Brewer's spent grain as a no-cost substrate for polyhydroxyalkanoates production: Assessment of pretreatment strategies and different bacterial strains

Polyhydroxyalkanoates (PHAs) are polyesters of significant interest due to their biodegradability and properties similar to petroleum-derived plastics, as well as the fact that they can be produced from renewable sources such as by-product streams. In this study, brewer's spent grain (BSG), the main by-product of the brewing industry, was subjected to a set of physicochemical pretreatments and their effect on the release of reducing sugars (RS) was evaluated. The RS obtained were used as a substrate for further PHA production in Burkholderia cepacia, Bacillus cereus, and Cupriavidus necator in liquid cultures. Although some pretreatments proved efficient in releasing RS (acid-thermal pretreatment up to 42.1 gRS L^-1 and 0.77 gRS g^-1 dried BSG), the generation of inhibitors in such scenarios likely affected PHA production compared with the process run without pretreatment (direct enzymatic hydrolysis of BSG). Thus, the maximum PHA accumulation from BSG hydrolysates was found in the reference case with 0.31 ± 0.02 g PHA per g cell dried weight, corresponding to 1.13 ± 0.06 g L^-1 and a PHA yield of 23 ± 1 mg g^-1 BSG. It was also found that C. necator presented the highest PHA accumulation of the tested strains followed closely by B. cepacia, reaching their maxima at 48 h. Although BSG has been used as a source for other bioproducts, these results show the potential of this by-product as a no-cost raw material for producing PHAs in a waste valorization and circular economy scheme.

Production of polyhydroxyalkanoates on waste frying oil employing selected Halomonas strains

The aim of this work was to study the potential of selected Halomonas species for conversion of waste frying oil into polyhydroxyalkanoates (PHA). In total nine Halomonas strains were experimentally screened for their capability of PHA production. Among them, Halomonas neptunia and Halomonas hydrothermalis were identified as potent PHA producers. Initial concentration of NaCl was identified as parameter influencing PHA yields as well as molecular weight of the polymer. In addition, H. hydrothermalis was capable of biosynthesis of a copolymer of 3-hydroxybutyrate and 3-hydroxyvalerate P(3HB-co-3HV). When valerate was utilized as a precursor, the 3HV fraction in the copolymer reached high values of 50.15 mol.%. PHA production on lipid substrates by Halomonas has not been reported so far. Bearing in mind all the positive aspects of employing extremophiles in industrial biotechnology, H. hydrothermalis seems to be a very interesting halophilic strain for production of PHA using lipid substrates.

Biotechnological Production of Poly(3-Hydroxybutyrate-co-4-Hydroxybutyrate-co-3-Hydroxyvalerate) Terpolymer by Cupriavidus sp. DSM 19379

The terpolymer of 3-hydroxybutyrate (3HB), 3-hydroxyvalerate (3HV), and 4-hydroxybutyrate (4HB) was produced employing Cupriavidus sp. DSM 19379. Growth in the presence of γ-butyrolactone, ε-caprolactone, 1,4-butanediol, and 1,6-hexanediol resulted in the synthesis of a polymer consisting of 3HB and 4HB monomers. Single and two-stage terpolymer production strategies were utilized to incorporate the 3HV subunit into the polymer structure. At the single-stage cultivation mode, γ-butyrolactone or 1,4-butanediol served as the primary substrate and propionic and valeric acid as the precursor of 3HV. In the two-stage production, glycerol was used in the growth phase, and precursors for the formation of the terpolymer in combination with the nitrogen limitation in the medium were used in the second phase. The aim of this work was to maximize the Polyhydroxyalkanoates (PHA) yields with a high proportion of 3HV and 4HB using different culture strategies. The obtained polymers contained 0–29 mol% of 3HV and 16–32 mol% of 4HB. Selected polymers were subjected to a material properties analysis such as differential scanning calorimetry (DSC), thermogravimetry, and size exclusion chromatography coupled with multi angle light scattering (SEC-MALS) for determination of the molecular weight. The number of polymers in the biomass, as well as the monomer composition of the polymer were determined by gas chromatography.

Characterization of the promising poly(3-hydroxybutyrate) producing halophilic bacterium Halomonas halophila

This work explores molecular, morphological as well as biotechnological features of the highly promising polyhydroxyalkanoates (PHA) producer Halomonas halophila. Unlike many other halophiles, this bacterium does not require expensive complex media components and it is capable to accumulate high intracellular poly(3-hydroxybutyrate) (PHB) fractions up to 82% of cell dry mass. Most remarkably, regulating the concentration of NaCl apart from PHB yields influences also the polymer's molecular mass and polydispersity. The bacterium metabolizes various carbohydrates including sugars predominant in lignocelluloses and other inexpensive substrates. Therefore, the bacterium was employed for PHB production on hydrolysates of cheese whey, spent coffee grounds, sawdust and corn stover, which were hydrolyzed by HCl; required salinity of cultivation media was set up during neutralization by NaOH. The bacterium was capable to use all the tested hydrolysates as well as sugar beet molasses for PHB biosynthesis, indicating its potential for industrial PHB production.

Production of Polyhydroxyalkanoates Using Hydrolyzates of Spruce Sawdust: Comparison of Hydrolyzates Detoxification by Application of Overliming, Active Carbon, and Lignite

Polyhydroxyalkanoates (PHAs) are bacterial polyesters which are considered biodegradable alternatives to petrochemical plastics. PHAs have a wide range of potential applications, however, the production cost of this bioplastic is several times higher. A major percentage of the final cost is represented by the price of the carbon source used in the fermentation. Burkholderia cepacia and Burkholderia sacchari are generally considered promising candidates for PHA production from lignocellulosic hydrolyzates. The wood waste biomass has been subjected to hydrolysis. The resulting hydrolyzate contained a sufficient amount of fermentable sugars. Growth experiments indicated a strong inhibition by the wood hydrolyzate. Over-liming and activated carbon as an adsorbent of inhibitors were employed for detoxification. All methods of detoxification had a positive influence on the growth of biomass and PHB production. Furthermore, lignite was identified as a promising alternative sorbent which can be used for detoxification of lignocellulose hydrolyzates. Detoxification using lignite instead of activated carbon had lower inhibitor removal efficiency, but greater positive impact on growth of the bacterial culture and overall PHA productivity. Moreover, lignite is a significantly less expensive adsorbent in comparison with activated charcoal and; moreover, used lignite can be simply utilized as a fuel to, at least partially, cover heat and energetic demands of fermentation, which should improve the economic feasibility of the process.

Accumulation of Poly(3-hydroxybutyrate) Helps Bacterial Cells to Survive Freezing

Accumulation of polyhydroxybutyrate (PHB) seems to be a common metabolic strategy adopted by many bacteria to cope with cold environments. This work aimed at evaluating and understanding the cryoprotective effect of PHB. At first a monomer of PHB, 3-hydroxybutyrate, was identified as a potent cryoprotectant capable of protecting model enzyme (lipase), yeast (Saccharomyces cerevisiae) and bacterial cells (Cupriavidus necator) against the adverse effects of freezing-thawing cycles. Further, the viability of the frozen-thawed PHB accumulating strain of C. necator was compared to that of the PHB non-accumulating mutant. The presence of PHB granules in cells was revealed to be a significant advantage during freezing. This might be attributed to the higher intracellular level of 3-hydroxybutyrate in PHB accumulating cells (due to the action of parallel PHB synthesis and degradation, the so-called PHB cycle), but the cryoprotective effect of PHB granules seems to be more complex. Since intracellular PHB granules retain highly flexible properties even at extremely low temperatures (observed by cryo-SEM), it can be expected that PHB granules protect cells against injury from extracellular ice. Finally, thermal analysis indicates that PHB-containing cells exhibit a higher rate of transmembrane water transport, which protects cells against the formation of intracellular ice which usually has fatal consequences.

Biotechnological conversion of spent coffee grounds into polyhydroxyalkanoates and carotenoids

Coffee is one of the world's most popular beverages and has been growing steadily in commercial importance. Nowadays, coffee is the second largest traded commodity in the world, after petroleum. Hence, coffee industry is responsible for the generation of large amounts of waste, especially spent coffee grounds (SCG). Various attempts to valorize this waste stream of coffee industry were made. This article summarizes our research and publications aiming at the conversion of SCG into valuable products - polyhydroxyalkanoates (PHAs) and carotenoids. At first, oil extracted from SCG (approx. 15 wt% oil in SCG) can be efficiently (YP/S=0.82 g/g) converted into PHA employing Cupriavidus necator H16. Further, the solid residues after oil extraction can be hydrolyzed (by the combination of chemical and enzymatic hydrolysis) yielding fermentable sugars, which can be further used as a substrate for the production of PHAs employing Bacillus megaterium (YP/S=0.04 g/g) or Burkholderia cepacia (YP/S=0.24 g/g). Alternatively, SCG hydrolysate can be used as a substrate for biotechnological production of carotenoids by carotenogenic yeast Sporobolomyces roseus. Solid residues after either oil extraction or hydrolysis can be used as fuel in industrial boilers to generate heat and energy. Therefore, entire biomass of SCG can be used for sustainable production of PHAs and/or carotenoids employing bio-refinery approach.

[Inferior vena cava filters in pulmonary embolism prevention]

Pulmonary embolism (PE) is the most serious sign of venous thromboembolism and the 3rd most frequent cause of cardiovascular death. Therapy with anticoagulants represents, among other measures, the mainstay of PE treatment. However, anticoagulant therapy does not prevent recurrence of pulmonary embolism in 3-20% of patients. Most frequently, the source of pulmonary embolism is in venous circulation of lower limbs and pelvis. Interception of the inferior vena cava, originally surgical, later using inferior vena cava filters, is used as a preventive measure. Indications and contraindications of inferior vena cava filters have been redressed and modified several times; the paper provides their list. Older filters used to be retained within the inferior vena cava (so called permanent filters). This was one of the causes of relatively high incidence of complications related to the use of these filters, particularly venous thromboses, as confirmed by so far the only randomised study PREPIC. Consequently, retrievable filters that are currently preferred have been developed. The authors also provide an overview of studies in progress, describe the process of implantation and describe own patient group.

[Case reports of family members with multiple occurrences of aortic dissection]

Aortal dissection belongs to the group of aortal diseases with a high mortality rate and varied clinical account. This disease does not appear very often and therefore it is often diagnosed late. Diagnostic and therapeutic developments have recently improved. Classification and indication criteria about prophylactic interventions on aorta have become more specific. It leads to the gradual decrease of mortality caused by this disease. Frequent accumulation of familiar aortal dissection was described. It can be important for the early identification of individuals at risk. In our casuistry we describe a family with the accumulation of aortal dissection coinciding with Marfan syndrome from the mother's side and the prevalence of this disease in siblings from their patient's father. The evident predisposition was not clearly demonstrated in these cases. We also examined and began to dispenser other members of the family but we did not find an evident predisposition factor. We would like to emphasize the importance of good interdisciplinary and institutional cooperation in diagnostic and treatment of this disease. Further we want to emphasize the contribution of careful sampling of familiar anamnesis in the cases stricken with the disease. We focused on sudden death. It is well known that the gene analysis may contribute to the identification of individuals at risk in these families. We do not have this possibility in our country now.

Segmentation of sequences of echocardiographic images using a simplified 3D active contour model with region-based external forces

A method of segmenting echocardiography images based on three dimensional (two spatial and one time) surface was developed and tested on transcutaneous images from 38 patients and a four-dimensional (three spatial and one time) transesophageal scan of one patient. Active contour models with finite elements representing the curves in the imaging planes and finite difference description linking curves from time frame to time frame were employed. Region-based external forces were incorporated into the framework of the model and an analytical procedure for estimating the values of most of the model parameters was developed and used.