Russian scientists have uncovered the mechanism of destruction of biopolymers in soil

  • Disposable tableware and household products rapidly degraded by natural biopolymers

 

The scale of production and use of non-degradable in the environment of synthetic polymers reached 200 million tons per year, which has become a global environmental problem. In this regard, more and more attention is paid to the creation of so-called biopolymers which in the environment are destroyed by microorganisms into harmless products. This, for example, polyhydroxyalkanoate (PHA) — hydroxyalkanoic acid polyesters are synthesized by certain microorganisms. From them, you can create rapidly degraded naturally packaging, disposable tableware and household products. At the same time, very little is known about the patterns and failure mechanisms of biopolymers in soils under the influence of various microorganisms. Russian scientists from several institutions have thoroughly studied this issue and found out how the microbes consume the organic polymer in the natural environment.

Most studies of the destruction of biopolymers, which have already published research articles, conducted in the laboratory. And here is how the processes of decomposition "of the material of the future" in a natural flow, natural environment, largely remained a mystery.

Russian team of scientists from several organizations — Institute of BiophysicsSiberian Federal UniversityInstitute of Chemical Biology and Fundamental Medicine of the Russian Academy of Sciences,Institute of Physics. Siberian Branch of Russian Academy of Sciences — Filled this gap: GGP has studied biodegradation in soil by microorganisms.

First scientists synthesized polyhydroxyalkanoates using microorganisms, biotechnological process. It is known that certain bacteria are capable during its life synthesize and accumulate these polymers in cells.

After culture, the filled polymer containing bacterial cells were centrifuged, the polymer was extracted from the biomass with organic solvents, and filtered to remove precipitated PHA.

Researchers have isolated organisms capable of destroying PGA and examined degradability of polymers depending on their molecular structure and ambient temperature.

During the experiment, which lasted for two field seasons, with an interval of three years, the polymer discs were placed in the soil under the roots of various trees about three months of the summer. At this time, scientists have studied the dynamics of changes in the mass of polymer samples and found that the effect on the process of destruction of the PGA. One of these factors — the chemical composition of the polymer is rapidly decomposed polyester hybrid (chemists call them copolymer) molecules exposed to greater destruction amorphous phase of polymers compared with the crystal. Also, the degree and rate of decomposition of organic polymers were dependent on the location of the samples in the soil in a moist and more populated by microorganisms soil under larch, the destruction of both types of PHA occurred more active than under the birch.

Total number of microbes on the surface of the polymer disks was several orders of magnitude higher than the titer control of soil. This indicates that either the polymer settled colonies of microorganisms (bacteria and fungi), the polymer substrate is fed, and not soil materials.

In addition, scientists have identified the qualitative and quantitative composition of microorganisms — destructors bioplastics and recorded the changes in the species composition of the colonies on the polymer over time.

These data allow us to better understand what factors influence the Biodecomposition PHAs in the soil, which will help expand the use of these polymers in the production of auto-disable household products.

In the future, the results of a study on microbial polymers can find both, a completely new application. In the polymer matrix can include biologically active agents such as insecticides or herbicides. They will be released to the environment is not a single occasion, when introduced into the soil, and metered, where destruction of the polymer structure. This will maintain a certain level of desired material in nature for a long time.

On the basis of the Institute of Biophysics in Krasnoyarsk, headed by the Deputy Director of the Institute, head of the Laboratory Chemoautotrophic biosynthesis, doctor of biological sciences, professor Tatyana Volovoi already created the first Russian pilot production of bioplastics. Abroad, there are pilot light commercial enterprises for the production of such materials, which are likely to be increasingly replaced by environmentally unfriendly synthetic polymers.

This work was supported by the project by the decision of the Russian government to government support of research conducted under the supervision of leading scientists at Russian institutions of higher education (contract № 11.G34.31.0013), and Integration Research Programme of the Presidium of SB RAS (project number 96).

Source of information:

AN Boyandin, SV Prudnikova, ML Filipenko, EA Khrapov, AD Vasiliev, T. Volova "Biodegradation of polyhydroxyalkanoates soil Microbiocenosis different structures and identification of microorganisms-destructors". Applied Biochemistry and Microbiology. , 2012, Volume 48, № 1, p. 35-44.

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