Showing papers in "Journal of Industrial Microbiology & Biotechnology in 1990"

Bifidobacteria and their role in human health.

Abstract: There is a growing consensus on the beneficial effects of bifidobacteria in human health. It is now clear that bifidobacteria that exist in the large intestine are helpful for maintenance of human health and are far more important thanLactobacillus acidophilus as beneficial intestinal bacteria throughout human life. In other words, the reduction or disappearance of bifidobacteria in the human intestine would indicate an “unhealthy” state. Oral administration of bifidobacteria may be effective for the improvement of intestinal flora and intestinal environment, for the therapy of enteric and hepatic disorders, for stimulation of the immune response, and possibly for the prevention of cancer and slowing the aging process. However, for consistent and positive results further well-controlled studies are urgently needed.

Pharmaceuticals from cultured algae

Abstract: An algae screening program, including cultured macroalgae, cultured cyanobacteria and cultured eukaryotic microalgae has been undertaken. Methods for the isolation, purification, preservation and cultivation of axenic cyanobacteria and eukaryotic cultures have been developed. Screening of these groups for biologically active components has lead to the isolation of pachydictyol and caulerpenyne from cultured macroalgae, while a series of hapalindoles and an antifungal depsipeptide have been isolated from cyanobacteria.

Properties of the biosurfactant produced by Bacillus licheniformis strain JF-2.

Abstract: The activity of the biosurfactant produced byBacillus licheniformis strain JF-2 was quantified using a unit defined as the amount of the acid-precipitated biosurfactant that lowered the surface tension by 10 mN/m. One unit was equivalent to 37 μg/ml of the acid-precipitated biosurfactant. Acid precipitation was very effective in the removal of the biosurfactant from the spent medium. Among the solvents tested methanol was the most efficient in extracting the surfactant activity from acid-precipitated material. Thin-layer chromatography of the acid-precipitated biosurfactant revealed four components, two of which contained a lipid moiety and one of which contained an amino group. The methanol-soluble fraction also contained these four components. Studies suggested that all four components were needed for full activity. The lowest interfacial tensions against octane were observed when NaCl concentrations were 50 g/l or greater. Calcium concentrations greater than 25 g/l significantly increased the interfacial tension

Microbial physiology of sidechain degradation of sterols

Abstract: A large number of valuable starting materials for steroids synthesis (e.g. 4-androstene-3,17-dione, 1,4-androstadiene-3,17-dione, 9α-hydroxy-4-androsten-17-one) have been produced by microbial transformation methods. This review helps to evaluate the microbial physiological interest of the widely used sterol sidechain degradation processes. Four inducible groups of the catabolic enzymes are involved in the sterol sidechain degradation pathway; the fatty acid β-oxidation system, the ω-oxidase reaction, a methyl-crotonyl-CoA carboxylation system and the propionyl-CoA carboylase system. Altogether nine catabolic enzymes are involved in the β-sitosterol sidechain degradation pathway. They work in 14 consecutive enzymatic steps. Summing up: three molecules of FADH2, three molecules of propionyl-SCoA, three of NADH and one molecule of acetic acid are formed, while the sidechain of one mole of sitosterol is removed selectively. The metabolism of the propionates and the acetate yield 18 molecules of NADH and 7 molecules of FADH2. Taking into consideration the whole process more than 80 molecules of ATP could be formed during the sitosterol sidechain degradation process.

Vitamin content of four marine microalgae. Potential use as source of vitamins in nutrition

Abstract: Certain marine microalgae contain water-and lipid-soluble vitamins and can be used as food supplements or food ingredients. A number of vitamins are present in higher concentrations in the microalgae than in conventional foods traditionally considered rich in them. Ingestion of relatively small quantities of microalgae can cover the requirements for some vitamins in animal nutrition, including human nutrition, while supplementing others. Marine microalgae can thus be considered to represent a non-conventional source of vitamins or a vitamin supplement for animal or human nutrition.

Characterization by high performance liquid chromatography (HPLC) of the solubilization of phosphorus in iron ore by a fungus

Abstract: The value of iron ore is adversely affected by phosphorus in concentrations over 0.03% by weight. The present research concerns the use of metabolic products of aPenicillium-like fungus to leach insoluble phosphates (hydroxyapatite) from ores. Ion chromatography was used to measure metabolism of glucose into acidic fragments. The rate and products of glucose degradation depended on both the chemical composition of the growth medium (buffered or not) and incubation conditions (shaken or quiescent). The principal products were identified as oxalic acid and isomers of propylene dicarboxylic acid, mainly itaconic acid. Continued, slow metabolism of itaconic acid generates more oxalic acid. Aliphatic acids were not detected. Both iron ore phosphate and calcium phosphate were partially solubilized by either the spent broth or aqueous oxalic acid. Solubilization of ore phosphorus was greatly assisted by hydrochloric acid added to the spent broth in small increments. The data suggest biological alternatives to costly leaching procedures that use only mineral acids.

Fermentation of hardwood hemicellulose hydrolysate by Pachysolen tannophilus, Candida shehatae and Pichia stipitis.

Abstract: Hardwood hemicellulose hydrolysate has been utilized as a substrate for ethanol production. Among the three different yeasts tested, the best performances have been obtained, in decreasing order, usingPachysolen tannophilus, Candida shehatae andPichia stipitis. Several pretreatments of this raw material have been studied to improve ethanol yields; in one such pretreatment a strain ofP. tannophilus produced ethanol with a yield of 0.29 gethanol/gsugars (gP/gS); which is only 15% less than the values observed with synthetic media. Neither aeration nor acetone addition improved the fermentation of this substrate; in fact, only a marked stimulation of biomass growth has been observed at the expense of both ethanol and xylitol production.

Copper toxicity and uptake in microorganisms

Abstract: Copper is a required trace element for growth of microorganisms since it is a cofactor for numerous enzymes. Also, proteins containing copper are important electron transfer carriers. However, at elevated concentrations, copper can be highly toxic to microorganisms. This review examines copper toxicity and uptake in microorganisms, with an emphasis on copper-resistance mechanisms.

Isolation and characterization of a surfactant produced by Bacillus licheniformis 86

Abstract: Surfactant (BL86) was isolated from foam produced during growth ofBacillus licheniformis 86 by acid-precipitation followed by extraction into tetrahydrofuran or methanol. The surfactant is anionic and dissolves in tetrahydrofuran, methanol, chloroform, dichloromethane, xylene, toluene, and alkaline water. The surfactant lowers the surface tension of water to 27 dynes/cm, and achieves the critical micelle concentration with as little as 10 μg surfactant/ml. Its interfacial tension can reach 0.36 dynes/cm when measured in 4% sodium chloride againstn-hexadecane. The surfactant is stable from pH 4.0 to 13.0, at temperatures ranging from 25 to 120°C, and in salt solutions ranging from 0 to 30% NaCl. Preliminary analytical results indicate that the surfactant is a mixture of lipopeptides different from previously reportedBacillus produced surfactants.

Glyphosate degradation by Agrobacterium radiobacter isolated from activated sludge

Abstract: Two species of bacteria capable of growth onN-phosphonomethylglycine (glyphosate) were isolated from a bench scale sequencing batch reactor degrading a waste stream containing glyphosate. The enrichment and isolation medium contained defined salts and glyphosate as the sole carbon and energy source. Glyphosate was stoichiometrically degraded to aminomethylphosphonic acid (AMPA). The bacteria have been identified asAgrobacterium radiobacter andAchromobacter Group V D.

Radiation resistance of Salmonella

Abstract: The ionizing radiation resistances of sixSalmonella species were examined. The experimental variables were the suspending medium, the presence or absence of air, and the temperature during the irradiation process.S. typhimurium ATCC 14028,S. enteritidis ATCC 9186,S. newport ATCC 6962,S. dublin ATCC 15480,S. anatum ATCC 9270, andS. arizonae ATCC 29933 were suspended in phosphate buffer (0.1 M, pH 7.0), brain heart infusion broth (BHI) or mechanically deboned chicken and exposed to gamma radiation from cesium-137 at 0.12 kGy per min. The radiation resistance of theSalmonella increased approximately two-fold when assayed in sterile mechanically deboned chicken rather than in buffer or BHI. The average radiation (0.30 to 1.20 kGy) D-value for all sixSalmonella strains was 0.56 kGy in mechanically deboned chicken.S. enteritidis was significantly more resistant to ionizing radiation than the other five strains ofSalmonella tested on mechanically deboned chicken. The temperature of irradiation but not the presence or absence of air significantly influenced the survival ofS. typhimurium andS. enteritidis in mechanically deboned chicken. Treatment of chicken meat with ionizing radiation would be an effective means for control ofSalmonella contamination.

Effect of controlled substrate feeding on butyric acid production by Clostridium tyrobutyricum

Abstract: Production of butyric acid from wheat flour hydrolysate was studied withClostridium tyrobutyricum. The mode of substrate supply was found a key parameter for fermentation performance as large improvements were obtained by feeding with a non-limiting supply of substrate. With this procedure, increases in product concentration and productivity but also in selectivity and yield for butyrate were obtained. Substrate feeding controlled by the rate of gas production was found preferable to constant rate feeding for reason of convenience and flexibility. In these conditions, a butyrate concentration of 62.8 gl−1 was obtained with a productivity of 1.25 gl−1 h−1, a selectivity of 91.5% and a yield of 0.45 g per g of glucose.

Degradation of 2,4-dichlorophenoxyacetic acid by mixed cultures of bacteria.

Abstract: We explored the feasibility of using mixed cultures for herbicide degradation, with the ultimate aim of application for effluent treatment. The present study reports on mixed cultures which were developed to grow aerobically with 2,4-dichlorophenoxyacetic acid (2,4-D) as the sole carbon substrate. Degradation of 2,4-D was verified by HPLC and UV-spectroscopic analysis of the residual 2,4-D concentration in the test cultures. Cultures that were initially developed with 2,4-D also grew readily with glucose, but the degradation of 2,4-D was effectively prevented under mixed substrate conditions. Mamor intermediates or metabolites resulting from 2,4-D degradation were not detected with the HPLC methodology except 2,4-dichlorophenol which appeared to accumulate transiently in the growth medium.

Environmental factors influencing methanogenesis in a shallow anoxic aquifer: a field and laboratory study

Abstract: The environmental factors influencing methanogenesis in a shallow anoxic aquifer were probed in a combined field and laboratory study. Field data collected over a year revealed that ‘in situ’ rates of methane production were depressed in winter and elevated in summer. Over the same period, ground water pH values ranged from 6.0 to 7.8 while temperatures varied from 7–22°C. ‘In situ’ methanogenesis was severely inhibited at temperatures < 13°C or by pH values < 7. The influence of these factors on microbial methane formation from both endogenous and exogenous substrates were tested in aquifer slurries adjusted to pH 5–9 and incubated at temperatures ranging from 5–45°C. Temperature optima for methane production from endogenous substrates varied as a function of pH, but the pH optimum was 8 at all temperatures. Optimal conditions for acetoclastic methanogenesis were found at pH 8 and 35°C. An analysis of variance revealed that pH, temperature, and a pH-temperature interaction are all significant variables influencing aquifer methanogenesis. In addition transient sulfate accumulations were also found to limit methane production in some areas. A comparison of field and laboratory methane production patterns suggest that pH, temperature, and sulfate accumultations are important, but not the only environmental variables influencing the mineralization of organic matter in shallow aquifers.

The effect of neutral resins on the fermentation production of rubradirin.

Abstract: Rubradirin is an antibiotic of complex chemical structure which is activevs. methicillin resistant staphylococci. Its development has been limited due to inadequate production yields. The incorporation of neutral resins into fermentations ofStreptomyces achromogenes v.rubradiris, UC® 8051 resulted in the enhanced production of rubradirin. Resins HP-20, HP-21, XAD-2, XAD-7 and XAD-16 were employed in flask and tank fermentations. The incorporation of these resins promoted 2- to 4-fold enhancements of the rubradirin activity produced in flask fermentations, and the incorporation of XAD-16 and HP-21 into tank fermentations promoted production titer increases >5 fold.

Characterization of the requirements and substrates for reductive dehalogenation by strain DCB-1.

Abstract: An obligately anaerobic bacterium known as strain DCB-1 was grown under a variety of conditions to determine the requirements for dehalogenation as well as factors which stimulated or inhibited the process. Dechlorination was obligately anaerobic since introduction of O2 immediately inhibited the reaction. Sulfuroxy anions, which also serve as electron acceptors for DCB-1, inhibited dechlorination but NO3 − and fumarate did not. The optimum growth medium for dechlorination was 0.2% Na pyruvate and 20% rumen fluid in basal salts. Media with either pyruvate or rumen fluid alone did not support dechlorination. DCB-1 also consumed H2 but typical substrate concentrations of H2 (80 kPa) delayed dechlorination. Once the H2 concentration was reduced to <20 μM (2.67 kPa), dechlorination resumed. Dehalogenation by DCB-1 was restricted to the meta substituted benzoates as halogens in other positions and chloroaromatic compounds with other functional groups were not dechlorinated.

Production of a fructosyl-transferring enzyme byAureobasidium sp. ATCC 20524

Abstract: Production of a fructose-transferring enzyme byAureobasidium sp. ATCC 20524 and reaction conditions for the production of fructooligosaccharide, isokestose, were studied. The maximum total enzymatic activity of culture broth was 103.2 U/ml. The optimum reation pH and temperature of intracellular enzyme was 5–6 and 50°C, respectively.

Extracellular mannanases and galactanases from selected fungi

Abstract: Eight thermophilic fungi were tested for production of mannanases and galactanases. Highest mannanase activities were produced byTalaromyces byssochlamydoides andTalaromyces emersonii. Mannanases from all strains tested were induced by locust bean gum except in the case ofThermoascus aurantiacus, where mannose had a greater inducing effect. Locust bean gum was also the best inducer of β-mannosidase and galactanase except in the case ofT. emersonii where galactose was a better inducer of both these enzymes. Highest mannanase activity was produced byTalaromyces species when peptone was used as nitrogen source whereas sodium nitrate promoted maximum production of this enzyme byThielavia terrestris andT. aurantiacus. The pH optima of mannanases from the thermophilic fungi were in the range 5.0–6.6 and contrasted with the low pH optimum (3.2) of the enzyme fromAspergillus niger. Galactanases had pH optima in the range 4.3–5.8. The mannanase fromT. emersonii and the galactanase fromT. terrestris were most thermostable, each retaining 100% activity for 3 h at 60°C.

Development of a stirred tank reactor system for the production of lignin peroxidases (ligninases) byPhanerochaete chrysosporium BKM-F-1767

Abstract: Lignin peroxidases produced byPhanerochaete chrysosporium have several important potential industrial applications based on their ability to degrade lignin and lignin-like compounds. A stirred tank reactor system for the production of lignin peroxidases is described here. Included in this study is an examination of the mechanics of pellet biocatalyst formation and the optimization of an acetate buffered medium. Higher levels of lignin peroxidase were obtained with acetate buffer compared to the other buffer systems tested. Concentrations of 0.05% (w/v) Tween 80 and 0.4 mM veratryl alcohol gave optimal lignin peroxidase activity in acetate buffered medium. In shake flask cultures, mycelial fragments in the inoculum aggregated into pellets during the first eight hours of incubation and thereafter increased in size through the eighth day. The agitation rate in shake flask cultures affected pellet size, the number of pellets formed, and lignin peroxidase activity. Transfer of fungal pellets from shake flask culture to a continuously oxygenated baffled stirred tank reactor (STR) resulted in production of high lignin peroxidase titres comparable to those of shake flask cultures when the agitation rate, oxygen dispersion and foaming were closely controlled.

Regulation of biosynthesis of bacilysin by Bacillus subtilis.

Abstract: Production of the dipeptide antibiotic bacilysin byBacillus subtilis 168 was growth associated and showed no evidence of repression by glucose or sucrose. Carbohydrates other than glucose and sucrose yielded lower specific titers of bacilysin. Bacilysin production in three such carbon sources (maltose, xylose, ribose) was delayed until growth slowed down. Ammonium salts were poor for bacilysin production when used as the sole nitrogen source. When added to the standard medium containing glutamate, they suppressed antibiotic production. Aspartate was slightly better than glutamate for antibiotic production as sole nitrogen source. No other nitrogen source tested, including inorganic, organic or complex, approached the activity of glutamate or aspartate. When added to glutamate, casamino acids, phenylalanine and alanine (a substrate of bacilysin synthetase) suppressed bacilysin production while stimulating growth. Phosphate provided for optimum growth and production at 7.5 mM and both processes were inhibited at higher concentrations. Ferric citrate stimulated growth and inhibited bacilysin production, the effects being due to both the iron and the citrate components. Elimination of ferric citrate stimulated production as did increasing the concentration of Mn to its optimum concentration of 6.6×10−4M.

The production of recombinant beta-galactosidase in Escherichia coli in yeast extract enriched medium.

Abstract: The productivity ofEscherichia coli biomass and recombinant beta-galactosidase was increased in Luria broth (LB) enriched with yeast extract. In flask culture under conditions of LB limitation, yeast extract suplementation gave the highest biomass (strain HB101/pRW756) stimulation per unit of component added compared with supplementation by various amounts of amino acids, vitamins, minerals, purines/pyrimidines, tryptone, casamino acids, casein peptone or gelatin peptone. The biomass production ofE. coli HB101/pRW756, XL-1 blue/puc118, XL-1 Blue FF/puc118 and TB-1/p1034 cells was stimulated in fermentor-scale experiments with additional yeast extract in LB. Total beta-galactosidase production from plasmid genes in fermentor-scale experiments was increased 105.4% in XL-1 blue/puc118 cells, 365.5% in XL-1 blue FF/puc118 cells and 421.4% in TB-1/p1034 cells by 0.5%, 1% and 1% weight per volume of additional yeast extract in LB, respectively. Depending on different strains, the increase of the enzyme production was obtained either by increased biomass, or the combination of enhanced gene expression and increased biomass. Neither the biomass nor beta-galactosidase production was stimulated in N4830/p1034 cells by the increase in yeast extract concentration in the medium.

Production of Streptomyces clavuligerus isopenicillin N synthase in Escherichia coli using two-cistron expression systems.

Abstract: Streptomyces clavuligerus isopenicillin N synthase (IPNS) gene expression was achieved inEscherichia coli by the construction of two-cistron expression systems formed in the high copy number plasmid vector pUC119. These two-cistron constructions were composed of the IPNS gene and its flanking sequences which encoded an upstream open reading frame (ORF), the IPNS ribosome binding site and a putative transcription terminator. NoE. coli- likeStreptomyces promoter motif was present upstream of the IPNS gene therefore transcriptional regulation of the two-cistron system was provided by thelac promoter of pUC119. Enzymatically active IPNS was detected inE. coli cells harboring the recombinant plasmids thereby providing evidence for the activity of the IPNS ORF and for the feasibility of production ofS. clavuligerus IPNS inE. coli. These results indicate that simple two-cistron constructions involving foreign gene flanking sequences may be used to express foreign proteins inE. coli.

The fermentation of xylose: studies by carbon-13 nuclear magnetic resonance spectroscopy

Abstract: The fermentation ofd-xylose byPachysolen tannophilus, Candida shehatae, andPichia stipitis has been investigated by13C-nuclear magnetic resonance spectroscopy of both whole cells and extracts. The spectra of whole cells metabolizingd-xylose with natural isotopic abundance had significant resonance signals corresponding only to xylitol, ethanol and xylose. The spectra of whole cells in the presence of [1-13C]xylose or [2-13C]xylose had resonance signals corresponding to the C-1 or C-2, respectively, of xylose, the C-1 or C-2, respectively, of xylitol, and the C-2 or C-1, respectively, of ethanol. Xylitol was metabolized only in the presence of an electron acceptor (acetone) and the only identifiable product was ethanol. The fact that the amount of ethanol was insufficient to account for the xylitol metabolized indicates that an additional fate of xylitol carbon must exist, probably carbon dioxide. The rapid metabolism of xylulose to ethanol, xylitol and arabinitol indicates that xylulose is a true intermediate and that xylitol dehydrogenase catalyzes the reduction (or oxidation) with different stereochemical specificity from that which interconverts xylitol andd-xylulose. The amino acidl-alanine was identified by the resonance position of the C-3 carbon and by enzymatic analysis of incubation mixtures containing yeast and [1-13C]xylose or [1-13C]glucose. The position of the label from both substrates and the identification of isotope also in C-1 of alamine indicates flux through the transketolase/transaldolase pathway in the metabolism. The identification of a resonance signal corresponding to the C-1 of ethanol in spectra of yeast in the presence of [1-13C]xylose and fluoroacetate (but not arsenite) indicates the existence of equilibration of some precursor of ethanol (e.g. pyruvate) with a symmetric intermediate (e.g. fumarate or succinate) under these conditions.

Production of extracellular emulsifying agent by Pseudomonas aeruginosa UG1.

Abstract: Twenty-three bacterial strains were isolated from oil-contaminated soil samples. Of these, 20 displayed some ability to effect oil dispersion and they were screened quantitatively for the ability to emulsify 0.5% (v/v) reference oil. One strain, identified as Pseudomonas aeruginosa UG1, produced extracellular material that emulsified reference oil, hexadecane and 2-methylnaphthalene at concentrations as high as 6% (v/v) in nutrient broth. Emulsification activity increased during a 10 day incubation period at 30 degrees C. The activity was not influenced by pH over the range 5 to 9. The emulsifying agent was precipitated by cold ethanol. The highest emulsifying activity was detected in the extracellular fraction precipitated between 30 and 50% (v/v) ethanol. A linear relationship was observed between emulsifier concentration (mg/ml) and emulsifying activity. Genetic analysis showed that the Pseudomonas aeruginosa UG1 strain did not carry extrachromosomal plasmids, suggesting that the gene(s) coding for emulsifying activity was carried on the chromosome.

Mutation and screening to increase chymosin yield in a genetically-engineered strain of Aspergillus awamori

Abstract: Through the course of five rounds of mutagenesis of a genetically-engineered strain ofAspergillus awamori, the yield of a heterologous protein (the acid protease, calf chymosin) increased four-fold. This was accomplished through the use of an agar plate screen incorporating the colony restrictor 2,6-dichloro-4-nitroaniline (dichloran) and the acid protease inhibitor diazoacetyl-norleucine methyl ester (DAN) to reduce high background concentrations of the native acid protease. A miniaturized liquid culture growth method using 24-well culture plates was an intermediate screen between agar plate and shake flask cultures. Analysis of broth samples for active calf chymosin was accomplished with a highly specific, 96-well microtiter plate turbidimetric assay.

The use of bacterial alginates to prepare biocontrol formulations

Abstract: Formulations which are economical and which can deliver a viable organism are critical to developing successful biocontrol products for plant pathogens. In the present study, alginates derived from commercial kelp and produced byAzotobacter vinelandii isolates ATCC 9104 and 12 837 were compared in their ability to form stable, biodegradable granular formulations of the biocontrol fungiTalaromyces flavus andGliocladium virens. Bacteria were grown in shake flask cultures (180 rpm) at 32°C for 104 h. The cultures were monitored for pH, dissolved oxygen, glucose concentration, dry cell weight, and alginate dry weight. Aqueous solutions of the bacterial alginates, as well as the kelp-derived alginate products, gelled readily in 0.25 M calcium chloride. Mannuronate (M) and guluronate (G) compositions of the alginate samples were determined by circular dichroism. M/G ratios for cultures of isolate 12837 averaged 0.98±0.18; for isolate 9104, 1.59±0.12; and for kelp, 1.54±0.39. The viability ofT. flavus in the kelp and bacterial alginate formulations were similar over 84 days. An exploratory experiment indicated good viability ofG. virens using the same bacterial alginates. This study demonstrated a practical use for bacterial alginate as a potentially less costly substitute for kelp alginate in the preparation of biocontrol agent formulations.

Spent brewery grains as substrate for the production of cellulases by Trichoderma reesei QM9414

Abstract: The cellulolytic fungusTrichoderma reesei QM9414 can be cultivated on spent brewery grains for the production of cellulases. The levels of the cellulase components endoglucanase and exoglucanase synthesized, and the complexes filter paper cellulase and grain-hydrolyzing cellulase synthesized by the organism on spent grains were as high as 287, 182, 187, and 449 units per g available cellulose, respectively. Scaling up the spent grains fermentation system by up to 40-fold (200g dry substrate/tray) demonstrated that cellulase production was comparable to laboratory scale (5g dry substrate/flask) yields. Cultivation of the fungus was feasible on spent grains without pretreatment or further adjustment, although the enzyme yield was somewhat lower than that on dried grains moistened with water orTrichoderma medium. This suggested the possible reutilization of spent grains, with minimal pretreatment, in the cultivation ofT.reesei QM9414 for cellulase synthesis and for future incorporation into animal feed.

Recycle of cellulases and the use of lignocellulosic residue for enzyme production after hydrolysis of steam-pretreated aspenwood

Abstract: Various modes of substrate and enzyme addition were used to hydrolyze a 10% concentration (w/v) of steam-exploded, water-and-alkali extracted aspenwood withTrichoderma harzianum E58 cellulases. Although cellulose conversion was high (94–100%), enzyme recovery was low in all cases. Low enzyme recovery was due to a combination of thermal inactivation and adsorption of the cellulases onto the lignocellulosic residue. Enzyme recycle was not feasible as the activity of the recovered cellulases towards crystalline cellulose was low. However, the residual material from enzyme hydrolysis was a suitable carbon source for cellulase enzyme production byT. harzianum based on enzyme yield and hydrolytic potential. These residues could only be used up to a 1% substrate concentration, since at higher substrate loadings cellulase production was reduced, likely because of lignin inhibitors.

Biosolubilization of low-rank coal by a Trametes versicolor siderophore-like product and other complexing agents

Abstract: A heat stable, low molecular weight (<1000) extracellular product inTrametes versicolor (=Coriolus versicolor=Polyporous versicolor) cultures was demonstrated to be a principal factor in the solubilization of leonardite and other low-rank coals. The solubilization of leonardite byT. versicolor cell-free cultures and active fractions was inhibited by Fe3+ and was mimicked by the siderophore desferal mesylate and the iron chelating agents EDTA and 8-hydroxyquinoline. Leonardite solubilization by these later compounds was also inhibited by Fe3+. The ferrated and unferrated form of the partially purified active component fromT. versicolor cultures demonstrated absorption spectra that were similar to the ferrated and unferrated form of desferal mesylate.

Purification and some properties of the mannanases fromThielavia terrestris

Abstract: Thielavia terrestris NRRL 8126 cell free supernatants contained mannanase and β-mannosidase when cultured on a complex media containing locust bean gum. Using acetone precipitation, SP-Sephadex C50 ion exchange chromatography and preparative gel electrophoresis, the crude enzyme was resolved into one β-d-mannosidase and four β-d-mannanase components. β-d-mannosidase had a specific activity of 0.02 (U/mg) onp-nitrophenyl-β-d-mannopyranoside substrate. Mannanase components M1, M2, M3 and M4 had specific activities of 28.2, 38.7, 52.8 and 4.17 (U/mg) respectively on purified locust bean galactomannan substrate. pH optima for the enzymes were in the range 4.5–5.5. Mannanase component M4 manifested the greatest thermostability, retaining full activity for 3 h at 60°C. Molecular weights determined by SDS-PAGE were 72 000 for β-mannosidase and 52 000, 30 000, 55 000 and 89 000 for M1, M2, M3 and M4 respectively. Carbohydrate contents of the enzymes ranged from 6–36%. Preliminary studies indicate that enzyme components hydrolyse the mannan substrate in a synergistic manner.