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FEA researchers use fungi and bacteria to degrade toxic products

The microbial legion
advances against pollutants

MANUEL ALVES FILHO

IImagine the following scene, which may be based on real events recently recorded in Brazil. A ship, loaded with millions of liters of diesel oil, has an accident. The cargo completely leaks, contaminating the sea and the beach. Concerned about the likely serious ecological damage, environmental authorities begin the immediate cleaning of water and soil. Instead of using suction pumps, sponges and shovels, as is conventionally done, technicians use fungi and bacteria to remove the fuel. After some time, microorganisms develop and "devour" the polluting material, reducing or even eliminating its toxicity. The process, called bioremediation, is already being carried out in the laboratory by researchers from the Faculty of Food Engineering (FEA) at Unicamp. Within a few years, according to them, the technology will be able to be applied in the field.

The results of research conducted by the FEA are encouraging. Laboratory experiments have shown that microorganisms are capable of degrading between 50% and 100% of pollutants. According to the coordinator of the studies, professor Lúcia Regina Durrant, the main objective is to prevent the leakage or even the dumping of toxic products from contaminating the soil, rivers and groundwater, causing damage to the food chain and, consequently, to people. To explain in a simplified way the work carried out by scientists, what they do is accelerate work that would take nature decades of years to carry out.

Thus, they identify and select bacteria and fungi that lend themselves to bioremediation. Then, they establish a kind of microbial consortium, since a microorganism is not capable of responding to decontamination alone. Currently, scientists' efforts are concentrated on two fronts. The first is focused on polycyclic aromatic hydrocarbons (PAHs), toxic and potentially carcinogenic substances generated from the combustion of petroleum derivatives, burning of garbage and industrial emissions. Among them, benzo(a)pyrene, dioxins and polychlorinated biphenyls (PCBs) stand out, used in capacitors and electrical transformers. The other line of investigation is specifically aimed at petroleum derivatives.

According to Professor Lúcia, the bacteria and fungi studied by her team produce biosurfactant compounds, a type of emulsifier. When it comes into contact with pollutants, this substance makes them soluble, thus facilitating their removal through additional measures. Furthermore, they also have the ability to promote the degradation of toxic material. As if that were not enough, biosurfactants can also be used in the food and cosmetic industries, as ingredients in the manufacture of ice creams and creams, respectively. To degrade dioxins, Unicamp researchers have used fungi that could even be considered prosaic: edible mushrooms, easily found on supermarket shelves.

Placed directly in contact with the toxic product, they produce an enzyme that degrades it. Against benzo(a)pyrene, experts have also used mushrooms, both edible and inedible. To combat the harm that can be caused by PCBs, the "weapon" used by researchers are bacteria, whose identification has not yet been made. Bacteria are also the "cleaners" of toxic substances released by petroleum products. Professor Lúcia clarifies, however, that the work of scientists is not limited to the identification and selection of microorganisms and the formation of the microbial consortium. Some fungi and bacteria, she explains, promote the degradation of pollutants, but end up generating elements that are more toxic than the originals. "For this reason, we also carry out toxicological tests to identify which substances may cause more problems than solutions. These are immediately discarded", she says.

Cake recipe - According to the study coordinator, some developed countries have already mastered bioremediation technology. Brazil also entered this race for two important reasons. Firstly, because, if it continues to be technologically dependent, the country will have to spend a lot of money to acquire, for example, foreign microbial consortia. Secondly, because this type of import could pose risks to biodiversity or people's health. “There is no way of knowing what the eventual spread of an unknown microorganism could cause here,” explains the FEA professor.

The trend, according to Professor Lúcia, is that within two to four years Unicamp researchers will be able to produce, in the laboratory, "packages" ready for bioremediation actions. Making a comparison free of scientific rigor, it is as if they created recipes like cakes, each with a "mixture" intended for a type of application. But when will the product hit the market? The FEA professor states that it is difficult to carry out this futurology exercise, but considers that, once the laboratory stage is reached, the transfer of technology to industry will not be so complicated.

Because it uses natural resources, bioremediation is considered an environmentally friendly technology. Furthermore, it is also between 65% and 85% cheaper than conventional models of decontamination and treatment of agro-industrial waste. Just to have a comparison parameter, it is enough to know that the cost to incinerate a ton of waste varies between US$ 250 and US$ 300. Degrading the same volume through biological treatment requires an expense of around US$ 40 at US$70.

real case - When learning about the work carried out by Unicamp scientists, some people often ask why the Faculty of Food Engineering is involved in environmental studies. The answer, according to Professor Lúcia, is simple. By contaminating the soil, groundwater, rivers or even the air, toxic products can also reach the food chain. “Our goal is to try to prevent this from happening,” says the expert. In 2002 alone, FEA's line of research generated seven doctoral theses. The studies are supported by scholarships granted by Capes, CNPq and Fapesp. Fapesp also finances several of the projects.

An example that can help laypeople understand how food chain contamination occurs comes from England, but has a direct connection with Brazil. In 2000, the British discovered that milk and dairy products produced in the country contained dioxins. After a long investigation, the source of the problem was identified: citrus pulp bran, a Brazilian product used in cattle feed. New analyzes were carried out in Tupiniquin lands, until the origin of all the evil was detected. The water used to irrigate the agricultural crop from which the bran is generated contained dioxins. These, in turn, came from the lime used in water treatment.

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