Production of insoluble exopolysaccharide of Agrobacterium sp. (ATCC 31749 and IFO 13140)

Agrobacterium isolated from soil samples produced two extracellular polysaccharides: succinoglycan, an acidic soluble polymer, and curdlan gum, a neutral, insoluble polymer. Maize glucose, cassava glucose, and maize maltose were used in fermentation medium to produce insoluble polysaccharide. Two Agrobacterium sp. strains which were used (ATCC 31749 and IFO 13140) in the production of insoluble exopolysaccharide presented equal or superior yields compared to the literature. The strain ATCC 31749 yielded better production when using maize maltose, whose yield was 85%, whereas strain IFO 13140 produced more when fed maize glucose, producing a yield of 50% (on reducing sugars).     

Production of insoluble exopolysaccharide of Agrobacterium sp. (ATCC 31749 and IFO 13140)

Agrobacterium isolated from soil samples produced two extracellular polysaccharides: succinoglycan, an acidic soluble polymer, and curdlan gum, a neutral, insoluble polymer. Maize glucose, cassava glucose, and maize maltose were used in fermentation medium to produce insoluble polysaccharide. Two Agrobacterium sp. strains which were used (ATCC 31749 and IFO 13140) in the production of insoluble exopolysaccharide presented equal or superior yields compared to the literature. The strain ATCC 31749 yielded better production when using maize maltose, whose yield was 85%, whereas strain IFO 13140 produced more when fed maize glucose, producing a yield of 50% (on reducing sugars).     

First Evidence of Aerobic Biodegradation of BTEX Compounds by Pure Cultures of <Emphasis Type="Italic">Marinobacter</Emphasis>

Marinobacter vinifirmus was shown to degrade toluene as sole carbon and energy source under aerobiosis and at NaCl concentrations in the range 30–150 g/L. Maximum toluene consumption rate, total CO₂, and biomass productions were measured in the presence of 60 g/L of NaCl. Under these conditions, 90% of the carbon from toluene was recovered as CO₂ and biomass. Maximum specific toluene consumption rate was about 0.12 mgC toluene mgC biomass⁻¹ h⁻¹ at NaCl concentrations between 30 and 60 g/L. It decreased to 0.03 mgC toluene mgC biomass⁻¹ h⁻¹ at 150 g/L. Besides toluene, M. vinifirmus degraded benzene, ethylbenzene, and p-xylene. Benzene and toluene were utilized to a lesser extent by another Marinobacter sp., Marinobacter hydrocarbonoclasticus.     

Ultrafast,Low‐Cost,and Mass Production of High‐Quality Graphene

Fast, mass, and low‐cost production of high‐quality graphene, which is alluring, remains a great challenge, even though some approaches have shown potential for mass synthesis of graphene. Very recently a great breakthrough was made by Tour and co‐workers (Nature 2020, 577, 647–651): in just a second, easily exfoliated and highly crystalline graphene was produced from abundant carbon‐containing species by cost‐effective flash Joule heating with a low energy input of 7.2 kJ per gram graphene. Such an ultrafast, economic, and scalable process for high‐quality graphene production can be considered as a milestone in the graphene field and is highlighted in this article.     

Transgenic expression of <Emphasis Type="Italic">Gluconacetobacter xylinus</Emphasis> strain ATCC 53582 cellulose synthase genes in the cyanobacterium <Emphasis Type="Italic">Synechococcus leopoliensis</Emphasis> strain UTCC 100

We report the transfer of cellulose synthesis genes (acsABΔC) from the heterotropic alpha proteobacterium, Gluconacetobacter xylinus strain ATCC 53582 to a photosynthetic microbe (Synechococcus leopoliensis strain UTCC 100). These genes were functionally expressed in this cyanobacterium, resulting in the production of non-crystalline cellulose. Although the cellulose lacks the structural integrity of the product synthesized by G. xylinus, the non-crystalline nature of the cyanobacterial cellulose makes it an ideal potential feedstock for biofuel production.     

Synthesis of a Heptasaccharide,Structurally Related to the Phytoelicitor Active Glucan of Phytophthora Megasperma F.SP. Glycinea

Abstract

A synthesis is described of the heptasaccharide 1, which may form part of the phytoelicitor-active glucan of Phytopkthora megasperma f. sp. glycinea. Silver triflate was used as the promoter in Koenigs-Knorr type condensations using glycosyl bromides, each with a participating benzoyl group in the 2-position, for the synthesis of the smaller oligosaccharide fragments. For joining the larger ones, methyl triflate was used as the promoter and an oligosaccharide thioglycoside carrying a participating benzoyl group in the 2-position was used as the glycosyl donor.     

Screening of potential antibiotic action of cellulolytic fungi

Twenty different strains of filamentous fungi were initially selected for evaluation of cellulolytic activity using a single test in a simple mineral salts culture medium with filter paper as the only carbon source. Those fungi strains that were capable of completely breaking the filter paper strip within 4–8 d were assayed also for antimicrobial action, using Staphyloccocus a ureus ATCC 6538P according to the so-called agar piece method. We screened three different strains with both capacities: the production of cellulolytic activity and antibiotic action. The experimental results suggest that the fungi Pinicillium sp. FOPCO1, Aspergillus sp. F0Q001, and Cephalosporium sp. F03800 have both capabilities because they grew rapidly on cellulose as the only carbon source and were able to produce an area of growth inhibition in S. aureus of approx 2.04, 1.57, and 2.39 cm, respectively, on agar plates using the agar piece method. Subsequently, the antibiotic production obtained with those cellulolytic strains was evaluated by submerged fermentation at the flask level, in a simple culture medium containing lactose without biosynthesis precursor, obtaining 3670, 2830, and 4060 antibiotic units/mL, referred to as penicillin G, whereas for cellulolytic activity, the results were 1.34, 1.81 and 0.57 FPU/mL, respectively.     

Steady-state measurements of lactic acid production in a wild-type and a putative d-lactic acid dehydrogenase-negative mutant of zymomonas mobilis

This work represents a continuation of our investigation into environmental conditions that promote lactic acid synthesis by Zymomonas mobilis. The characteristic near theoretical yield of ethanol from glucose by Z. mobilis can be compromised by the synthesis of d- and l-lactic acid. The production of lactic acid is exacerbated by the following conditions: pH 6.0, yeast extract, and reduced growth rate. At a specific growth rate of 0.048/h, the average yield of dl-lactate from glucose in a yeast extract-based medium at pH 6.0 was 0.15 g/g. This represents a reduction in ethanol yield of about 10% relative to the yield at a growth rate of 0.15/h. Very little lactic acid was produced at pH 5.0 or using a defined salts medium (without yeast extract) Under permissive and comparable culture conditions, a tetracycline-resistant, d-ldh negative mutant produced about 50% less lactic acid than its parent strain Zm ATCC 39676. d-lactic acid was detected in the cell-free spent fermentation medium of the mutant, but this could be owing to the presence of a racemase enzyme. Under the steady-state growth conditions provided by the chemostat, the specific rate of glucose consumption was altered at a constant growth rate of 0.075/h. Shifting from glucose-limited to nitrogen-limited growth, or increasing the temperature, caused an increase in the specific rate of glucose catabolism. There was good correlation between an increase in glycolytic flux and a decrease in lactic acid yield from glucose. This study points to a mechanistic link between the glycolytic flux and the control of end-product glucose metabolism. Implications of reduced glycolytic flux in pentose-fermenting recombinant Z. mobilis strains, relative to increased byproduct synthesis, is discussed.     

The Correlations Between TCA-Glyoxalate Metabolite and Antibiotic Production of <Emphasis Type="Italic">Streptomyces</Emphasis> sp. M4018 Grown in Glycerol,Glucose, and Starch Mediums

The alterations of organic acids citrate, α-ketoglutarate, succinate, fumarate, malate production together with isocitrate lyase activity as a glyoxalate shunt enzyme, and antibiotic production of Streptomyces sp M4018 were investigated in relation to changes in the glucose, glycerol and starch concentrations (5–20 g/L) after identification as a strain of Streptomyces hiroshimensis based on phenotypic and genotypic characteristics. The highest intracellular citrate and α-ketoglutarate levels in 20 g/l of glucose, glycerol, and starch mediums were 399.47 ± 4.78, 426.93 ± 6.40, 355.84 ± 5.38 ppm and 444.81 ± 5.12, 192.96 ± 2.26, 115.20 ± 2.87 ppm, respectively. The highest succinate, malate, and fumarate levels were also determined in 20 g/l of glucose medium as 548.9 ± 11.21, 596.15 ± 8.26, and 406.42 ± 6.59 ppm and the levels were significantly higher than the levels in glycerol and starch. Extracellular organic acid levels measured also showed significant correlation with carbon source concentrations by showing negative correlation with pH levels of the growth medium. The antibiotic production of Streptomyces sp. M4018 was also higher in glucose medium as was the case also for organic acids when compared with glycerol. On the other hand, there is no production in starch.     

Comparison of Glucose and Glycerol as Carbon Sources for ε-Poly-l-Lysine Production by Streptomyces sp. M-Z18

Glucose is widely used in the production of ε-poly-l-lysine (ε-PL); however, glycerol is an emerging carbon source for ε-PL production in recent years. Glycerol is superior to glucose for ε-PL production according to batch and fed-batch fermentations by Streptomyces sp. M-Z18 in this study. To elaborate this difference, physiological metabolism of Streptomyces sp. M-Z18 on glycerol has compared with glucose during batch fermentation. The activities of key enzymes showed that aspartate kinase (ASPK) and ε-PL synthetase (Pls) in glycerol medium was higher than those in glucose, and especially the activity of Pls could enhance by 2.3- and 3.6-fold at 24 and 36 h, respectively. Moreover, metabolism flux analysis demonstrated that a 25 % higher fluxes derived from glycerol are directed into ε-PL synthesis than glucose. As a result, the mechanism of glycerol better than glucose is determined: the activities of ASPK and Pls in glycerol higher than those in glucose, and result in carbon fluxes directed into ε-PL synthesis increased. This study offers a reference to substitute glycerol for conventional glucose as carbon source for ε-PL production.     

Synthesis of Some 3‐(4‐Aryl‐benzofuro[3,2‐b]pyridin‐2‐yl)coumarins and Their Antimicrobial Screening

The synthesis of some 3‐(4‐aryl‐benzofuro[3,2‐b]pyridin‐2‐yl)coumarins 3a–r has been carried out by the reaction of 3‐coumarinoyl methyl pyridinium salts 1a–c with 2‐arylidene aurones 2a–f in the presence of ammonium acetate and acetic acid under Kröhnke's reaction conditions. All the synthesized compounds were characterized by analytical and spectral data. They have been screened for their antibacterial activity against Escherichia coli (ATCC 25922) as Gram‐negative bacteria, Bacillus subtillis (ATCC 1633) as Gram‐positive bacteria and antifungal activity against Aspergillus niger (ATCC 9029).     

Synthesis gas as substrate for the biological production of fuels and chemicals

Synthesis gas provides a simple substrate for the production of fuels and chemicals. Synthesis gas can be produced via established technologies from a variety of feedstocks including coal, wood, and agricultural and municipal wastes. The gasification is thermally efficient and results in complete conversion of the feedstock to fermentable substrate.Clostridium ljungdahlii grows on the synthesis gas components, carbon monoxide, hydrogen, and carbon dioxide. Production of acetic acid and ethanol accompanies growth with synthesis gas as sole source of energy and carbon. Rate and yield parameters are compared forC. ljungdahlii grown on carbon monoxide, or hydrogen with carbon dioxide.

     

Arthrobacter sp. JS443‐Based Whole Cell Amperometric Biosensor for p‐Nitrophenol

An amperometric microbial biosensor for highly sensitive and selective determination of p‐nitrophenol (PNP) is reported. The biosensor consisted of PNP‐degrader Arthrobacter sp. JS443 immobilized by entrapment in Nafion polymer deposited on the top of the carbon paste electrode transducer. The biosensor was based on the measurement of the oxidation current of the intermediates 4‐nitrocatechol and 1,2,4‐benzenetriol formed by the highly selective oxidation of PNP by Arthrobacter sp. The sensor signal and response time were optimized with applied potential of +0.4 V (vs. Ag/AgCl reference electrode) and 0.03 mg of cells and operating in pH 7.5, 50 mM citrate‐phosphate buffer at room temperature. When operated at optimized conditions, the Arthrobacter sp.‐based biosensor measured as low as 5 nM (0.7 ppb) of PNP. The biosensor demonstrated excellent selectivity with no interference from phenolic compounds such as 2‐nitrophenol, phenol and 3‐chlorophenol but was interfered by 3‐nitrophenol and 3‐methyl‐4‐nitrophenol. It had good precision and intra‐ and inter‐day reproducibility, accuracy and was stable up to 3 days when stored in buffer at 4 °C. When applied for measurement in water from Lake Elsinore, CA, the results obtained were in excellent agreement with the amounts determined spectrophotometrically.     

Optimization of culture medium and conditions for penicillin acylase production by streptomyces lavendulae ATCC 13664

The culture medium for Streptomyces lavendulae ATCC 13664 was optimized on a shake-flask scale by using a statistical factorial design for enhanced production of penicillin acylalse. This extracellularenzyme recently has been reported to bea penicillin Kacylase, presenting also high hydrolytic activity against penicillin V and other natural aliphatic penicillins such as penicillin K, penicillin F, and penicillin dihydroF,. The factorial design indicated that the main factors that positively affect penicillin acylase production by S. lavendulae were the concentration of yeast extract and the presence of oligoelements in the fermentation medium, whereas the presence of olive oil in the medium had no effect on enzyme production. An initial concentration of 2.5% (w/v) yeast extract and 3 μg/mL of CuSO₄·5H₂O was found to be best for acylase production. In such optimized culture medium, fermentation, of the microorganism yielded 289 IU/L of enzyme in 72 h when employing a volume medium/volume flask ratio of 0.4 and a 300-rpm shaking speed. The presence of copper, alone and in combination with other metals, stimulated biomass as well as penicillin acylase production. The time course of penicillin acylase production was also studied in the optimized medium and conditions. Enzyme production showed catabolite repression by different carbon sources such as glucose, lactose, citrate, glycerol, and glycine.     

Structure elucidation of uniformly <Superscript>13</Superscript>C-labeled bacterial celluloses from different <Emphasis Type="Italic">Gluconacetobacter xylinus</Emphasis> strains

The morphological and supramolecular structures of native cellulose pellicles from two strains of Gluconacetobacter xylinus (ATCC 53582, ATCC 23769) were investigated. Samples had been statically cultivated in Hestrin-Schramm medium containing fully ¹³C-labeled β-d-glucose-U-¹³C₆ as the sole source of carbon. The results are compared with structure data of bacterial celluloses with a natural ¹³C abundance of 1.1%. Non-enriched and ¹³C-labeled cellulose pellicles formed crystalline structures as revealed by cross-polarized/magic-angle spinning (CP/MAS) ¹³C{¹H}-NMR and near infrared (NIR) FT-Raman spectroscopic measurements as well as wide-angle X-ray diffraction (WAXD) investigations. Atomic force microscopy (AFM) was applied for analyzing fiber morphologies and surface properties. For the first time, details about the manipulation of fiber widths and pellicle formation were shown for different bacterial strains of G. xylinus depending on the use of β-d-glucose-U-¹³C₆ for the biosynthesis.     

Biosynthesis of Silver Nanoparticles by <Emphasis Type="Italic">Geotricum</Emphasis> sp.

Nanoparticles are usually 1–100 nm in each spatial dimension considered as building blocks of the next generation of optoelectronics, electronics, and various chemical and biochemical sensors. In the synthesis of nanoparticles use of microorganisms emerges as an eco-friendly and exciting approach that reduce waste products (ultimately leading to atomically precise molecular manufacturing with zero waste); the use of nanomaterials as catalysts for greater efficiency in current manufacturing processes by minimizing or eliminating the use of toxic materials (green chemistry principles); the use of nanomaterials and nanodevices to reduce pollution (e.g. water and air filters); and the use of nanomaterials for more efficient alternative energy production (e.g. solar and fuel cells). Fungi have many advantages for nanoparticle synthesis compared with other organisms. In this study, Geotricum sp. found to successfully produce Ag nanoparticles. Geotricum sp. was grown in SDA (Sabro Dextrose Agar) medium at 25 ± 1 °C for 96 h. The mycelia were used to convert silver nitrate solution into nano-silver. Silver nanoparticles were synthesized using these fungi (Geotricum sp.) extracellularly. UV–VIS spectroscopy, Atomic Force Microscopy (AFM) and Scanning Electron Microscopy images shows the nanoparticle formation in the medium. Energy-dispersive X-ray spectroscopy (EDX) also confirmed that silver nanoparticles in the range of 30–50 nm were synthesized extracellularly. FTIR analyses confirmed the presence of amide (I) and (II) bands of protein as capping and stabilizing agent on the surface of nanoparticles.     

Effects of Carbon and Nitrogen Sources and Oxygenation on the Production of Inulinase by <Emphasis Type="Italic">Kluyveromyces marxianus</Emphasis>

Cultivations of Kluyveromyces marxianus var. bulgaricus ATCC 16045 were performed on both minimal and complex media using different carbon and nitrogen sources either in the presence or absence of aeration. The results collected were worked out and compared so as to provide a useful contribution to the optimization of inulinase production. Kinetics of extracellular inulinase release were similar on glucose, fructose, and sucrose. Inulinase was detected at basal level since the beginning of batch runs on these three carbon sources and overproduced after their depletion. The highest inulinase activity in minimal medium containing 10 g/l sucrose (6.4 IU/ml) was obtained at an initial (NH₄)₂SO₄ concentration of 5 g/l, whereas it was reduced to about one fourth of this value and detected only at the beginning under nitrogen-limited conditions. The best sucrose concentrations for the enzyme production were 30 and 20 g/l in minimal and complex media, yielding 15.4 and 208 IU/ml, respectively. In general, the enzyme activity was much higher in complex than in minimal medium under all conditions. O₂-enriched air neither improved inulinase production nor prevented ethanol formation.     

A Practical One‐Step Synthesis of 1,2‐Oxazoline Derivatives from Unprotected Sugars and Its Application to Chemoenzymatic β‐N‐Acetylglucosaminidation of Disialo‐oligosaccharide

A facile and practical method for synthesis of sugar oxazolines (=dihydrooxazoles) from the corresponding N‐acetyl‐2‐amino sugars has been developed by using 2‐chloro‐1,3‐dimethyl‐1H‐benzimidazol‐3‐ium chloride (CDMBI) as a dehydrative condensing agent. The intramolecular dehydrative reaction between the 2‐acetamido group and the anomeric OH group of unprotected N‐acetyl‐2‐amino sugars took place smoothly in H₂O, leading to the formation of a 1,2‐oxazoline (=4,5‐dihydrooxazole) moiety in good yield. Since the reaction proceeds in H₂O without using any protecting groups, the resulting oxazolines can be utilized as effective glycosyl donors for the subsequent enzymatic glycosylation. We have successfully demonstrated a highly efficient chemoenzymatic transglycosylation of a disialo‐oligosaccharide moiety to p‐nitrophenyl N‐acetylglucosaminide catalyzed by a mutant endo‐N‐acetylglucosaminidase without isolating disialo‐oligosaccharide oxazoline as synthetic intermediate.     

Efficient Method for the Elongation of the N‐Acetylglucosamine Unit by Combined Use of Chitinase and β‐Galactosidase

A novel strategy for the regio‐ and stereoselective synthesis by two enzymatic steps of oligosaccharides having an N‐acetylglucosamine unit at the nonreducing end was developed. The first step involves a chitinase‐catalyzed highly selective β‐N‐acetyllactosamination of an oligosaccharide acceptor with a 4,5‐dihydrooxazole derivative of N‐acetyllactosamine as the glycosyl donor. The usage of a transition‐state‐analogue substrate for the chitinase under basic conditions allows the reaction to proceed only in the synthetic direction while suppressing hydrolysis of the product in aqueous media. Several chitinase mutants also catalyzed the glycosylation efficiently under neutral conditions. The second step is a regioselective cleavage of the glycosidic bond between the terminal galactose unit and the adjacent N‐acetylglucosamine unit by the action of a β‐galactosidase. This constitutes a very useful method to add an N‐acetylglucosamine unit to the nonreducing end of chito‐ and cello‐oligosaccharide derivatives in a regio‐ and stereoselective manner.     

Facile green one‐pot synthesis of novel thiazolo[3,2‐a]pyrimidine derivatives using Fe3O4@l‐arginine and their biological investigation as potent antimicrobial agents

Thiazolopyrimidine derivatives are well known because of their excellent therapeutic properties. In this investigation, an effective one‐pot three‐component method is described for the synthesis of novel 2‐[(Z )‐1‐(substituted phenyl)methylidine]‐7‐methyl‐3‐oxo‐5‐(substituted phenyl)‐2,3‐dihydro‐5H ‐thiazolo[3,2‐a]pyrimidine‐6‐carboxilic acid tert ‐butyl ester derivatives by condensation reaction of 3,4‐dihydropyrimidine‐2(1H )‐thiones, various aromatic aldehydes and chloroacetyl chloride under reflux conditions in the presence of Fe₃O₄@l ‐arginine nanoparticles as a magnetically reusable and eco‐friendly catalyst with short reaction times and moderate yields. The chemical structures of all synthesized compounds were determined using infrared, ¹H NMR and ¹³C NMR spectroscopies. In vitro antimicrobial activities of 3,4‐dihydropyrimidine‐2(1H )‐thiones and newly fused thiazolo[3,2‐a]pyrimidine derivatives were examined using the well diffusion method against diverse pathogenic strains, namely Staphylococcus aureus ATCC 6538, S. epidermidis ATCC 12228, Escherichia coli ATCC 8739 and Pseudomonas aeruginosa ATCC 9027 (bacteria), Candida albicans ATCC 10231 (yeast) and Aspergillus niger ATCC 16404 (fungus). The compounds having 2‐hydroxy, 4‐hydroxy, 2‐chloro and 4‐chloro groups attached to the phenyl ring on the pyrimidine and 4‐CH₃, 4‐OCH₃ and 3‐NO₂ groups attached to benzylidine on the thiazolo moiety showed significant antibacterial activity.