Specific character of bacterial biodegradation of polyhydroxyalkanoates with different chemical structure in soil.

The study addresses the influence of the physicochemical properties of the reserve cellular macromolecules (polyhydroxyalkanoates, PHA) with different chemical composition on their biodegradation in the agro-transformed field soil of the Siberian region (Krasnoyarsk Territory, Russia). It was shown that the degradation of the PHA samples depends on the degree of polymer crystallinity (Cx). For the first time, it was shown that the range of PHA-degrading microorganisms differs for each of PHA types. The study defines the primary degraders specific to each PHA type and common to all types of examined polymers.

Physiological-biochemical properties and the ability to synthesize polyhydroxyalkanoates of the glucose-utilizing strain of the hydrogen bacterium Ralstonia eutropha B8562.

Physiological-biochemical, genetic, and cultural properties of the glucose-utilizing mutant strain Ralstonia eutropha B8562 have been compared with those of its parent strain R. eutropha B5786. It has been shown that growth characteristics of the strain cultured on glucose as the sole carbon and energy source are comparable with those of the parent strain. Strain B8562 is characterized by high polyhydroxyalkanoate (PHA) yields on different carbon sources (CO(2), fructose, and glucose). PHA accumulation in the strain batch cultured on glucose under nitrogen deficiency reaches 90 %. The major monomer in the PHA is beta-hydroxybutyric acid (more than 99 mol %); the identified minor components are beta-hydroxyvaleric acid (0.25-0.72 mol %) and beta-hydroxyhexanoic acid (0.08-1.5 mol %). The strain is a promising PHA producer on available sugar-containing media with glucose.