Evaluation of simplified ester-linked fatty acid analysis (ELFA) for phospholipid fatty acid (PLFA) analysis of bacterial population

Phospholipid fatty acid (PLFA) analysis is used for characterizing microbial communities based on their lipid profiles. This method avoids biases from PCR or culture, allowing data collection in a natural state. However, PLFA is labor-intensive due to lipid fractionation. Simplified ester-linked fatty acid analysis (ELFA), which skips lipid fractionation, offers an alternative. It utilizes base-catalyzed methylation to derivatize only lipids, not free fatty acids, and found glycolipid and neutral lipid fractions are scarcely present in most bacteria, allowing lipid fractionation to be skipped. ELFA method showed a high correlation to PLFA data (r = 0.99) and higher sensitivity than the PLFA method by 1.5-2.57-fold, mainly due to the higher recovery of lipids, which was 1.5-1.9 times higher than with PLFA. The theoretical limit of detection (LOD) and limit of quantification (LOQ) for the ELFA method indicated that 1.54-fold less sample was needed for analysis than with the PLFA method. Our analysis of three bacterial cultures and a simulated consortium revealed the effectiveness of the ELFA method by its simple procedure and enhanced sensitivity for detecting strain-specific markers, which were not detected in PLFA analysis. Overall, this method could be easily used for the population analysis of synthetic consortia.

The green revolution of food waste upcycling to produce polyhydroxyalkanoates

This review emphasizes the urgent need for food waste upcycling as a response to the mounting global food waste crisis. Focusing on polyhydroxyalkanoates (PHAs) as an alternative to traditional plastics, it examines the potential of various food wastes as feedstock for microbial fermentation and PHA production. The upcycling of food waste including cheese whey, waste cooking oil, coffee waste, and animal fat is an innovative practice for food waste management. This approach not only mitigates environmental impacts but also contributes to sustainable development and economic growth. Downstream processing techniques for PHAs are discussed, highlighting their role in obtaining high-quality materials. The study also addresses sustainability considerations, emphasizing biodegradability and recycling, while acknowledging the challenges associated with this path.

Novel differential scanning calorimetry (DSC) application to select polyhydroxyalkanoate (PHA) producers correlating 3-hydroxyhexanoate (3-HHx) monomer with melting enthalpy

Polyhydroxyalkanoate (PHA) is an environmental alternative to petroleum-based plastics because of its biodegradability. The polymer properties of PHA have been improved by the incorporation of different monomers. Traditionally, the monomer composition of PHA has been analyzed using gas chromatography (GC) and nuclear magnetic resonance (NMR), providing accurate monomer composition. However, sequential analysis of the thermal properties of PHA using differential scanning calorimetry (DSC) remains necessary, providing crucial insights into its thermal characteristics. To shorten the monomer composition and thermal property analysis, we directly applied DSC to the analysis of the obtained PHA film and observed a high correlation (r2 = 0.98) between melting enthalpy and the 3-hydroxyhexanoate (3-HHx) mole fraction in the polymer. A higher 3-HHx fraction resulted in a lower melting enthalpy as 3-HHx provided the polymer with higher flexibility. Based on this, we selected the poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P(3HB-co-3HHx)) producing strain from Cupriavidus strains that newly screened and transformed with vectors containing P(3HB-co-3HHx) biosynthetic genes, achieving an average error rate below 1.8% between GC and DSC results. Cupriavidus sp. BK2 showed a high 3-HHx mole fraction, up to 10.38 mol%, with Tm (℃) = 171.5 and ΔH of Tm (J/g) = 48.0, simultaneously detected via DSC. This study is an example of the expansion of DSC for PHA analysis from polymer science to microbial engineering.

Microbial production of levulinic acid from glucose by engineered Pseudomonas putida KT2440

Levulinic acid(LA) is produced through acid-catalyzed hydrolysis and dehydration of lignocellulosic biomass. It is a key platform chemical used as an intermediate in various industries including biofuels, cosmetics, pharmaceuticals, and polymers. Traditional LA production uses chemical conversion, which requires high temperatures and pressures, strong acids, and produces undesirable side reactions, repolymerization products, and waste problems Therefore, we designed an integrated process to produce LA from glucose through metabolic engineering of Pseudomonas putida KT2440. As a metabolic engineering strategy, codon optimized phospho-2-dehydro-3-deoxyheptonate aldolase (AroG), 3-dehydroshikimate dehydratase (AsbF), and acetoacetate decarboxylase (Adc) were introduced to express genes of the shikimate and β-ketoadipic acid pathways, and the 3-oxoadipate CoA-transferase (pcaIJ) gene was deleted to prevent loss of biosynthetic intermediates. To increase the accumulation of the produced LA, the lva operon encoding levulinyl-CoA synthetase (LvaE) was deleted resulting in the high LA-producing strain P. putida HP203. Culture conditions such as medium, temperature, glucose concentration, and nitrogen source were optimized, and under optimal conditions, P. putida HP203 strain biosynthesized 36.3mM (4.2g/L) LA from glucose in a fed-batch fermentation system. When lignocellulosic biomass hydrolysate was used as the substrate, this strain produced 7.31mM of LA. This is the first report of microbial production of LA from glucose by P. putida. This study suggests the possibility of manipulating biosynthetic pathway to produce biological products from glucose for various applications.

Production of Polyhydroxybutyrate by halotolerant Halomonas cerina YK44 using sugarcane molasses and soybean flour in tap water

As environmental pollution intensifies, the interest in bioplastics is growing. The bioplastic polyhydroxyalkanoates (PHAs), which are produced and degraded by microorganisms, have received considerable attention. However, the production cost of PHA is still high, and several ways to increase economy of PHA production have been studied. Therefore, as one way of solution, Halomonas species were screened and evaluated with cheap substrates such as molasses and soybean flour. Among tested strains, Halomonas cerina YK44 was selected and used for polyhydroxybutyrate (PHB) production with molasses and soybean flour together, whose combination was not evaluated well before, in tap water. The medium composition optimization showed maximum PHB production at 4 % sugarcane molasses, 2 % NaCl, 0.05 % soybean flour, and pH 8 in tap water (9.2 g/L DCW, 7.3 g/L PHB, and 79.7 % PHB contents). However, cell growth of halotolerant H. cerina YK44 was disturbed by 0.2 % furfural, which existed in biomass based sugars as inhibitors. Physical and thermal analyses revealed that PHB film started from sugarcane molasses and soybean flour was no different from that initiated from simple sugars (Tm was 175.8 °C and 176.2 °C, PDI was 1.29, and 1.31, respectively).

Expanding the utilization of alkane mixtures: Enhancing medium chain length polyhydroxyalkanoate production in Pseudomonas resinovorans through alkane monooxygenase overexpression

Medium chain length Polyhydroxyalkanoate (mcl-PHA) is a biodegradable bioplastic material with promising applications in various fields, including the medical, packaging, and agricultural industries. This mcl-PHA can be biosynthesized by microorganisms from various carbon sources, and notably, it can also be produced from alkane mixtures contained in pyrolysis oil derived from low-grade waste plastics. In this study, Pseudomonas resinovorans was engineered to overexpress alkane monooxygenase from Lysinibaillus fusiformis JJY0216, enhancing its ability to utilize alkanes as carbon sources and thereby increasing mcl-PHA production. The engineered strain, P. resinovorans JJY01, demonstrated a notable increase in cell dry weight (CDW) to 0.97 g/L and mcl-PHA production to 0.33 g/L from an optimized alkane mixture, achieving a 1.7-fold enhancement compared to the wild type. The PHA content reached 39.5 %, which is 3.1 times higher than the wild type. Further optimization through fed-batch cultivation resulted in P. resinovorans JJY01 achieving 5.65 g/L of CDW, 3.07 g/L of PHA, and a PHA content of 57.5 % within 96 h. In addition, produced mcl-PHA were characterized through various analytical techniques to assess their physical properties and monomer compositions, highlighting the potential of mcl-PHA produced by P. resinovorans JJY01 as a candidate for medical-grade biopolymers.

Dual Application of p-Nitrophenol Alkanoate-Based Assay for Soil Selection and Screening of Microbial Strains for Bioplastic Degradation

With an increase in the commercialization of bioplastics, the importance of screening for plastic-degrading strains and microbes has emerged. Conventional methods for screening such strains are time-consuming and labor-intensive. Therefore, we suggest a method for quickly and effectively screening plastic-degrading microbial strains through dual esterase assays for soil and isolated strains, using p-nitrophenyl alkanoates as substrates. To select microbe-abundant soil, the total amount of phospholipid fatty acids (PLFAs) included in each soil sample was analyzed, and esterase assays were performed for each soil sample to compare the esterase activity of each soil. In addition, by analyzing the correlation coefficients and sensitivity between the amount of PLFAs and the degree of esterase activity according to the substrate, it was confirmed that substrate pNP-C2 is the most useful index for soil containing several microbes having esterase activity. In addition, esterase assays of the isolated strains allowed us to select the most active strain as the degrading strain, and 16S rRNA results confirmed that it was Bacillus sp. N04 showed the highest degradation activity for polybutylene succinate (PBS) as measured in liquid culture for 7 days, with a degradation yield of 99%. Furthermore, Bacillus sp. N04 showed degradation activity against various bioplastics. We propose the dual application of p-nitrophenyl alkanoates as an efficient method to first select the appropriate soil and then to screen for plastic-degrading strains in it, and conclude that pNP-C2 in particular, is a useful indicator.

A review on microbes mediated resource recovery and bioplastic (polyhydroxyalkanoates) production from wastewater

BACKGROUND

Plastic is widely utilized in packaging, frameworks, and as coverings material. Its overconsumption and slow degradation, pose threats to ecosystems due to its toxic effects. While polyhydroxyalkanoates (PHA) offer a sustainable alternative to petroleum-based plastics, their production costs present significant obstacles to global adoption. On the other side, a multitude of household and industrial activities generate substantial volumes of wastewater containing both organic and inorganic contaminants. This not only poses a threat to ecosystems but also presents opportunities to get benefits from the circular economy. Production of bioplastics may be improved by using the nutrients and minerals in wastewater as a feedstock for microbial fermentation. Strategies like feast-famine culture, mixed-consortia culture, and integrated processes have been developed for PHA production from highly polluted wastewater with high organic loads. Various process parameters like organic loading rate, organic content (volatile fatty acids), dissolved oxygen, operating pH, and temperature also have critical roles in PHA accumulation in microbial biomass. Research advances are also going on in downstream and recovery of PHA utilizing a combination of physical and chemical (halogenated solvents, surfactants, green solvents) methods. This review highlights recent developments in upcycling wastewater resources into PHA, encompassing various production strategies, downstream processing methodologies, and techno-economic analyses.

SHORT CONCLUSION

Organic carbon and nitrogen present in wastewater offer a promising, cost-effective source for producing bioplastic. Previous attempts have focused on enhancing productivity through optimizing culture systems and growth conditions. However, despite technological progress, significant challenges persist, such as low productivity, intricate downstream processing, scalability issues, and the properties of resulting PHA.

Identification of Oil-Loving Cupriavidus necator BM3-1 for Polyhydroxyalkanoate Production and Assessing Contribution of Exopolysaccharide for Vegetable Oil Utilization

Polyhydroxyalkanoates (PHA) have received attention owing to their biodegradability and biocompatibility, with studies exploring PHA-producing bacterial strains. As vegetable oil provides carbon and monomer precursors for poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P(3HB-co-3HHx)), oil-utilizing strains may facilitate PHA production. Herein, Cupriavidus necator BM3-1, which produces 11.1 g/L of PHB with 5% vegetable oil, was selected among various novel Cupriavidus necator strains. This strain exhibited higher preference for vegetable oils over sugars, with soybean oil and tryptone determined to be optimal sources for PHA production. BM3-1 produced 33.9 g/L of exopolysaccharides (EPS), which was three-fold higher than the amount produced by H16 (10.1 g/L). EPS exhibited 59.7% of emulsification activity (EI24), higher than that of SDS and of EPS from H16 with soybean oil. To evaluate P(3HB-co-3HHx) production from soybean oil, BM3-1 was engineered with P(3HB-co-3HHx) biosynthetic genes (phaCRa, phaARe, and phaJPa). BM3-1/pPhaCJ produced 3.5 mol% of 3HHx and 37.1 g/L PHA. BM3-1/pCB81 (phaCAJ) produced 32.8 g/L PHA, including 5.9 mol% 3HHx. Physical and thermal analyses revealed that P(3HB-co-5.9 mol% 3HHx) was better than PHB. Collectively, we identified a novel strain with high vegetable oil utilization capacity for the production of EPS, with the option to engineer the strain for P(3HB-co-3HHx).

Establishment of efficient 5-hydroxyvaleric acid production system by regenerating alpha-ketoglutaric acid and its application in poly(5-hydroxyvaleric acid) production

5-hydroxyvaleric acid (5-HV) is a versatile C5 intermediate of bio-based high-value chemical synthesis pathways. However, 5-HV production faces a few shortcomings involving the supply of cofactors, especially α-ketoglutaric acid (α-KG). Herein, we established a two-cell biotransformation system by introducing L-glutamate oxidase (GOX) to regenerate α-KG. Additionally, the catalase KatE was adapted to inhibit α-KG degradation by the H2O2 produced during GOX reaction. We searched for the best combination of genes and vectors and optimized the biotransformation conditions to maximize GOX effectiveness. Under the optimized conditions, 5-HV pathway with GOX showed 1.60-fold higher productivity than that of without GOX, showing 11.3 g/L titer. Further, the two-cell system with GOX and KatE was expanded to produce poly(5-hydroxyvaleric acid) (P(5HV)), and it reached at 412 mg/L of P(5HV) production and 20.5% PHA contents when using the biotransformation supernatant. Thus, the two-cell biotransformation system with GOX can potentially give the practical and economic alternative of 5-HV production using bio-based methods. We also propose direct utilization of 5-HV from bioconversion for P(5HV) production.

Controlled production of a polyhydroxyalkanoate (PHA) tetramer containing different mole fraction of 3-hydroxybutyrate (3HB), 3-hydroxyvalerate (3 HV), 4 HV and 5 HV units by engineered Cupriavidus necator

Polyhydroxyalkanoates (PHAs) are promising alternatives to existing petrochemical-based plastics because of their bio-degradable properties. However, the limited structural diversity of PHAs has hindered their application. In this study, high mole-fractions of Poly (39 mol% 3HB-co-17 mol% 3 HV-co-44 mol% 4 HV) and Poly (25 mol% 3HB-co-75 mol% 5 HV) were produced from 4- hydroxyvaleric acid and 5-hydroxyvaleric acid, using Cupriavidus necator PHB-4 harboring the gene phaCBP-M-CPF4 with modified sequences. In addition, the complex toxicity of precursor mixtures was tested, and it was confirmed that the engineered C. necator was capable of synthesizing Poly (32 mol% 3HB-co-11 mol% 3 HV-co-25 mol% 4 HV-co-32 mol% 5 HV) at low mixture concentrations. Correlation analyses of the precursor ratio and the monomeric mole fractions indicated that each mole fractions could be precisely controlled using the precursor proportion. Physical property analysis confirmed that Poly (3HB-co-3 HV-co-4 HV) is a rubber-like amorphous polymer and Poly (3HB-co-5 HV) has a high tensile strength and elongation at break. Poly (3HB-co-3 HV-co-4 HV-co-5 HV) had a much lower glass transition temperature than the co-, terpolymers containing 3 HV, 4 HV and 5 HV. This study expands the range of possible physical properties of PHAs and contributes to the realization of custom PHA production by suggesting a method for producing PHAs with various physical properties through mole-fraction control of 3 HV, 4 HV and 5 HV.

Tryptophan-Based Hyperproduction of Bioindigo by Combinatorial Overexpression of Two Different Tryptophan Transporters

Indigo is a valuable, natural blue dye that has been used for centuries in the textile industry. The large-scale commercial production of indigo relies on its extraction from plants and chemical synthesis. Studies are being conducted to develop methods for environment-friendly and sustainable production of indigo using genetically engineered microbes. Here, to enhance the yield of bioindigo from an E. coli whole-cell system containing tryptophanase (TnaA) and flavin-containing monooxygenase (FMO), we evaluated tryptophan transporters to improve the transport of aromatic compounds, such as indole and tryptophan, which are not easily soluble and passable through cell walls. Among the three transporters, Mtr, AroP, and TnaB, AroP enhanced indigo production the most. The combination of each transporter with AroP was also evaluated, and the combination of AroP and TnaB showed the best performance compared to the single transporters and two transporters. Bioindigo production was then optimized by examining the culture medium, temperature, isopropyl β-D-1-thiogalactopyranoside concentration, shaking speed (rpm), and pH. The novel strain containing aroP and tnaB plasmid with tnaA and FMO produced 8.77 mM (2.3 g/l) of bioindigo after 66 h of culture. The produced bioindigo was further recovered using a simple method and used as a watercolor dye, showing good mixing with other colors and color retention for a relatively long time. This study presents an effective strategy for enhancing indigo production using a combination of transporters.

Enhanced theanine production with reduced ATP supply by alginate entrapped Escherichia coli co-expressing γ-glutamylmethylamide synthetase and polyphosphate kinase

L-theanine is an amino acid with a unique flavor and many therapeutic effects. Its enzymatic synthesis has been actively studied and γ-Glutamylmethylamide synthetase (GMAS) is one of the promising enzymes in the biological synthesis of theanine. However, the theanine biosynthetic pathway with GMAS is highly ATP-dependent and the supply of external ATP was needed to achieve high concentration of theanine production. As a result, this study aimed to investigate polyphosphate kinase 2 (PPK2) as ATP regeneration system with hexametaphosphate. Furthermore, the alginate entrapment method was employed to immobilize whole cells containing both gmas and ppk2 together resulting in enhanced reusability of the theanine production system with reduced supply of ATP. After immobilization, theanine production was increased to 239 mM (41.6 g/L) with a conversion rate of 79.7% using 15 mM ATP and the reusability was enhanced, maintaining a 100% conversion rate up to the fifth cycles and 60% of conversion up to eighth cycles. It could increase long-term storage property for future uses up to 35 days with 75% activity of initial activity. Overall, immobilization of both production and cofactor regeneration system could increase the stability and reusability of theanine production system.

Validating a Xylose Regulator to Increase Polyhydroxybutyrate Production for Utilizing Mixed Sugars from Lignocellulosic Biomass Using Escherichia coli

Polyhydroxybutyrate (PHB) production from lignocellulosic biomass is economically beneficial. Because lignocellulosic biomass is a mixture rich in glucose and xylose, Escherichia coli, which prefers glucose, needs to overcome glucose repression for efficient biosugar use. To avoid glucose repression, here, we overexpressed a xylose regulator (xylR) in an E. coli strain expressing bktB, phaB, and phaC from Cupriavidus necator and evaluated the effect of xylR on PHB production. XylR overexpression increased xylose consumption from 0% to 46.53% and produced 4.45-fold more PHB than the control strain without xylR in a 1% sugar mixture of glucose and xylose (1:1). When the xylR-overexpressed strain was applied to sugars from lignocellulosic biomass, cell growth and PHB production of the strain showed a 4.7-fold increase from the control strain, yielding 2.58 ± 0.02 g/l PHB and 4.43 ± 0.28 g/l dry cell weight in a 1% hydrolysate mixture. XylR overexpression increased the expression of xylose operon genes by up to 1.7-fold. Moreover, the effect of xylR was substantially different in various E. coli strains. Overall, the results showed the effect of xylR overexpression on PHB production in a non-native PHB producer and the possible application of xylR for xylose utilization in E. coli.

[Preliminary study on automatic quantification and grading of leopard spots fundus based on deep learning technology]

Objective: To achieve automatic segmentation, quantification, and grading of different regions of leopard spots fundus (FT) using deep learning technology. The analysis includes exploring the correlation between novel quantitative indicators, leopard spot fundus grades, and various systemic and ocular parameters. Methods: This was a cross-sectional study. The data were sourced from the Beijing Eye Study, a population-based longitudinal study. In 2001, a group of individuals aged 40 and above were surveyed in five urban communities in Haidian District and three rural communities in Daxing District of Beijing. A follow-up was conducted in 2011. This study included individuals aged 50 and above who participated in the second 5-year follow-up in 2011, considering only the data from the right eye. Color fundus images centered on the macula of the right eye were input into the leopard spot segmentation model and macular detection network. Using the macular center as the origin, with inner circle diameters of 1 mm, 3 mm, and outer circle diameter of 6 mm, fine segmentation of the fundus was achieved. This allowed the calculation of the leopard spot density (FTD) and leopard spot grade for each region. Further analyses of the differences in ocular and systemic parameters among different regions' FTD and leopard spot grades were conducted. The participants were categorized into three refractive types based on equivalent spherical power (SE): myopia (SE<-0.25 D), emmetropia (-0.25 D≤SE≤0.25 D), and hyperopia (SE>0.25 D). Based on axial length, the participants were divided into groups with axial length<24 mm, 24-26 mm, and>26 mm for the analysis of different types of FTD. Statistical analyses were performed using one-way analysis of variance, Kruskal-Wallis test, Bonferroni test, and Spearman correlation analysis. Results: The study included 3 369 participants (3 369 eyes) with an average age of (63.9±10.6) years; among them, 1 886 were female (56.0%) and 1, 483 were male (64.0%). The overall FTD for all eyes was 0.060 (0.016, 0.163); inner circle FTD was 0.000 (0.000, 0.025); middle circle FTD was 0.030 (0.000, 0.130); outer circle FTD was 0.055 (0.009, 0.171). The results of the univariate analysis indicated that FTD in various regions was correlated with axial length (overall: r=0.38, P<0.001; inner circle: r=0.31, P<0.001; middle circle: r=0.36, P<0.001; outer circle: r=0.39, P<0.001), subfoveal choroidal thickness (SFCT) (overall: r=-0.69, P<0.001; inner circle: r=-0.57, P<0.001; middle circle: r=-0.68, P<0.001; outer circle: r=-0.72, P<0.001), age (overall: r=0.34, P<0.001; inner circle: r=0.30, P<0.001; middle circle: r=0.31, P<0.001; outer circle: r=0.35, P<0.001), gender (overall: r=-0.11, P<0.001; inner circle: r=-0.04, P<0.001; middle circle: r=-0.07, P<0.001; outer circle: r=-0.11, P<0.001), SE (overall: r=-0.20; P<0.001; inner circle: r=-0.19, P<0.001; middle circle: r=-0.20, P<0.001; outer circle: r=-0.20, P<0.001), uncorrected visual acuity (overall: r=-0.18, P<0.001; inner circle: r=-0.26, P<0.001; middle circle: r=-0.24, P<0.001; outer circle: r=-0.22, P<0.001), and body mass index (BMI) (overall: r=-0.11, P<0.001; inner circle: r=-0.13, P<0.001; middle circle: r=-0.14, P<0.001; outer circle: r=-0.13, P<0.001). Further multivariate analysis results indicated that different region FTD was correlated with axial length (overall: β=0.020, P<0.001; inner circle: β=-0.022, P<0.001; middle circle: β=0.027, P<0.001; outer circle: β=0.022, P<0.001), SFCT (overall: β=-0.001, P<0.001; inner circle: β=-0.001, P<0.001; middle circle: β=-0.001, P<0.001; outer circle: β=-0.001, P<0.001), and age (overall: β=0.002, P<0.001; inner circle: β=0.001, P<0.001; middle circle: β=0.002, P<0.001; outer circle: β=0.002, P<0.001). The distribution of overall (H=56.76, P<0.001), inner circle (H=72.22, P<0.001), middle circle (H=75.83, P<0.001), and outer circle (H=70.34, P<0.001) FTD differed significantly among different refractive types. The distribution of overall (H=373.15, P<0.001), inner circle (H=367.67, P<0.001), middle circle (H=389.14, P<0.001), and outer circle (H=386.89, P<0.001) FTD differed significantly among different axial length groups. Furthermore, comparing various levels of FTD with systemic and ocular parameters, significant differences were found in axial length (F=142.85, P<0.001) and SFCT (F=530.46, P<0.001). Conclusions: The use of deep learning technology enables automatic segmentation and quantification of different regions of theFT, as well as preliminary grading. Different region FTD is significantly correlated with axial length, SFCT, and age. Individuals with older age, myopia, and longer axial length tend to have higher FTD and more advanced FT grades.

Positive effect of phasin in biohydrogen production of non polyhydroxybutyrate-producing Clostridium acetobutylicum ATCC 824

In this study, the goal was to enhance the tolerance of Clostridium acetobutylicum ATCC 824 to biomass-based inhibitory compounds for biohydrogen production and evaluate various known genes that enhance the production of biochemicals in various hosts. The introduction of phaP, the major polyhydroxyalkanoate granule-associated protein that has been reported as a chaperone-like protein resulted in increased tolerance to inhibitors and leads to higher levels of hydrogen production, cell growth, and glucose consumption in the presence of these inhibitors. It was observed that the introduction of phaP led to an increase in the transcription of the hydrogenase gene, whereas transcription of the chaperone functional genes decreased compared to the wild type. Finally, the introduction of phaP could significantly enhance biohydrogen production by 2.6-fold from lignocellulosic hydrolysates compared to that of wild type. These findings suggested that the introduction of phaP could enhance growth and biohydrogen production, even in non-polyhydroxyalkanoate-producing strains.

Understanding microplastic pollution: Tracing the footprints and eco-friendly solutions

Microplastics (MPs) pollution has emerged as a critical environmental issue with far-reaching consequences for ecosystems and human health. These are plastic particles measuring <5 mm and are categorized as primary and secondary based on their origin. Primary MPs are used in various products like cosmetics, scrubs, body wash, and toothpaste, while secondary MPs are generated through the degradation of plastic products. These have been detected in seas, rivers, snow, indoor air, and seafood, posing potential risks to human health through the food chain. Detecting and quantifying MPs are essential to understand their distribution and abundance in the environment. Various microscopic (fluorescence microscopy, scanning electron microscopy) and spectroscopy techniques (FTIR, Raman spectroscopy, X-ray photoelectron spectroscopy) have been reported to analyse MPs. Despite the challenges in scalable removal methods, biological systems have emerged as promising options for eco-friendly MPs remediation. Algae, bacteria, and fungi have shown the potential to adsorb and degrade MPs in wastewater treatment plants (WWTPs) offering hope for mitigating this global crisis. This review examines the sources, impacts, detection, and biological removal of MPs, highlighting future directions in this crucial field of environmental conservation. By fostering global collaboration and innovative research a path towards a cleaner and healthier planet for future generations can be promised.

Reproducible Polybutylene Succinate (PBS)-Degrading Artificial Consortia by Introducing the Least Type of PBS-Degrading Strains

Polybutylene succinate (PBS) stands out as a promising biodegradable polymer, drawing attention for its potential as an eco-friendly alternative to traditional plastics due to its biodegradability and reduced environmental impact. In this study, we aimed to enhance PBS degradation by examining artificial consortia composed of bacterial strains. Specifically, Terribacillus sp. JY49, Bacillus sp. JY35, and Bacillus sp. NR4 were assessed for their capabilities and synergistic effects in PBS degradation. When only two types of strains, Bacillus sp. JY35 and Bacillus sp. NR4, were co-cultured as a consortium, a notable increase in degradation activity toward PBS was observed compared to their activities alone. The consortium of Bacillus sp. JY35 and Bacillus sp. NR4 demonstrated a remarkable degradation yield of 76.5% in PBS after 10 days. The degradation of PBS by the consortium was validated and our findings underscore the potential for enhancing PBS degradation and the possibility of fast degradation by forming artificial consortia, leveraging the synergy between strains with limited PBS degradation activity. Furthermore, this study demonstrated that utilizing only two types of strains in the consortium facilitates easy control and provides reproducible results. This approach mitigates the risk of losing activity and reproducibility issues often associated with natural consortia.

[Hemodynamic changes with serial balloon pulmonary angioplasty in chronic thromboembolic pulmonary hypertension]

Objective: To monitor hemodynamic changes during serial balloon pulmonary angioplasty (BPA) for chronic thromboembolic pulmonary hypertension (CTEPH). Methods: General clinical data of CTEPH patients diagnosed from October 2017 to January 2022 in Beijing Chaoyang Hospital were collected, and 83 patients who underwent at least 1 BPA treatment were included to analyze their 6 min walking distance, WHO functional class, N-terminal B-type natriuretic peptide precursor (NT-proBNP), troponin I (cTnI) and haemodynamic indices. Baseline and follow-up after the final BPA clinical data and hemodynamics, functional status and serial hemodynamics before each series of BPA were collected to evaluate the efficacy of BPA for CTEPH patients. Complications and managements were documented to confirm the safety of BPA for CTEPH patients. Results: Three hundred and forty BPA procedures were performed in 83 CTEPH patients. The median number of BPA procedures was 4.0 and a total of 2104 vessels were dilated. In general, mPAP [from 50.0(42.0-55.25) mmHg(1 mmHg=0.133 kPa) to 32.0(27.0-42.0) mmHg, P<0.001], PVR[from (806.6±323.2) dyn·s·cm-5 to 420.0(295.0-613.5) dyn·s·cm-5, P<0.001] were significantly improved compared with baseline, but not CO and CI. Functional parameters including WHO functional class Ⅰ/Ⅱ/Ⅲ/Ⅳ (from 0/35/34/14 to 43/32/7/1, P<0.001), 6MWD [from 364.5(300.0-429.5)m to 461.0(409.0-501.0)m, P<0.001], NT-proBNP [from 1 357.0(232.0-2 715.0) ng/L to 141.0(57.0-627.8) ng/L,P<0.001] were significantly improved compared with baseline. A cumulative (compared to baseline) and serial (compared to preceding BPA session) analysis of the sequential BPA session confirmed that a major hemodynamic improvement in PVR and mPAP occurred in the first 3 serial BPA treatments. There was a dose-response relationship: the more segments that were treated, the greater were the subsequent reduction in PVR and mPAP. There were 32.0 complications (9.4%) associated with BPA procedures, and the most common complication was pulmonary hemorrhage caused by catheter-related vascular injury. Conclusions: BPA is an effective and safe alternative for technically non-operable CTEPH patients. The hemodynamic benefits of BPA in CTEPH patients were cumulative and correlated with the total number of vessels successfully dilated.

An efficient and eco-friendly approach for the sustainable recovery and properties characterization of polyhydroxyalkanoates produced by methanotrophs

Synthetic biodegradable and bio-based polymers have emerged as sustainable alternatives to nonrenewable petroleum-derived polymers which cause serious environmental issues. In particular, polyhydroxyalkanoates (PHA) are promising biopolymers owing to their outstanding biodegradability and biocompatibility. The production of the homopolymer poly(3-hydroxybutyrate) (PHB) and copolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) from type II methanotrophs via microbial fermentation was presented. For the efficient extraction and recovery of intracellular PHA from methanotrophs, different extraction approaches were investigated including solvent extraction using 1,3-dioxolane as a green solvent, integrated cell lysis and solvent extraction, and cell digestion without the use of organic solvents. Among various extraction approaches, the integrated method exhibited the highest extraction performance, with PHA recovery and purity exceeding 91 % and 93 %, respectively, even when the PHA content of the cells was low. Furthermore, the molecular weight, thermal stability, and mechanical properties of the recovered PHA were comprehensively analyzed to suggest its suitable practical applications. The obtained properties were comparable to that of the commercial PHA products and PHA produced from other microbial species, indicating an efficient recovery of high-quality PHA produced from methanotrophs.

Application of liquid-based colorimetric method for high throughput screening of bioplastic-degrading strains using esterase assay

To alleviate environmental problems caused by using conventional plastics, bioplastics have garnered significant interest as alternatives to petroleum-based plastics. Despite possessing better degradability traits compared to traditional plastics, the degradation of bioplastics still demands a longer duration than initially anticipated. This necessitates the utilization of degradation strains or enzymes to enhance degradation efficiency, ensuring timely degradation. In this study, a novel screening method to identify bioplastic degraders faster was suggested to circumvent the time-consuming and laborious characteristics of solid-based plate assays. This liquid-based colorimetric method confirmed the extracellular esterase activity with p-nitrophenyl esters. It eliminated the needs to prepare plastic emulsion plates at the initial screening system, shortening the time for the overall screening process and providing more quantitative data. p-nitrophenyl hexanoate (C6) was considered the best substrate among the various p-nitrophenyl esters as substrates. The screening was performed in liquid-based 96-well plates, resulting in the discovery of a novel strain, Bacillus sp. SH09, with a similarity of 97.4% with Bacillus licheniformis. Furthermore, clear zone assays, degradation investigations, scanning electron microscopy, and gel permeation chromatography were conducted to characterize the biodegradation capabilities of the new strain, the liquid-based approach offered a swift and less labor-intensive option during the initial stages.

[A case of heritable pulmonary arterial hypertension treated with long-term oral low-dose imatinib]

Heritable pulmonary arterial hypertension (HPAH) is a rare type of pulmonary arterial hypertension that often presents with progressive exertional dyspnea and for which there is no significant effective drug. A HPAH patient was admitted to our hospital more than three years ago, and the gene mutation was bone morphogenetic protein 2 (BMPR2). For the first 45 months, she was given oral imatinib 100 mg once daily, and her symptoms and hemodynamics improved significantly, with no apparent side effects. It is reported that, in combination with the characteristics of the case and related literatures, it provides clinicians with other feasible treatment options for HPAH.

Indigo production goes green: a review on opportunities and challenges of fermentative production

Indigo is a widely used dye in various industries, such as textile, cosmetics, and food. However, traditional methods of indigo extraction and processing are associated with environmental and economic challenges. Fermentative production of indigo using microbial strains has emerged as a promising alternative that offers sustainability and cost-effectiveness. This review article provides a critical overview of microbial diversity, metabolic pathways, fermentation strategies, and genetic engineering approaches for fermentative indigo production. The advantages and limitations of different indigo production systems and a critique of the current understanding of indigo biosynthesis are discussed. Finally, the potential application of indigo in other sectors is also discussed. Overall, fermentative production of indigo offers a sustainable and bio-based alternative to synthetic methods and has the potential to contribute to the development of sustainable and circular biomanufacturing.

Maximization of 3-hydroxyhexanoate fraction in poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) using lauric acid with engineered Cupriavidus necator H16

As polyhydroxybutyrate (P(3HB)) was struggling with mechanical properties, efforts have been directed towards increasing mole fraction of 3-hydroxyhexanoate (3HHx) in P(3HB-co-3HHx) to improve the properties of polyhydroxyalkanoates (PHAs). Although genetic modification had significant results, there were several issues related to cell growth and PHA production by deletion of PHA synthetic genes. To find out easier strategy for high 3HHx mole fraction without gene deletion, Cupriavidus necator H16 containing phaC2Ra-phaACn-phaJ1Pa was examined with various oils resulting that coconut oil gave the highest 3HHx mole fraction. When fatty acid composition analysis with GC-MS was applied, coconut oil was found to have very different composition from other vegetable oil containing very high lauric acid (C12) content. To find out specific fatty acid affecting 3HHx fraction, different fatty acids from caproic acid (C6) to stearic acid (C18) was evaluated and the 3HHx mole fraction was increased to 26.5 ± 1.6 % using lauric acid. Moreover, the 3HHx mole fraction could be controlled from 9 % to 31.1 % by mixing bean oil and lauric acid with different ratios. Produced P(3HB-co-3HHx) exhibited higher molecular than P(3HB-co-3HHx) from phaB-deletion mutant. This study proposes another strategy to increase 3HHx mole fraction with easier way by modifying substrate composition without applying deletion tools.