A team of scientists from the Madrid Biological Research Center (CIB-CSIC) has managed to develop a system for the production of PHA bioplastics –considered as an alternative to plastics derived from petroleum– “by manipulating a predatory bacterium to extract this product from the interior of other bacteria that it kills, ”Virginia Martínez, first author of the study, explains to Sinc. The results of the work have been published in the journal Scientific Reports, of the Nature group.
Martínez is currently a researcher at the biotechnology firm Evolva, in Copenhagen, after having worked at the CIB's Polymer Biotechnology Laboratory, a specialist in bacterial cell factories. "It is about obtaining products of interest in a sustainable way, as is the case of bioplastic, which is a very interesting alternative and where there is a lot of money at stake."
What happens - he adds - “is that the bioplastic contained in bacteria, which produce it and accumulate up to 90% of its weight, is difficult to extract. So far, what has been done is to apply detergents or disruption systems to break the cell and release the product. These processes are polluting and not very efficient, which affects the environment and makes the production process more expensive ”, he highlights.
With the aim of making the process cheaper and improving, the team chose one predatory bacterium from others, called Bdellovibrio bacteriovorus, which was genetically redesigned to transform it into a tool that would allow breaking the membranes of bioplastic-producing strains, facilitating the extraction and purification process. of the product.
The new extraction method is a pioneer in the world and has already been patented. “What we have done is to use B. bacteriovorus as a lytic agent so that it preys on another bacterium called P. putida KT2440 –producer of PHA– and to remove what is inside. Furthermore, we have genetically redesigned the predatory bacteria so that it does not degrade the bioplastic accumulated by the prey ”, the researcher explains.
This lysis system –breaking the cell membrane– allows the bioplastic to be recovered in a single step, “without the need for complex equipment or toxic compounds”, insists Martínez.
The method could also be used to obtain other compounds such as enzymes or proteins that have accumulated in bacteria.
This is because B. bacteriovoruses capable of attacking a wide variety of bacterial species, including those most used in industry and at high cell density. Furthermore, "its use is safe for humans since it does not attack mammalian cells," says the researcher.
After the patent there is already interest from some companies in the new system. “We hope that it will be used commercially to produce bioplastic or any intracellular compound of interest. It is an innovative process because it is the first time that a predatory bacteria strategy has been used as an alternative method to facilitate recovery of intracellular products of industrial interest ”, concludes Martínez.
Virginia Martínez, Cristina Herencias, M. Auxiliadora Prieto. "Engineering a predatory bacterium as a proficient killer agent for intracellular bio-products recovery: The case of the polyhydroxyalkanoates". Scientific Reports (2016)
Photo: Purified PHA bioplastic obtained from P. putida KT2440 bacteria. Image: CIB