A team from the Technical University of Munich (TUM) has developed an alternative to traditional pesticides – a biodegradable agent that keeps pests at bay without poisoning them.
Professor Thomas Bruck, who heads the Werner Siemens Chair of Synthetic Biotechnology at TU Munich, said: “It’s not just about the bees, it’s about the survival of humanity. Without the bees that pollinate a wide variety of plants, not only would our supermarket shelves be quite bare, but within a short time, it would no longer be possible to supply the world’s population with food.”
Synthetically produced insecticides endanger not only bees but also beetles, butterflies and grasshoppers. They affect biodiversity in soils, lakes, rivers and seas. Their use has consequently been highly controversial for many years.
Brück and his team have now found an alternative: The insect repellent they have developed is biodegradable and ecologically harmless. Sprayed on plants, it works much like mosquito repellent used by bathers in the summer, spreading a smell that keeps away unwanted insects.
“With our approach, we are opening the door to a fundamental change in crop protection,” said Brück. “Instead of spraying poison, which inevitably also endangers useful species, we deliberately merely aggravate the pests.”
The Munich researchers were inspired by the tobacco plant, which produces cembratrienol in its leaves, CBTol for short. The plant uses this molecule to protect itself from pests.
Using synthetic biotechnology tools, Professor Brück’s team isolated the sections of the tobacco plant genome responsible for the formation of the CBTol molecules. They then built these into the genome of coli bacteria. Fed with wheat bran, a by-product from grain mills, the genetically modified bacteria now produce the desired active agent.
Professor of Biothermodynamics at the TUM Weihenstephan Campus Mirjana Minceva said: “The key challenge during production was to separate the active ingredients from the nutrient solution at the end of the process.”
The solution was centrifugal separation chromatography: a highly efficient process that works equally well on an industrial scale, but hitherto, had never been used to separate products from fermentation processes.
Initial investigations indicate that the CBTol spray is non-toxic to insects, yet still 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 can thus be used as a disinfectant spray that acts specifically against pathogens such as Staphylococcus aureus (MRSA pathogen), Streptococcus pneumoniae (pneumonia pathogen) or Listeria monocytogenes (listeriosis pathogen).
The paper was by Wolfgang Mischko, Max Hirte, Simon Roehrer, Hannes Engelhardt, Norbert Mehlmer, Mirjana Minceva and Thomas BrückModular and titled Biomanufacturing for a Sustainable Production of Terpenoid-based Insect DeterrentsGreen chemistry at DOI: 10.1039/C8GC00434J
The project was funded by the Bavarian Ministry of Economic Affairs, Energy and Technology and the Werner Siemens Foundation. The research team used the equipment pool of the TUM Center for Industrial Biotechnology in Garching to do the technical scaling and validation of the cembratrienol production. The bioactivity tests were carried out in the Department of Biochemical Engineering of the Friedrich Alexander University Erlangen-Nürnberg.
Written by Matthew Appleby in Horticulture Week. See original article link here.