The inherent brittleness of poly(3-hydroxybutyrate) (PHB) prevents its use as a substitute of petroleum-based polymers. Low molecular weight plasticizers, such as tributyl 2-acetyl citrate (TAC), cannot properly solve this issue. Herein, PHB films were obtained using a biosynthesized poly(3-hydroxyoctanoate) (PHO) and a commercially available TAC as toughening agents. The use of TAC strongly decreased the PHB thermal stability up to 200 °C due to the loss of low boiling point plasticizer, while minor weight loss was noticed at this temperature for the PHB-PHO blend. Both agents shifted the glass transition temperature of PHB to a lower temperature, the effect being more pronounced for TAC. The elongation at break of PHB increased by 700% after PHO addition and by only 185% in the case of TAC; this demonstrates an important toughening effect of the polymeric modifier. Migration of TAC to the upper surface of the films and no sign of migration in the case of PHO were highlighted by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) results. In vitro biocompatibility tests showed that all the PHB films are non-toxic towards L929 cells and have no proinflammatory immune response. The use of PHO as a toughening agent in PHB represents an attractive solution to its brittleness in the case of packaging and biomedical applications while conserving its biodegradability and biocompatibility.

Polyhydroxyalkanoates (PHAs) are biodegradable and biocompatible biopolymers. These biomaterials have grown in importance in the fields of tissue engineering and tissue reconstruction for structural applications where tissue morphology is critical, such as bone, cartilage, blood vessels, and skin, among others. Furthermore, they can be used to accelerate the regeneration in combination with drugs, as drug delivery systems, thus reducing microbial infections. When cells are cultured under stress conditions, a wide variety of microorganisms produce them as a store of intracellular energy in the form of homo- and copolymers of [R]—hydroxyalkanoic acids, depending on the carbon source used for microorganism growth. This paper gives an overview of PHAs, their biosynthetic pathways, producing microorganisms, cultivation bioprocess, isolation, purification and characterization to obtain biomaterials with medical applications such as tissue engineering.

Abstract. Polyhydroxyalcanoates (PHAs) are specifically produced by a wide variety of bacteria, as an intracellular energy reserve in the form of homo-and copolymers of [R]-β-hydroxyalkanoic acids, depending on the C source used for microorganism growth, when the cells are grown under stressing conditions. In this paper we present microbiological accumulation of poly-3-hydroxyoctanoate (PHO) by using a consortium of bacterial strains, Pseudomonas putida and Bacillus subtilis, in a rate of 3:1, grown on a fermentation medium based on sodium octanoate as the sole carbon source. The experiments performed in the above mentioned conditions led to the following results: from 18.70 g sodium octanoate (7.72 g/L in the fermentation medium) used up during the bioprocess, 3.93-3.96 g/L dry bacterial biomass and 1.834 -1.884 g/L PHA, containing 85.83 -86.8% PHO, were obtained.

Helichrysum arenarium (L.) Moench, belonging to the Asteraceae family, is known in traditional medicine for its diuretic, choleretic, and anti-inflammatory properties. This review focuses on the superiority of Helichrysum arenarium (sandy everlasting) over other known plants as a source of active pharmacological compounds used in complementary medicine to prevent digestive and hepatobiliary illnesses. Because the species exists both in spontaneous flora and in crops, this article highlights the development of a controlled culture of H. arenarium, following the reproducible quality of the plant as a biological material. The diversity of phytocompounds, especially well-characterized flavonoid extracts, and the differences between extraction procedures are discussed. Antiviral, antibacterial, and antifungal activities against human pathogens proved by different plant extracts and their mechanisms of action are analyzed. This study aims to contribute to the insufficient knowledge regarding the effects of Helichrysum species and to reveal that their extracts can be a valuable source for new active pharmaceutical ingredients.

Medium-chain-length polyhydroxyalkanoates (mcl-PHAs) are naturally produced by bacteria and accumulates in cytoplasm in the form of granules, in particular culture broth conditions. PHAs are biodegradable, biocompatible and have useful mechanical properties that recommend them for divers applications in various fields. In order to obtain mcl-PHAs of microbial origin we used two Pseudomonas spp. strains, namely Pseudomonas putida ICCF 391 and Pseudomonas fluorescens ICCF 392. Researches have focused the ability of these two strains to use structurally related or not related substrates, to obtain biopolymers with controlled composition, and growth the amount of PHAs in reproducible conditions. Moreover, bioprocess conditions for mcl-PHAs biosynthesis, fermentation broth processing, and polymers composition-were reproducible. As the results achieved with the two strains were similar, researches continued with Pseudomonas fluorescens strain, which is less studied regarding the potential of PHA biosynthesis. Were carried out (co) polymer films containing more than 85% PHO, as determined by GC-FID.