be no fish. Nothing. No food chain. All what Oceans produce starts from microalgae. Similarly, on land the primary food comes from plants.


CG: Microalgae are also the origin of fossil resources.

MT: Microalgae originated fossils, specially oil. It is commonly considered that Diatom cells, rich in oil, fossilized in a few hundreds of million years. We are about to finish these reserves. I personally think that it’s a good thing. I believe that, if man didn’t discover these reserves of fossil fuel, we would still be here anyway but with a completely different civilization because we would have been obliged to find renewable sources of energy. We would be able to use the sun in a more efficient way. Wind. Tides. It’s been a disaster having discovered fossil fuels.
CG: It’s what we are beginning to do today, but of course, until there is an industrial lobbyist interest in fossils it’s very difficult.

MT: I don’t condemn these people. It’s such an immediate source of energy, easy to use, with such a high energy return. I don’t know exactly the present petroleum EROEI (Energy Returned On Energy Invested). At the beginning of industrial era it was 100. If you were spending 1 unit of energy to get it, it will give you back 100. Today, it might be 20 or 30. Probably coal is higher. The problem with alternative sources of energy is that usually the energy return is very low. We have done works in perspective to find out how algae as an energy source can perform. It’s interesting because they use the sun energy that we have (it’s not free!), the use CO2 in the air and some mineral salts. And we can make oil that can be converted in bio-diesel.

Perfect! It resembles the squaring of the circle. Even more interesting (and that’s why we dedicated so much of our energy in developing these technologies): they use water, that can be sea water. So that there is no need of using fresh water that is precious, and that can be left to traditional cultivations. They need fertilizers but it can be dispensed in a very efficient way. In traditional cultivations, fertilizers go in the soil, so that more than half gets wasted and creates enormous damages by contaminating rivers and oceans. There are areas of dead oceans. Microalage cultivation don’t need pesticides, and that is an enormous advantage.

CG: And also they don’t need to be cultivated in good arable land in competition with food agriculture causing instability in the food markets.

MT: They are not competing with traditional food cultivations, not using arable land, they could be cultivated in a desert. When you describe it, it’s fantastic: it really looks that we found The Solution.

But what happens? That to have the combustible oil, you have to produce biomass. And it’s not kilos or tons. It’s millions of tons. You need gigantic structures, that occupy hundreds of hectares. I remember one of the first contacts we had with Enel for a plant in Brindisi, they wanted to fix some of the CO2 emissions of the plant. We have made a few calculations, and we discovered that we would have needed an area as big as the entire Puglia region to fix significant amounts.

Making millions of tons of biomass starting from an algae of 5 microns, it’s a huge work. You have to cultivate. And when you cultivate algae you realize that they cannot be left on their own. Other plants, for instance palms, may need three or four years to grow, but when they’re settled in the soil, they just need some water from time to time and nothing else. They can be left alone for a few days, and they are always there and growing. Not the algae. Algae need to be kept it in constant agitation with all growing parameters under control. This kind of cultivation requires a certain amount of energy, simply to agitate the solution. The algae while growing produce oxygen that have to be removed from the solution. That’s why we use bubbling: air bubbles at the same time move the solution and release the oxygen. Growing operations require energy. When the algae are grown, they need to be harvested, and they are tiny. Normally it’s not possible to filter them. They need to be separated from water with a centrifuge. Then maybe they have to be dried, and in this case the energy needed to dry is higher than the energy embedded in the biomass. When at the end of the day you do the energy balance, if you get to 1 you have to be happy. And 1 means that the energy required for production equals the energy embedded in the biomass. There is no way it can become an energy source.

Why in the last years billions of Euros and Dollars have been invested in developing that technology? Because it’s an appealing idea. Everybody likes it. Maybe in the future there will be systems with low energy input. But there is a lot of work to do. We achieved and energy balance of 1.3, that means producing a little bit more energy than the one used, by combining photovoltaic systems into algae cultures. By using some of the photons for photosynthesis and some for the photovoltaics we managed not to reduce the algae production and to produce at the same time the energy needed to run the system. We reached 1.3, but we are very far from hydraulic or wind systems that have well higher energy balances. We should reach at least 3. With less, we don’t have energy enough for the society, for all the other activities. An energy source with an energy return of 1.5 does not allow society to progress, to exist.


CG: What about other applications such as bioplastics or integrated applications (we spoke many times of architecture and algae), symbiotic systems in which the waste from one part becomes the energy for the other?

MT: It is possible to make different kinds of bioplastic out from algae. But we are still in the discourse of commodities, and always we go back to the same point: technically it’s possible, but the costs are out of the market as long as there will be the possibility to make plastic out of oil. When we won’t have this possibility anymore, everything will change and become easier. With algae we can make many products: pigments, polyunsaturated fatty acids (like Omega 3), anti-cancer, bio-stimulants, black/grey water treatment systems. We have collaborations in all these sectors.

I like to consider them as the food source of the future. I think that the problem of energy in some way will be solved. I strongly believe in alternative energy with sun, wind, tides, waves, water, photosynthesis, etc. I am more worried about food production. A part from the disequalities in distribution, it is clear that there will always be a part of population that has plenty of food. But the real question is related to the population growth, that is continuing and will probably stop when we reach 11 billions in 2050. Today, more than 800,000 people suffer because they do not have food enough. There is also another problem, that often is forgotten: it’s not only about the lack of food, it’s also about the kind of food. Often food is not adequate. Available food is calories, carbohydrates, cereals, and this brings to the serious phenomenon of malnutrition. If we have 800,000 people starving, we have another 2 billions malnourished. They lack proteins, vitamins, and mineral salts. It’s a serious phenomenon that happens both in developing and developed countries, and is related to overweight and obesity.

Algae are a simple and effective way to make efficient food, not only for their composition that is very bio-diverse and changes a lot from species to species. The production system can be controlled very precisely, much better than in traditional agriculture because it’s a simple system. Water, nutrients, light (easier to control if it’s artificial), temperature, CO2. An interesting thing is that it’s easy to modify the composition of a specific algae strain to enhance its nutritional properties. They can be enriched in odium, selenium, zinc. It’s possible to do it also in traditional agriculture, with potatoes for instance. But with algae it’s much easier, because the only thing to do is to add the required elements (like iron) to the culture medium, and the culture becomes rich of that specific component.

CG: Without any genetic modification of the species, only with a special “diet”?

MT: Yes. I have nothing against genetic modifications, but it’s not necessary here. It’s like cultivating plants in a soil richer in some elements. They get richer, but there is always a transfer from soil that adds complexity to the process. With algae it’s immediate. You just put the nutrients in the culture medium and they have this great capacity of absorbing it directly. For instance, if I were to enrich with zinc, that is an element very important to prevent some sickness, I would only need to add zinc. Obviously one must be careful about overdoses. Food produced with algae can be used directly or can be used as animal feed to convey nutrients through animals.

Using microalgae to produce food in a simple manner presents a large series of advantages: we can easily modify them, we can use marginal areas or deserts, we don’t need fresh water. But we have always to consider the same discourse: the problem of energetic and economical efficiency. It’s relatively simple to make food with insects or microalgae, but then if the cost is 10 or 50 times traditional food, then it will only be an exclusive trend for a restricted elite, and it will be impossible to affect nutrition on a large scale. So, it is necessary to produce at competitive prices. And we go back to the problem we were discussing earlier.

We are working on that direction and we think that in large scale plants, well located (location in crucial, if you produce in northern Europe using natural light, you know that you will have a lower productivity with higher prices, some areas around the mediterranean appear to be very attractive), we calculated that we could go under 2 Euro/kg of dry biomass. It’s still a high price, because food stuffs cost much less (150, 200, 300 Dollars/ton), but it’s already something that allows us to think at it as a valuable way. We have also to take in account that some of these microalage are very rich in proteins. Spirulina has 60% of proteins. If I make the cost per protein, algal protein produced in those plants costs less than soya protein.

CG: Also a comparison with animal proteins is important. It’s true that cow’s meat is relatively cheap, but it’s also true that the price does not consider the environmental cost.

MT: This is another major problem that we have on every kind of product but in particular for the production of food. We don’t consider externalities of any kind, nor positive or negative. Specially the negatives. I feel sorry to say that because I am an agronomist and that is my world, but agriculture is the cause of major environmental damages: 1/4 or 1/3 of Greenhouse Gases are produced by agriculture.

CG: I’m an architect, and we also are good in producing GHG.

MT: You are good too! Agriculture produce a lot of nitrous oxide (N2O), methane (CH4) from animal farms, and has definitely a major impact on the greenhouse effect. And there’s more. Agriculture, specially intensive agriculture, consumes a lot of water, and water will be one of the major problems to be solved in future agriculture. Agriculture consumes 70% of fresh water. Certain kinds of agriculture, in long times, destroy soil fertility, that is related to the presence of organic compounds. Intensive agriculture, with its kinds of labor, generates fertility loss and terrains are less and less productive. There is erosion, and fertilizers in some areas are used in excessive ways. There is more and more attention and an attempt to reduce the use of fertilizers, but still it’s a major issue, and a consistent part of them go into rivers and seas and kill them because they create the conditions for the formation of algal blooms that produce and consume oxygen. When, at the end of the algal bloom, the algal colonies die, they consume the whole oxygen killing all the components of the food chain. These areas are getting bigger. At the mouth of the Mississippi there is one of the biggest Ocean Dead Zones where some animals managed to escape, and the others died.


CG: Some time ago you proposed the idea of a Food Island, that I draw here on my map, that fascinates me a lot. It came to my mind because the mouth of Mississippi is one of the places in the oceans with the highest number of oil rigs, most of which are today obsolete or in stand by. It’s interesting to note that three seas with high oil/gas productivity have similar configurations: the Mexican Gulf, the Persian Gulf and the Adriatic Sea.

They are all low deep basins, with sand, and a lot of nutrients coming from the River Mississippi, the Rivers Tigris and Euphrates, and the River Po. But in all these areas, flora and fauna do not take root because of the sand. In these cases, the oil rigs become an incredible opportunity for the creation of artificial reefs with great biodiversity. In front of Ravenna in Italy there is the interesting case of Paguro, a gas platform that exploded only a few days after opening in 1965, that is today a natural reserve with rich biodiversity.

Being the oil rigs decommissioning an expensive operation, and often postponed because the rigs in standby could become productive again if the oil price rises, it could be interesting to think to alternative decommissioning systems that act to transform old oil rigs into Food Islands, giving them a new life with an environmental positive outcome.

MT: The Food Island is an idea I elaborated a couple of years ago. In a first moment I was enthusiast, then I thought that maybe I was going too far. I had an invitation from the European Commission. They asked me, from your point of view of algae cultivator, how do you see the world in 2050? The truth is that I have no clue of what it could be, but I was happy to give my contribution and so I conceived the Food Island.

First of all it’s something that does not stay on land. It does not occupy arable land. I imagined floating platforms that you cannot place in open sea, but in protected bays, or maybe in former oil structures, even if they probably have limited usable surfaces. Primary production depends on the light that they receive and therefore on surface. At the end of the day, to produce food you need hectares. The idea was to use the sun light to produce not only algae, but also vegetables of all kinds that we commonly use and consume, using only sea water. For microalgae, it’s easy because they come from the sea. For the other plants it’s necessary to use a process of desalination to produce distilled water that can be mixed with some sea water to add nutrients. It’s a research that is being developed by my colleague at Florence University, Prof. Mancuso. Talking together, we thought at ways to integrate microalgae and vegetables in which algae could be used also as fertilizer for plants.

The Food Island needs light, seawater, and also CO2. You could bring it from land, but the idea was to be self-sufficient using the CO2 contained in the air. The problem with air is that, there is too much CO2, but not enough for being used directly for cultivation. We are waiting for innovative systems of Air Capture that are able to fix and concentrate in an energy efficient manner, the CO2 contained in the air. This would be a major revolution for us because it would allow to produce algae in plants everywhere, not only in areas connected to CO2 sources.

CG: What about using in a symbiotic manner CO2 produced by other organisms like fishes in aquaculture plants?

MT: It’s possible, but we figured out another system. In the Food Island we don’t have only microalgae and plants in a greenhouse, with a thermoregulation system that uses seawater evaporation for cooling and produces freshwater. The idea was to use also the macroalgae, the seaweeds. In Europe we don’t have much this sensibility, but in Asia, there is a very important production of seaweeds. There are kilometers of nets used to grow seaweeds. Millions of tons of marcoalgae are produced yearly and used for food. If we could integrate these seaweeds cultivation systems to our floating platform, we would have a source of biomass quite economic on site, using the nutrients that are usually in sediments and deep waters. We got nitrate, that we can fix with nitrate fixer organisms.

But another important product that will be lacking in the future is phosphorus. There is less and less phosphorus. Some countries like Morocco and the United States have reserves, but we talk about tens of years not hundreds. And without phosphorus there is no agriculture. This missing phosphorus is probably deposited in sediments and deep waters through the percolation of fertilizers. These seaweeds could fix this lost phosphorus and bring it back to us through the biomass. The harvested biomass, according to quality, could be used to feed some food chains, or be used to feed an anaerobic digester, that produces methane that can be used as an energy source, and CO2. To be more sophisticated, we could also use part of the microalage to breed clams. You got energy, nutrients, water, and you produce food.

CG: I like the idea of a complete cycle, very simple and very complex at the same time.

MT: It’s a little ecosystem that self sustains itself. The food produced here, in some way will go to the land to be consumed.


CG: In my imaginary map, we started from Ithaca to talk about the origins of our world, then we went to Troy where we talked about action through photosynthesis, then we went to the doors of the future with new products and bio-economy, and finally we also have Circe that represents the magics with its opportunities and its threats. So, talking about future speculations, that sometimes go close to science fiction, if one would think to make energy again out of algae but not by burning them, but by cracking the photosynthetic mechanism and achieve artificial photosynthesis that could move cars by using just water, light and CO2. Photosynthetic energy could be a revolution? The new nuclear energy?

MT: The problem is always to go and search for the electrons. Electrons are at he very base of organisms, cells, biology. They are also at the base of the energy we use to move our cars. Also in this fuel, it’s the electrons that oxidize with oxygen and generate energy. There are some researches on artificial photosynthesis with artificial pigments, that I don’t know much. But there are some projects in which micro-algae are used to detach electrons from water and bring them to something that becomes the fuel. When we say that we produce oil, we have trapped these electrons into oil, so one could in some way extract this oil and use the algae as a catalyst in a process called milking. With oil it’s difficult because it’s inside the algae and it’s difficult to extract without damaging the cell. With hydrocarbons it should be easier.

There is an algae species, pretty complex, called Botryococcus that is being studied since a few years. It lives in colonies, and if you look at the colonies through the microscope, you see some droplets between the colonies. They look like oil drops but they are not. They are hydrocarbons. Somebody thinks this is the origin of fossil fuels. These colonies float in water because the hydrocarbons are light and they sustain them. These hydrocarbons are almost ready for being a fuel. The idea is to grow them trying to stimulate the production of these hydrocarbons, and extract with a solvent the hydrocarbons keeping the cells intact. What you do here is to transform solar energy directly into usable fuel. It’s not a viable way because these strains are extremely complex to cultivate, easy to contaminate, and the extraction is difficult. We are in an European project called Photofuel whose leader is Volkswagen, and also Volvo and Fiat are involved as partners. So, yes, it’s futuristic, but these companies are already investing in these kind of technologies. It is realistic to think that these organisms, so as other plants, can give us liquid fuels, that in any case, it will be hard to do without it.

CG: We always think in terms of fuel. It’s not possible to think to other kinds of energy?

MT: Another possibility is to produce hydrogen, and electric energy. In general, some microorganisms have this peculiarity (it seems science fiction): in the mechanisms of respiration and photosynthesis there are electrons that move using electron-transporters. Some of these passages correspond to ATP synthesis. In some cases, like some bacteria, the electrons can be passed to a metal. Moreover, bacteria have some little channels that put them in communication with each other called pili, that they use to exchange informations. And also plasmids that can codify for the resistance to antibiotics. That is a problem, because a resistant bacterium, passes the information with its plasmids to others. Not only to its descent, but also to the others living with it. Also electrons can pass through these pili. A cell, that uses electrons coming from organic or inorganic origins, can transfer them. It’s like an electric cable. There is a lot of research in that. The goal is to produce electric energy trough photosynthesis using a living organism instead of a photovoltaic.

But, all the time that there is a cell, I never forget that cells are made in large part of proteins, and I don’t like to burn proteins. We can extract the oil, the hydrocarbons and use them to make electric energy or hydrogen. There are a number of projects in which algae and photosynthetic bacteria are used to produce hydrogen. In lab environment it always works. The problem is upscaling. Another problem is that the energy balances are often negatives. When we cultivate microalgae, bacteria, fungi, I always see proteins, vitamins and mineral salts. And since I know that there is an enormous lack of these nutrients, I don’t want to burn them, not in combustion, or in an anaerobic digester. It’s one of the negative aspects of the use of biomass. The burning, the degradation. And also to waste it. Food waste is a real disaster. 1/3 of what is produced, with all the resources needed and the contaminations generated for production, is thrown away. And it’s so difficult to limit this phenomenon. It’s an incredible craziness of our world.


CG: My last drawing is this little man with a toxic mask: when somebody plays with physics he can break something, while playing with chemistry he can produce explosions, with biology it could be pandemic.

MT: There is a lot of fear. Mainly due to a lack of knowledge. It’s clear that among microorganisms (microalgae, bacteria, fungi) there are also bad guys, pathogens, toxic.

CG: There are also good ones. The problem is that we live in the era of detergents.

MT: The good ones are the majority. And woe if they were not there.

CG: We wouldn’t have nor bear or cheese.

MT: We wouldn’t be here neither: in our cells there are mitochondria that are bacteria. Our bodies have 1.5 kg of bacteria. A man of 80kg has 1.5 kg of bacteria. Bacteria that are all around in the mucous, in the skin, and mostly in the digestive tract. The majority of microorganisms are good. They close cycles. Nitrate cycle, Carbon cycle… Without them, life as we know it wouldn’t exist. There are also the bad ones, that are the ones that medicine tries to control. And it’s being more and more difficult because bacteria, with all their mechanisms of adaptation, are very efficient in becoming resistant to new antibiotics, new medicines. They modify and change all the time. Fight antibiotic resistant bacteria is a big issue.

I was once invited in Saudi Arabia, where there is a profound sensibility on the possible biologic dangers. We were talking about making microalage cultures. An important representative of the government raised the problem that whatever these cultures would have been, he would never allow the entrance of microalgae coming from abroad. Non autochthonous. We will use only algae coming from here. I said: we can go to the Red Sea where there is a huge biodiversity, so that we don’t need to import strains from Asia or Europe. But we have to go and find them. Isolate, characterize, and check if it’s the strains that you want, usable for making pigments, proteins, polysaccharides. It’s a very long work, while we have already a number of already characterized strains.

I said: you see, you can close the borders at airports and customs, restricting the entry of biological matter, like in Australia and in the United States. But you have to consider the fact that microalgae, and every microorganism, are very tiny, and are present not only in water but also in soil, in desert sand. Winds carry sands for thousands of kilometers, to Europe, to the Caribbeans, bringing with them a very biodiverse microbic population. These microorganisms arrive in new areas, and in some cases can proliferate. If you happen to isolate strains the next day, you will probably think that they are autochthonous. Moreover, when big ships arrive in harbors, before entering, they have to unload ballast waters, that have been loaded maybe on the other side of the globe. And also small boats have on the hull a biofilm that is very rich in all kind of microroganims.

We must relativize the concerns on contamination. It’s clear that if traveling organisms don’t find the proper conditions, they won’t grow. It’s also clear that if only a few cells arrive, nothing happens, while with an important population we have what we call inoculum effect, and a new population can establish. If we work with organisms that we know, I don’t have any fear on possible loss of control. Specially if we work with organisms that we can easily use and eat. Of course, it’s completely another case if you are talking about labs with pathogens, or with microalgae and cyanobacteria that can produce toxins. In these cases, there are levels of control that make sure that nothing can escape. And laws in every country are very strict.

CG: Years ago I was in the United States and I attended some biology community labs, sort of maker spaces for biology, in which everybody can experiment a kind of Do It Yourself biology in specific workshops like extracting DNA from strawberries, or adding Green Fluorescent Protein (GFP) to e.coli, etc. Very basic stuff. What I realized is that the entire american DIY bio community is strictly controlled by FBI because of bioterrorism controls.

MT: You have to have knowledge. When you work with a microorganism, but also with a plant, you have to be sure of what you have in your hands. When we cultivate microalage, it’s not only microalgae. For every algae cell, there are around 50, 100, maybe 1,000 cells of bacteria, that most of the times are helpful. We cultivate very complex ecosystems. Some of these bacteria can be there by chance. Some others are always there. They are always associated to specific strains. They are saying: look, we are interacting. We are doing researches in which the algae deprived of its bacteria (we call it axenic) is being added one by one with single bacterium, and we realized that some of them make it grow better. It’s not only because they give vitamins and other growing factors. It’s about positive interactions. There is also the fact that algae produce oxygen and consume CO2, and the bacterium does the opposite. In the case of black/grey waters treatments, without bacteria, algae couldn’t make much work: it’s precisely the association algae-bacteria that generates the degradation of the organic matter in the black waters. Then the algae fix the mineralized nitrates and phosphorus. Also here, we have to pay attention. We could have dangerous bacteria.

I have to stress it: we have to know what we are doing. And we go to another point that worries me. We talk a lot of Spirulina, and there are a lot of small production facilities, family run by farmers that heard about it, without specific knowledge, that try cultivations, sometimes in little ponds. It’s a kind of culture that after a bit, if not controlled properly, goes on its own, algae deteriorate, and the whole thing transforms in a bacteria culture. You have to be very careful in harvesting and using it. These cultures can get contaminated by other cyanobacteria that can produce toxins and microcystins. They can poison people.

Threats are there, they are not too dangerous, but as in every productive and transformation food process, you have to pay attention. In the United States, some studies demonstrate that food intoxication counts tens of thousands of victims every year, with some dead. People die because they get intoxicated by contaminated food. The press is not paying much attention to this phenomenon. How many people die for terrorist attacks in one year? 3,000? 5,000? I don’t know. And we are all terrorized, which is the goal of terrorists. But if we go to see people that die for food intoxication, then we realize that we are talking about hundreds of thousands. On the other hand, I neither like the mother that compulsively cleans the floor. Our kids can’t live in a sterile environment, they have to live in a natural environment.

CG: Thank you Mario. I would finish remembering the claim that is at the origins of this series of conversations. The fact of adapting and modifying nature is part of human beings from their origins, mainly because our ancestors were the only around without fangs and claws.

MT: I always say to my students: the fact that you enrolled in a School of Argriculture means that you accepted the idea that we intervene heavily on nature. It’s impossible that human life doesn’t have an impact on nature. Of course there are different kinds of possible impacts.

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