Biopolymer Production Research Articles

Highly efficient liquid-phase oxidation of 5-hydroxymethylfurfural over Co-Cu/activated carbon catalysts

Selective oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) is a key reaction in biopolymer production. A non-noble metal catalyst and mild reaction conditions are highlighted in this work. Co-Cu nanoparticles supported on activated carbon (Co-Cu/AC) were introduced in the liquid-phase oxidation of HMF. The catalysts were prepared via a co-impregnation method, followed by reduction with hydrazine. The presence of the Cu promoter resulted in dispersion of the metal particles. The good distribution and small crystal size of Co3O4 significantly increased the active surface area and enhanced the catalytic activity. In addition, the presence of CuO synergized with the oxidation ability of the Co catalyst to increase the FDCA yield. The catalytic activity at different reaction temperatures, reaction times, catalyst loadings, and Co:Cu ratios revealed that the highest selectivity for FDCA (92%) was achieved using the 4Co-Cu/AC catalyst. According to the proposed reaction mechanism, the redox reaction between Cu2+/Cu+ and Co3+/Co4+, together with H2O2 as the oxidant, promotes the complete oxidation of HMF to FDCA.

Rapid combinatorial rewiring of metabolic networks for enhanced poly(3-hydroxybutyrate) production in Corynebacterium glutamicum

BackgroundThe disposal of plastic waste is a major environmental challenge. With recent advances in microbial genetic and metabolic engineering technologies, microbial polyhydroxyalkanoates (PHAs) are being used as next-generation biomaterials to replace petroleum-based synthetic plastics in a sustainable future. However, the relatively high production cost of bioprocesses hinders the production and application of microbial PHAs on an industrial scale.ResultsHere, we describe a rapid strategy to rewire metabolic networks in an industrial microorganism, Corynebacterium glutamicum, for the enhanced production of poly(3-hydroxybutyrate) (PHB). A three-gene PHB biosynthetic pathway in Rasltonia eutropha was refactored for high-level gene expression. A fluorescence-based quantification assay for cellular PHB content using BODIPY was devised for the rapid fluorescence-activated cell sorting (FACS)-based screening of a large combinatorial metabolic network library constructed in C. glutamicum. Rewiring metabolic networks across the central carbon metabolism enabled highly efficient production of PHB up to 29% of dry cell weight with the highest cellular PHB productivity ever reported in C. glutamicum using a sole carbon source.ConclusionsWe successfully constructed a heterologous PHB biosynthetic pathway and rapidly optimized metabolic networks across central metabolism in C. glutamicum for enhanced production of PHB using glucose or fructose as a sole carbon source in minimal media. We expect that this FACS-based metabolic rewiring framework will accelerate strain engineering processes for the production of diverse biochemicals and biopolymers.

Biodegradable Ecoflex encapsulated bacterial cellulose/polypyrrole strain sensor detects motion with high sensitivity, flexibility and scalability

Microbial production of biopolymers are non-standard materials in wearable resistive-strain sensors, despite established and desirable scale-up, rheological, ecological and economical properties. In this study, we report a biodegradable bacterial cellulose (BC) crack-based strain sensor prepared by in-situ fermentation with polypyrrole (PPy) and encapsulation with Ecoflex (EF) for human-interactive sensing. In-situ microbial fermentation method not only optimizes the distribution state of PPy but also constructs the three-dimensional conductive network, which contributing to the formation of crack-based sensing mechanism. The as-prepared BC/Ppy@EF strain sensor exhibits high sensitivity (gauge factor of 3.21–4.86), large strain ranges (up to 90% strain), ultralow strain detection limit (0.05%) and remarkable long-term stability without any distinct decline in sensitivity after a constant applied stretching of 90% for 1000 cycles. The strain sensor accurately detected a full range of body motions, including subtle vital signs like pulse, respiration and vocalizations, and was successfully integrated into textiles for human–computer interactions. Consequently, this study provides empirical value for the bio-fabrication and all-green construction design of wearable devices, as well as the development of human–computer interaction.

Optimisation of alkaline pretreatment of spent coffee grounds for microbial oil production by Cryptococcus curvatus

In a world of finite resources, the transition to a sustainable post-fossil resources economy is essential. Within this concept, spent coffee grounds (SCGs) could be used for the production of bio-based chemicals, biopolymers and value-added products. Lipids and phenolics were initially extracted from SCGs. Alkaline pretreatment of the remaining SCGs solids has been optimised in this study via Central Composite Design to maximise lignin removal and overall sugar to polysaccharide conversion yield. The optimal SCGs pretreatment conditions were 0.06% (w/v) NaOH and 99.5 °C resulting in 35.7% lignin removal at 60 min pretreatment duration with low glucan and hemicellulose losses (ca. 2.5%). Enzymatic hydrolysis of the remaining SCGs alkaline pretreated solids resulted in 79.4% glucan, 74.5% mannan and 54.8% hemicellulose hydrolysis yield. The SCGs hydrolysate was used as fermentation feedstock in bioreactor cultures of Cryptococcus curvatus resulting in 36.1 g/L microbial oil with 0.25 g/g yield and 0.41 g/(L∙h) productivity. The total dry weight reached 62.7 g/L corresponding to 57.5% (w/w) intracellular lipid content. The microbial oil was rich in oleic acid (55.6%) followed by palmitic acid (18.9%) and stearic acid (14.0%). The proposed process led to the production of 7.81 g microbial oil per 100 g antioxidant- and oil-free SCGs.

Technoeconomic Assessment of Biopolymer Production from Crustacean Waste with the UK as a Case Study

Marine pollution has increased in recent decades, largely due to the proliferation of seafood processing plants and the improper disposal of their associated waste streams. The waste streams consist mainly of shells that are composed of chitin, which is the most abundant aminopolysaccharide biopolymer in nature. Recognizing the value of chitin, the potential for the valorization of crustacean waste for chitin production was explored. In this regard, biogenic crab waste was subjected to chemical-only, enzymatic–chemical, and microbial treatments for chitin production. The results were employed as inputs for process simulation as a precursor to undertaking performance assessments. This study subsequently showed that the net present values (NPVs) of the chemical-only, enzyme–chemical, and microbial chitin production pathways were GBP 118.63 million, GBP 115.67 million, and GBP 132.34 million, respectively, indicating that the microbial chitin production pathway constituted the most appropriate technology for future investment. Employing a cost–benefit (CB) analysis, the CB ratios for the chemical-only, enzymatic–chemical, and microbial approaches were determined to be 7.31, 0.45, and 0.23, respectively. These results reinforced the dominant status of the microbial approach for chitin production from crab waste as the preferred valorization strategy. This study was able to provide information regarding the implications of executing alternative scenarios for crustacean waste.

Sustainable Vegetable Oil-Based Biomaterials: Synthesis and Biomedical Applications.

One of the main criteria for ecological sustainability is that the materials produced for common use are green. This can include the use of biomaterials and materials that are environmentally friendly, biodegradable and produced at low cost. The exploration of natural resources as sustainable precursors leads to the production of biopolymers that are useful for 3D printing technology. Recently, waste vegetable oils have been found to be a good alternative source for the production of biopolymers in various applications from the engineering to the biomedicine. In this review, the processes for the synthesis of vegetable oil-based biomaterials are described in detail. Moreover, the functionalization strategies to improve the mechanical properties of these materials and the cell-material interaction for their potential use as micro-structured scaffolds in regenerative medicine are discussed.

Circular PHB production via Paraburkholderia sacchari cultures using degradation monomers from PHB-based post-consumer bioplastics as carbon sources

The circular and sustainable production of biopolymers necessitates the development of efficient chemical and biological recycling of post-consumer bioplastics. Chemical or enzymatic degradation of poly(3-hydroxybutyrate) (PHB) based bioplastics will result into crotonic acid (CA), 3-hydoxybutyrate methyl ester (3HMB) and 3-hydroxybutyrate (3HB). These PHB-derived monomers should be subsequently used as carbon sources for circular PHB production. This study presents results of shake flask fermentations carried out by Paraburkholderia sacchari using CA, 3HB and 3HMB for PHB production. Sequential addition of 3HB led to 6.5 g/L total dry weight and 2.5 g/L PHB with 0.26 g/g yield, which was slightly higher than the respective values achieved on glucose. CA consumption was not observed neither when it was added at the beginning of fermentation nor when it was supplied together with glucose. CA was only consumed when bacterial growth was initially carried out on glucose. Bacterial growth and PHB production were lower in 3HMB. The BioSupPack project aims to develop circular biological recycling of PHB-based post-consumer bioplastics via enzymatic hydrolysis and sequential fermentation of monomers into new PHB. The production of PHB by P. sacchari shows that the development of such circular process is feasible.

Insights of Bioeconomy: Biopolymer Evaluation Based on Sustainability Criteria

Abstract Sustainable development in the agriculture sector can be boosted by integrating a sustainable bioeconomy and transforming renewable resources into added-value products. There are various methods to determine, measure, and compare the extent of sustainability. We promote the bioeconomy concept by utilizing agricultural waste in biopolymers considering the sustainable development in the agriculture sector. This research aims to evaluate biopolymer alternatives based on sustainability criteria and indicators using the integrated multi-criteria decision analysis approach under the sustainability umbrella. We evaluated the PLA, PHA/PHB, starch, protein, and cellulose-based biopolymers. As a result, the cellulose-based biopolymer shows the best performance. The research findings provide valuable information to establish a sustainable pathway for biopolymer production for industries.

Pilot scale production of Crocosphaera chwakensis CCY0110 and evaluation of its biomass nutritional potential

In recent years, the large-scale cultivation and commercialization of microalgae/cyanobacteria biomasses have become a worldwide trend, mainly directed to the animal and human nutrition markets due to their outstanding nutritional value. However, only a very limited number are currently classified as food ingredients by Food Safety regulators worldwide. Crocosphaera chwakensis CCY0110 is a marine unicellular cyanobacterium that produces a promising and versatile extracellular carbohydrate polymer (Cyanoflan). Therefore, envisaging a biorefinery approach with a multi-product stream (zero-waste), C. chwakensis biomass was for the first time cultivated at pilot-scale in a 120 L flat panel photobioreactor and its nutritional composition was evaluated. The results obtained revealed high protein and fat-soluble vitamins content (∼54 g of protein, 6 mg vitamin A and 25 mg vitamin E per 100 g biomass dry weight), coupled with a balanced amount of essential amino acids and n-3 polyunsaturated fatty acids (36 % of total fatty acids). Moreover, C. chwakensis biomass can also be considered as a great source of important minerals, such as potassium (3 g per 100 g DW), magnesium (0.5 g per 100 g DW) and iron (95 mg per 100 g DW), as well as phycocyanin, a high-value blue pigment with a wide array of applications. Overall, C. chwakensis biomass displays a nutritional composition that outdo traditional feedstocks and competes with already established and commercially available cyanobacteria and microalgae. This work highlights the potential of C. chwakensis as a multi-product cyanobacterium for blue bioeconomy, combining the production of a promising biopolymer with biomass valorization.

The Effect of the Extrusion Method on Processing and Selected Properties of Poly(3-hydroxybutyric-co-3-hydroxyvaleric Acid)-Based Biocomposites with Flax and Hemp Fibers.

The paper presents a comparative analysis of two extrusion methods of biocomposites with a poly(3-hydroxybutyrate-co-3-hydroxyvalerate acid) (PHBV) matrix filled with flax and hemp fibers in terms of biopolymer production, its processing in the further injection process, and an evaluation of the mechanical and functional properties of the products. Biocomposites containing 15% by weight of the filler were produced using single- and twin-screw extruders. The biocomposites were then processed by injection molding and then, among other things, the pressures in the mold cavity during processing were analyzed. The produced samples were tested by means of the following tests: uniaxial tensile strength, hardness, and impact tensile strength. The biocomposite's microstructure was also analyzed using scanning electron microscopy (SEM), as were the shrinkage and water absorption of the manufactured products. In addition, thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) tests were performed. It was found that the extrusion method changed significantly the geometry of the filler fibers and the processing capabilities of the manufactured materials. Significant differences in the mechanical and functional properties of the obtained biocomposite products were also found. On their basis, the advantages and disadvantages of both extrusion methods were discussed. Most of the obtained properties of injection products indicate the choice of single-screw extrusion. The products were characterized by slightly better mechanical properties and lower processing shrinkage. In turn, composites obtained by the screw method were characterized by lower water absorption and lower viscosity of the composite during injection molding.

Evaluating the effect of aeration rate on quorum quenching membrane bioreactors: Performance of activated sludge, membrane fouling behavior, and the energy consumption analysis

Microbial quorum quenching (QQ) has recently been proven to be an efficient approach to mitigate biofouling in membrane bioreactors (MBRs). It can reduce biopolymers production and improve sludge conditions. Also, aeration intensity is considered to be directly interconnected with membrane fouling. In this study, the impact of aeration rate on the performance, membrane fouling, and the energy consumption of quorum quenching membrane bioreactor (QQ-MBR) and conventional membrane bioreactor (C-MBR) were exposed. We investigated the synergistic effects of aeration intensity and QQ on membrane fouling control in MBRs and analyzed the energy consumption of reactors under different conditions. QQ was found to mitigate biofouling significantly, but the membrane fouling mitigation efficiency was lowest (only 17.9 %) at high aeration intensity. Moreover, QQ reduced the content of SMP and EPS in sludge (over 20 % decreasing), and a better QQ performance was observed at middle aeration intensity. As for energy consumption, the most energy was consumed at high aeration intensity. QQ can minimize the aeration intensity required for the regular operation of MBR, thereby optimizing the energy consumption.

Bio-refinery of xylose processing wastes for green polymalic acid production and l-malic acid recovery by engineered Aureobasidium pullulans in a non-waste-disposal system

Commercial carboxylic acid fermentation is susceptible to CaSO4 solid waste pollution owing to the heavy use of neutralizer CaCO3. Polymalic acid (PMA), a biodegradable polyester generated from the fungus Aureobasidium pullulans, has attracted attention in the bioplastic and biomedical fields and is easily hydrolyzed to release the monomer l-malic acid (L-MA). This study evaluated the feasibility of using waste xylose-containing mother liquor (WXML) for efficient PMA fermentation under low pH control and L-MA recovery in a non-waste-disposal system. Herein, the multi-adaptive evolution of A. pullulans under high concentrations of WXML, coupled with low pH, was demonstrated. Subsequently, an engineered calcineurin signaling pathway overexpressing the exogenous cnb gene from Beauveria bassiana was employed to further regulate cell tolerance. A mutant strain AE-59 was obtained, and a comparable PMA titer of 49.47 ± 0.48 g/L and a yield of 0.33 g/g at low pH control with Na2CO3 in a 5-L fermenter were achieved. Finally, the direct-aqueous-phase-crystal method was employed to obtain 78.55 % of the total L-MA (with a purity of 95.4 %) from the acidic downstream broth using a low dosage of sulfuric acid for acid hydrolysis. This result showed the feasibility of L-MA production in the low-pH control mode with Na2CO3 without solid waste CaSO4. In conclusion, this study overcomes the major obstacles of calcium waste pollution for future industrial fermentative L-MA production and provides a green and sustainable route from lignocellulosic biorefinery for the production of future biopolymers and carboxylic acids.

Simultaneous production of renewable biohydrogen, biobutanol and biopolymer from phytogenic CoNPs-assisted Clostridial fermentation for sustainable energy and environment

Considering the environmental impacts, rapid fossil fuel depletion and production costs, sustainable production of clean biofuels from alternative sources is required to meet the increasing demand for energy while avoiding environmental pollution. In this study, phytogenic cobalt nanoparticles (CoNPs)-assisted dark fermentation process was developed for the simultaneous production of biohydrogen, biobutanol and biopolymer from glucose using Clostridium acetobutylicum NCIM 2337. The maximum biohydrogen yield of 2.89 mol H2/mol glucose was achieved at 1.5 mg of CoNPs, which is 1.6 folds higher than that of the control experiment. The high level of soluble metabolites, specifically acetate and butyrate, confirmed the production of biohydrogen through acetate/butyrate pathways. The modified Gompertz model fitted well with experimental results of CoNPs-assisted biohydrogen production. The CoNPs could act as an electron carrier in intracellular metabolism to enhance the activity of ferredoxin and hydrogenase enzymes, thus improving biohydrogen production. Furthermore, biobutanol and biopolymer yields of 975 ± 2.5 mg/L and 1182 ± 1.4 mg/L were achieved, with 2.0 mg and 2.5 mg of CoNP, respectively, which were 1.27 and 1.19 folds higher than the control values. Hence, the inclusion of CoNPs in the fermentation medium seems to be a promising technique for the enhanced simultaneous production of biohydrogen, biobutanol and biopolymer. The environmental perspectives of the obtained renewable biohydrogen, biobutanol and biopolymer are also discussed.

Sustainable Biopolymers Production Using a Bioethanol Residue as Raw Material

Sustainable Biopolymers Production Using a Bioethanol Residue as Raw Material

Green bioprocessing and applications of microalgae-derived biopolymers as a renewable feedstock: Circular bioeconomy approach

An expeditious pace of expanding industrialization and urbanization is a global vulnerability which immediately requires utmost attention towards the replacement of prosaic petroleum-based polymer assimilation. Thus, greening the innovative route of microalgae derived biopolymers has attained significant interest as an improved and sustainable approach towards the worldwide circular bioeconomy. In this context, the use of as synthesized biopolymers from microalgae attributing as a potential feedstock has bestowed for a biodegradable solution to reduce the greenhouse gases emission and rapid biomass productivity with metabolic flexibility. However, the confront of high microalgae cultivation cost and low metabolites’ accumulation have triggered the advancement of microalgae metabolic cultivation strategy. Hence, the current review portrays to propose a novel multi-phasic fed batch light depleted low-cost wastewater cultivation approach and a clear mechanistic phenomenon for accelerating the biopolymer production. This review also provides a comprehensive summary on several microalgae strains which are capable for biopolymer synthesis and various effective extraction techniques to isolate the biopolymers. The future endeavour and challenges on the microalgae circular bioeconomy which involves the current issues regarding the cell harvesting method, scale up and bioprocessing cost of microalgae cultivation have been highlighted. The applications for microalgae derived biopolymer in industrial and nutraceutical sectors have also been emphasized. This review is expected to bring new insights to the industrial stakeholders for further advancement of microalgae-based biopolymer field economically, and eventually contributing towards environmental sustainability. • Bioprocessing of microalgae derived biopolymer via circular bioeconomy approach. • Multiphasic fed batch for enhancing the microalgae mediated biopolymer yield. • Green processing and scale up biopolymer production. • Applications of microalgae mediated biopolymers in the industry.

Developing pretreatment methods to promote the production of biopolymer and bioethanol from residual algal biomass (RAB)

This study investigates the effect of acidic pretreatment (HT-ACPT), enzymatic pretreatment (ENZ-PT), and microwave laser-hydrogen peroxide-Fe-nanoparticle pretreatment (Mv-H2O2-Fe-PT) on the production of bioethanol (bio-eth.) and biopolymer (bio-p) from residual algal biomass (RAB). The effectiveness of these pretreatments is based on using the entire RAB and maximizing sugar liberation to produces bio-p and bio-eth under optimized conditions. The Mv-H2O2-Fe-PT yielded the maximum total and soluble sugar liberation of 0.988 ± 0.08 and 0.6888 ± 0.08 g/gDCW compared with HT-ACPT (0.588 ± 0.02 and 0.488 ± 0.02 g/gDCW) and ENZ-PT (0.528 ± 0.06 and 0.428 ± 0.06 g/gDCW). All pretreatment methods split the β-1, 4-glycosidic bonds into cellulose and liberate sugars that were later used to produce bio-p and bio-eth. The algal strains treated by Mv-H2O2-Fe-PT produced the highest bio-p of 0.740 ± 0.004 gpolyemer/gDCW, which is 1.3 folds higher than the productivity of HT-ACPT and ENZ-PT. The HT-ACPT and ENZ-PT produced 67 to 72 % and 59 to 63 % lower biopolymer yield. The maximum bioethanol production (Mbio−ethP) of 0.950 ± 0.005 mL/gRAB was achieved using microalgae pretreated with Mv-H2O2-Fe-PT and incubated at pH = 5.5 and 37 °C. The Mbio−ethP was negatively affect by increasing the pH or decreasing the temperature. The Mbio−ethP decreased to 0.853 ± 0.002 mL/gRAB by increasing the pH to 6 and to 0.761 ± 0.002 mL/g when the temperature decreased to 33 °C. The Mbio−ethP as a fraction of theoretical yield (%ThY) were in the ranges of 21 to 33 %, 33.3 to 51.1 % and 59.52 to 91.2 % for RAB pretreated with HT-ACPT, ENZ-PT and Mv-H2O2-Fe-PT, respectively. The produced bio-p exhibited excellent properties and can be used in a variety of applications including soil additives, biofuel production, regenerative medicine, and other medical applications. The Mv-H2O2-Fe-PT pretreatment offers complete use of RAB to produce different bio-products.

Metabolic engineering of Cupriavidus necator H16 for heterotrophic and autotrophic production of 3-hydroxypropionic acid

3-Hydroxypropionate (3-HP) is a versatile compound for chemical synthesis and a potential building block for biodegradable polymers. Cupriavidus necator H16, a facultative chemolithoautotroph, is an attractive production chassis and has been extensively studied as a model organism for biopolymer production. Here, we engineered C. necator H16 for 3-HP biosynthesis from its central metabolism. Wild type C. necator H16 can use 3-HP as a carbon source, a highly undesirable trait for a 3-HP production chassis. However, deletion of its three (methyl-)malonate semialdehyde dehydrogenases (mmsA1, mmsA2 and mmsA3) resulted in a strain that cannot grow on 3-HP as the sole carbon source, and this strain was selected as our production host. A stepwise approach was used to construct pathways for 3-HP production via β-alanine. Two additional gene deletion targets were identified during the pathway construction process. Deletion of the 3-hydroxypropionate dehydrogenase, encoded by hpdH, prevented the re-consumption of the 3-HP produced by our engineered strains, while deletion of gdhA1, annotated as a glutamate dehydrogenase, prevented the utilization of aspartate as a carbon source, one of the key pathway intermediates. The final strain carrying these deletions was able to produce up to 8 mM 3-HP heterotrophically. Furthermore, an engineered strain was able to produce 0.5 mM 3-HP under autotrophic conditions, using CO2 as sole carbon source. These results form the basis for establishing C. necator H16 as an efficient platform for the production of 3-HP and 3-HP-containing polymers.

Influence of salt addition to stimulating biopolymers production in aerobic granular sludge systems

The influence of salt addition to stimulating biopolymers production in aerobic granular sludge (AGS) systems was evaluated. The control systems (R1: acetate and R2: propionate) initially obtained less accumulation of mixed liquor volatile suspended solids (MLVSS), indicating that the osmotic pressure in the salt-supplemented systems (R3: acetate and R4: propionate) contributed to biomass growth. However, the salt-supplemented systems collapsed between days 110 and 130 of operation. R3 and R4 showed better performance regarding nutrients removal due to the greater abundance of nitrifying and denitrifying bacteria and phosphate-accumulating organisms. Salt also contributed to the higher production of biopolymers such as alginate-like exopolymers (ALE) per gram of volatile suspended solids (VSS) (R1: 397 mgALE∙gVSS−1, R2: 140 mgALE∙gVSS−1, R3: 483 mgALE∙gVSS−1, R4: 311 mgALE∙gVSS−1). Amino acids like tyrosine and tryptophan were better identified in extracellular polymeric substances extract from salt-operated reactors. This study brings important results in the context of resource recovery by treating saline effluents.

Insights into the temperature responses of Pseudomonas species in beneficial and pathogenic host interactions.

Pseudomonas species are metabolically versatile bacteria able to exploit a wide range of ecological niches. Different Pseudomonas species can grow as free-living cells, biofilms, or associated with plants or animals, including humans, and their ecological success partially lies in their ability to grow and adapt to different temperatures. These bacteria are relevant for human activities, due to their clinical importance and their biotechnological potential for different applications such as bioremediation and the production of biopolymers, surfactants, secondary metabolites, and enzymes. In agriculture, some of them can act as plant growth promoters and are thus used as inoculants, whereas others, like P. syringae pathovars, can cause disease in commercial crops. This review aims to provide an overview of the temperature-response mechanisms in Pseudomonas species, looking for novel features or strategies based on techniques such as transcriptomics and proteomics. We focused on temperature-dependent traits mainly associated with virulence, host colonization, survival, and production of secondary metabolites. We analyzed human, animal, and plant pathogens and plant growth-promoting Pseudomonas species, including P. aeruginosa, P. plecoglossicida, several P. syringae pathovars, and P. protegens. Our aim was to provide a comprehensive view of the relevance of temperature-response traits in human and animal health and agricultural applications. Our analysis showed that features relevant to the bacterial-host interaction are adjusted to the environmental or host temperature regardless of the optimal growth temperature in the laboratory, and thus contribute to improving bacterial fitness. KEY POINTS: • In Pseudomonas species, temperature impacts the bacterial-host interaction. • Interaction traits are expressed at temperatures different from the optimal reported. • The bacterial-host interaction could be affected by climate change.

From Agri-Food Wastes to Polyhydroxyalkanoates through a Sustainable Process

The biologically-derived polymers polyhydroxyalkanoates (PHAs) are biodegradable and can be considered a valuable alternative to conventional fossil-based plastics. However, upstream and downstream processes for PHA production are characterized by high energy and chemical consumption and are not economically competitive with petroleum-based polymers. Aiming to improve both the environmental and economical sustainability of PHAs production, in this work, corn straw was used as raw material to obtain a mixture of fermentable sugars after microwave-assisted flash hydrolysis (2 min, 0.01 g/L, 50.7% yield). A mixed microbial culture enriched from dairy industry waste was used for fermentation in a shake flask, allowing us to achieve good poly(hydroxy-butyrate-co-hydroxy-valerate) yields (41.4%, after 72 h of fermentation). A scale-up in a stirred tank bioreactor (3 L) gave higher yields (76.3%, after 96 h), allowing in both cases to achieve a concentration of 0.42 g/L in the fermentation medium. The possibility of producing PHAs from agricultural waste using a mixed microbial culture from the food industry with enabling technologies could make the production of biopolymers more competitive.