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Without risks and side effects: Biodegradable pesticides developed
Plant protection products have a toxic effect on harmful organisms. However, the impact of most funds is not limited to them. Other animal and plant species can also be damaged. In addition, some of the chemicals can harm human health. Now there is an alternative: German researchers have developed a biodegradable crop protection product.
Massive use of pesticides
Plant protection products are used in agriculture in large areas and in relatively large quantities to protect plants from harmful organisms. "On an hectare of agricultural land, an average of around nine kilograms of pesticides or 2.8 kilograms of active ingredients are used per year," reports the Federal Environment Agency on its website. The chemicals can also have negative effects on other animal and plant species and on human health. A team from the Technical University of Munich (TUM) has now developed an alternative: A biodegradable active ingredient keeps pests away without poisoning.
Insecticides don't just destroy pests
According to a TUM statement, traditional crop protection products are killers: Synthetic insecticides not only destroy pests, they also endanger bees and other useful insects such as beetles, butterflies and grasshoppers.
They also affect biodiversity in soils and endanger many bodies of water such as lakes and rivers.
In addition, it has long been known that pesticides can harm health. They disrupt the body's hormonal balance and can damage the human immune system. Nevertheless, pesticides are not uncommon in food.
The use of such chemicals has therefore been highly controversial for many years.
Keep away instead of poisoning
"It's not just about the bees, it's about human survival," says Professor Thomas Brück, owner of the Werner Siemens Chair for Synthetic Biotechnology at the Technical University of Munich.
"Without the bees, which pollinate a large number of plants, not only would our supermarket shelves be fairly empty, but within a short time, the world's population would no longer be supplied with food."
Brück and his team have now developed an insect repellent that they claim is biodegradable and ecologically harmless.
Sprayed on plants is similar to a mosquito spray that bathers apply in summer: it spreads an odor that keeps unwanted insects away.
"With our approach, we enable a fundamental change in crop protection," says Brück. "Instead of spraying poison that always endangers useful species, we deliberately only scour the pests."
Bacteria as chemical factories
The Munich researchers' model was the tobacco plant, which produces cembratrienol, or CBT-ol for short, in its leaves. With this molecule, the plant protects itself from pests.
Using synthetic biotechnology tools, the research team isolated those sections from the genome of the tobacco plant that are responsible for the formation of the CBT-ol molecules.
Then they built them into the genetic makeup of coli bacteria. Lined with wheat bran, a by-product from grain mills, the genetically modified bacteria now produce the desired active ingredient.
Efficiency in both small and large
"The biggest challenge in production was to separate the active ingredients from the nutrient solution at the end of the process," explains Mirjana Minceva, Professor of Biothermodynamics at the TUM Campus Weihenstephan.
Centrifugal separation chromatography provided the solution. The process is extremely efficient and also works on an industrial scale, but has never been used for the separation of products from fermentation processes.
Also effective against bacteria
According to the information, initial studies show that the CBT spray is non-toxic to insects and yet effectively protects against aphids. Since it is biodegradable, it does not accumulate.
In addition, the bioactivity tests showed that cembratrienol has an antibacterial effect on gram-positive bacteria.
It could therefore be used as a disinfectant spray that works specifically against pathogens such as Staphylococcus aureus (MRSA pathogen), Streptococcus pneumoniae (pathogen pneumonia) or Listeria monocytogenes (pathogen of listeriosis).
The results of the scientists were published in the "Green Chemistry" magazine. (ad)