This study investigates the techno-economic viability of synthesizing polyhydroxyalkanoates (PHA) from lignocellulosic biomass through the utilization of extremophilic microorganisms, framed within the context of Next-Generation Industrial Biotechnology (NGIB). Microbial platforms characterized by halophilic and thermophilic properties, specifically Halomonas halophila and Caldimonas thermodepolymerans, were utilized to tackle issues related to sterility demands, process efficiency, and sustainability. Scenarios incorporating rice straw and discarded softwood, which are low-cost feedstocks that do not interfere with the human food supply, were modeled as resources for PHA biosynthesis. Additionally, a comparison was conducted between traditional chloroform extraction methods and environmentally friendly hypotonic lysis for the recovery of PHA from extremophilic microbial cultures prone to this treatment. Economic indicators such as net present value, internal rate of return, and payback period, were analyzed to evaluate the economic viability of the process. Findings indicate that the incorporation of extremophilic microorganisms alongside waste valorization techniques could make PHA production economically viable, thereby decreasing dependence on fossil-derived plastics while simultaneously addressing ecological issues. This initial study highlights the necessity for subsequent scale-up investigations to authenticate the proposed methodology, which shows potential for the sustainable production of PHA.
- Klíčová slova
- Caldimonas thermodepolymerans, Halomonas halophila, Polyhydroxyalkanoates, Process simulation, Techno-economic assessment,
- MeSH
- biomasa MeSH
- biotechnologie metody ekonomika MeSH
- fermentace MeSH
- Halomonas metabolismus MeSH
- lignin * metabolismus MeSH
- polyhydroxyalkanoáty * biosyntéza MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- lignin * MeSH
- lignocellulose MeSH Prohlížeč
- polyhydroxyalkanoáty * MeSH
The limited number of well-characterised model bacteria cannot address all the challenges in a circular bioeconomy. Therefore, there is a growing demand for new production strains with enhanced resistance to extreme conditions, versatile metabolic capabilities and the ability to utilise cost-effective renewable resources while efficiently generating attractive biobased products. Particular thermophilic microorganisms fulfil these requirements. Non-virulent Gram-negative Caldimonas thermodepolymerans DSM15344 is one such attractive thermophile that efficiently converts a spectrum of plant biomass sugars into high quantities of polyhydroxyalkanoates (PHA)-a fully biodegradable substitutes for synthetic plastics. However, to enhance its biotechnological potential, the bacterium needs to be 'domesticated'. In this study, we established effective homologous recombination and transposon-based genome editing systems for C. thermodepolymerans. By optimising the electroporation protocol and refining counterselection methods, we achieved significant improvements in genetic manipulation and constructed the AI01 chassis strain with improved transformation efficiency and a ΔphaC mutant that will be used to study the importance of PHA synthesis in Caldimonas. The advances described herein highlight the need for tailored approaches when working with thermophilic bacteria and provide a springboard for further genetic and metabolic engineering of C. thermodepolymerans, which can be considered the first model of thermophilic PHA producer.
- Klíčová slova
- Caldimonas thermodepolymerans, gene deletion, genetic engineering, polyhydroxyalkanoates, thermophiles,
- MeSH
- editace genu * metody MeSH
- elektroporace MeSH
- genom bakteriální MeSH
- homologní rekombinace MeSH
- metabolické inženýrství metody MeSH
- polyhydroxyalkanoáty * biosyntéza metabolismus MeSH
- transpozibilní elementy DNA MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- polyhydroxyalkanoáty * MeSH
- transpozibilní elementy DNA MeSH
Lignocellulose is a major biopolymer in plant biomass with a complex structure and composition. It consists of a significant amount of high molecular aromatic compounds, particularly vanillin, syringeal, ferulic acid, and muconic acid, that could be converted into intracellular metabolites such as polyhydroxyalkanoates (PHA) and hydroxybutyrate (PHB), a key component of bioplastic production. Several pre-treatment methods were utilized to release monosaccharides, which are the precursors of the relevant pathway. The consolidated bioprocessing of lignocellulose-capable microbes for biomass depolymerization was discussed in this study. Carbon can be stored in a variety of forms, including PHAs, PHBs, wax esters, and triacylglycerides. From a biotechnology standpoint, these compounds are quite adaptable due to their precursors' utilization of hydrogen energy. This study lays the groundwork for the idea of lignocellulose valorization into value-added products through several significant dominant pathways.
- Klíčová slova
- bioplastics production, consolidated bioprocessing, kitchen waste, lignocellulose depolymerization, polyhydroxyalkanoates (PHA), renewable aromatics,
- MeSH
- biomasa MeSH
- biopolymery chemie metabolismus MeSH
- lignin * chemie metabolismus MeSH
- odpadní produkty MeSH
- polyhydroxyalkanoáty chemie biosyntéza metabolismus MeSH
- potraviny MeSH
- ztráty potravin a plýtvání s nimi MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
- Názvy látek
- biopolymery MeSH
- lignin * MeSH
- lignocellulose MeSH Prohlížeč
- odpadní produkty MeSH
- polyhydroxyalkanoáty MeSH
- ztráty potravin a plýtvání s nimi MeSH
Polyhydroxyalkanoates (PHAs) are intracellular biopolymers that microorganisms use for energy and carbon storage. They are mechanically similar to petrochemical plastics when chemically extracted, but are completely biodegradable. While they have potential as a replacement for petrochemical plastics, their high production cost using traditional carbon sources remains a significant challenge. One potential solution is to modify heterotrophic PHA-producing strains to utilize alternative carbon sources. An alternative approach is to utilize methylotrophic or autotrophic strains. This article provides an overview of bacterial strains employed for PHA production, with a particular focus on those exhibiting the highest PHA content in dry cell mass. The strains are organized according to their carbon source utilization, encompassing autotrophy (utilizing CO2, CO) and methylotrophy (utilizing reduced single-carbon substrates) to heterotrophy (utilizing more traditional and alternative substrates).
- Klíčová slova
- PHA, PHB, autotrophy, heterotrophy, methylotrophy,
- MeSH
- Bacteria * metabolismus MeSH
- polyhydroxyalkanoáty * biosyntéza metabolismus MeSH
- uhlík metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
- Názvy látek
- polyhydroxyalkanoáty * MeSH
- uhlík MeSH
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.
- Klíčová slova
- Hydrolysate, Lignocellulosic material, Polyhydroxyalkanoates, Pretreatments, Waste valorization,
- MeSH
- Bacillus cereus metabolismus MeSH
- Burkholderia cepacia metabolismus MeSH
- Cupriavidus necator metabolismus MeSH
- jedlá semena chemie metabolismus MeSH
- polyhydroxyalkanoáty biosyntéza chemie MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- polyhydroxyalkanoáty MeSH
AIM: This study aimed at unprecedented physical and chemical evaluation of the 'green plastics' polyhydroxyalkanoates (PHAs), in an extremely halotolerant Halomonas elongata strain 2FF under high-salt concentration. METHODS AND RESULTS: The investigated bacterial strain was isolated from the surface water of the hypersaline Fără Fund Lake. The 16S rRNA gene sequence phylogeny and phenotypic analysis indicated that the isolate belonged to H. elongata. PHA inclusions were observed by Sudan Black B, Nile Red staining, and transmission electron microscopy during growth at high salinity (10%, w/v, NaCl) on 1% (w/v) d-glucose. The produced polymer was quantitatively and qualitatively assessed using crotonic acid assay, elemental analysis, Fourier transform infrared and Raman spectroscopies. Additionally, X-ray powder diffraction, 1 H-NMR spectroscopy, and differential scanning calorimetry were applied. The investigations showed that the intracellular polymer was polyhydroxybutyrate (PHB) of which the strain produced up to 40 wt% of total cell dry weight after 48 h. The analysis of phaC gene from the isolated H. elongata strain indicated that the encoded PHA synthase belongs to Class I PHA synthase family. CONCLUSIONS: Overall, our investigations pointed out that the halotolerant H. elongata strain 2FF was capable to produce significant amounts of PHB from d-glucose, and PHAs from various carbon substrates at high-salt concentrations. SIGNIFICANCE AND IMPACT OF THE STUDY: The tested strain showed the ability for significant production of natural, biodegradable polymers under nutrient limitation and hypersaline conditions suggesting its potentiality for further metabolic and molecular investigations towards enhanced biopolymer production. Additionally, this study reports on the unprecedented use of Raman and XPRD techniques to investigate PHAs of an extremely halotolerant bacterium, thus expanding the repertoire of physical methods to study green plastics derived from extremophilic microorganisms.
- Klíčová slova
- Halomonas sp., green plastics, halotolerant bacteria, high salinity, nutrient limitation, polyhydroxybutyrate,
- MeSH
- biopolymery biosyntéza MeSH
- chlorid sodný metabolismus MeSH
- fylogeneze MeSH
- Halomonas genetika izolace a purifikace metabolismus MeSH
- jezera mikrobiologie MeSH
- polyhydroxyalkanoáty biosyntéza chemie MeSH
- RNA ribozomální 16S genetika MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Rumunsko MeSH
- Názvy látek
- biopolymery MeSH
- chlorid sodný MeSH
- polyhydroxyalkanoáty MeSH
- RNA ribozomální 16S MeSH
The current commercial production of polyhydroxyalkanoates (PHA) is based on heterotrophic bacteria, using organic carbon sources from crops. To avoid the competition with food and feed production, cyanobacteria, metabolising PHA from carbon dioxide can be used. This research focuses on the investigation of the thermal and rheological properties of PHA polymers accumulated by Synechocystis salina, which had been cultivated in digestate supernatant and a mineral medium. The dried bacterial cells had a polymer content of 5.5-6.6%. The relevance of the derived PHA polymers for the common melt polymer processing was correlated with their molecular mass distribution as well as with their thermal and rheological properties. The determined thermal and rheological properties showed that PHA polymers accumulated by S. salina on digestate supernatant or mineral medium are comparable with the commercial available poly(3-hydroxybutyrate). However, the results showed that PHA polymers in general require modification before melt processing to increase their stability in the molten state.
- Klíčová slova
- Digestate, Polyhydroxyalkanoates, Synechocystis salina,
- MeSH
- kultivační média chemie metabolismus MeSH
- molekulová hmotnost MeSH
- oxid uhličitý metabolismus MeSH
- polyhydroxyalkanoáty biosyntéza chemie MeSH
- Synechocystis metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- kultivační média MeSH
- oxid uhličitý MeSH
- polyhydroxyalkanoáty MeSH
UNLABELLED: The chicken feather hydrolysate (FH) has been tested as a potential complex nitrogen source for the production of polyhydroxyalkanoates by Cupriavidus necator H16 when waste frying oil was used as a carbon source. The addition of FH into the mineral salt media with decreased inorganic nitrogen source concentration improved the yields of biomass and polyhydrohyalkanoates. The highest yields were achieved when 10 vol.% of FH prepared by microwave-assisted alkaline hydrolysis of 60 g l-1 feather was added. In this case, the poly(3-hydroxybutyrate) (PHB) yields were improved by more than about 50% as compared with control cultivation. A positive impact of FH was also observed for accumulation of copolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) when sodium propionate was used as a precursor. The copolymer has superior processing and mechanical properties in comparison with PHB homopolymer. The application of FH eliminated the inhibitory effect of propionate and resulted in altered content of 3-hydroxyvalerate (3HV) in copolymer. Therefore, the hydrolysed feather can serve as an excellent complex source of nitrogen for the polyhydroxyalkanoates (PHA) production. Moreover, by the combination of two inexpensive types of waste, such as waste frying oil and feather hydrolysate, it is possible to produce PHA with substantially improved efficiency and sustainability. SIGNIFICANCE AND IMPACT THE STUDY: Millions of tons of feathers, important waste product of poultry-processing industry, are disposed off annually without any further benefits. Thus, there is an inevitable need for new technologies that enable ecologically and economically sensible processing of this waste. Herein, we report that alkali-hydrolysed feathers can be used as a complex nitrogen source considerably improving polyhydroxyalkanoates production on waste frying oil employing Cupriavidus necator.
- Klíčová slova
- Cupriavidus necator, complex nitrogen source, feather valorization, poly(3-hydroxybutyrate), polyhydroxyalkanoates, waste frying oil,
- MeSH
- aminokyseliny analýza MeSH
- biomasa MeSH
- Cupriavidus necator metabolismus MeSH
- dusík metabolismus MeSH
- hydrolýza MeSH
- hydroxybutyráty metabolismus MeSH
- kur domácí MeSH
- kyseliny pentanové metabolismus MeSH
- odpad tekutý - odstraňování MeSH
- oleje rostlin metabolismus MeSH
- peří chemie MeSH
- polyestery metabolismus MeSH
- polyhydroxyalkanoáty biosyntéza MeSH
- uhlík metabolismus MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- aminokyseliny MeSH
- beta-hydroxyvaleric acid MeSH Prohlížeč
- dusík MeSH
- hydroxybutyráty MeSH
- kyseliny pentanové MeSH
- oleje rostlin MeSH
- poly-beta-hydroxybutyrate MeSH Prohlížeč
- polyestery MeSH
- polyhydroxyalkanoáty MeSH
- uhlík MeSH
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.
- MeSH
- biopaliva mikrobiologie MeSH
- biotechnologie metody MeSH
- extrakce kapalina-kapalina metody MeSH
- karotenoidy biosyntéza chemie izolace a purifikace MeSH
- káva chemie mikrobiologie MeSH
- odpadky - odstraňování metody MeSH
- polyhydroxyalkanoáty biosyntéza chemie izolace a purifikace MeSH
- zachování přírodních zdrojů metody MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
- Názvy látek
- biopaliva MeSH
- karotenoidy MeSH
- káva MeSH
- polyhydroxyalkanoáty MeSH
Spent coffee grounds (SCG), an important waste product of the coffee industry, contain approximately 15 wt% of coffee oil. The aim of this work was to investigate the utilization of oil extracted from SCG as a substrate for the production of poly(3-hydroxybutyrate) (PHB) by Cupriavidus necator H16. When compared to other waste/inexpensive oils, the utilization of coffee oil resulted in the highest biomass as well as PHB yields. Since the correlation of PHB yields and the acid value of oil indicated a positive effect of the presence of free fatty acids in oil on PHB production (correlation coefficient R (2) = 0.9058), superior properties of coffee oil can be probably attributed to the high content of free fatty acids which can be simply utilized by the bacteria culture. Employing the fed-batch mode of cultivation, the PHB yields, the PHB content in biomass, the volumetric productivity, and the Y P/S yield coefficient reached 49.4 g/l, 89.1 wt%, 1.33 g/(l h), and 0.82 g per g of oil, respectively. SCG are annually produced worldwide in extensive amounts and are disposed as solid waste. Hence, the utilization of coffee oil extracted from SCG is likely to improve significantly the economic aspects of PHB production. Moreover, since oil extraction decreased the calorific value of SCG by only about 9 % (from 19.61 to 17.86 MJ/kg), residual SCG after oil extraction can be used as fuel to at least partially cover heat and energy demands of fermentation, which should even improve the economic feasibility of the process.
- MeSH
- Cupriavidus necator růst a vývoj metabolismus MeSH
- káva chemie MeSH
- oleje rostlin izolace a purifikace metabolismus MeSH
- polyhydroxyalkanoáty biosyntéza MeSH
- techniky vsádkové kultivace MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- káva MeSH
- oleje rostlin MeSH
- polyhydroxyalkanoáty MeSH
