C1 Compounds Research Articles

Effects of microbial fermentation on enzyme activity and volatile properties of Massa Medicata Fermentata

ABSTRACTAimMassa Medicata Fementata (MMF) is a crude drug used in East Asia to treat anorexia and dyspepsia. It is prepared from wheat and several herbs through microbial fermentation using Aspergillus sp. and Rhizopus sp. There is great difference in the quality of commercial MMF, and the microbes of MMF are suggested to affect its quality. We investigated the effects of microbial fermentation on the quality of MMF.MethodsRaw materials of MMF were mixed according to the ratio listed in the National Standard for Chinese Patent Drugs, and MMF was prepared using pure cultures of Aspergillus oryzae or Rhizopus oryzae. Digestive enzyme activities (α‐amylase, protease, and lipase) and volatile compounds were measured using an analytical kit and GC–MS, respectively.ResultsEnzyme activity increased in MMF. MMF prepared with A. oryzae (MMF‐A) showed higher α‐amylase and lipase activities than that prepared with R. oryzae (MMF‐R). Protease activity was marginally higher in MMF‐R than in MMF‐A. GC–MS analysis revealed that terpenoids decreased with fermentation; however, 2,3‐butanediol, acetoin, and guaiacol were detected in MMF only. C8 compounds such as 1‐octen‐3‐ol were higher in MMF‐A than MMF‐R; however, aromatic compounds such as 4‐vinylguaiacol and pyrazines were higher in MMF‐R than MMF‐A.ConclusionMicrobial fermentation contributes to increased enzyme activity and changes in MMF volatiles. These properties of MMF were considerably affected by the microbes used, and it is proposed in this study that it is important to have microbial control in the production of commercial MMF.

Molecular composition of secondary organic aerosol from styrene under different NOx and humidity conditions

Styrene is highly reactive in the atmosphere, which has been identified as a hazardous air pollutant by the Clean Air Act, and as an important secondary organic aerosol (SOA) precursor. In this study, the SOA formation from styrene under different NOx and relative humidity (RH) conditions were explored in an indoor chamber. The chemical composition of SOA was characterized using a Fourier transform infrared spectroscopy (FTIR) and a modified atmospheric pressure chemical ionization mass spectrometry (APCI-MS). The results show that the SOA yields decrease from 11.4% to 7.2% at about 70 μg m−3 SOA as RH increases from 8.5% to 62.4% in the H2O2 system; the SOA yields decrease from 1.1% to 0.7% at about 10 μg m−3 SOA as RH increases from 8.4% to 60.9% in the NOx system. In the H2O2 system, C7 and C8 series compounds are major components of SOA at both RHs. The total signal ratio of less oxidized C7 and C8 compounds (nO < 4) to the total SOA at 8.8% RH is 2.2 times higher than that at 63.3% RH. The OSc values of SOA were determined to be −0.2 at 8.8% RH and 0.04 at 63.3% RH based on MS data. It is proposed that high RH can accelerate the heterogeneous uptake of H2O2 onto particles and promote the further oxidation of less oxidized compounds in the particle phase. In the NOx system, SOA formation is significantly suppressed by the competitive reaction of RO2 with NO. The FTIR and MS results show that the main composition of SOA is organonitrates. At 8.3% RH, OH, O3 and NO3 are oxidants in the styrene-NOx irritation system. Among these oxidants, NO3 plays a minor role due to its photolysis. While at 60.9% RH, SOA formation from O3 is significantly inhibited by the reaction of stabilized Criegee intermediates (SCIs) with H2O, and SOA from the NO3 pathway is suppressed by the heterogeneous uptake of N2O5 to humid particles.

Chemical composition of nanoparticles from &amp;lt;i&amp;gt;α&amp;lt;/i&amp;gt;-pinene nucleation and the influence of isoprene and relative humidity at low temperature

Abstract. Biogenic organic precursors play an important role in atmospheric new particle formation (NPF). One of the major precursor species is α-pinene, which upon oxidation can form a suite of products covering a wide range of volatilities. Highly oxygenated organic molecules (HOMs) comprise a fraction of the oxidation products formed. While it is known that HOMs contribute to secondary organic aerosol (SOA) formation, including NPF, they have not been well studied in newly formed particles due to their very low mass concentrations. Here we present gas- and particle-phase chemical composition data from experimental studies of α-pinene oxidation, including in the presence of isoprene, at temperatures (−50 and −30 ∘C) and relative humidities (20 % and 60 %) relevant in the upper free troposphere. The measurements took place at the CERN Cosmics Leaving Outdoor Droplets (CLOUD) chamber. The particle chemical composition was analyzed by a thermal desorption differential mobility analyzer (TD-DMA) coupled to a nitrate chemical ionization–atmospheric pressure interface–time-of-flight (CI-APi-TOF) mass spectrometer. CI-APi-TOF was used for particle- and gas-phase measurements, applying the same ionization and detection scheme. Our measurements revealed the presence of C8−10 monomers and C18−20 dimers as the major compounds in the particles (diameter up to ∼ 100 nm). Particularly, for the system with isoprene added, C5 (C5H10O5−7) and C15 compounds (C15H24O5−10) were detected. This observation is consistent with the previously observed formation of such compounds in the gas phase. However, although the C5 and C15 compounds do not easily nucleate, our measurements indicate that they can still contribute to the particle growth at free tropospheric conditions. For the experiments reported here, most likely isoprene oxidation products enhance the growth of particles larger than 15 nm. Additionally, we report on the nucleation rates measured at 1.7 nm (J1.7 nm) and compared with previous studies, we found lower J1.7 nm values, very likely due to the higher α-pinene and ozone mixing ratios used in the present study.

Reticular-Chemistry-Inspired Supramolecule Design as a Tool to Achieve Efficient Photocatalysts for CO2 Reduction.

Photocatalytic CO2 reduction into C1 products is one of the most trending research subjects of current times as sustainable energy generation is the utmost need of the hour. In this review, we have tried to comprehensively summarize the potential of supramolecule-based photocatalysts for CO2 reduction into C1 compounds. At the outset, we have thrown light on the inert nature of gaseous CO2 and the various challenges researchers are facing in its reduction. The evolution of photocatalysts used for CO2 reduction, from heterogeneous catalysis to supramolecule-based molecular catalysis, and subsequent semiconductor–supramolecule hybrid catalysis has been thoroughly discussed. Since CO2 is thermodynamically a very stable molecule, a huge reduction potential is required to undergo its one- or multielectron reduction. For this reason, various supramolecule photocatalysts were designed involving a photosensitizer unit and a catalyst unit connected by a linker. Later on, solid semiconductor support was also introduced in this supramolecule system to achieve enhanced durability, structural compactness, enhanced charge mobility, and extra overpotential for CO2 reduction. Reticular chemistry is seen to play a pivotal role as it allows bringing all of the positive features together from various components of this hybrid semiconductor–supramolecule photocatalyst system. Thus, here in this review, we have discussed the selection and role of various components, viz. the photosensitizer component, the catalyst component, the linker, the semiconductor support, the anchoring ligands, and the peripheral ligands for the design of highly performing CO2 reduction photocatalysts. The selection and role of various sacrificial electron donors have also been highlighted. This review is aimed to help researchers reach an understanding that may translate into the development of excellent CO2 reduction photocatalysts that are operational under visible light and possess superior activity, efficiency, and selectivity.

The chemical transformations of C1 compounds

While the selective C−F bond activation of perfluorinated toluene (CF3C6F5) by a trimethylphosphine-supported cobalt(0) complex Co(PMe3)4 has been achieved in our previous work (Organometallics, 2009, 28, 5771–5776), the proposed mechanism has not been demonstrated directly through quantum chemistry calculations. The present work provides a supplementary theoretical study on a detailed mechanism to better understand the synergistic effect of cobalt center and free PMe3 ligand on the selective C−F bond activation of CF3C6F5. The calculated results indicate two C−F bonds in CF3C6F5 are activated successively via a similar mechanism: the initial oxidative addition of C−F bond to cobalt(0) center, followed by F atom abstraction by a free PMe3 ligand. However, it is found that the F atom abstraction with a barrier of 34.92 kcal mol−1 is the bottle-neck step of the first C−F bond activation, while the oxidative addition of C−F bond is the rate-determining step of the second C−F bond activation with a barrier of 30.85 kcal mol−1. The theoretical results confirm the C−F activation mechanism proposed in our early work, i.e., the Co complex and free PMe3 ligands cooperatively promote the C−F bond activation.

Fast Pyrolysis as a Valorization Mechanism for Banana Rachis and Low‐Density Polyethylene Waste

AbstractBanana rachis and low‐density polyethylene (LDPE) were selected as secondary feedstocks for the study of fast pyrolysis in a free‐fall reactor. The experiments were performed at 600 °C for banana rachis and 450 °C for LDPE, based on literature and thermogravimetric analysis. The gaseous products of both feedstocks present similar composition in the C1–C2 compounds, while C3 compounds are only found in LDPE. The liquid products from banana and LDPE correspond to functional groups and shorter hydrocarbons, respectively. Scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) analyses of the char showed important morphological changes to spheres in LDPE and structural changes due to thermal decomposition in the biomass. The pyrolysis char has high potential as adsorbent, encapsulation, or catalyst.

Effects of vine top shading on the accumulation of C6/C9 compounds in 'Cabernet Sauvignon' (Vitis vinifera L.) grape berries in northwestern China.

The Xinjiang Uygur Autonomous Region is an arid and semi-arid region with low rainfall and strong sunlight; thus, grape berries in this region accumulate sugar content rapidly, and the ripening process is shorter than that in other regions. Although previous studies illustrated that altered sunlight conditions could influence the aroma profiles of grape berries, less attention has been paid to the effect of vine top shading on volatile compounds under a dry-hot climate. We focused on the effects of vine top shading on the concentrations of linolenic and linoleic acids, as well as their metabolites, the C6/C9 compounds, in grape berries. Four vine top shading treatments at veraison (ripening onset) and post-veraison (skin full coloration) were performed by reducing solar exposure to the grapevines by 20% and 50% respectively. Apart from (E)-2-hexenal in the 20% shading treatment of 2016, (E)-2-hexenal were not promoted by the 50% shading and 20% shading treatments during veraison to harvest in both of the vintages. By contrast, the influence of vine top shading from post-veraison till harvest was different between the two vintages; these C6 compounds were decreased in both of the shading treatments in 2016, whereas most of them were promoted in 2017, possibly related to daily sunshine hours in this period. In addition, the C9 compound nonanal with very low concentration exhibits a significant difference among various treatments by two-factor analysis of variance. As for linolenic acid and linoleic acid, two types of C6 compound biosynthetic precursors, four shading treatments all reduced their concentration, except for linolenic acid in the 50% shading treatment of 2016. Moreover, it appeared to have no apparent correlation between the variations of two precursors and their volatile metabolites, indicating that there is a complex impact of vine shading on C6 compound biosynthesis. Vine top shading at veraison can reduce the accumulation of some C6 compounds in grape berries, but no consistent consequence was attained for the vine shading at pre-veraison. The findings indicate the significance of grapevine solar exposure management at veraison in controlling the level of C6 compounds in a dry-hot region like Xinjiang. © 2021 Society of Chemical Industry.

Oenological Characteristics of Four Non-Saccharomyces Yeast Strains With β-Glycosidase Activity.

Non-Saccharomyces yeast with β-glucosidase activity might positively contribute to the flavor and quality of wines. The contribution of four non-Saccharomyces yeast strains Issatchenkia terricola SLY-4, Pichia kudriavzevii F2-24, P. kudriavzevii F2-16, and Metschnikowia pulcherrima HX-13 with β-glucosidase activity to the flavor and quality of wine making was studied. Compared with those of S. cerevisiae single fermentation, the four non-Saccharomyces yeast strains could grow and consume sugar completely with longer fermentation periods, and with no significantly negative effect on chemical characteristics of wines. Moreover, they produced lower content of C6 compounds, benzene derivative, and fatty acid ethyl ester compounds and higher content of terpene, β-ionone, higher alcohol, and acetate compounds. Different yeast strains produced different aroma compounds profiles. In general, the sensory evaluation score of adding non-Saccharomyces yeast-fermented wine was better than that of S. cerevisiae, and I. terricola SLY-4 fermentation received the highest one, followed by P. kudriavzevii F2-24, P. kudriavzevii F2-16, and M. pulcherrima HX-13 from high to low. The research results provide a theoretical basis for the breeding of non-Saccharomyces yeast and its application in wine making.

Prenylated C6–C3 derivatives from the stems and branches of Illicium ternstroemioides A. C. Smith with antiviral activity

Thirteen compounds were isolated from the lipid-soluble extracts of Illicium ternstroemioides A. C. Smith, including eleven previously undescribed prenylated C6–C3 compounds, a previously undescribed prenylated C6–C3 derivative-abscisic acid ester hybrid, and a known compound (4S)-illicinone I. Their structures and configurations were mainly elucidated by spectroscopic analyses, CD experiments and X-ray crystallography. (2S,4R,11S)-4-O-methyl-12-chloroillifunone C, (2S,4R,11R)-2,3-dihydro-4-O-methyl illioliganfunone D, and illiternfunol A were found to exhibit weak activity against Coxsackievirus B3, with IC50 values ranging from 27.8 to 33.3 μM. Illiternone B exhibited more potent activities against Coxsackievirus B3 and influenza virus A than did its geometric isomer illiternone A, with IC50 values of 7.7 μM and 2.5 μM, respectively. None of these compounds displayed cytotoxic activities.

Evaluation of composition and carbon atoms distribution of the exhaust hydrocarbons by varying post-injection parameters in DI diesel engine

This study was aimed to explore the effects of different post-injection parameters on the cracking, formation mechanism, composition, and carbon atoms distribution of exhaust hydrocarbon (HC) compounds of the diesel engine. The influence of three post-injection fuel masses (PIM) and six dwell duration with different start of injection (SOI) timings were assessed with an operating speed of 1000 rpm and a basic engine load of 0.5 MPa. Post-injection strategy greatly influenced the composition and carbon atoms distribution of exhaust gases emissions. It was noted that the formation of light HC species was lowered during early post-injection at SOI 20-40° crank angle (CA) due to the high in-cylinder temperature and more oxidation but increased as the SOI delayed due to more cracking of diesel fuel. An increase in the PIM also increased the formation of HC species at all SOI. Peak values of C1 (one carbon), C2 (two carbon), and C3 (three-carbon) compounds were recorded at SOI 60°CA with 15 mg PIM respectively, and the maximum value of 2700 ppm was observed for non-methane hydrocarbon (NMHC) at SOI 80°CA. While higher HC (C8) compounds achieved a peak of 275 ppm at SOI 80°CA with 15 mg PIM. At early SOI 20-40°CA, lighter HCs compounds concentration fractions were accounted for about 50–80% of THC emissions with 5–15 mg PIM. While at later SOI 80-120°CA C8 concentration fractions were dominant over all other HC fractions occupying a concentration fraction of more than 50% with 5, 10, and 15 mg PIM.

Coal gasification fine slags: Investigation of the potential as both microwave adsorbers and catalysts in microwave-induced biomass pyrolysis applications

The coal gasification fine slags (CGFS) are rich in porous carbon and various metal elements (Al, Fe, Ca, Na, K, Mg). In this work, three types of CGFS-based catalysts (CGFS@GSP, CGFS@OMB, and CGFS@TEX) were prepared and used in microwave-induced biomass pyrolysis to investigate the possibility of CGFSs as both microwave absorbing materials and catalysts for synergistic renewable phenols and fuel gas production. The CGFS-based catalysts displayed rough and porous structures, containing a variety of active metals and compounds. Remarkable microwave absorbing ability with higher heating rates than SiC was achieved by the CGFS-based catalysts during biomass pyrolysis. The catalysts showed high activity for biomass pyrolysis under microwave heating conditions, resulted in the increase of gas yield and the decrease of water and bio-oil yields. The bio-oil chemical composition was significantly simplified and was dominated by C3–C10 compounds. Phenols are the dominant component in the produced bio-oil, and the content reached 69.6% and 71.3% using CGFS@OMB and CGFS@TEX as the catalysts. Meanwhile, the gas yield was significant improved by the catalysts at a higher temperature of 650 °C, and the value reached 64.4% using CGFS@OMB as the catalyst with a remarkable hydrogen concentration of 44.9%.

Pyrolysis of High-Ash Natural Microalgae from Water Blooms: Effects of Acid Pretreatment.

Natural microalgae (NA, cyanobacteria) collected from Taihu Lake (Jiangsu, China) were used for biofuel production through pyrolysis. The microalgae were de-ashed via pretreatment with deionized water and hydrochloric acid, and the samples obtained were noted as 0 M, 0.1 M, 1 M, 2 M, 4 M, 6 M, 8 M, respectively, according to the concentration of hydrochloric acid used in the pretreatment. Pyrolysis experiments were carried out at 500 °C for 2 h. The products were examined by various techniques to identify the influence of the ash on the pyrolysis behavior. The results showed that the ash inhibited the thermal transformation of microalgae. The 2 mol/L hydrochloric acid performed the best in removing ash and the liquid yield increased from 34.4% (NA) to 40.5% (2 M). Metal-oxides (mainly CaO, MgO, Al2O3) in ash promoted the reaction of hexadecanoic acid and NH3 to produce more hexadecanamide, which was further dehydrated to hexadecanenitrile. After acid pretreatment, significant improvement in the selectivity of hexadecanoic acid was observed, ranging from 22.4% (NA) to 58.8% (4 M). The hydrocarbon compounds in the liquid product increased from 12.90% (NA) to 26.67% (2 M). Furthermore, the acid pretreatment enhanced the content of C9–C16 compounds and the HHV values of bio-oil. For natural microalgae, the de-ashing pretreatment before pyrolysis was essential for improving the biocrude yield and quality, as well as the biomass conversion efficiency.

Photocatalytic and Electrocatalytic Properties of Cu-Loaded ZIF-67-Derivatized Bean Sprout-Like Co-TiO2/Ti Nanostructures.

ZIF-derivatized catalysts have shown high potential in catalysis. Herein, bean sprout-like Co-TiO2/Ti nanostructures were first synthesized by thermal treatment at 800 °C under Ar-flow conditions using sacrificial ZIF-67 templated on Ti sheets. It was observed that ZIF-67 on Ti sheets started to thermally decompose at around 350 °C and was converted to the cubic phase Co3O4. The head of the bean sprout structure was observed to be Co3O4, while the stem showed a crystal structure of rutile TiO2 grown from the metallic Ti support. Cu sputter-deposited Co-TiO2/Ti nanostructures were also prepared for photocatalytic and electrocatalytic CO2 reduction performances, as well as electrochemical oxygen reaction (OER). Gas chromatography results after photocatalytic CO2 reduction showed that CH3OH, CO and CH4 were produced as major products with the highest MeOH selectivity of 64% and minor C2 compounds of C2H2, C2H4 and C2H6. For electrocatalytic CO2 reduction, CO, CH4 and C2H4 were meaningfully detected, but H2 was dominantly produced. The amounts were observed to be dependent on the Cu deposition amount. Electrochemical OER performances in 0.1 M KOH electrolyte exhibited onset overpotentials of 330–430 mV (vs. RHE) and Tafel slopes of 117–134 mV/dec that were dependent on Cu-loading thickness. The present unique results provide useful information for synthesis of bean sprout-like Co-TiO2/Ti hybrid nanostructures and their applications to CO2 reduction and electrochemical water splitting in energy and environmental fields.

Rewiring the microbial metabolic network for efficient utilization of mixed carbon sources.

Carbon sources represent the most dominant cost factor in the industrial biomanufacturing of products. Thus, it has attracted much attention to seek cheap and renewable feedstocks, such as lignocellulose, crude glycerol, methanol, and carbon dioxide, for biosynthesis of value-added compounds. Co-utilization of these carbon sources by microorganisms not only can reduce the production cost but also serves as a promising approach to improve the carbon yield. However, co-utilization of mixed carbon sources usually suffers from a low utilization rate. In the past few years, the development of metabolic engineering strategies to enhance carbon source co-utilization efficiency by inactivation of carbon catabolite repression has made significant progress. In this article, we provide informative and comprehensive insights into the co-utilization of two or more carbon sources including glucose, xylose, arabinose, glycerol, and C1 compounds, and we put our focus on parallel utilization, synergetic utilization, and complementary utilization of different carbon sources. Our goal is not only to summarize strategies of co-utilization of carbon sources, but also to discuss how to improve the carbon yield and the titer of target products.

Strategies and challenges with the microbial conversion of methanol to high‐value chemicals

As alternatives to traditional fermentation substrates, methanol (CH3 OH), carbon dioxide (CO2 ) and methane (CH4 ) represent promising one-carbon (C1) sources that are readily available at low-cost and share similar metabolic pathway. Of these C1 compounds, methanol is used as a carbon and energy source by native methylotrophs, and can be obtained from CO2 and CH4 by chemical catalysis. Therefore, constructing and rewiring methanol utilization pathways may enable the use of one-carbon sources for microbial fermentations. Recent bioengineering efforts have shown that both native and nonnative methylotrophic organisms can be engineered to convert methanol, together with other carbon sources, into biofuels and other commodity chemicals. However, many challenges remain and must be overcome before industrial-scale bioprocessing can be established using these engineered cell refineries. Here, we provide a comprehensive summary and comparison of methanol metabolic pathways from different methylotrophs, followed by a review of recent progress in engineering methanol metabolic pathways in vitro and in vivo to produce chemicals. We discuss the major challenges associated with establishing efficient methanol metabolic pathways in microbial cells, and propose improved designs for future engineering.

Bio-electro CO2 recycling platform based on two separated steps

The present work assessed the alliance of microbial electrochemical technologies (METs) and fermentation in a two-step process for the electro-bioconversion of carbon dioxide (CO2) into elongated chemical building blocks. The electro bio-reduction of CO2 into acetic acid and ethanol (EtOH:HAc) at a 1-to-1 ratio is linked to a subsequent elongation step to produce C4 and C6 compounds. Key operational conditions of each step were assessed. Key parameters considered in the first step were pH, and both hydrogen and CO2 partial pressures. Concerning the second stage, selected parameters were pH, ethanol to acetate ratio, and hydrogen availability. The aim was to steer each stage's performance and to obtain higher value products. Reached EtOH:HAc proportion was over 1:1 when fed with CO2, with H2 availability and at pH around 5.3. Formed product reinforced the follow-up chain elongation processes. The fermentation step got up to C6 compounds at pH 7.0, when fed with CO2 and H2. Outcomes demonstrated that pH was a crucial factor in the overall process. The overall process carbon conversion efficiency was 38% being the CO2 transformation the limiting step. 1 kg of CO2 fed in the system resulted in the production of 0.38 kg of elongated acids (C4-C6). In other words, 1 m3 of CO2 (normal conditions) captured resulted firstly in the production of 0.90 kg CC2 and then, 0.75 kg CC4-C6 are finally acquired. The presented results pave the ground for improving the selectivity during the production of reduced commodity chemicals from CO2 and electricity.

Verrucomicrobial methanotrophs grow on diverse C3 compounds and use a homolog of particulate methane monooxygenase to oxidize acetone

Short-chain alkanes (SCA; C2-C4) emitted from geological sources contribute to photochemical pollution and ozone production in the atmosphere. Microorganisms that oxidize SCA and thereby mitigate their release from geothermal environments have rarely been studied. In this study, propane-oxidizing cultures could not be grown from acidic geothermal samples by enrichment on propane alone, but instead required methane addition, indicating that propane was co-oxidized by methanotrophs. “Methylacidiphilum” isolates from these enrichments did not grow on propane as a sole energy source but unexpectedly did grow on C3 compounds such as 2-propanol, acetone, and acetol. A gene cluster encoding the pathway of 2-propanol oxidation to pyruvate via acetol was upregulated during growth on 2-propanol. Surprisingly, this cluster included one of three genomic operons (pmoCAB3) encoding particulate methane monooxygenase (PMO), and several physiological tests indicated that the encoded PMO3 enzyme mediates the oxidation of acetone to acetol. Acetone-grown resting cells oxidized acetone and butanone but not methane or propane, implicating a strict substrate specificity of PMO3 to ketones instead of alkanes. Another PMO-encoding operon, pmoCAB2, was induced only in methane-grown cells, and the encoded PMO2 could be responsible for co-metabolic oxidation of propane to 2-propanol. In nature, propane probably serves primarily as a supplemental growth substrate for these bacteria when growing on methane.

Synthesis, characterization, biological evaluation, BSA binding properties, density functional theory and molecular docking study of Schiff bases

In order to make an advancement in the discovery of the more effective ways to eliminate ROS, which causes oxidative stress or to eliminate the harmful microorganisms from the organism in humans, and bearing in mind the fact that Schiff bases belong to a class of biologically active compounds, a series of Schiff bases were synthesized and tested to evaluate their antioxidant and antimicrobial activity. DPPH, superoxide anion, and reducing power assays were used in assessing the antioxidative potential of studied compounds. Among tested compounds, the B1 compound showed the largest activity in all antioxidant assays. IC50 values in DPPH radical and superoxide anion radical scavenging activities were 15.64 µg/mL and 54.72 μg/mL, respectively (even better than positive control ascorbic acid). Moreover, these compounds had effective reducing power (absorbance was in the range 2.415–1.270, depending on the concentrations tested). A high antioxidant effect was also found in B2 and C3 compounds. The remaining tested compounds showed slightly weaker antioxidant activity. Besides, the antioxidative capacity of selected compounds was studied by density functional theory (DFT). The antimicrobial activity of B1, B2 and C1–4 compounds was examined towards eight microorganisms (four species of bacteria and five species of fungi) using the microdilution method. Among tested compounds, B1 and B2 showed marked antibacterial activity (MIC values ranged from 0.15 to 1.25 mg/mL), while C4 and B1 compounds showed very strong antifungal activity (MIC values ranged from 0.07 to 1.25 mg/mL). Molecular docking simulations were performed to better understand the binding modes selected compounds with DNA and BSA, as well as to comprehend their antioxidative or antimicrobial activity.

Phylogenomic Reconstruction and Metabolic Potential of the Genus Aminobacter.

Bacteria belonging to the genus Aminobacter are metabolically versatile organisms thriving in both natural and anthropized terrestrial environments. To date, the taxonomy of this genus is poorly defined due to the unavailability of the genomic sequence of A. anthyllidis LMG 26462T and the presence of unclassified Aminobacter strains. Here, we determined the genome sequence of A. anthyllidis LMG 26462T and performed phylogenomic, average nucleotide identity and digital DNA-DNA hybridization analyses of 17 members of genus Aminobacter. Our results indicate that 16S rRNA-based phylogeny does not provide sufficient species-level discrimination, since most of the unclassified Aminobacter strains belong to valid Aminobacter species or are putative new species. Since some members of the genus Aminobacter can utilize certain C1 compounds, such as methylamines and methyl halides, a comparative genomic analysis was performed to characterize the genetic basis of some degradative/assimilative pathways in the whole genus. Our findings suggest that all Aminobacter species are heterotrophic methylotrophs able to generate the methylene tetrahydrofolate intermediate through multiple oxidative pathways of C1 compounds and convey it in the serine cycle. Moreover, all Aminobacter species carry genes implicated in the degradation of phosphonates via the C-P lyase pathway, whereas only A. anthyllidis LMG 26462T contains a symbiosis island implicated in nodulation and nitrogen fixation.

Inhibitory effect of thiourea derivatives on the growth of blue-green algae

High nutrient loading in aquatic environment has become the main causative of harmful algae blooms (HABs) in water resources particularly pond, lake and river. HABs are mostly dominated by microalgae derived from the group of blue-green algae which are capable of releasing harmful toxins. Therefore, this study aims to investigate the inhibitory effects of thiourea derivatives on the growth of such blue-green algae. Thiourea derivatives have been proven to exhibit antifungal and antibacterial effects. However, there is still limited study had been conducted on the effect of thiourea derivatives toward blue-green algae species in recent years. In this research, a species of blue-green algae from Kenyir Lake, Terengganu, Malaysia was successfully isolated using morphological characters and molecularly identified as Synechoccus elongatus. Four new thiourea derivative compounds were also successfully synthesised. The compounds were designed with variation on different R-substitution group and characterised using Nuclear Magnetic Resonance (NMR) to confirm their molecular structure. Those compounds were characterised as 1-Benzyl-3-(3,5-dimethoxy-benzoyl)-thiourea (C1), 1-(3-Chloro-benzyl)-3-(3,5-dimethoxy-benzoyl)-thiourea (C2), 1-(3,5-Dimethoxy-benzoyl)-3-(3-methyl-benzyl)-thiourea (C3) and 1-(3,5-Dimethoxy-benzoyl)-3-(3-trifluoromethyl-benzyl)-thiourea (C4). For the inhibition assessment,S. elongatus were treated with C1–C4 for 5 day at concentration of 2, 5, 10 and 20 μg/ml, respectively. C3 compound showed the highest inhibition percentage with 98% of inhibition after 5 days treatment. By using Bradford method, protein extraction of S. elongatus was conducted at the highest inhibition percentage. Protein concentration of treated species was observed with 3.28 μg/ml as compared to protein concentration of control with 6.48 μg/ml. This result indicated the reduction of protein content after the treatment. Protein band pattern was identified intensed after the treatment SDS PAGE was carried out. The thiourea derivatives compound proved to have successfully inhibited the growth of blue-green algae. Hence, further study should be carried out to ensure the compound can be practically utilized in the pond and in natural environment.