Comparison of the Fatty Acid Composition in Phospholipid Species from Korean Human Milk.

In this study, the phospholipid species [i.e., phosphatidylethanolamine (PE), phosphatidylcholine (PC), and sphingomyelin (SM)] in human milk (HM) were compared according to their fatty acid (FA) composition. 34 HM samples were collected and classified into three groups (A < B < C) according to their fat content. Stearic acid (C18:0) was the main FA in PE, PC, and SM. The highest concentrations of arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosapentaenoic acid (DPA) were observed in PE, whereas docosahexaenoic acid (DHA) was predominant in SM. Although PC exhibited the highest total saturated FAs (SFAs) and PE contained the highest unsaturated FAs (UFAs), very long-chain SFAs and monounsaturated FAs (MUFAs) were preferentially distributed in SM. PC and SM had higher saturation compared to PE. Regarding the effect of the fat content of HM on the FA composition of the phospholipid species, a limited influence was observed on the composition of SFAs and MUFAs of PE, SM, and particularly PC. However, a more pronounced effect on the composition of polyunsaturated FAs (PUFAs) in phospholipids was observed, especially for linoleic acid (LA), α-linolenic acid (ALA), EPA, and DHA, indicating that the composition of FAs in the phospholipid species was probably affected by the maternal diet.

Compositional Study of Phospholipids from the Dried Big Head and Opossum Shrimp, Mussel, and Sea Cucumber Using 31P NMR Spectroscopy: Content and Fatty Acid Composition of Plasmalogen.

Herein, we present a qualitative and quantitative analysis of the compositions of plasmalogens and phospholipids (PLs) in dried big head shrimp (Solenocera melantho), opossum shrimp (Neomysis awatschensis), mussel (Mytilus galloprovincialis), and sea cucumber (Apostichopus japonicus). We also analyze the fatty acid composition of the extracted lipids, phosphatidyl choline (PtdCho), and plasmalogen choline (PlsCho) from each sample. In big head shrimp, opossum shrimp, and mussel, phosphatidyl choline (PtdCho) was the most abundant PL at 1677.9, 1603, and 1661.6 mg/100 g of dried sample, respectively, whereas the most abundant PL in sea cucumber was PlsCho (206.9 mg/100 g of dried sample). In all four samples, plasmalogen ethanolamine (PlsEtn) was higher than phosphatidyl ethanolamine (PtdEtn). The content (mg/100 g of dried sample) of PlsCho was highest in mussel (379.0), and it was higher in big head shrimp (262.3) and opossum shrimp (245.6) than sea cucumber (206.9). The contents (mg/100 g of dried sample) of PlsEtn were in the order of mussel (675.4) > big head shrimp (629.5) > opossum shrimp (217.9) > sea cucumber (51.5). For analyzing the fatty acids at the sn-2 position of PlsCho, the consecutive treatment with phospholipase A1, solid phase extraction, thin-layer chromatography (TLC), and GC-FID were applied. The most abundant fatty acid was eicosapentaenoic acid (EPA, C20:5, n-3) in big head shrimp and sea cucumber, palmitoleic acid (C16:1, n-7) in opossum shrimp, and docosadienoic acid (C22:2, n-6) in mussel.

Experimental Study on the Detection of Hazardous Chemicals Using Alternative Sensors in the Water Environment.

Chemical accidents in rivers may be triggered by natural or anthropogenic causes and refer to the flow of large quantities of hazardous chemicals into rivers. In South Korea, domestic water is sourced from large rivers, such as the Nakdong River. However, owing to rapid industrialization, industrial facilities have become heavily concentrated in the middle and upper reaches of the Nakdong River. Therefore, severe problems could arise if harmful chemicals are leaked from industrial facilities into the river, and this contaminated river water is supplied to cities. Quantitative evaluation based on instrumental analysis during chemical accidents and prediction research based on modeling is actively being conducted however, research on the initial response is insufficient. Therefore, in this study, the variations in pH and EC were analyzed according to their chemical concentrations for seven chemicals. These seven chemicals are designated accident-preparedness substances that frequently cause chemical spills in South Korea. Additionally, we evaluated the possibility of identifying unknown substances by comparing the variations in pH and EC and statistics while diluting unknown substances. Thus, the potential of pH and EC as alternative indicators for detecting and identifying chemicals was evaluated in this study. NaF, NH4HF2, NaCN, and NH4OH were classified by comparing their spatial distributions in a pH-EC relation curve. However, H2SO4, HCl, and SOCl2 showed similar spatial distributions in the pH-EC curves and were difficult to identify. The results of this study provide information for chemical detection and identification using alternative sensors that permit easy and rapid field measurements in the event of a chemical spill and could be used as preliminary data for rapidly responding to accidents.

EMT-mediated regulation of CXCL1/5 for resistance to anti-EGFR therapy in colorectal cancer.

The emergence of RAS/RAF mutant clone is the main feature of EGFR inhibitor resistance in KRAS wild-type colon cancer. However, its molecular mechanism is thought to be multifactorial, mainly due to cellular heterogeneity. In order to better understand the resistance mechanism in a single clone level, we successfully isolated nine cells with cetuximab-resistant (CR) clonality from in vitro system. All CR cells harbored either KRAS or BRAF mutations. Characteristically, these cells showed a higher EMT (Epithelial to mesenchymal transition) signature, showing increased EMT markers such as SNAI2. Moreover, the expression level of CXCL1/5, a secreted protein, was significantly higher in CR cells compared to the parental cells. In these CR cells, CXCL1/5 expression was coordinately regulated by SNAI2/NFKB and transactivated EGFR through CXCR/MMPI/EGF axis via autocrine singling. We also observed that combined cetuximab/MEK inhibitor not only showed growth inhibition but also reduced the secreted amounts of CXCL1/5. We further found that serum CXCL1/5 level was positively correlated with the presence of RAS/RAF mutation in colon cancer patients during cetuximab therapy, suggesting its role as a biomarker. These data indicated that the application of serum CXCL1/5 could be a potential serologic biomarker for predicting resistance to EGFR therapy in colorectal cancer.

Fructose-Based Production of Short-Chain-Length and Medium-Chain-Length Polyhydroxyalkanoate Copolymer by Arctic Pseudomonas sp. B14-6.

Arctic bacteria employ various mechanisms to survive harsh conditions, one of which is to accumulate carbon and energy inside the cell in the form of polyhydroxyalkanoate (PHA). Whole-genome sequencing of a new Arctic soil bacterium Pseudomonas sp. B14-6 revealed two PHA-production-related gene clusters containing four PHA synthase genes (phaC). Pseudomonas sp. B14-6 produced poly(6% 3-hydroxybutyrate-co-94% 3-hydroxyalkanoate) from various carbon sources, containing short-chain-length PHA (scl-PHA) and medium-chain-length PHA (mcl-PHA) composed of various monomers analyzed by GC-MS, such as 3-hydroxybutyrate, 3-hydroxyhexanoate, 3-hydroxyoctanoate, 3-hydroxydecanoate, 3-hydroxydodecenoic acid, 3-hydroxydodecanoic acid, and 3-hydroxytetradecanoic acid. By optimizing the PHA production media, we achieved 34.6% PHA content using 5% fructose, and 23.7% PHA content using 5% fructose syrup. Differential scanning calorimetry of the scl-co-mcl PHA determined a glass transition temperature (Tg) of 15.3 °C, melting temperature of 112.8 °C, crystallization temperature of 86.8 °C, and 3.82% crystallinity. In addition, gel permeation chromatography revealed a number average molecular weight of 3.6 × 104, weight average molecular weight of 9.1 × 104, and polydispersity index value of 2.5. Overall, the novel Pseudomonas sp. B14-6 produced a polymer with high medium-chain-length content, low Tg, and low crystallinity, indicating its potential use in medical applications.

Revealing of sugar utilization systems in Halomonas sp. YLGW01 and application for poly(3-hydroxybutyrate) production with low-cost medium and easy recovery.

Poly(3-hydroxybutyrate) (PHB) is a common polyhydroxyalkanoate (PHA) with potential as an alternative for petroleum-based plastics. Previously, we reported a new strain, Halomonas sp. YLGW01, which hyperproduces PHB with 94% yield using fructose. In this study, we examined the PHB production machinery of Halomonas sp. YLGW01 in more detail by deep-genome sequencing, which revealed a 3,453,067-bp genome with 65.1% guanine-cytosine content and 3054 genes. We found two acetyl-CoA acetyltransferases (Acetoacetyl-CoA thiolase, PhaA), one acetoacetyl-CoA reductase (PhaB), two PHB synthases (PhaC1, PhaC2), PHB depolymerase (PhaZ), and Enoyl-CoA hydratase (PhaJ) in the genome, along with two fructose kinases and fructose transporter systems, including the phosphotransferase system (PTS) and ATP-binding transport genes. We then examined the PHB production by Halomonas sp. YLGW01 using high-fructose corn syrup (HFCS) containing fructose, glucose, and sucrose in sea water medium, resulting in 7.95 ± 0.11 g/L PHB (content, 67.39 ± 0.34%). PHB was recovered from Halomonas sp. YLGW01 using different detergents; the use of Tween 20 and SDS yielded micro-sized granules with high purity. Overall, these results reveal the distribution of PHB synthetic genes and the sugar utilization system in Halomonas sp. YLGW01 and suggest a possible method for PHB recovery.

NaCl Concentration-Dependent Aminoglycoside Resistance of Halomonas socia CKY01 and Identification of Related Genes.

Among various species of marine bacteria, those belonging to the genus Halomonas have several promising applications and have been studied well. However, not much information has been available on their antibiotic resistance. In our efforts to learn about the antibiotic resistance of strain Halomonas socia CKY01, which showed production of various hydrolases and growth promotion by osmolytes in previous study, we found that it exhibited resistance to multiple antibiotics including kanamycin, ampicillin, oxacillin, carbenicillin, gentamicin, apramycin, tetracycline, and spectinomycin. However, the H. socia CKY01 resistance pattern to kanamycin, gentamicin, apramycin, tetracycline, and spectinomycin differed in the presence of 10% NaCl and 1% NaCl in the culture medium. To determine the mechanism underlying this NaCl concentration-dependent antibiotic resistance, we compared four aminoglycoside resistance genes under different salt conditions while also performing time-dependent reverse transcription PCR. We found that the aph2 gene encoding aminoglycoside phosphotransferase showed increased expression under the 10% rather than 1% NaCl conditions. When these genes were overexpressed in an Escherichia coli strain, pETDuet-1::aph2 showed a smaller inhibition zone in the presence of kanamycin, gentamicin, and apramycin than the respective control, suggesting aph2 was involved in aminoglycoside resistance. Our results demonstrated a more direct link between NaCl and aminoglycoside resistance exhibited by the H. socia CKY01 strain.

Effects of a Δ-9-fatty acid desaturase and a cyclopropane-fatty acid synthase from the novel psychrophile Pseudomonas sp. B14-6 on bacterial membrane properties.

Psychrophilic bacteria, living at low and mild temperatures, can contribute significantly to our understanding of microbial responses to temperature, markedly occurring in the bacterial membrane. Here, a newly isolated strain, Pseudomonas sp. B14-6, was found to dynamically change its unsaturated fatty acid and cyclic fatty acid content depending on temperature which was revealed by phospholipid fatty acid (PLFA) analysis. Genome sequencing yielded the sequences of the genes Δ-9-fatty acid desaturase (desA) and cyclopropane-fatty acid-acyl-phospholipid synthase (cfa). Overexpression of desA in Escherichia coli led to an increase in the levels of unsaturated fatty acids, resulting in decreased membrane hydrophobicity and increased fluidity. Cfa proteins from different species were all found to promote bacterial growth, despite their sequence diversity. In conclusion, PLFA analysis and genome sequencing unraveled the temperature-related behavior of Pseudomonas sp. B14-6 and the functions of two membrane-related enzymes. Our results shed new light on temperature-dependent microbial behaviors and might allow to predict the consequences of global warming on microbial communities.

Enhancement of pipecolic acid production by the expression of multiple lysine cyclodeaminase in the Escherichia coli whole-cell system.

Pipecolic acid, a non-proteinogenic amino acid, is a metabolite in lysine metabolism and a key chiral precursor in local anesthesia and macrolide antibiotics. To replace the environmentally unfriendly chemical production or preparation procedure of pipecolic acid, many biological synthetic routes have been studied for a long time. Among them, synthesis by lysine cyclodeaminase (LCD), encoded by pipA, has several advantages, including stability of enzyme activity and NAD+ self-regeneration. Thus, we selected this enzyme for pipecolic acid biosynthesis in a whole-cell bioconversion. To construct a robust pipecolic acid production system, we investigated important conditions including expression vector, strain, culture conditions, and other reaction parameters. The most important factor was the introduction of multiple pipA genes into the whole-cell system. As a result, we produced 724 mM pipecolic acid (72.4 % conversion), and the productivity was 0.78 g/L/h from 1 M l-lysine after 5 days. This is the highest production reported to date.

Effects of osmolytes on salt resistance of Halomonas socia CKY01 and identification of osmolytes-related genes by genome sequencing.

Bacteria from the genus Halomonas hold promise in biotechnology as sources of salt-tolerant enzymes, biosurfactants, biopolymers, osmolytes, and as actors in bioremediation processes. In a previous work, we have identified Halomonas socia strain CKY01 having various hydrolase activities. Here, we aimed to study the survival strategies of marine bacteria. A deep genome sequencing study of H. socia CKY01 has revealed 4627 genes reaching 4,753,299 bp with 64 % of GC content. This strain produced polyhydroxybutyrate (PHB) having one gene clusters having phaC and phasin, and it has several genes responsible for the uptake, synthesis, and transport of the osmolytes such as betaine, choline, ectoine, carnitine, and proline in the bacterial genome. The addition of 60 mM glutamate, 60 mM proline and 60 mM ectoine enhanced growth 300.8 %, 294.2 % and 235.0 %, respectively, under 10 % saline conditions. In particular, ectoine and proline increased salt resistance and allowed cells to survive in more than 15 % NaCl. By combining experimental and genome sequencing data, we have investigated the importance of osmolytes on the survival of this Halomonas strain.

Production of L-Theanine Using Escherichia coli Whole-Cell Overexpressing γ-Glutamylmethylamide Synthetase with Bakers Yeast.

L-Theanine, found in green tea leaves has been shown to positively affect immunity and relaxation in humans. There have been many attempts to produce L-theanine through enzymatic synthesis to overcome the limitations of traditional methods. Among the many genes coding for enzymes in the L-theanine biosynthesis, glutamylmethylamide synthetase (GMAS) exhibits the greatest possibility of producing large amounts of production. Thus, GMAS from Methylovorus mays No. 9 was overexpressed in several strains including vectors with different copy numbers. BW25113(DE3) cells containing the pET24ma::gmas was selected for strains. The optimal temperature, pH, and metal ion concentration were 50°C, 7, and 5 mM MnCl2, respectively. Additionally, ATP was found to be an important factor for producing high concentration of L-theanine so several strains were tested during the reaction for ATP regeneration. Bakers yeast was found to decrease the demand for ATP most effectively. Addition of potassium phosphate source was demonstrated by producing 4-fold higher L-theanine. To enhance the conversion yield, GMAS was additionally overexpressed in the system. A maximum of 198 mM L-theanine was produced with 16.5 mmol/l/h productivity. The whole-cell reaction involving GMAS has greatest potential for scale-up production of L-theanine.

Increased resistance of a methicillin-resistant Staphylococcus aureus Δagr mutant with modified control in fatty acid metabolism.

Methicillin-resistant Staphylococcus aureus (MRSA) strains are distinct from general Staphylococcus strains with respect to the composition of the membrane, ability to form a thicker biofilm, and, importantly, ability to modify the target of antibiotics to evade their activity. The agr gene is an accessory global regulator of gram-positive bacteria that governs virulence or resistant mechanisms and therefore an important target for the control of resistant strains. However, the mechanism by which agr impacts resistance to ß-lactam antibiotics remains unclear. In the present study, we found the Δagr mutant strain having higher resistance to high concentrations of ß-lactam antibiotics such as oxacillin and ampicillin. To determine the influence of variation in the microenvironment of cells between the parental and mutant strains, fatty acid analysis of the supernatant, total lipids, and phospholipid fatty acids were compared. The Δagr mutant strain tended to produce fewer fatty acids and retained lower amounts of C16, C18 fatty acids in the supernatant. Phospholipid analysis showed a dramatic increase in the hydrophobic longer-chain fatty acids in the membrane. To target membrane, we applied several surfactants and found that sorbitan monolaurate (Span20) had a synergistic effect with oxacillin by decreasing biofilm formation and growth. These findings indicate that agr deletion allows for MRSA to resist antibiotics via several changes including constant expression of mecA, fatty acid metabolism, and biofilm thickening.

Simultaneous monitoring of the bioconversion from lysine to glutaric acid by ethyl chloroformate derivatization and gas chromatography-mass spectrometry.

Glutaric acid is a precursor of a plasticizer that can be used for the production of polyester amides, ester plasticizer, corrosion inhibitor, and others. Glutaric acid can be produced either via bioconversion or chemical synthesis, and some metabolites and intermediates are produced during the reaction. To ensure reaction efficiency, the substrates, intermediates, and products, especially in the bioconversion system, should be closely monitored. Until now, high performance liquid chromatography (HPLC) has generally been used to analyze the glutaric acid-related metabolites, although it demands separate time-consuming derivatization and non-derivatization analyses. To substitute for this unreasonable analytical method, we applied herein a gas chromatography - mass spectrometry (GC-MS) method with ethyl chloroformate (ECF) derivatization to simultaneously monitor the major metabolites. We determined the suitability of GC-MS analysis using defined concentrations of six metabolites (l-lysine, cadaverine, 5-aminovaleric acid, 2-oxoglutaric acid, glutamate, and glutaric acid) and their mass chromatograms, regression equations, regression coefficient values (R2), dynamic ranges (mM), and retention times (RT). This method successfully monitored the production process in complex fermentation broth.

Fructose based hyper production of poly-3-hydroxybutyrate from Halomonas sp. YLGW01 and impact of carbon sources on bacteria morphologies.

Polyhydroxyalkanoates (PHA), such as poly (3-hydroxybutyrate) (PHB), have emerged as potential alternatives to petroleum-based plastics and can be produced through the appropriate selection of marine bacteria that are already adapted to high salt and low temperature conditions without the requirement of antibiotic treatment. The present study, thus, aimed to screen and characterize thirteen PHA-producing microbial strains isolated from the Gwangalli beach in Busan, South Korea. Among them, Halomonas sp. YLGW01 produced the highest amount of PHB (94.6 ± 1.8% (w/w)) using fructose. Interestingly Halomonas sp. YLGW01 showed increase in cell size (8.39 ± 3.63 µm) with fructose as carbon source as compared to glucose (2.34 ± 0.44 µm). Fructose syrup was investigated as carbon source under unsterilized conditions and 95.26 ± 1.78% of PHB was produced. Overall, this strain showed the highest PHB contents in halotolerant bacteria.

Conversion of waste cooking oil into biodiesel using heterogenous catalyst derived from cork biochar.

In this study, a heterogeneous catalyst prepared by pyrolysis of waste cork (Quercus suber) was used for the transesterification of waste cooking oil (WCO). Physicochemical properties of the synthesized biochar catalyst were studied using BET, SEM, FTIR, and XRD. The experiment results demonstrate that heterogeneous catalyst synthesized at 600 °C showed maximum fatty acids methyl esters (FAMEs) conversion (98%) at alcohol:oil (25:1), catalyst loading (1.5% w/v) and temperature 65 °C. Biodiesel produced from WCO (Canola oil) mainly composed of FAMEs in following order C18:1 > C18:2 > C16:0 > C18:0 > C20:0. Properties of produced biodiesel were analysed as cetane number (CN) 50.56, higher heating value (HHV) 39.5, kinematic viscosity (ʋ) 3.9, and density (ρ) 0.87.

Enhanced tolerance to inhibitors of Escherichia coli by heterologous expression of cyclopropane-fatty acid-acyl-phospholipid synthase (cfa) from Halomonas socia.

Bacteria have evolved a defense system to resist external stressors, such as heat, pH, and salt, so as to facilitate survival in changing or harsh environments. However, the specific mechanisms by which bacteria respond to such environmental changes are not completely elucidated. Here, we used halotolerant bacteria as a model to understand the mechanism conferring high tolerance to NaCl. We screened for genes related to halotolerance in Halomonas socia, which can provide guidance for practical application. Phospholipid fatty acid analysis showed that H. socia cultured under high osmotic pressure produced a high portion of cyclopropane fatty acid derivatives, encoded by the cyclopropane-fatty acid-acyl phospholipid synthase gene (cfa). Therefore, H. socia cfa was cloned and introduced into Escherichia coli for expression. The cfa-overexpressing E. coli strain showed better growth, compared with the control strain under normal cultivation condition as well as under osmotic pressure (> 3% salinity). Moreover, the cfa-overexpressing E. coli strain showed 1.58-, 1.78-, 3.3-, and 2.19-fold higher growth than the control strain in the presence of the inhibitors furfural, 4-hydroxybenzaldehyde, vanillin, and acetate from lignocellulosic biomass pretreatment, respectively. From a practical application perspective, cfa was co-expressed in E. coli with the polyhydroxyalkanoate (PHA) synthetic operon of Ralstonia eutropha using synthetic and biosugar media, resulting in a 1.5-fold higher in PHA production than that of the control strain. Overall, this study demonstrates the potential of the cfa gene to boost cell growth and production even in heterologous strains under stress conditions.

Adsorption behavior of tetracycline onto Spirulina sp. (microalgae)-derived biochars produced at different temperatures.

We evaluated the production of Spirulina sp. (microalgae)-derived biochars (SPAL-BCs) at different pyrolysis temperatures for the removal of an emerging water contaminant, tetracycline (TC). Physicochemical properties of SPAL-BCs were characterized and related with their capacity to adsorb TC. Increasing pyrolysis temperatures led to higher aromaticity, higher hydrophobicity, and higher specific surface area. In particular, SPAL-BC750 possessed the highest hydrophobicity, various strong crystallizations (i.e., calcite, hydroxyapatite, and rhenanite) and functional groups (i.e., CH2, CN, CO, and CO32-), which may be associated with high TC adsorption. SPAL-BC750 also presented the highest TC adsorption capacity (132.8 mg TC/g biochar) via batch experimentation because of hydrophobic, π-π interactions, functional groups, and metal complexation. The best fitting isotherm and kinetic models of TC adsorption by SPAL-BC750 were the Langmuir and pseudo-first order models, respectively. SPAL-BCs obtained as a by-product of pyrolysis may be an economical and potentially valuable adsorbent for aqueous antibiotic removal.

Treatment of furazolidone contaminated water using banana pseudostem biochar engineered with facile synthesized magnetic nanocomposites.

The present study enlightens facile synthesis and characterization of magnetic biochar derived from waste banana pseudostem biomass for the removal of nitrofuran antibiotic 'furazolidone' (FZD). Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), magnetic hysteresis, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) revealed successful hybridization of magnetic nanocomposites with biochar (BPB600). The maximum adsorption capacity of magnetic BPB600 was 96.81% (37.86 mg g-1), which was significantly higher than the non-coated BPB600 (77.25%; 31.45 mg g-1). Adsorption kinetics data fitted well with pseudo-second order, and Elovich model demonstrating dominance of the chemisorption mechanism. Furthermore, the response surface methodology (RSM) was applied to evaluate the interactive effect of pH, temperature, and FZD concentration on adsorption. Therefore, the results of present study would provide an effective strategy to tackle antibiotic contaminants responsible for the antibiotic resistance genes or bacteria that decreases the therapeutic value of antibiotics.

Development of glutaric acid production consortium system with α-ketoglutaric acid regeneration by glutamate oxidase in Escherichia coli.

Glutaric acid is a C5 dicarboxylic acid that can be used as a building block for bioplastics. Although high concentrations of glutaric acid can be produced by fermentation or bioconversion, a large amount of α-ketoglutaric acid (α-KG) is necessary to accept the amine group from 5-aminovaleric acid. To decrease the demand for α-KG, we introduced l-glutamate oxidase (GOX) from Streptomyces mobaraensis in our previous system for cofactor regeneration in combination with a glutaric acid production system from 5-aminovaleric acid. To enhance glutaric acid production, critical factors were optimized such as the expression vector, pH, temperature, and cell ratio. As a result, the demand for α-KG was decreased by more than 6-fold under optimized conditions. Additionally, the effect of catalase was also demonstrated by blocking the degradation of α-KG to succinic acid because of the hydrogen peroxide. Finally, 468.5 mM glutaric acid was produced from 800 mM 5-aminovaleric acid using only 120 mM α-KG. Moreover, this system containing davBA, gabTD-nox, and gox can be applied to produce glutaric acid from L-lysine by reusing α-KG with GOX. This improved cofactor regeneration system has a potential to apply much larger production of glutaric acid.

Chitin biomass powered microbial fuel cell for electricity production using halophilic Bacillus circulans BBL03 isolated from sea salt harvesting area.

Incessant depletion of non-renewable energy sources has gained attention to search for new biological systems to transform organic biomass into electricity using microbial fuel cell (MFC). The main approach of the existing study was to develop a single step process to produce electrical energy from underutilized chitin biomass. Halophilic bacterium Bacillus circulans BBL03 isolated from anodic biofilm showed higher electricity production (26.508 µAcm2) in a natural seawater medium fed with 1.0% chitin. Maximum chitinase activity (94.24 ±â€¯4.2 U mL-1) and N-acetylglucosamine (GlcNAc) production (136.30 ±â€¯2.8 mg g-1 chitin) were achieved at 48 h. Prominent metabolites detected in chitin hydrolysis were lactate, formate, acetate, propionate, and butyrate. Furthermore, cyclic voltammetry (CV) studies revealed the possibility of direct electron transfer by anodic biofilm to anode without any external redox mediators. Polarization and coulombic efficiency (CE) analysis showed maximum power density (PD) 1.742 mWcm2 and 47% CE using 1% chitin as a substrate. Alteration in crystallinity and functional group on chitin were analysed using FTIR and XRD. Therefore, natural seawater-chitin powered MFCs could be a cheap asset for longer electricity production.