Utilization of Enzymatically Hydrolyzed Wood Hemicelluloses by Microorganisms for Production of Liquid Fuels

Hemicellulose-derived sugars were obtained from a variety of pretreated wood substrates such as water-soluble fractions from steam-exploded aspen, solvent-extracted aspen, and commercial xylan. These fractions were enzymatically hydrolyzed by commercial enzyme preparations and by the culture filtrates of eight highly cellulolytic fungi. The sugars released were assayed by high-pressure liquid chromatography. Over 30% of the hemicellulose fractions, at a 10% substrate concentration, could be hydrolyzed to monosaccharides. These hemicellulose hydrolysates were used as the substrates for growth of Clostridium acetobutylicum and Klebsiella pneumoniae. Comparatively low butanol values were obtained with C. acetobutylicum, although over 50% of the hemicellulose fraction, at a 1% substrate concentration, could be converted to 2,3-butanediol, ethanol, and acetic acid by K. pneumoniae.     

l-Glutamate Formation from Hydrocarbons by Microorganisms

Large quantities of l-glutamic acid from liquid paraffins by microorganisms were produced with an addition of penicillin to the growing culture, and the action of penicillin to the glutamate production was studied. One of main effects of penicillin seems to exist in the cellular permeability of l-glutamic acid.     

Production of Fluorescent Compounds from Guanine by Microorganisms

One species of hydrocarbon utilizing bacteria was isolated from soil. This strain was named as Achromobacter petrophilum No. 4017. This bacterial species utilizes normal hydrocarbons with carbon chains of nC₁₀ to nC₁₈, but does not utilize glucose or other carbohydrates. Achromobacter petrophilum forms small amounts of green-yellow, green-blue and violet fluorescent compounds in the medium containing n-hexadecane (nC₁₆) as a carbon source. The mutant strain, No. 4510, which requires hypoxanthine and thiamine for growth, was obtained from Achromobacter petrophilum No. 4017 by ultraviolet irradiation and formed considerable amounts of green-yellow fluorescent compound by the addition of guanine to the n-hexadecane medium. This fluorescent compound was crystallized from culture broth.     

Laccase-Catalyzed Surface Modification of Thermo-Mechanical Pulp (TMP) for the Production of Wood Fiber Insulation Boards Using Industrial Process Water

Low-density wood fiber insulation boards are traditionally manufactured in a wet process using a closed water circuit (process water). The water of these industrial processes contains natural phenolic extractives, aside from small amounts of admixtures (e.g., binders and paraffin). The suitability of two fungal laccases and one bacterial laccase was determined by biochemical characterization considering stability and substrate spectra. In a series of laboratory scale experiments, the selected commercial laccase from Myceliophtora thermophila was used to catalyze the surface modification of thermo-mechanical pulp (TMP) using process water. The laccase catalyzed the covalent binding of the phenolic compounds of the process water onto the wood fiber surface and led to change of the surface chemistry directly via crosslinking of lignin moieties. Although a complete substitution of the binder was not accomplished by laccase, the combined use of laccase and latex significantly improved the mechanical strength properties of wood fiber boards. The enzymatically-treated TMP showed better interactions with the synthetic binder, as shown by FTIR-analysis. Moreover, the enzyme is extensively stable in the process water and the approach requires no fresh water as well as no cost-intensive mediator. By applying a second-order polynomial model in combination with the genetic algorithm (GA), the required amount of laccase and synthetic latex could be optimized enabling the reduction of the binder by 40%.     

Catalytic Efficiency of some Mediators in Laccase-Catalyzed Alcohol Oxidation

The enzyme laccase oxidises phenolic groups of lignin but not the non-phenolic ones. Redox mediators activate laccase towards the non-phenolic groups, particularly the benzyl alcohols. The oxidation step is performed by the oxidised form of the mediator, generated on its interaction with laccase. The oxidised mediator can follow an electron transfer, a radical hydrogen atom transfer or an ionic mechanism in the oxidation of the non-phenolic subunits. Support for these conclusions is provided by (i) investigating the product pattern with suitable probe substrates, (ii) measuring the intramolecular kinetic isotope effect. Determination of electrochemical properties and bond dissociation energies via semiempirical calculations enabled us to rationalise the origin of the different mechanistic behaviour of the mediators. Finally, a comparison of different laccase-mediator-systems (LMS), when applied to the delignification of wood pulp, indicates violuric acid as the most efficient mediator, in an oxidation that is selectively directed towards lignin only.     

Catalytic Efficiency of some Mediators in Laccase-Catalyzed Alcohol Oxidation

The enzyme laccase oxidises phenolic groups of lignin but not the non-phenolic ones. Redox mediators activate laccase towards the non-phenolic groups, particularly the benzyl alcohols. The oxidation step is performed by the oxidised form of the mediator, generated on its interaction with laccase. The oxidised mediator can follow an electron transfer, a radical hydrogen atom transfer or an ionic mechanism in the oxidation of the non-phenolic subunits. Support for these conclusions is provided by (i) investigating the product pattern with suitable probe substrates, (ii) measuring the intramolecular kinetic isotope effect. Determination of electrochemical properties and bond dissociation energies via semiempirical calculations enabled us to rationalise the origin of the different mechanistic behaviour of the mediators. Finally, a comparison of different laccase-mediator-systems (LMS), when applied to the delignification of wood pulp, indicates violuric acid as the most efficient mediator, in an oxidation that is selectively directed towards lignin only.     

Polysaccharides from Extremophilic Microorganisms

Several marine thermophilic strains were analyzed for exopolysaccharide production. The screening process revealed that a significant number of thermophilic microorganisms were able to produce biopolymers, and some of them also revealed interesting chemical compositions. We have identified four new polysaccharides from thermophilic marine bacteria, with complex primary structures and with different repetitive units: a galacto-mannane type from strain number 4004 and mannane type for the other strains. The thermophilic Bacillus thermantarcticus produces two exocellular polysaccharides (EPS 1, EPS 2) that give the colonies a typical mucous character. The exopolysaccharide fraction was produced with all substrates assayed, although a higher yield 400 mg liter(-1) was obtained with mannose as carbon and energy source. NMR spectra confirmed that EPS 1 was a heteropolysaccharide of which the repeating unit was constituted by four different alpha-D-mannoses and three different beta-D-glucoses. It seems to be close to some xantan polymers. EPS 2 was a mannan. Four different alpha-D-mannoses were found as the repeating unit. Production and chemical studies of biopolymers produced by halophilic archaea, Haloarcula species were also reported.     

Chitinolytic Microorganisms and Their Possible Application in Environmental Protection

This paper provides a review of the latest research findings on the applications of microbial chitinases to biological control. Microorganisms producing these enzymes can inhibit the growth of many fungal diseases that pose a serious threat to global crop production. Currently, efforts are being made to discover producers of chitinolytic enzymes. The potential exists that natural biofungicides will replace chemical fungicides or will be used to supplement currently used fungicides, which would reduce the negative impact of chemicals on the environment and support the sustainable development of agriculture and forestry.     

Iodination and oxidation of thyroglobulin catalyzed by thyroid peroxidase

The kinetics of iodination and oxidation of hog thyroglobulin were studied with purified hog thyroid peroxidase and the results were compared with the reactions of free tyrosine. From Lineweaver-Burk plots and on the basis of a value of 0.83 for delta epsilon mM at 289 nm/iodine atom incorporated, the rate constant for transfer of an assumed enzyme-bound iodinium cation to thyroglobulin was estimated to be 6.7 X 10(7) and 2.3 X 10(7) M-1 s-1 in native (iodine content = 1.0%) and more iodinated (iodine content = 1.2%) thyroglobulins, respectively. This iodine-transferring reaction was stimulated by iodothyronines, similarly as observed in the reaction with free tyrosine. The iodination of thyroglobulin was inhibited by GSH, the inhibition being competitive with thyroglobulin. Thyroglobulin was oxidized in the presence of a thyroid peroxidase system without giving any appreciable change in absorbance around 300 nm. From stopped flow data, the oxidation was concluded to occur by way of two-electron transfer and the rate constant for the reaction of thyroid peroxidase Compound I with thyroglobulin was estimated to be 1.0 X 10(7) M-1 s-1. The stopped flow kinetic pattern was similar to that observed on the reaction with free tyrosine and monoiodotyrosine. About 6 mol of hydrogen peroxide were consumed per mol of thyroglobulin. Thyroid peroxidase catalyzed thyroglobulin-mediated oxidation of GSH, but lactoperoxidase did not.     

Milk-clotting Enzyme from Microorganisms

The milk-clotting activity of Mucor-rennin (Milk clotting enzyme of Mucor pusillus Lindt) was inhibited by reaction of diazo-l-H-tetrazole accompanied with increase of the value of the absorbance of biazo-histidine at 480 nm. The activity did not remain when the absorbance reached 50% of maximum value. It is concluded from these results that one mole of histidine in 2 moles of histidine contained in the enzyme has a relation to active center.     

从铅锌矿渣中分离的微生物对重金属吸附特性的研究

从铅锌矿渣中分离到 16种菌 (包括 7株细菌和 9株真菌 ) ,并研究了它们对Zn2 + ,Pb2 + ,Cu2 + 的吸附特性。发现大多数菌株对Pb2 + 与Zn2 + 有不同程度的吸附 ,但对Cu2 + 的吸附能力较小。菌株对Zn2 + 的吸附率大于对Pb2 + 的吸附 ,能吸附Pb2 + 的菌株也能吸附Zn2 + 。pH 4～ 6是真菌吸附金属离子的较好范围 ,细菌仅在pH =5 .0条件下 ,对Pb2 + 与Zn2 + 有吸附。在测试的不同金属离子浓度范围内 (5 0mg/L 相似文献   

Iodination of Ricin D

Approximately five tyrosine residues of ricin D were iodinated preferentially under appropriate conditions probably forming diiodotyrosine. Iodination of this toxin carried out in 0.1 m phosphate buffer at pH 7.0 and 0°C for 60 min with a 20 fold molar excess of iodine per mole of protein, yielded a main component which appeared as a single band on polyacrylamide gel disc electrophoresis. Analysis of protein-bound radioactivity and the content of diiodotyrosine of ¹⁸¹I-labeled ricin D revealed that two tyrosine residues in the isoleucyl chain and three in the alanyl chain were substituted. The toxicity of iodinated ricin D decreased to one hundredth of that of native protein, However, the hemagglutinating activity of this protein was not affected by the iodination reaction.     

Iodination of staphylococcal enterotoxin B by use of chloramine-T.

This report describes the conditions that are necessary for iodination of staphylococcal enterotoxin B (SEB) by use of chloramine-T. Makor Chemical Co. SEB and the two major SEB components, which were prepared by isoelectric focusing of partially purified SEB, were used in these studies. The antigenic activity of the SEB preparations was monitored by radioimmunoassay as the oxidation/reduction (O/R) potential was increased by addition of chloramine-T. The SEB preparations lost antigenic activity rapidly at pH 7.5 and room temperature when sufficient chloramine-T was added to raise the O/R potential above 250 mV. Iodinated SEB with satisfactory immunoreactivity was prepared by omitting carrier iodide from the iodination reaction mixture and by using at least 1 mg of SEB/ml, steps which made the O/R potential more stable, and by stopping the reaction before the O/R potential exceeded 250 mV. Comparison of the chloramine-T method with a lactoperoxidase/H2O2 method of iodinating SEB showed the latter to cause a greater loss of immunoreactivity.     

Iodination of staphylococcal enterotoxin B by use of chloramine-T.

This report describes the conditions that are necessary for iodination of staphylococcal enterotoxin B (SEB) by use of chloramine-T. Makor Chemical Co. SEB and the two major SEB components, which were prepared by isoelectric focusing of partially purified SEB, were used in these studies. The antigenic activity of the SEB preparations was monitored by radioimmunoassay as the oxidation/reduction (O/R) potential was increased by addition of chloramine-T. The SEB preparations lost antigenic activity rapidly at pH 7.5 and room temperature when sufficient chloramine-T was added to raise the O/R potential above 250 mV. Iodinated SEB with satisfactory immunoreactivity was prepared by omitting carrier iodide from the iodination reaction mixture and by using at least 1 mg of SEB/ml, steps which made the O/R potential more stable, and by stopping the reaction before the O/R potential exceeded 250 mV. Comparison of the chloramine-T method with a lactoperoxidase/H2O2 method of iodinating SEB showed the latter to cause a greater loss of immunoreactivity.     

Studies on Xylanase from Microorganisms

As xylanase-producing microorganisms, 64 strains belonging to the genus Streptomyces were isolated from the barn-yard manures, silages and litters collected in Hokkaido district. Among these isolates the strain 102–1–4, which was found to be a new species under taxonomical studies and named Streptomyces xylophagus nov. sp., had the most outstanding ability for the enzyme production. In addition to the isolates, 38 strains of Streptomyces and 480 strains of filamentous fungi which have been preserved in our culture collection were also examined on their ability to produce the enzyme. 1) Among the strains of Streptomyces tested, only two strains, St. albogriseolus IAM 0031 and St. olivaceus IAM 0025 were found to have the ability, but their abilities were less than that of St. xylophagus nov. sp. 2) Out of 480 strains of fungi tested, Chaetomium, Schyzophyllum, Trametes, Echinodontium, Alternaria, Cepharosporium, Cercospora, Gibberella, Glomerella and Macrosporium produced the enzyme. Especially, Ch. trilateral 2264 was the most excellent.     

Utilization of Hydrocarbons by Microorganisms

As already reported, Corynebacterium hydrocarboclastus S10B1 was able to accumulate a good deal of l-glutamate in a thiamine-deficient medium at the sole expense of n-alkanes, but unable to form l-glutamate in a thiamine-sufficient medium though an abundant cell growth was observed.

α-Ketoglutaric acid and dl-alanine were found to be produced in the same thiamine-deficient medium in which l-glutamate was accumulated. Both products formed from n-tetradecane by this organism were isolated from culture broth, purified and identified. The optimum concentration of thiamine in the culture medium was 3 to 5 µg per liter for their production. The maximum yields of α-ketoglutaric acid and dl-alanine reached 16 g and 1.5 g per liter in the calcium carbonate-added medium, respectively. However, the addition of more than 30 μg per liter of thiamine extremely repressed their accumulation.