The archaeon Haloferax mediterranei was selected for production of PHA co- and terpolyesters using inexpensive crude glycerol phase (CGP) from biodiesel production as carbon source. CGP was assessed ...by comparison with the application of pure glycerol. Applying pure glycerol, a copolyester with a molar fraction of 3-hydroxybutyrate (3HB) of 0.90 mol/mol and 3-hydroxyvalerate (3HV) of 0.10 mol/mol, was produced at a volumetric productivity of 0.12 g/Lh and an intracellular PHA content of 75.4 wt.-% in the sum of biomass protein plus PHA. Application of CGP resulted in the same polyester composition and volumetric productivity, indicating the feasibility of applying CGP as feedstock. Analysis of molar mass distribution revealed a weight average molar mass Mw of 150 kDa and polydispersity Pi of 2.1 for pure glycerol and 253 kDa and 2.7 for CGP, respectively; melting temperatures ranged between 130 and 140°C in both setups. Supplying γ-butyrolactone as 4-hydroxybutyrate (4HB) precursor resulted in a poly(R)-3-hydroxybutyrate-co-(R)-3-hydroxyvalerate-co-4-hydroxybutyrate (PHBHV4HB) terpolyester containing 3HV (0.12 mol/mol) and 4HB (0.05 mol/mol) in the poly(R)-3-hydroxybutyrate (PHB) matrix; in addition, this process runs without sterilization of the bioreactor. The terpolyester displayed reduced melting (melting endotherms at 122 and 137°C) and glass transition temperature (2.5°C), increased molar mass (391 kDa), and a polydispersity similar to the copolyesters.
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► Pseudomonas chlororaphis was investigated for production of mcl-PHA latex under controlled conditions on bioreactor scale ► A surplus material, namely saturated biodiesel fraction ...from animal waste lipids, was used as the sole carbon source ► A detailed kinetic analysis of the bioprocess is provided ► Productivity of the mcl-PHA latex is competitive to other mcl-PHA producing organisms on expensive carbon sources.
A novel description of mcl-PHA biosynthesis by Ps. chlororaphis from tallow-based biodiesel as an inexpensive carbon feed stock is presented. Fermentation protocols, kinetic analysis, an efficient product recovery strategy, and product characterization are included. Maximum specific growth rates (μmax.) of 0.08 h−1, 0.10 h−1 and 0.13 h−1, respectively, were achieved in three different fermentation set-ups. Volumetric productivity for mcl-PHA amounted to 0.071g/L h, 0.094g/L h and 0.138g/L h, final intracellular PHA contents calculated from the sum of active biomass and PHA from 22.1 to 29.4wt.-%, respectively. GC-FID analysis showed that the obtained biopolyester predominantly consists of 3-hydroxyoctanoate and 3-hydroxydecanoate, and, to a minor extent, 3-hydroxydodecanoate, 3-hydroxynonanoate, 3-hydroxyhexanoate, and 3-hydroxyheptanoate monomers. The overall distribution of the monomers remained similar, regardless to working volumes, biodiesel concentrations and pre-treatment of the inoculum.
► Valuable mathematical models for PHA production by Cupriavidus necator on combined substrates. ► PHA production on waste substrates from biodiesel (FAME and glycerol). ► New low structured model ...for fed-batch fermentation on glucose with glycerol. ► New low structured model for fed-batch fermentation on FAME with valeric acid. ► In silico optimized feeding of C-sources and PHB/PHBV content by mathematical models.
Two low structured mathematical models for fed-batch production of polyhydroxybutyrate and polyhydroxybutyrate-co-hydroxyvalerate by Cupriavidus necator DSM 545 on renewable substrates (glycerol and fatty acid methyl esters-FAME) combined with glucose and valeric acid, were established. The models were used for development/optimization of feeding strategies of carbon and nitrogen sources concerning PHA content and polymer/copolymer composition. Glycerol/glucose fermentation featured a max. specific growth rate of 0.171h−1, a max. specific production rate of 0.038h−1 and a PHB content of 64.5%, whereas the FAME/valeric acid fermentation resulted in a max. specific growth rate of 0.046h−1, a max. specific production rate of 0.07h−1 and 63.6% PHBV content with 4.3% of 3-hydroxyvalerate (3HV) in PHBV. A strong inhibition of glycerol consumption by glucose was confirmed (inhibition constant ki,G=4.28×10−4gL−1). Applied concentration of FAME (10–12gL−1) positively influenced on PHBV synthesis. HV/PHBV ratio depends on applied VA concentration.
As major part of the phytoplankton, microalgae are pivotal for the global food chain. Their exceptional capacity for CO2-fixation illustrates their indispensable significance to sustain earth's ...ecosystems. Further, they play a still underestimated role in eliminating contaminants from various environments. In addition to ecological benefit, many microalgal species exhibit high nutritional value and, at the same time, generate valued bio-products: Pigments, lipids, bioactive compounds, certain polysaccharides, bio-hydrogen and even biopolyesters with plastic-like properties have the potential for successful market penetration.
Three substantial pigment groups, namely chlorophylls, carotenoids, and phycobilins, are essential for light harvesting and CO2 fixation. Those pigments will most likely undergo quick commercial success in “functional food”, cosmetics, aquaculture, pharmaceuticals, or food technology.
Due to often high contents of polyunsaturated fatty acids essential for human metabolism, microalgal oils can be commercialized as health food and in the pharmaceutical and therapeutic field, creating much higher value than by converting them to biofuel.
Finally, algal biomass remaining as residue after product recovery can be used as forage, biogas feedstock or biofertilizer. This utilization is needed for balancing the material- and energy cycles of the entire process. Thus, technology platforms following the principles of bio-refineries shall be established to enable the design of sustainable and economically feasible production of marketable microalgal products.
•Microalgae provide versatile unicellular factories for various valued bioproducts.•Pigments, PUFAs, bioactive compounds, and PHA are described.•Alternative “green energy carriers” can be generated by microalgae.•Market success requires the enhancement of microalgal cultivation conditions.
•PHB production by Cupriavidus necator DSM 545 on glycerol.•Developed mathematical model well predicts real cultivation of C. necator on glycerol.•Glycerol-substrate inhibition proposed by Yanno was ...upgraded on double substrate kinetic.•Inoculum concentration is the most influential factor regarding PHB productivity.•Carefully chosen C/N ratio prevents biomass death but does not antagonize PHB synthesis.
Glycerol was utilized by Cupriavidus necator DSM 545 for production of poly-3-hydroxybutyrate (PHB) in fed-batch fermentation. Maximal specific growth rates (0.12 and 0.3h−1) and maximal specific non-growth PHB production rate (0.16gg−1h−1) were determined from two experiments (inocula from exponential and stationary phase). Saturation constants for nitrogen (0.107 and 0.016gL−1), glycerol (0.05gL−1), non-growth related PHB synthesis (0.011gL−1) and nitrogen/PHB related inhibition constant (0.405gL−1), were estimated. Five relations for specific growth rate were tested using mathematical models. In silico performed optimization procedures (varied glycerol/nitrogen ratio and feeding) has resulted in a PHB content of 70.9%, shorter cultivation time (23h) and better PHB yield (0.347gg−1). Initial concentration of biomass 16.8gL−1 and glycerol concentration in broth between 3 and 5gL−1 were decisive factors for increasing of productivity.
mcl-PHA biosynthesis by Pseudomonas citronellolis from tallow-based biodiesel as inexpensive carbon feed stock was accomplished. Fermentation protocols, kinetic analysis, an efficient product ...recovery strategy, and a detailed product characterization are presented.
A maximum specific growth rate, μmax. of 0.10 and 0.08h−1, respectively, was achieved in two different fermentation set-ups. Volumetric productivity for mcl-PHA amounted to 0.036g/Lh and 0.050g/Lh, final intracellular PHA contents calculated from the sum of active biomass and PHA to 20.1 and 26.6wt.%, respectively. GC-FID analysis showed that the obtained biopolyester predominantly consists of 3-hydroxyoctanoate and 3-hydroxydecanoate, and, to a minor extent, 3-hydroxydodecanoate, 3-hydroxynonanoate, 3-hydroxyhexanoate, and 3-hydroxyheptanoate monomers. This was confirmed by 1H- and 13C NMR, also evidencing the occurrence of low quantities of unsaturated and 3-hydroxyvalerate building blocks. High purity of the recovered materials was proofed by elemental analysis. Regarding the results from thermogravimetric analysis, differential scanning calorimetry and molecular mass determination, results were in a range typical for this type of PHA (1st fermentation: decomposition temperature Td=296°C, peak of melting range Tm=48.6°C; glass transition temperature Tg=−46.9°C, degree of crystallinity Xc=12.3%, Mw=66,000, Mn=35,000, dispersity index Pi=1.9; 2nd fermentation: Td=295°C, Tm=53.6°C, Tg=-43.5°C, Xc=10.4%, Mw=78,000, Mn=196,000, Pi=2.5).
Over the past decade optical quality CVD diamond has found its way into many high -power laser applications. In these demanding high -power applications, diamond is able to succeed due to its ...extraordinary physical properties. The highest thermal conductivity of any known material, low absorption over a broad spectrum, and exceptional strength all contribute towards an excellent optical material. As diamond is a high refractive index material, a solution is generally needed to manage Fresnel reflections from polished diamond surfaces. This is especially important for high -power laser applications, where even just a few percent of total power reflected must be carefully handled. Currently the industry standard solution is to apply thin film coatings to the polished diamond surfaces, and for many applications this is a perfectly adequate solution. In fact it has been shown that thin film coated diamond windows greatly outperform similar thin film coated windows 1. For the most demanding and highest power density applications, applications that are pushing the boundaries of technology, thin film coatings can be a limitation. This is due to the relatively poor thermal properties of the coating materials; at high enough power -density the rate of heat generation through absorption overwhelms the ability of the coating to dissipate heat, leading to thermal runaway and often catastrophic failures. Laser Induced Damage Threshold (LIDT), a common measure of an optic's power handling capability, describes the power density at which this tipping point occurs. Thankfully nature has demonstrated an alternative solution towards eliminating reflections. Close inspection of the eyes of moths reveals a tightly packed array of conical structures on a sub -micron scale. In nature these tightly packed arrays eliminate reflections that otherwise may give the moth away to predators. Likewise, in demanding laser applications this "moth -eye" solution can be applied to eliminate Fresnel reflections. The advantage to this approach is that the LIDT of a moth -eye optic is limited by only the material properties of the optic itself, rather than by the material properties of a thin film coating. Given diamond's extraordinary material properties, the moth -eye approach is especially advantageous when creating a diamond optic.
The oxidative ratio (OR) of organic material integrates the ratio of CO2 sequestered in biomass vs. O2 produced over longer timescales, but the temporal and spatial variability within a single ...ecosystem has received very limited attention. Between October 2017 and October 2019, we repeatedly sampled leaves, twigs, bark, outer stem wood, understorey vegetation and litter in a temperate beech forest close to Leinefelde (Germany) for OR measurements across a seasonal and spatial gradient. Plant component OR ranged from 1.004 ± 0.010 for fine roots to 1.089 ± 0.002 for leaves. Inter- and intra-annual differences for leaf and twig OR exist, but we found no correlation with sampling height within the canopy. Leaf OR had the highest temporal variability (minimum 1.069 ± 0.007, maximum 1.098 ± 0.002). This was expected, since leaf biomass of deciduous trees only represents the signal of the current growing season, while twig, stem and litter layer OR integrate multiple years. The sampling years 2018 and 2019 were unusually hot and dry, with low water availability in the summer, which could especially affect the August leaf OR. Total above-ground OR is dominated by the extremely stable stem OR and shows little variation (1.070 ± 0.02) throughout the two sampling years, even when facing extreme events.
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