3-hydroxyvalerate Research Articles

Plastic-degrading microbial communities reveal novel microorganisms, pathways, and biocatalysts for polymer degradation and bioplastic production

Plastics derived from fossil fuels are used ubiquitously owing to their exceptional physicochemical characteristics. However, the extensive and short-term use of plastics has caused environmental challenges. The biotechnological plastic conversion can help address the challenges related to plastic pollution, offering sustainable alternatives that can operate using bioeconomic concepts and promote socioeconomic benefits. In this context, using soil from a plastic-contaminated landfill, two consortia were established (ConsPlastic-A and -B) displaying versatility in developing and consuming polyethylene or polyethylene terephthalate as the carbon source of nutrition. The ConsPlastic-A and -B metagenomic sequencing, taxonomic profiling, and the reconstruction of 79 draft bacterial genomes significantly expanded the knowledge of plastic-degrading microorganisms and enzymes, disclosing novel taxonomic groups associated with polymer degradation. The microbial consortium was utilized to obtain a novel Pseudomonas putida strain (BR4), presenting a striking metabolic arsenal for aromatic compound degradation and assimilation, confirmed by genomic analyses. The BR4 displays the inherent capacity to degrade polyethylene terephthalate (PET) and produce polyhydroxybutyrate (PHB) containing hydroxyvalerate (HV) units that contribute to enhanced copolymer properties, such as increased flexibility and resistance to breakage, compared with pure PHB. Therefore, BR4 is a promising strain for developing a bioconsolidated plastic depolymerization and upcycling process. Collectively, our study provides insights that may extend beyond the artificial ecosystems established during our experiments and supports future strategies for effectively decomposing and valorizing plastic waste. Furthermore, the functional genomic analysis described herein serves as a valuable guide for elucidating the genetic potential of microbial communities and microorganisms in plastic deconstruction and upcycling.

Bioplastic Production from Agri-Food Waste through the Use of Haloferax mediterranei: A Comprehensive Initial Overview.

The research on bioplastics (both biobased and biodegradable) is steadily growing and discovering environmentally friendly substitutes for conventional plastic. This review highlights the significance of bioplastics, analyzing, for the first time, the state of the art concerning the use of agri-food waste as an alternative substrate for biopolymer generation using Haloferax mediterranei. H. mediterranei is a highly researched strain able to produce polyhydroxybutyrate (PHB) since it can grow and produce bioplastic in high-salinity environments without requiring sterilization. Extensive research has been conducted on the genes and pathways responsible for PHB production using H. mediterranei to find out how fermentation parameters can be regulated to enhance cell growth and increase PHB accumulation. This review focuses on the current advancements in utilizing food waste as a substitute for costly substrates to reduce feedstock expenses. Specifically, it examines the production of biomass and the recovery of PHB from agri-food waste. Furthermore, it emphasizes the characterization of PHB and the significance of hydroxyvalerate (HV) abundance in the formation of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) copolymer. The downstream processing options are described, and the crucial factors associated with industrial scale-up are assessed, including substrates, bioreactors, process parameters, and bioplastic extraction and purification. Additionally, the economic implications of various options are discussed.

Submission to Journal of Polymers and the Environment Evaluation of Thermal Properties and Crystallinity in PHB-Based Systems – A DoE Approach

Complex formulations based on poly(hydroxybutyrate) (PHB) and poly(hydroxybutyrate-co-valerate) (PHBV) were studied to statistically assess the effect of formulation (i.e., hydroxyvalerate (HV) content, plasticiser chemistry and content, filler type and content) on their thermal properties and degree of crystallinity (Xc). In binary systems, thermal properties were mainly influenced by filler type rather than its content, while for plasticised systems the changes were dependent on both increasing plasticiser content and PHB-plasticiser compatibility. Variations in HV content affected the ability of the polymer chain to fold, leading to significant changes in both thermal properties and Xc. In ternary systems, presence of multiple additives and consequent changes in intermolecular interactions lead to multifaceted behaviours that were not easily predicted by results from binary systems alone. For example, melting temperature did not show dependence on filler presence in PHBV systems despite introducing variations in pure PHB systems. In general, thermal properties and Xc are affected by all parameters studied, with changes in system free volume (i.e. changes in HV content and plasticisation) playing the most significant role. These results expand the understanding of factors controlling crystallisation in complex polymer systems and can be used to control matrix properties in new generations of packaging materials.

Solubility of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) in sustainable and green solvents: Effect of HV content and comparison between experimental results and theoretical prediction

For the first time, a quantitative analysis of the solubility of poly-3hydroxybutyrrate-co-3hydroxyvalerate (PHBV) in green solvents is proposed. The solubility of two commercial co-polymers, with hydroxyvalerate (HV) contents of 8 %mol and 12 %mol, in 1,3-dioxolane, dimethyl carbonate and butyl acetate was experimentally determined using chloroform as the benchmark and water as the control. The results showed a direct correlation between solubility and temperature, with a maximum at the boiling point of the solvent. For PHBV with an HV content of 8 %mol, solubilities of 265 mg mL−1 for 1,3-dioxolane and dimethyl carbonate and 274 mg mL−1 for butyl acetate were measured; for PHBV with an HV content of 12 %mol, solubilities of 225 mg mL−1, 197 mg mL−1 and 137 mg mL−1 for 1,3-dioxolane, dimethyl carbonate and butyl acetate were measured, respectively. Following Hansen's theory, the PHBV solubility sphere was defined to predict the solubility of the co-polymers in solvents qualitatively. The validation of the sphere was performed by the experimental results herein obtained.

The Halophilic Bacterium Paracoccus haeundaensis for the Production of Poly(3-Hydroxybutyrate-co-3-Hydroxyvalerate) from Single Carbon Sources.

The study objective was to evaluate the potential production of polyhydroxyalkanoates (PHAs), a biodegradable plastic material, by Paracoccus haeundaensis for which PHA production has never been reported. To identify the most effective nitrogen-limited culture conditions for PHAs production from this bacterium, batch fermentation using glucose concentrations ranging from 4 g l-1 to 20 g l-1 with a fixed ammonium concentration of 0.5 g l-1 was carried out at 30°C and pH 8.0. A glucose supplement of 12 g l-1 produced the highest PHA concentration (1.6 g l-1) and PHA content (0.63 g g-1) thereby identifying the optimal condition for PHA production from this bacterium. Gas chromatography-mass spectrometry analysis suggests that P. haeundaensis mostly produced copolymer types of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] from glucose concentrations at 12 g l-1 or higher under the nitrogen-limited conditions. When several other single carbon sources were evaluated for the most efficient PHA production, fructose provided the highest biomass (2.8 g l-1), and PHAs (1.29 g l-1) concentrations. Results indicated that this bacterium mostly produced the copolymers P(3HB-co-3HV) from single carbon sources composing a range of 93-98% of 3-hydroxybutyrate and 2-7% of 3-hydroxyvalerate, whereas mannose-supplemented conditions produced the only homopolymer type of P(3HB). However, when propionic acid as a secondary carbon source were supplemented into the media, P. haeundaensis produced the copolymer P(3HB-co-3HV), composed of a 50% maximum monomeric unit of 3-hydroxyvaleric acid (3HV). However, as the concentration of propionic acid increased, cell biomass and PHAs concentrations substantially decreased due to cell toxicity.

Polyhydroxyalkanoate production from rice straw hydrolysate: Insights into feast-famine dynamics and microbial community shifts

Activated sludge contains a versatile microbiome capable of converting wastes into valuable chemicals like polyhydroxyalkanoates (PHA). This study investigated the influence of repeated feast and famine phases on PHA production as well as the corresponding microbial population dynamics using waste activated sludge (WAS) as inoculum. Hydrolysate derived from rice straw was employed as a substrate for PHA production. The 16sRNA analysis results revealed that Corynebacteriaceae (40%), Bacillaceae (23%), and Pseudomonas (5%) were the primary contributors to PHA synthesis. Notably, Bacillaceae and Pseudomonas thrived in all the feast and famine phases. The achieved PHA concentration was 3.5 ± 0.2 g/L, and its structure and composition were assessed using Fourier Transform Infrared Spectroscopy (FTIR) and Nuclear Magnetic Resonance (NMR). The analysis revealed that the PHA consists of a copolymer of hydroxybutyrate (HB) and hydroxyvalerate (HV), specifically identified as Poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV).

Effect of Chemical Composition on Molecular Mobility and Phase Coupling in Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) with Different Comonomer Contents

Two series of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBHV) and poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) with different amounts of hydroxyvalerate (HV) and hydroxyhexanoate (HHx) units are compared. The influence of chemical composition on the molecular mobility in quenched samples is discussed, as well as the consequences on the aptitude to crystallize and the microstructures developed during cold-crystallization. In both quenched PHBHV and PHBHHx, $$T_g$$ decreases as the content of comonomer unit increases. The HHx units (propyl side-groups) are better molecular spacers and produce a stronger $$T_g$$ shift as compared to the HV units (ethyl side-groups). Copolymerization has no striking effect on the width of the glass transition and the cooperativity length in quenched samples, but in cold-crystallized samples the glass transition is dramatically broadened. When the fully amorphous copolymers are heated from the glassy state to room temperature, crystallization occurs but is largely disrupted, suggesting that the molecular environment in the amorphous phase is significantly changed. The HHx units, which are excluded from the host crystals, delay and slow down the crystallization kinetics in a stronger way as compared to the HV units, which can partially co-crystallize. The obtained crystalline phases are prone to reorganization and the residual amorphous phases appear to have strong differences in composition and large density fluctuations. A practical consequence is that microstructures with different coupling between phases, and thus different properties and stability over time, can be obtained by controlling the nature and content of the comonomer units.

Clinical, biochemical, and genetic analysis of 28 Chinese patients with holocarboxylase synthetase deficiency

BackgroundThis study aimed to describe the clinical, biochemical, and molecular characteristics of Chinese patients with holocarboxylase synthetase (HLCS) deficiency, and to investigate the mutation spectrum of HCLS deficiency as well as their potential correlation with phenotype.MethodsA total of 28 patients with HLCS deficiency were enrolled between 2006 and 2021. Clinical and laboratory data were reviewed retrospectively from medical records.ResultsAmong the 28 patients, six patients underwent newborn screening, of which only one was missed. Therefore, 23 patients were diagnosed because of disease onset. Among all the patients, 24 showed varying degrees of symptoms such as rash, vomiting, seizures, and drowsiness, while only four cases remained asymptomatic nowadays. The concentration of 3-hydroxyisovalerylcarnitine (C5-OH) in blood and pyruvate, 3-hydroxypropionate, methylcitric acid, 3-hydroxyvaleric acid, 3-methylcrotonylglycine in urine were increased greatly among affected individuals. After prompt supplement of biotin, both the clinical and biochemical symptoms were dramatically resolved and nearly all patients developed normal intelligence and physique on follow-up. DNA sequencing revealed 12 known and 6 novel variants in the HLCS gene of patients. Among them, the variant of c.1522C > T was the most common.ConclusionsOur findings expanded the spectrum of phenotypes and genotypes for HLCS deficiency in Chinese populations and suggested that with timely biotin therapy, patients with HLCS deficiency showed low mortality and optimistic prognosis. Newborn screening is crucial for early diagnosis, treatment, and long-term outcomes.

Co-Culture of Halotolerant Bacteria to Produce Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Using Sewage Wastewater Substrate.

The focus of the current study was the use of sewage wastewater to obtain PHA from a co-culture to produce a sustainable polymer. Two halotolerant bacteria, Bacillus halotolerans 14SM (MZ801771) and Bacillus aryabhattai WK31 (MT453992), were grown in a consortium to produce PHA. Sewage wastewater (SWW) was used to produce PHA, and glucose was used as a reference substrate to compare the growth and PHA production parameters. Both bacterial strains produced PHA in monoculture, but a copolymer was obtained when the co-cultures were used. The co-culture accumulated a maximum of 54% after 24 h of incubation in 10% SWW. The intracellular granules indicated the presence of nucleation sites for granule initiation. The average granule size was recorded to be 231 nm; micrographs also indicated the presence of extracellular polymers and granule-associated proteins. Fourier transform infrared spectroscopy (FTIR) analysis of the polymer produced by the consortium showed a significant peak at 1731 cm-1, representing the C=O group. FTIR also presented peaks in the region of 2800 cm-1 to 2900 cm-1, indicating C-C stretching. Proton nuclear magnetic resonance (1HNMR) of the pure polymer indicated chemical shifts resulting from the proton of hydroxy valerate and hydroxybutyrate, confirming the production of poly(3-hydroxybutyrate-co-3-hydroxy valerate) (P3HBV). A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay showed that the copolymer was biocompatible, even at a high concentration of 5000 µg mL-1. The results of this study show that bacterial strains WK31 and 14SM can be used to synthesize a copolymer of butyrate and valerate using the volatile fatty acids present in the SWW, such as propionic acid or pentanoic acid. P3HBV can also be used to provide an extracellular matrix for cell-line growth without causing any cytotoxic effects.

Fermentative bioconversion of food waste into biopolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) using Cupriavidus necator

Dependency on plastic commodities has led to a recurrent increase in their global production every year. Conventionally, plastic products are derived from fossil fuels, leading to severe environmental concerns. The recent coronavirus disease 2019 pandemic has triggered an increase in medical waste. Conversely, it has disrupted the supply chain of personal protective equipment (PPE). Valorisation of food waste was performed to cultivate C. necator for fermentative production of biopolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). The increase in biomass, PHBV yield and molar 3-hydroxy valerate (3HV) content was estimated after feeding volatile fatty acids. The fed-batch fermentation strategy reported in this study produced 15.65 ± 0.14 g/L of biomass with 5.32 g/L of PHBV with 50% molar 3HV content. This is a crucial finding, as molar concentration of 3HV can be modulated to suit the specification of biopolymer (film or fabric). The strategy applied in this study addresses the issue of global food waste burden and subsequently generates biopolymer PHBV, turning waste to wealth.

Evaluation of different nutrient limitation strategies for the efficient production of poly(hydroxybutyrate‐co‐hydroxyvalerate) from waste frying oil and propionic acid in high cell density fermentations of Cupriavidus necator H16

Because of its application potential and biodegradability, poly(3-hydroxybutyrate-co-3-hydroxyvalerate;PHBV), a member of the polyhydroxyalkanoates (PHA) biopolymer family, is one of the most extensively studied PHA. High PHBV productivity with a significant amount of hydroxyvalerate (HV) content is very appealing for commercial scale production. The goal of this study was to investigate the efficiency of various defined limitation strategies, namely nitrogen, phosphorus, and oxygen-limitation, for high yield PHBV production by Cupriavidus necator H16 with increased HV unit using waste frying vegetable oil (WFO) and propionic acid (PA) in a high cell density culture (5 L bioreactor). With optimized WFO and PA feeding, highest PHBV harvest (121.7 ± 2.59 g/L; HV 13.9 ± 0.44% (w/w)) and volumetric productivity (2.03 ± 0.04 gPHBV/L·h) were obtained in oxygen-limited operation, while highest HV content (19.8 ± 0.28 wt%) and yield coefficient (0.43 ± 0.017 gHV/gPA) were observed during phosphorus-limited cultivation. Although nitrogen limitation is widely applied in the production of PHA, nitrogen-limited cultivation had the lowest cell dry matter, PHBV production, volumetric productivity, oil-to-HB and PA-to-HV yield coefficients for the given conditions. The results of the present study demonstrate the highest PHBV yield together with the highest HV content using WFO as main carbon source and PA as the HV precursor ever reported in the literature.

Corn stover hydrolysate and levulinic acid: Mixed substrates for short-chain polyhydroxyalkanoate production

The plastic disposal problem has been augmented over the years due to the surge in utilization of single-use plastics, the indiscriminate discarding of plastics, and space limitations associated with landfill sites. Therefore, in this study the biodegradable, biorenewable, and biocompatible plastic substitutes, poly(hydroxyalkanoate) (PHA) biopolymers were synthesized from low-value and high-volume corn stover in combination with levulinic acid (LevA). Acid hydrolysis liberated the fermentable sugars from the cellulosic and hemicellulosic fractions of the corn stover. This hydrolysate was used as a feedstock in combination with LevA to produce a terpolyester composed of 3-hydroxybutyric acid (3-HB), 3-hydroxyvaleric acid (3-HV), and 4-hydroxyvaleric acid (4-HV) by the bacterium Azohydromonas lata, and a copolymer of 3-HB and 3-HV by the bacterium Burkholderia sacchari. Detoxification of the hydrolysate through ‘overliming’ was necessary to induce bacterial growth and PHA production in A. lata, while B. sacchari was able to utilize the hydrolysate without detoxification achieving a maximum PHA titer of 1.2 g PHA/L. The inclusion of higher LevA in the medium affected the monomeric composition of the copolymers produced by B. sacchari resulting in a 3-HB:3-HV ratio of 39:61 when grown in the presence of 0.4% (w/v) LevA. In contrast, the monomeric compositions were relatively unaffected by the LevA media concentration for the PHA biopolymers produced by A. lata. The results of this study should help reduce the overall costs to synthesize bacterially derived PHA biopolymers and increase their applicability, thus reducing our dependence on recalcitrant petroleum-based plastics.

Polyhydroxyalkanoates from industrial cheese whey: Production and characterization of polymers with differing hydroxyvalerate content

The composition of polyhydroxyalkanoate (PHA) monomers affects the properties and final applications of PHA polymers. This study focused on the feasibility of producing tailored PHA differing in hydroxyvalerate (HV) content, through manipulation of the acidogenic fermented stream composition, and on the characterization of PHA properties to determine the best composition for melt processing. Cheese whey was used as a feedstock, and changes in the organic loading rate during acidogenic fermentation led to the production of a fermented stream with an HV precursor content of 9–33 wt%. In the PHA production assays, a PHA content of 50 ± 11 wt%. (VSS basis) and yield of 0.76 ± 0.14 gCODPHA.gCODFP-1 were obtained. Fermented stream supplementation with HV precursors during the PHA accumulation assays indicated the feasibility of producing tailored PHA with differing HV content without a need for the selection of new cultures. The thermal properties of PHA were found to be controlled by the HV content, and PHA with approximately 30 wt% HV had the lowest melting temperature. These results demonstrated the robustness of the process at pilot scale, thus supporting full-scale applications in tailored PHA production.

Development and validation of a LC-MS/MS method for quantitation of 3-hydroxypentanoic acid and 3-oxopentanoic acid in human plasma and its application to a clinical study of glucose transporter type I deficiency (G1D) syndrome

Interest in human and experimental animal metabolism of substrates containing an odd number of carbons capable of fueling the tricarboxylic acid cycle such as heptanoic acid has motivated us to develop and validate a selective and specific liquid chromatographytandem mass spectrometric method for the simultaneous, quantitative determination of the ketone body byproducts 3-hydroxypentanoic acid and 3-oxopentanoic acid in plasma. Human plasma samples were protein-precipitated with methanol containing 0.2% formic acid. Chromatographic resolution was achieved on a Phenomenex Luna C18 column using gradient elution with mobile phases of water containing 0.1% formic acid and methanol containing 0.1% formic acid at 0.3 mL/min flow rate. The retention times of 3-hydroxypentanoic acid, 3-oxopentanoic acid and sulbactam (internal standard) were 3.85, 4.23, and 5.11 min, respectively. Validation was conducted in accordance with United States Food and Drug Administration guidance. The validated range of 3-hydroxypentanoic acid was 0.078–5 µg/mL and 0.156–10 µg/mL for 3-oxopentanoic acid. The method was accurate and precise over this range and exhibited 10-fold dilution integrity in human plasma. Recovery> 88% was achieved for analytes and internal standard. There was no matrix effect observed in human plasma. Both 3-hydroxypentanoic acid and 3-oxopentanoic acid were stable across conditions including autosampler, benchtop and freeze-thaw, as well as demonstrated long-term stability at −80 °C. The method was applied to the measurement of 3-hydroxypentanoic acid and 3-oxopentanoic acid concentrations in plasma from subjects receiving the triglyceride triheptanoin (as a source of heptanoate) for the experimental treatment of glucose transporter type I deficiency (G1D) syndrome.

A Two-Stage Process for Conversion of Brewer’s Spent Grain into Volatile Fatty Acids through Acidogenic Fermentation

This work is focused on the valorization of brewer’s spent grains (BSG) into volatile fatty acids (VFA) through acidogenic fermentation. VFAs are building blocks for several applications, such as bioplastics’ production. Using acid hydrolysis as pre-treatment, several batch assays were performed and the impact of organic load (OL) and pH on VFA production from BSG hydrolysate was assessed. Regardless of the condition, the produced acids were mainly butyric and acetic acids followed by propionic acid. The OL had a direct impact on the total organic acid concentration with higher concentrations at the highest OL (40 gCOD L−1). pH affected the concentration of individual organic acid, with the highest fermentation products (FP) diversity attained at pH 5.0 and OL of 40 gCOD L−1. To assess the potential application of organic acids for biopolymers (such as polyhydroxyalkanoates) production, the content in hydroxybutyrate (HB) and hydroxyvalerate (HV) monomers was estimated from the respective precursors produced at each pH and OL. The content in HV precursors increased with pH, with a maximum at pH 6.0 (ca. 16% C-mol basis). The acidogenic fermentation of BSG hydrolysate was also assessed in continuous operation, using an expanded granular sludge bed reactor (EGSB). It was shown that the BSG hydrolysate was successfully converted to VFAs without pH control, achieving higher productivities than in the batch operation mode.

Experimental data and thermodynamics modeling (PC-SAFT EoS) of the {CO2 + chloroform + PHBV} system at high pressures

Herein, the influence of HV (hydroxyvalerate) addition (8.0 and 8.7 wt% HV) on the PHBV (poly(3-hydroxybutyrate-co-3-hydroxyvalerate)) composition from the perspective of phase equilibrium in high-pressure {(CO2 (1) + chloroform (2) + [PHBV - 8.0 wt%] (3) and (CO2 (1) + chloroform (2) + [PHBV - 8.7 wt%] (3)} systems was examined using the static synthetic method with a visual variable-volume view cell at temperatures ranging from 303.15 to 333.15 K, pressures approximately 10 MPa, and different concentrations of PHBV (HV = 8.0 and 8.7 wt%) in chloroform (0.01 and 0.02 g.cm−3). Transitions of the solid-vapor-liquid (SVL) were observed. The experimentally determined phase transitions were successfully modeled using the PC-SAFT equation of state.

Production of the Polyhydroxyalkanoate PHBV from Ricotta Cheese Exhausted Whey by Haloferax mediterranei Fermentation.

In the last decade, the dairy industry underwent a rapid expansion due to the increasing demand of milk-based products, resulting in high quantity of wastewater, i.e., whey and ricotta cheese exhausted whey (RCEW). Although containing high content of nutritional compounds, dairy by-products are still disposed as waste rather being reintroduced in a new production chain, hence leading to environmental and economic issues. This study proposes a new biotechnological approach based on the combination of membrane filtration and fermentation to produce poly-hydroxyalkanoates (PHA), biodegradable bioplastics candidate as an alternative to petroleum-derived plastics. The protocol, exploiting the metabolic capability Haloferax mediterranei to synthesize PHA from RCEW carbon sources, was set up under laboratory and pilot scale conditions. A multi-step fractionation was used to recover a RCEW fraction containing 12.6% (w/v) of lactose, then subjected to an enzymatic treatment aimed at releasing glucose and galactose. Fermentation conditions (culture medium for the microorganism propagation, inoculum size, time, and temperature of incubation) were selected according to the maximization of polymer synthesis, under in-flasks experiments. The PHA production was then tested using a bioreactor system, under stable and monitored pH, temperature, and stirring conditions. The amount of the polymer recovered corresponded to 1.18 g/L. The differential scanning calorimetry (DSC) analysis revealed the poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) as the polymer synthesized, with a relatively high presence of hydroxyvalerate (HV). Identity and purity of the polymer were confirmed by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) and X-ray photoelectron (XPS) spectroscopy analyses. By combining the fractionation of RCEW, one of the most abundant by-products from the agri-food industry, and the use of the halophile Hfx mediterranei, the production of PHBV with high purity and low crystallinity has successfully been optimized. The process, tested up to pilot scale conditions, may be further implemented (e.g., through fed-batch systems) and used for large-scale production of bioplastics, reducing the economical and environmental issues related the RCEW disposal.

Metabolic profiling and pathway analysis in red arillus of Salacca sumatrana demonstrate significant pyruvate, sulfur, and fatty acid metabolisms

Abstract. Fendiyanto MH, Satrio RD, Darmadi D. 2020. Metabolic profiling and pathway analysis in red arillus of Salacca sumatrana demonstrate significant pyruvate, sulfur, and fatty acid metabolisms. Biodiversitas 21: 4361-4368. Salak or snake fruit (Salacca Reinw.; Arecaceae) is a tropical fruit that has high biodiversity in a tropical country such as Indonesia. Several types of salak can be found in Indonesia, one of which is Salacca sumatrana (Becc.) Mogea. Research on profiling metabolites in S. sumatrana has not been conducted. Therefore, the aim of this study was to determine the metabolite profile and pathway analysis in S. sumatrana, especially in red arillus tissue. This research was conducted by the method of gas chromatography-mass spectrometry (GC-MS) and the study of bioinformatics through metabolomics approaches. The results showed that red arillus had metabolites consisting of groups of fatty acids, esters, alcohols, xylene, phenols, etc.. Significant metabolites found were isobutyl acetate, palmitic acid, formic acid, 2-pentanoic acid, ethylic acid, n-hexadecoic acid, hydroxypentanoic acid, etc. There was a tendency that metabolite ethylic acid, identified as C00033 accession, was a key metabolite in either the pyruvate metabolism pathway or sulfur metabolisms with relatively high impact values. Pathway analysis using bioinformatics studies using MetaboAnalyst shows that four of ten pathways detected had a high log-ratio (p)/pathway impact, i.e., pyruvate metabolism, sulfur metabolism, fatty acid biosynthesis, and biosynthesis of unsaturated fatty acids. Thus, pyruvate, sulfur, and fatty acid metabolisms are important pathways in the red arillus of S. sumatrana. This study can be used as a reference in early metabolomic studies on S. sumatrana using GC-MS and the metabolites identified as metabolite markers can be used for plant breeding and biologists to understand the metabolic mechanism of the red arillus tissues from S. sumatrana.

Statistical optimization and enhanced synthesis of polyhydroxyalkanoates from Ceiba pendantra oil as novel non-edible feedstock

Polyhydroxyalkanoates (PHA) are biopolymer synthesized as storage granules by microbes in the cell’s cytoplasm under excess carbon and limited nitrogen conditions. This study aims to examine the production and optimization of PHA from Ceiba pentandra oil, a non-edible feedstock, by Cupriavidus necator. Response surface methodology was used to optimize the concentrations of carbon, nitrogen, and inoculum for the production of PHA. To improve the physical, mechanical, and thermal properties of PHA, it was blended with polylactic acid (PLA) which possesses high bio-compatibility and bio-absorbability. Furthermore, batch mode cultivation of PHA in a 3-L bioreactor was performed under the optimized conditions (Ceiba pentandra oil—17.13 g/L, urea—1.34 g/L, and inoculum—53.42 mL/L), and 8.51 g/L (0.47 g PHA/g of Ceiba pentandra oil) of PHA product was obtained. The PHA was characterized by FTIR and the presence of functional groups such as C=O, OH, and CH were observed. 1H and 13C NMR spectroscopy revealed the existence of hydroxy valerate (HV) and hydroxybutyrate (HB), and maximal decomposition temperature was identified to be 217.7 °C from TGA analysis. Therefore, Ceiba pendantra oil appears to be an attractive alternate carbon source for PHA production.

Production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) using agro-industrial effluents with tunable proportion of 3-hydroxyvalerate monomer units.

With increasing concerns about future oil depletion and plastic pollution, bioplastics saw an increasing interest from scientists and industrials. Among bioplastics, the polyhydroxyalkanoates (PHA) are a promising family of polyester which are both biosourced and biodegradable. Biosynthesized by microorganisms, especially bacteria, control of their monomeric composition, and thus their thermal and mechanical properties, is still a challenge to really make tailor-made syntheses. Moreover, one way to decrease the high cost of production is to use waste as substrates for the microorganisms. In this study, a marine bacteria, Halomonas sp. SF2003 was grown on agro-industrial effluents as the sole carbon sources and was able to produce poly(3-hydroxybutyrate) (PHB) with a productivity of 1.3 g·L-1 in 40 h of culture and a number-average molar weight of 342,000 g·mol-1. With the addition of valeric acid in the substrates, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBHV) with controlled proportion of hydroxyvalerate (HV) monomers were obtained. Their thermal and mechanical characteristics were investigated as a function of HV amount and showed a decrease of the glass transition and melting temperatures and in Young modulus with the HV content increase.