Biosynthesis of Polyhydroxyalkanoates in B-10646 on Saturated Fatty Acids.

It has been established that the wild-type B-10646 strain uses saturated fatty acids (SFAs) for growth and polyhydroxyalkanoate (PHA) synthesis. It uses lauric (12:0), myristic (14:0), palmitic (16:0) and stearic (18:0) acids as carbon sources; moreover, the elongation of the C-chain negatively affects the biomass and PHA yields. When bacteria grow on C12 and C14 fatty acids, the total biomass and PHA yields are comparable up to 7.

Properties of Degradable Polyhydroxyalkanoates Synthesized from New Waste Fish Oils (WFOs).

The synthesis of PHA was first investigated using WFOs obtained from smoked-sprat heads, substandard fresh sprats, and fresh mackerel heads and backbones. All the WFOs ensured the growth of the wild-type strain B-10646 and the synthesis of PHA, regardless of the degree of lipid saturation (from 0.52 to 0.

Biodegradable Polyhydroxyalkanoates with a Different Set of Valerate Monomers: Chemical Structure and Physicochemical Properties.

The properties, features of thermal behavior and crystallization of copolymers containing various types of valerate monomers were studied depending on the set and ratio of monomers. We synthesized and studied the properties of three-component copolymers containing unusual monomers 4-hydroxyvalerate (4HV) and 3-hydroxy-4-methylvalerate (3H4MV), in addition to the usual 3-hydroxybutyrate (3HB) and 3-hydroxyvalerate (3HV) monomers. The results showed that P(3HB--3HV--4HV) and P(3HB--3HV--3H4MV) terpolymers tended to increase thermal stability, especially for methylated samples, including an increase in the gap between melting point (T) and thermal degradation temperature (T), an increase in the melting point and glass transition temperature, as well as a lower degree of crystallinity (40-46%) compared with P(3HB--3HV) (58-66%).

Effect of Monomers of 3-Hydroxyhexanoate on Properties of Copolymers Poly(3-Hydroxybutyrate- 3-Hydroxyhexanoate).

The properties of poly(3-hydroxybutyrate--3-hydroxyhexanoate) P(3HB--3HHx) copolymers with different ratios of monomers synthesized by the wild-type strain B-10646 on sugars, and an industrial sample from Kaneka synthesized by the recombinant strain NSDG-ΔfadB1 on soybean oil, were studied in a comparative aspect and in relation to poly(3-hydroxybutyrate) P(3HB). The copolymer samples, regardless of the synthesis conditions or the ratio of monomers, had reduced values of crystallinity degree (50-60%) and weight average molecular weight (415-520 kDa), and increased values of polydispersity (2.8-4.

Biosynthesis and Properties of Sulfur-Containing Polyhydroxyalkanoates (PHAs) Produced by Wild-Type Strain B-10646.

The study addresses the growth of the wild-type strain B-10646 and the synthesis of sulfur-containing polyhydroxyalkanoates (PHA) by this strain on media containing fructose and three different precursors (3-mercaptopropionic acid, 3',3'-dithiodipropionic acid and 3',3'-thiodipropionic acid). By varying the concentration and number of doses of the precursors added into the bacterial culture, it was possible to find conditions that ensure the formation of 3-mercaptopropionate (3MP) monomers from the precursors and their incorporation into the C-chain of poly(3-hydroxybutyrate). A series of P(3HB--3MP) copolymer samples with different content of 3MP monomers (from 2.

Modification of Polyhydroxyalkanoates Polymer Films Surface of Various Compositions by Laser Processing.

The results of surface modification of solvent casting films made from polyhydroxyalkanoates (PHAs) of various compositions are presented: homopolymer poly-3-hydroxybutyrate P(3HB) and copolymers comprising various combinations of 3-hydroxybutyrate (3HB), 3-hydroxyvalerate (3HV), 4-hydroxybutyrate(4HB), and 3-hydroxyhexanoate (3HHx) monomers treated with a CO laser in continuous and quasi-pulsed radiation modes. The effects of PHAs film surface modification, depending on the composition and ratio of monomers according to the results of the study of SEM and AFM, contact angles of wetting with water, adhesion and growth of fibroblasts have been revealed for the laser radiation regime used. Under continuous irradiation with vector lines, melted regions in the form of grooves are formed on the surface of the films, in which most of the samples have increased values of the contact angle and a decrease in roughness.

Biosynthesis and Properties of a P(3HB--3HV--4HV) Produced by B-10646.

Synthesis of P(3HB--3HV--4HV) copolymers by the wild-type strain B-10646 on fructose or sodium butyrate as the main C-substrate with the addition of γ-valerolactone as a precursor of 3HV and 4HV monomers was studied. Bacterial cells were cultivated in the modes that enabled production of a series of copolymers with molar fractions of 3HV (from 7.3 to 23.

Degradable Poly(3-hydroxybutyrate)-The Basis of Slow-Release Fungicide Formulations for Suppressing Potato Pathogens.

Three-component slow-release fungicide formulations with different modes of action of the active ingredients for suppressing potato pathogens were constructed for the first time. The difenoconazole, mefenoxam, prothioconazole, and azoxystrobin fungicides were embedded in the degradable polymer P(3HB)/birch wood flour blend and examined using SEM, IR spectroscopy, X-ray analysis, DTA, and DSC. Results showed that no chemical bonds were established between the components and that they were physical mixtures that had a lower degree of crystallinity compared to the initial P(3HB), which suggested different crystallization kinetics in the mixtures.

Sugar Beet Molasses as a Potential C-Substrate for PHA Production by .

To increase the availability and expand the raw material base, the production of polyhydroxyalkanoates (PHA) by the wild strain B-10646 on hydrolysates of sugar beet molasses was studied. The hydrolysis of molasses was carried out using -fructofuranosidase, which provides a high conversion of sucrose (88.9%) to hexoses.

Production and Properties of Microbial Polyhydroxyalkanoates Synthesized from Hydrolysates of Jerusalem Artichoke Tubers and Vegetative Biomass.

One of the major challenges in PHA biotechnology is optimization of biotechnological processes of the entire synthesis, mainly by using new inexpensive carbon substrates. A promising substrate for PHA synthesis may be the sugars extracted from the Jerusalem artichoke. In the present study, hydrolysates of Jerusalem artichoke (JA) tubers and vegetative biomass were produced and used as carbon substrate for PHA synthesis.

Assessment of the efficacy of slow-release formulations of the tribenuron-methyl herbicide in field-grown spring wheat.

The efficacy of slow-release formulations of tribenuron-methyl (TBM) embedded in the matrix of degradable poly(3-hydroxybutyrate) blended with birch wood flour [polymer/wood flour/herbicide 50/30/20 wt.%] was compared with the efficacy of TBM as the active ingredient of the Mortira commercial formulation, which was applied as post-emergence spray to treat spring wheat cv. Novosibirskaya 15.

Properties of Degradable Polyhydroxyalkanoates (PHAs) Synthesized by a New Strain, IBP/SFU-1, from Various Carbon Sources.

The bacterial strain isolated from soil was identified as IBP/SFU-1 and investigated as a PHA producer. The strain was found to be able to grow and synthesize PHAs under autotrophic conditions and showed a broad organotrophic potential towards different carbon sources: sugars, glycerol, fatty acids, and plant oils. The highest cell concentrations (7-8 g/L) and PHA contents were produced from oleic acid (78%), fructose, glucose, and palm oil (over 80%).

Constructing sustained-release herbicide formulations based on poly-3-hydroxybutyrate and natural materials as a degradable matrix.

Background: The purpose of the present study was to develop ecofriendly herbicide formulations. Its main aim was to develop and investigate slow-release formulations of herbicides (metribuzin, tribenuron-methyl, and fenoxaprop-P-ethyl) of different structure, solubility, and specificity, which were loaded into a degradable matrix of poly-3-hydroxybutyrate (P(3HB)) blended with available natural materials (peat, clay, and wood flour).

Results: Differences in the structure and physicochemical properties of the formulations were studied depending on the type of the matrix.

Antifungal activity of P3HB microparticles containing tebuconazole.

In this study, tebuconazole (TEB)-loaded poly-3-hydroxybutyrate (P3HB)-based microparticles were developed and comprehensively characterized. TEB-loaded microparticles with the initial loading amounts of the fungicide of 10, 25, and 50% of the polymer mass (TEB 10, TEB 25, and TEB 50%) were prepared using emulsion technique. Encapsulation efficiency of TEB varied from 59 to 86%.

Fungicidal activity of slow-release P(3HB)/TEB formulations in wheat plant communities infected by Fusarium moniliforme.

Fungicidal activity of experimental tebuconazole (TEB) formulations was investigated in laboratory soil ecosystems in wheat plant communities infected by Fusarium moniliforme. TEB was embedded in the matrix of poly-3-hydroxybutyrate, shaped as films and microgranules. These formulations were buried in the soil with wheat plants, and their efficacy was compared with that of commercial formulation Raxil and with the effect of pre-sowing treatment of seeds.

Efficacy of tebuconazole embedded in biodegradable poly-3-hydroxybutyrate to inhibit the development of Fusarium moniliforme in soil microecosystems.

Background: An important line of research is the development of a new generation of formulations with targeted and controlled release of the pesticide, using matrices made from biodegradable materials. In this study, slow-release formulations of the fungicide tebuconazole (TEB) have been prepared by embedding it into the matrix of poly-3-hydroxybutyrate (P3HB) in the form of films, microgranules and pellets.

Results: The average rates of P3HB degradation were determined by the geometry of the formulation, reaching, for 63 days, 0.

Constructing Slow-Release Formulations of Metribuzin Based on Degradable Poly(3-hydroxybutyrate).

Experimental formulations of herbicide metribuzin embedded in matrices of degradable natural polymer poly(3-hydroxybutyrate) (P3HB) and its composites with poly(ethylene glycol) (PEG), poly-ε-caprolactone (PCL), and wood powder have been prepared in the form of pressed pellets containing 75% polymeric basis (pure P3HB or its composite with a second component at a ratio of 7:3) and 25% metribuzin. Incubation of formulations in soil laboratory systems led to the degradation of the matrix and herbicide release. The most active release of metribuzin (about 60% of the embedded herbicide over 35 days) was detected for the P3HB/PEG carrier compared to the P3HB, P3HB/wood, and P3HB/PCL forms (30-40%).

Constructing herbicide metribuzin sustained-release formulations based on the natural polymer poly-3-hydroxybutyrate as a degradable matrix.

Polymer poly(3-hydroxybutyrate) [P(3HB)] has been used as a matrix in slow-release formulations of the herbicide metribuzin (MET). Physical P(3HB)/MET mixtures in the form of solutions, powders, and emulsions were used to construct different metribuzin formulations (films, granules, pellets, and microparticles). SEM, X-Ray, and DSC proved the stability of these formulations incubated in sterile water in vitro for long periods of time (up to 49 days).

Cell growth and accumulation of polyhydroxyalkanoates from CO2 and H2 of a hydrogen-oxidizing bacterium, Cupriavidus eutrophus B-10646.

Synthesis of polyhydroxyalkanoates (PHAs) by a new strain of Cupriavidus - Cupriavidus eutrophus B-10646 - was investigated under autotrophic growth conditions. Under chemostat, at the specific flow rate D=0.1h(-1), on sole carbon substrate (CO2), with nitrogen, sulfur, phosphorus, potassium, and manganese used as growth limiting elements, the highest poly(3-hydroxybutyrate) [P(3HB)] yields were obtained under nitrogen deficiency.

Effects of intracellular poly(3-hydroxybutyrate) reserves on physiological-biochemical properties and growth of Ralstonia eutropha.

Microbial polyhydroxyalkanoates (PHAs), because of their well studied complex physiology and commercial potential, are vehicles for carbon and potential storage reduction for many microbial species. Even with the wealth of studies about microbial PHAs in the scientific literature, polymer accumulation and degradation are still not comprehensively understood. Poly(3-hydroxybutyrate) (P3HB) granule formation and polymer mobility were studied here in the bacterium Ralstonia eutropha strain B5786 in autotrophic cultures.