Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “CEPHALOSPORIUM”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5Linked to original sources
PubMed1975

Glutamate dehydrogenase specific activity and cephalosporin C synthesis in the M8650 series of Cephalosporium acremonium mutants.

Conditions for the accurate measure of glutamic dehydrogenase (GDH) from Cephalosporium acremonium were determined. K(m) values for alpha-ketoglutarate and ammonium ion were 7 and 15 mM, respectively. The half-saturation for reduced nicotinamide adenine dinucleotide phosphate was 5 muM. Reduced nicotinamide adenine dinucleotide did not serve as a cofactor for the enzyme. The specific activity of GDH was measured in six mutants of C. acremonium which varied in their ability to synthesize cephalosporin C. The mutants represented two separately derived lines, A and B. The four mutants in line B were characterized by a derepression of the GDH upon entry into stationary phase. The two mutants in line A were characterized by repressed levels of GDH during the same period. Both lines exhibited high GDH activity early in their fermentations, but activity decreased during the period of active cell growth. Cytochrome c concentrations followed the same pattern as total soluble intracellular protein. Line A mutants were low in cephalosporin C productivity and line B encompassed low, intermediate, and high productivity mutants. The relative frequency of yield improvements in line A and B indicate that the altered regulation pattern for GDH in line B may have removed a nitrogen limitation for cephalosporin C synthesis.

Acremonium↗
PubMed1975

Production of cephalosporin C by single and double sulfur auxotrophic mutants of Cephalosporium acremonium.

An early blocked sulfur amino acid auxotroph, Cephalosporium acremonium mutant 274-1 (which could be satisfied by methionine or cysteine), utilized organic sulfur compounds for cephalosporin C production in the following order of decreasing effectiveness; methionine > cystathionine > cysteine, despite the fact that cysteine is considered to be the immediate precursor of the antibiotic. When a genetic block was added to mutant 274-1 in the transsulfuration pathway from cysteine to methionine, the double mutant 11-8 (which grows on methonine but not cysteine) failed to produce cephalosporin C from cysteine even though enough methionine was added to support normal growth. Addition of the non-sulfur analogue, norleucine, resulted in antibiotic production from cysteine in the double mutant. These facts support the hypothesis that methionine stimulation of cephalosporin C production is due to a role of methionine other than that of sulfur donation.

Acremonium↗
PubMed1976

Enzymatic hydrolysis of cephalosporin C by an extracellular acetylhydrolase of Cephalosporium acremonium.

Extracellular hydrolases from Cephalosporium acremonium were analyzed according to their ability to deacetylate the beta-lactam antibiotic cephalosporin C. One out of at least six hydrolases exhibits appreciable cephalosporin C acetylhydrolase (CAH) activity. This enzyme was separated from other hydrolases and purified 220-fold. The purified CAH has a relatively low affinity for cephalosporin C (K(m), 20 mM) and is strongly inhibited by diisopropylfluorophosphate and less markedly affected by fluoride. Addition of glucose, maltose, and sucrose to the culture broth suppresses CAH production, whereas glycerol and succinate have no effect. Verrucarin A prevented the enzyme from appearing in the medium, which indicates the necessity of protein synthesis for CAH formation. When 1-thio-d-glucose was added to the culture medium, the results suggested that this glucose analogue is able to inhibit CAH synthesis. Our data provide evidence for a regulation of CAH synthesis similar to the catabolite repression system in bacteria.

Acremonium↗
PubMed1982

Factors Affecting Yield and Safety of Protein Production from Cassava by Cephalosporium eichhorniae.

The properties of Cephalosporium eichhorniae 152 (ATCC 38255) affecting protein production from cassava carbohydrate, for use as an animal feed, were studied. This strain is a true thermophile, showing optimum growth at 45 degrees to 47 degrees C, maximum protein yield at 45 degrees C, and no growth at 25 degrees C. It has an optimum pH of about 3.8 and is obligately acidophilic, being unable to sustain growth at pH 6.0 and above in a liquid medium, or pH 7.0 and above on solid media. The optimum growth conditions of pH 3.8 and 45 degrees C were strongly inhibitive to potential contaminants. It rapidly hydrolyzed cassava starch. It did not utilize sucrose, but some (around 16%) of the small sucrose component of cassava was chemically hydrolyzed during the process. Growth with cassava meal (50 g/liter [circa 45 g/liter, glucose equivalent]) was complete in around 20 h, yielding around 22.5 g/liter (dry biomass), containing 41% crude protein (48 to 50% crude protein in the mycelium) and 31% true protein (7.0 g/liter). Resting and germinating spores (10 to 10 per animal) injected by various routes into normal and gamma-irradiated 6-week-old mice and 7-day-old chickens failed to initiate infections.

Journal Article↗
PubMed1982

Characteristics of Protease Production by Cephalosporium sp.

We investigated protease formation by Cephalosporium sp. strain KM388, which produced trypsin inhibitor in the same cultures, in medium containing polypeptone, meat extract, and glucose (natural medium) and in medium containing NaNO(3), glucose, and yeast extract (semisynthetic medium). In natural medium, protease was secreted into the culture broth after cessation of growth caused by consumption of the polypeptone, the growth-limiting substrate. Enzyme formation in the stationary growth phase was due to de novo and so-called preferential synthesis, because cycloheximide immediately inhibited enzyme formation. In semisynthetic medium, protease was produced in parallel with mycelial growth, but production was repressed by the addition of polypeptone to the medium; protease production began after the added polypeptone was consumed. On the other hand, if glucose was eliminated from natural medium, the lag period of initiation of enzyme production was reduced until the late exponential phase. The addition of phosphate up to a concentration of 1.0% to natural medium also shortened the lag period and damped the pH change of the broth during cultivation.

Journal Article↗
PubMed1987

Production of Microbial Biomass Protein from Potato Processing Wastes by Cephalosporium eichhorniae.

The use of Cephalosporium eichhorniae 152 (ATCC 38255) (reclassified as Acremonium alabamense; see Addendum in Proof), a thermophilic, acidophilic, amylolytic fungus, for the conversion of potato processing wastes into microbial protein for use as animal feed was studied. The fungus was not inhibited by alpha-solanine or beta-2-chaconine, antimicrobial compounds in potatoes, or by morpholine or cyclohexylamine (additives to steam used in the peeling process) at levels likely to be encountered in this substrate. Mixed effluent from holding tanks at a potato-processing plant contained about 10 bacteria per ml and inhibited fungal growth. The fungus grew well on fresh potato wastes containing up to 5% total carbohydrate and utilized both starch and protein at 45 degrees C and pH 3.75. On potato homogenate medium containing 2% carbohydrate (about 14% fresh potato) supplemented with monoammonium phosphate (0.506 g/liter) and ferric iron (0.1 g/liter), with pH control (at 3.75) and additional nitrogen supplied by the automatic addition of ammonium hydroxide, typical yields were 0.61 g (dry weight) of product and 0.3 g of crude protein per g of carbohydrate supplied. An aerobic, spore-forming bacterium, related to Bacillus brevis, commonly contaminated nonsterilized batch cultures but was destroyed by heating for 15 min at 100 degrees C.

Journal Article↗
PubMed1994

Changes in Cellular Fatty Acid Composition of Cephalosporium acremonium during Cephalosporin C Production.

Cephalosporium acremonium was cultivated in fermentation medium containing sucrose or methyl oleate as a carbon source for cephalosporin C production. The level of antibiotic production was 48 g of cephalosporin C per liter under optimum conditions when methyl oleate was used. The C(18:1) (oleic acid) methyl ester appeared to be utilized faster than the C(18:2) (linoleic acid) methyl ester in fermentation broth. Physiological characteristics of C. acremonium were investigated by determining the fatty acid composition of the total cellular free lipid. Significant changes in cellular fatty acid composition occurred during inoculum cultivation and fermentation. The percentage of C(18:1) increased from 19.1 to 38.5%, but the percentage of C(18:2) decreased from 56.7 to 36.1%, and there was an increase in pH during inoculum cultivation. The cellular fatty acid composition of C. acremonium grown in fermentation medium containing methyl oleate (methyl oleate medium) was significantly different from that in fermentation medium containing sucrose (sucrose medium). The major fatty acids detected were C(16:0) (palmitic acid), C(18:1), and C(18:2). In methyl oleate medium, the ratio of C(18:1) to C(18:2) increased from 0.34 to 1.37, while the cell morphology changed from hyphae to arthrospores and conidia. In contrast, in sucrose medium, the ratio of C(18:1) to C(18:2) decreased from 0.70 to 0.43, and most of the cells remained hyphal at the end of fermentation. We observed that hyphae contained a higher proportion of C(18:2) but arthrospores and conidia contained a higher proportion of C(18:1).

Journal Article↗
PubMed1995

Kinetics and Thermostability of NADP-Isocitrate Dehydrogenase from Cephalosporium acremonium.

NADP-isocitrate dehydrogenase [isocitrate:NADP(sup+) oxidoreductase (decarboxylating); EC 1.1.1.42] was purified from Cephalosporium acremonium as a single species. The enzyme is a dimer of 140 kDa with identical subunits of 75 kDa. The existence of a monomer-dimer equilibrium is apparent as revealed by an enzyme dilution approach. The chelate complex of the tribasic form of isocitrate and Mg(sup2+) is the true substrate. The V(infmax) depends on a basic form of an ionizable group of the enzyme-substrate complex with a pK(infes) (pK of the enzyme-substrate complex) of 6.9 and a (Delta)H(infion) (activation enthalpy) of -2 (plusmn) 0.4 kcal mol(sup-1) (ca. 8 (plusmn) 2 kJ mol(sup-1)). The enzyme showed maximum activity at 60(deg)C, an unusually high temperature for a nonthermophilic fungus. The thermodynamic parameters for isocitrate oxidative decarboxylation and for the binding of isocitrate and NADP(sup+) were calculated. We analyzed the kinetic thermal stability of the enzyme at pH 6.5 and 7.6. It was inactivated above 40(deg)C following a first-order kinetics. The presence of 12 mM Mg(sup2+) plus 10 mM dl-isocitrate led to 100% protection of enzyme activity against inactivation at 60(deg)C for 120 min. Removal of either or both compounds led to activity loss. A greater stabilizing role for Mg(sup2+) was seen at pH 6.5 than at pH 7.6, whereas the stabilizing effect of isocitrate was not dependent on pH.

Journal Article↗
PubMed1968

Proteinase production by a species of Cephalosporium.

An unidentified Cephalosporium species produced an extracellular proteinase when grown in a variety of fermentation media under submerged culture conditions. Maximal enzyme yields were obtained in a medium containing 2% corn meal, 1% soybean meal, and 0.5% CaCO(3) in tap water. Optimal proteinase production in this medium occurred within a 72- to 96-hr growth period. High enzyme yields were also attained with media in which cottonseed meal, Fermatein, Pharmamedia, or soybean-alpha-protein was substituted for the soybean meal. The substitution of these ingredients for the corn meal resulted in significantly decreased proteinase yields. The addition of minerals or vitamins to the corn meal-soybean meal fermentation medium failed to enhance proteinase production. The enzyme was most active in an alkaline environment; maximal caseinolysis occurred at pH 7.5, whereas pH 8.5 was optimal for either hemoglobin or beta-lactoglobulin hydrolysis. Enzymatic activity was also noted with either bovine albumin fraction V or soybean-alpha-protein substrates, whereas ovalbumin was not susceptible to enzymatic attack. The enzyme was stable within the pH range of 3.0 to 9.5 at 25 C for 2 hr, and at 5 C for 24 hr. The proteinase was stable upon heating for 10 min at 35 to 45 C, but it was totally inactivated at 70 C. The proteinase was unaffected by soybean inhibitor, partially inactivated by lima bean inhibitor, and completely inactivated by ovomucoid inhibitor.

Acremonium↗
PubMed1968

Effect of Methionine and Sulfate on the Metabolism of Cephalosporium acremonium.

The metabolism of Cephalosporium acremonium grown in a complex medium supplemented with DL-methionine or inorganic sulfate was studied. More growth occurred in a sulfate medium than in a methionine medium. Methionine-grown cells had an increased rate of respiration, a higher rate of catabolism with acetate and glucose as substrate, and higher specific activities of certain respiratory enzymes than sulfate-grown cells. Labeled acetate and glucose were assimilated at a faster rate by methionine-grown cells than sulfate-grown cells. Taurine, cystathionine, and small quantities of four acidic compounds were present in the amino acid pool of methionine-grown cells, but they were not detected in the pool of sulfate-grown cells. The differences in metabolic activity of sulfate and methionine-grown cells are discussed in regard to cephalosporin C synthesis.

Journal Article↗
PubMed1971

Arylamidase of Cephalosporium acremonium and its specificity for cephalosporin C.

Three aggregational forms of arylamidase are produced by Cephalosporium acremonium. The exocellular enzyme, with an approximate molecular weight of 60,000, was purified 300-fold by diethylaminoethyl cellulose chromatography, gel filtration, and gel electrophoresis. With l-leucyl-beta-naphthylamide as the substrate, the K(m) is 4.2 x 10(-4)m; the optimum pH, 7.7; and the temperature optimum, 35 C. The enzymatic hydrolysis of l-leucyl-beta-naphthylamide is inhibited by a number of cephalosporins, whereas a variety of penicillins show no effect. Alternatively, the enzyme specifically catalyzes the beta-lactam hydrolysis of a number of cephalosporins; a number of penicillins are resistant. The K(m) for cephalosporin C is 9.09 x 10(-4)m.

Acremonium↗
PubMed1971

Antibiotic synthesis and morphological differentiation of Cephalosporium acremonium.

In submerged cultures, Cephalosporium acremonium exists in four morphological forms: hyphae, arthrospores, conidia, and germlings. The phase of hyphal differentiation into arthrospores coincides with the maximum rate of beta-lactam antibiotic synthesis. Furthermore, arthrospores, separated by density-gradient centrifugation, possess 40% greater antibiotic-producing activity than any other morphological cell type. In a series of mutants, each with an increased potential to produce beta-lactam antibiotics, differentiation into arthrospores was proportional to the increased titer of these antibiotics. Thus, arthrospores exhibit enhanced synthesis of beta-lactam antibiotics and appear to be a determining factor in high-yielding mutants. Since a non-antibiotic-producing mutant readily differentiated into arthrospores, antibiotic synthesis and cellular differentiation are not obligately related.

Acremonium↗
PubMed1971

Virus-like particles in Cephalosporium acremonium.

Cephalosporium acremonium cultures were studied for the presence of virus-like particles. Relatively few particles were found in the preparations, indicating that the number of particles present in these cells may be much lower than in Penicillium species.

Acremonium↗
PubMed1975

Isolation and Some Properties of Glucoamylase from Cephalosporium charticola Lindau.

High glucoamylase (alpha-D-/1 --> 4/glucan glucohydrolase, EC 3.2.1.3.) activity was obtained in the cell-free culture fluid of Cephalosporium charticola. Glucoamylase seems to be the only amylolytic enzyme produced by C. charticola. The enzyme, purified on diethylaminoethyl-cellulose, was homogeneous by disc gel electrophoresis. The optimum pH on starch was 5.4, and optimum temperature was 60 C. Starch was degraded more rapidly than several other substrates; maltose was hydrolyzed about one-fifth as rapidly as starch. The molecular weight was 69,000, as determined by Sephadex G-100 filtration. The enzyme is a glycoprotein and contains about 6.6% sugars (mannose and glucosamine).

Journal Article↗
PubMed1976

Purification and properties of polyol dehydrogenase from Cephalosporium chrysogenus.

A polyol dehydrogenase of broad specificity was purified 178-fold from extracts of the filamentous fungus Cephalosporium chrysogenum. The enzyme was found to act as an oxido-reductase in two substrate-coenzyme systems: D-sorbitol (or xylitol)-nicotinamide-adenine dinucleotide (NAD) and D-mannitol-nicotinamide adenine dinucleotide phosphate (NADP). The dehydrogenase was composed of five isozymes, which, as a mixture, exhibited these properties: Km to D-sorbitol and D-mannitol, 7.15 to 10(-2) M; PH optimum, 9 to 10; molecular weight, 300,000 subunit weight, 29,000; PI, 5.8 to 7.5. The NADP-linked activity was labile to treatment with heat or ethylenediaminetetraacetic acid. Mixed substrate assays support the hypothesis that both NAD-, and NADP-linked activities are associated with isozymes of a single dehydrogenase.

Acremonium↗
PubMed1987

Copurification and characterization of deacetoxycephalosporin C synthetase/hydroxylase from Cephalosporium acremonium.

Deacetoxycephalosporin C synthetase (expandase), which catalyzes ring expansion of penicillin N to deacetoxycephalosporin C (DAOC), has been stabilized in vitro and purified to near homogeneity from the industrially important fungus Cephalosporium acremonium. Throughout the purification, the expandase activity remained physically associated with and in a constant ratio of 7:1 to DAOC hydroxylase activity. The latter activity mediates hydroxylation of DAOC to deacetylcephalosporin C (DAC). The copurified expandase/hydroxylase appeared to be monomeric, with a molecular weight of 41,000 +/- 2,000 and an isoelectric point of 6.3 +/- 0.3. Both catalytic activities required alpha-ketoglutarate, Fe2+, and O2 and were stimulated by ascorbate, dithiothreitol, and ATP. The Fe2+ requirement was specific, and sulfhydryl groups in the purified protein were apparently essential for both ring expansion and hydroxylation. The kinetics and stoichiometry of DAOC/DAC formation from the expandase/hydroxylase-catalyzed reactions suggested that ring expansion of penicillin N preceded hydroxylation of DAOC.

Acremonium↗
PubMed1991

Characterization of the Cephalosporium acremonium pcbAB gene encoding alpha-aminoadipyl-cysteinyl-valine synthetase, a large multidomain peptide synthetase: linkage to the pcbC gene as a cluster of early cephalosporin biosynthetic genes and evidence of multiple functional domains.

A 24-kb region of Cephalosporium acremonium C10 DNA was cloned by hybridization with the pcbAB and pcbC genes of Penicillium chrysogenum. A 3.2-kb BamHI fragment of this region complemented the mutation in the structural pcbC gene of the C. acremonium N2 mutant, resulting in cephalosporin production. A functional alpha-aminoadipyl-cysteinyl-valine (ACV) synthetase was encoded by a 15.6-kb EcoRI-BamHI DNA fragment, as shown by complementation of an ACV synthetase-deficient mutant of P. chrysogenum. Two transcripts of 1.15 and 11.4 kb were found by Northern (RNA blot) hybridization with probes internal to the pcbC and pcbAB genes, respectively. An open reading frame of 11,136 bp was located upstream of the pcbC gene that matched the 11.4-kb transcript initiation and termination regions. It encoded a protein of 3,712 amino acids with a deduced Mr of 414,791. The nucleotide sequence of the gene showed 62.9% similarity to the pcbAB gene encoding the ACV synthetase of P. chrysogenum; 54.9% of the amino acids were identical in both ACV synthetases. Three highly repetitive regions occur in the deduced amino acid sequence of C. acremonium ACV synthetase. Each is similar to the three repetitive domains in the deduced sequence of P. chrysogenum ACV synthetase and also to the amino acid sequence of gramicidin synthetase I and tyrocidine synthetase I of Bacillus brevis. These regions probably correspond to amino acid activating domains in the ACV synthetase protein. In addition, a thioesterase domain was present in the ACV synthetases of both fungi. A similarity has been found between the domains existing in multienzyme nonribosomal peptide synthetases and polyketide and fatty acid synthetases. The pcbAB gene is linked to the pcbC gene, forming a cluster of early cephalosporin-biosynthetic genes.

Acremonium↗