bluuebunny/crossref_metadata_2025_split huggingface dataset:
Coagulation autolysis in microorganisms and its relation to coagulase production
Authors: Zaslavskaya P. L. , Chekalina I. V. , Nys P. S. , Bartoshevich Yu. E. 
Published: February 2007

AbstractThe phenomenon of coagulation autolysis was observed in two model microorganisms, i.e., a bacterial culture and an imperfect fungus. It was characterized by impairment of the cell membranes, followed by condensation and dehydration of the cytoplasm and long‐term preservation of the cells in the form of coagulated cytoplasm. In this respect, it was similar to coagulation necrosis of human tissues. The autolysis in the microorganisms was accompanied by increase of their coagulase activity, the substrate specificity of the enzyme rather broad. The coagulase activity of the microorganisms was detected during the culture period between the lag‐phase and the exponential growth phase, i.e., the phase of their active growth. It served as a signal to induce biosynthesis of peptidohydrolase and cleavage of proteins. We believe that the phenomenon of coagulation autolysis in these microorganisms is rather typical and can be considered as an adaptative reaction, inducing a cascade of events from synthesis of coagulase to overproduction of peptidohydrolases with proteolytic activity.
Morpho‐physiologic characteristics of Escherichia coli and Shigella flexneri 2a carrying the htpR15 gene
Authors: Tetz Victor V. , Rybalchenko Oksana V. , Savkova Galina A. 
Published: February 2007

AbstractElectron microscopic examination of the morphology of normal Escherichia coli MC4100 and Shigella flexneri cells and their htpR‐defective recombinants has shown the presence in the latter of noncrystalline granules after growth at 37 °C. The defect of the htpR gene leads to some changes in ultrastructure of bacterial colonies and the intensification of the processes of development and aging of colonies as integral structures. These phenomena are manifested by early formation of intercellular contacts and thick surface films as well as the enhanced destruction of microorganisms. The recombinant Shigella strain grown at 30 °C retained its ability to provoke keratoconjunctivitis.
Cellulase from Humicola spp.
Authors: Ali Md. Showkat , Akhand Anwarul Azim , Gomez Paul Fabrian , Sarker Rafiqul Islam 
Published: February 2007

AbstractThe newly isolated Humicola strain secreted cellulases in the culture medium supplemented with 1% water hyacinth as carbon source. Of the nitrogen sources investigated, ammonium sulphate (0.5%) and yeast extract (4%) produced the highest amount of the enzyme complex. Maximal cellulases were synthesized at pH 6.0 and temperature 35 °C. The culture filtrate from this organism was used to study the saccharification of lignocellulosic wastes and adsorption onto avicel. About 48% saccharification was achieved with rice straw after a period of 24 h hydrolysis. The endoglucanase in the culture filtrate was adsorbed onto avicel to the extent of 13%.
Different factors affecting growth and amylase production by fungi inhabiting poultry feeds
Authors: Mahmoud A.‐L. E. 
Published: February 2007

AbstractExtracellular amylase synthesis by Aspergillus flavus and A. fumigatus, isolated from poultry feeds, was studied in stationary liquid medium. Maximum mycelium and extracellular amylase were produced after 7 days of incubation at 30 °C and after 5 days at 35 °C by A. flavus and A. fumigatus, respectively. Optimal amylase yield was obtained at pH 8 and 6 by the two fungi, respectively. Amylase production did not depend on the presence of starch in the growth medium but its inclusion in the medium enhanced amylase production by A. fumigatus. Sucrose appeared to be a poor carbon source for amylase synthesis by the test fungi. Growth on varying nitrogen sources showed that glycine promoted amylase production by A. flavus while yeast extract achieved maximum enzymatic yield by A. fumigatus.
Production of cell wall‐degrading enzymes by three isolates of Aspergillus niger under different cultivation conditions
Authors: Mehta A. , Chopra S. , Mehta P. 
Published: February 2007

AbstractThree strongly pathogenic isolates of Aspergillus niger were capable of producing pectolytic, cellulolytic and proteolytic enzyme activities in various culture media, extracellularly, indicating the positive correlation between in vitro enzyme production and virulence of the pathogens.
Dodecylguanidine monoacetate (dodine) causes severe membrane damage in Pseudomonas syringae above the critical micelle concentration
Authors: Cabral João P. S. 
Published: February 2007

AbstractThe release of K + from Pseudomonas syringae cells treated with dodecylguanidine monoacetate (dodine) was followed with a K+‐selective glass electrode. Treatment of the cells with 5–15 μmol/1 dodine resulted in low levels of K+ release, but higher surfactant concentrations caused extensive and rapid K+ efflux. Dodine concentrations that caused high K+ release also induced significant leakage of inorganic phosphate. The addition of 5–10 μmol/1 dodine also caused an increase in the rate of oxygen consumption in the presence of glycerol or succinate, but an increase in concentration from 10 to 40 μmol/1 resulted in a concomitant decrease in O2 consumption. The results from this and previous work suggest that dodine inhibits respiration firstly by causing drainage of coenzymes, and then by a direct interaction with the components of the respiratory chain.Previous work showed that above 25 μmol/1, dodine molecules aggregate to form micelles. The results therefore suggests that, in contrast with other cationic amphiphiles, the micellar form of dodine is more damaging to the cytoplasmic membrane than the free molecules.
The formation of N‐acetyl‐β‐D‐hexosaminidase is repressed by glucose in Penicillium chrysogenum
Authors: Pócsi István , Pusztahelyi Tünde , Bogáti Magdolna sz. , Szentirmai Attila 
Published: February 2007

AbstractThe formation of N‐acetyl‐β‐D‐hexosaminidase is under carbon catabolite repression in growing Penicillium chrysogenum. The enzyme accumulates inside the cells during the stationary phase of growth and is released into the culture fluid when the cell‐wall lysis has started and progressed. The time‐course of enzyme formation strongly supports the suggestion that fungal N‐acetyl‐β‐D‐hexosaminidase may have a role in the degradation of intermediate cell‐wall breakdown products during starvation. Regarding that analogous enzymes from other fungi have been shown to be able to liberate GlcNAc monomers from different glycoproteins and glycopeptides a possible participation in the orderly destruction of cellular glycoprotein components cannot be excluded. The physical and enzyme kinetic properties of both intracellular and extracellular N‐acetyl‐β‐D‐hexosaminidase are essentially the same indicating that the enzyme is probably released into the culture fluid without modification.
Periplasmic aminopeptidases in Acinetobacter calcoaceticus and Pseudomonas aeruginosa
Authors: Fricke Beate , Aurich Harald 
Published: February 2007

AbstractThe greater part of the intracellular aminopeptidases in Pseudomonas aeruginosa and Acinetobacter calcoaceticus is soluble. The localization of aminopeptidases in the cells was examined using the osmotic shock method with some modifications. When the cells of A. calcoaceticus and P. aeruginosa of the logarithmic phase were subjected to an osmotic shock, all aminopeptidases investigated were mainly localized in the sucrose supernatants and in the periplasm. Acid phosphatase as marker enzyme for periplasm showed a similar distribution between the fractions as the aminopeptidases.The periplasmic aminopeptidases of both microorganisms were separated by FPLC on Superose 12 and their molecular masses were determined. The results obtained show that at least four different aminopeptidases occur in the periplasm, a leucyl aminopeptidase (LAP, cleaving Leu‐NH‐NH2. 400 kDa), a glutamyl aminopeptidase (GAP, 200 kDa), an alanyl aminopeptidase (AAP, 80 kDa) and a prolyl aminopeptidase (PAP, 65 kDa). The results are in agreement for both species.Our results show clearly that aminopeptidases of these typical members of Gram‐negative bacteria are mainly periplasmic like degrading enzymes (alkaline and acid phosphatases, 5′‐nucleotidase, cyclic phosphodiesterase), detoxifying enzymes and binding proteins for amino acids and sugars.
Numerical taxonomy of Monascus species based on the electrophoretic analysis of intracellular enzymes
Authors: Nishikawa Jiro , Iizuka Hiroshi 
Published: February 2007

AbstractFour isozymes in fifteeen species of Monascus were analyzed using polyacrylamide gel electrophoresis. A numerical analysis was carried out on the basis of similarity values obtained from the electrophoretic mobilities of the enzymes. Non‐specific esterase and lactate dehydrogenase showed clearly distinguishable mobilities amont two clusters. From these results obtained, the strains used were divided into two clusters of Group‐I and Group‐II. Both groups were further subdivided into two subclusters. The type strain, M. ruber VAN TIEGHEM MR MO‐10 (IAM 8009) and M. kaoliang MR MO‐F2 were found to belong to the Group‐I. M. pilosus SATO MR MO‐4 (IAM8003) and M. pubigerus SATO MR MO‐8 (IAM 8004) were found to belong to the Group‐II. Nearly 100% similarity values were found between M. anka SATO MR MO‐6 (IAM 8001) and M. rubiginosus SATO IFO 4484, between M. anka var. rubellus SATO MR MO‐5 (IAM 8081) and M. purpureus WENT MR MO‐9 (IAM 8010), and, moreover, among M. vitreus SATO MR MO‐3 (IAM 8007), M. fuliginosus SATO IFO 4483 and M. serorubescens SATO 4487, respectively.Therefore, it was concluded that electrophoretic analysis of enzymes may be useful in presenting a new classification system of Monascus spp.
Occurrence of antimicrobial activities of bacteria from soybean leaf spots
Authors: Völksch B. , Ullrich M. , Fritsche W. 
Published: February 2007

AbstractBacteria were isolated from leaf spots of field grown soybeans during two growing seasons. The leaf spots yielded up to 4 different species and a total population size of about 107–108 bacteria/cm2. The majority of the 192 isolates belonged to the species Pseudomonas syringae pv. glycinea (55%), causing leaf spots of bacterial blight on soybeans, and Erwinia herbicola (22%). The remaining isolates included bacteria from other genera, but occurred occasionally.The determination of biological activity of the isolates demonstrated that a high percentage of strains from the group Erwinia/Enterobacter produced biological active substances against Escherichia coli (69%) and against Chlorella pyrenoidosa (88%). The majority of P. syringae pv. glycinea strains failed to do so. None of the isolates affected the growth of Geotrichum candidum. The E. herbicola strains showed clear antagonistic properties against a wide range of isolated bacteria. Four E. herbicola strains inhibited the growth of nearly all other E. herbicola isolates and 6 other strains were active against most of the P. syringae pv. glycinea isolates. However, antagonistic interactions among strains isolated from a distinct leaf spot were very rarely.
Isolation and characterization of the thermoresistant gluconokinase from Escherichia coli
Authors: Vivas Eugenio I. , Liendo Andreina , Dawidowicz Karl , Istúriz Tomás 
Published: February 2007

AbstractIt is known that two gluconokinases are inducibly expressed during the utilization of gluconate by E. coli. One is thermoresistant (activity stable for 3 h at 30 °C) and the other thermosensitive (losses 75% or more of its activity under the above conditions). The thermoresistant gluconokinase (EC 2.7.1.12) was isolated, purified and characterized for the first time from the E. coli mutant Ca26, a K12 derivative which lacks the thermosensitive activity. The enzyme was purified 43 fold with a recovery of 11%. The Mr of the enzyme was 100 kDa with three equal subunits of approximately 29.5 kDa. The enzyme exhibited Michaelis‐Menten kinetics and the Km values for gluconate and ATP were 0.02 mM and 0.045 mM respectively.
Optimization of alkaline amylase production by thermophilic Bacillus stearothermophilus AN 002
Authors: Bezbaruah R. L. , Gogoi B. K. , Pillai K. R. 
Published: February 2007

AbstractBacillus stearothermophilus AN 002 secreted thermostable alkaline amylase into a liquid growth medium containing 2 g/l starch. Amylase activity was highest at early stationary phase of growth. Among the various carbohydrates tested maximum amylase production was obtained with starch. When starch was replaced by other carbon sources, amylase production was reduced. Peptone and corn steep liquor (CSL) were the ideal nitrogen sources for amylase production by this strain. Of the phosphate sources tested, (NH4)2HPO4 showed best restults. Amylase production was highest in a laboratory fermenter at a initial pH of 6.5 and at a constant pH of 7.0. The optimum aeration and agitation for amylase production were 0.66 v/v/m and 400 rev/min, respectively. Maximum growth was obtained at 55 °C and maximum amylase was produced at 50 °C. The amylase was found to be stable between pH 6.0 to 11.0.
Growth response of the cyanobacterium Microcystis aeruginosa to herbicides and pesticides
Authors: Swain N. , Rath B. , Adhikary S. P. 
Published: February 2007

AbstractGrowth response of the planktonic cyanobacterium Microcystis aeruginosa to various concentrations of the herbicides and pesticides viz. CuSO4, DCMU (analytical grade Diuron), Karmex (commercial grade Diuron), 2,4‐D, Fernoxone, BHC and bleaching powder (CCH) was studied in laboratory culture. The organism was sensitive to very low concentrations of CuSO4, DCMU and Karmex. Lethal concentration of Karmex and CuSO4 were found to be 0.1 μg · ml−1 and 5.0 μg · ml−1 respectively. The cyanobacterium could tolerate the other chemicals tested up to a concentration of over 500 μg · ml−1. On culturing the organism in the CuSO4 containing media, toxic effect of the chemical was reduced to a significant extent. This indicated that CuSO4 was accumulated or detoxified in the Microcystis cells. Toxic effect of Karmex on the organism was not reduced under similar experimental conditions.
A method for screening diacetyl and acetoin‐producing bacteria on agar plates
Authors: Phalip V. , Schmitt P. , Diviès C. 
Published: February 2007

AbstractA simple method for screening bacteria for diacetyl and acetoin production was developed. This method is based on the ability of diacetyl and acetoin to form a red insoluble complex with α‐naphthol in the presence of creatine. Addition of carboxymethyl‐cellulose containing calcium citrate in the medium allowed discrimination between citrate utilizing and non‐utilizing bacteria.
Radiation sensitivities of Acinetobacter strains isolated from clinical sources
Authors: Nishimura Yukimasa , Uchida Kazuyuki , Tanaka Kunio , Ino Takeshi , Ito Hitoshi 
Published: February 2007

AbstractFor twelve clinical strains genetically grouped together with Acnetinobacter radioresistens FO‐1T, the radiation sensitivity was measured. Their D10 values in γ‐ray irradiation under N2‐equilibrium were 0.24 to 0.93 kGy and about 1/10 to 1/3 of that of the radiation‐resistant strain FO‐1. The results showed that the genospecies A. radioresistens contained some radiation‐sensitive strains.
Inhibition of nitrite reductase and urease by arginine and proline in the cyanobacterium Anabaena cycadeae
Authors: Singh Surendra , Bisen P. S. 
Published: February 2007

AbstractThe arginine and proline inhibition of nitrite reductase and urease activities have been studied in the cyanobacterium Anabaena cycadeae and its mutant strain lacking glutamine synthetase (GS)1) activity. Arginine and proline inhibited the nitrite reductase and urease activities in the parent strain, however, they could not do so in the mutant strain. The level of arginine‐ and proline‐dependent NH production in the outer medium was several fold higher in the mutant strain as compared to its parent strain. These results suggest that (1) nitrite reductase and urease activities are arginine‐ and proline‐repressible; (2) the catalytic function of GS is necessarily required for the arginine and proline inhibition of nitrite reductase and urease systems; and (3) the NH resulting from the catabolism of arginine and proline should be metabolized via GS for repression of nitrite reductase and urease to occur.
Transformation reactions of progesterone by different species of Streptomyces
Authors: Atta F. M. , Zohri A. A. 
Published: February 2007

AbstractA systematic study of transformation reactions of the genus Streptomyces with respect to the progesterone molecule was undertaken. The types of transformation reactions by different Streptomyces species were evaluated from the point of view of taxonomy. The isolates tested were divided according to the transformation types into six groups: (1) a group of species transform progesterone to 16α‐hydroxyprogesterone; (2) a group of species transform progesterone to 6β‐hydroxyprogesterone; (3) a group of species transform progesterone to 6β, 11α‐dihydroxyprogesterone; (4) a group of species dehydrogenate progesterone in C1 ‐ 2 position; (5) a group of species transform progesterone to 3 derivatives namely 6β‐hydroxyprogesterone, 6β, 11α‐dihydroxyprogesterone and dehydrogenation in position C1 ‐ 2; (6) a group of species with no capacity to transform progesterone into another steroid derivative. From the point of view of Streptomyces classification, the transformation reaction of progesterone fulfil all the requirements of taxonomic feature of Streptomyces. These appear to be specific properties and common to all the strains of individual Streptomyces species tested.
Effect of salts on the activity of nitrate reductase from the photosynthetic bacterium Rhodobacter sphaeroides SW
Authors: Paggi Roberto A. , De Castro Rosana E. , Kerber Norma L. , Garcia Augusto F. 
Published: February 2007

AbstractThe effect of different salts on the nitrate reductase (NR) activity of Rhodobacter sphaeroides SW was studied. An increase of the activity in the presence of monovalent cations was observed (90, 80 and 77% with Na+, K+ and NH, respectively), whereas divalent cations inhibited the enzyme activity (30 and 85% with Ca2+ and Mg2+). Both activation or inhibition of the NR activity were reversible. These results could be explained by the interaction of cations with negatively charged amino acids. On the other hand, several anions were also effective in stimulating NR activity (Cl− > NO > Br− > I− > SCN−), suggesting that the degree of hydration of the enzyme molecule might influence its activity. Finally, the effect of salts on the NR activity of R. sphaeroides SW can be atributed to both electrostatic and hydrophobic interactions.
Seasonal fluctuations of aquatic fungi recovered from Egyptian soil (Delta Region)
Authors: Khallil A. M. , El‐Hissy Farida T. , Ali E. H. 
Published: February 2007

AbstractOne hundred and eleven identified and seven unidentified species in addition to 5 varieties belonging to forty‐three aquatic fungal genera were recovered from 452 soil samples collected randomly from different localities in Nile Delta and Suez canal regions including eleven governorates. The investigated soil samples were collected seasonally during the period from autumn 1990 to summer 1991 (113 samples each season). The richest season (85 identified and 5 unidentified species in addition to 2 varieties) in aquatic fungi was the winter season (10.0‐15.5°C) whereas the poorest (32 identified and 5 unidentified species in addition to one variety) was summer (24.0‐27.5°C). The richest soil samples in aquatic fungi were those of low or moderate temperature seasons, high contents of organic matter and considerably poor in total soluble salts. The pH value did not show any regular seasonal variation and did not exhibit any considerable influence on fungal populations. Some aquatic fungal genera and species were disappeared completely in certain seasons and vice versa.The most dominant aquatic fungal genera were Pythium, Allomyces, Aqualinderella and Nowa‐kowskiella. The commonest aquatic fungal species were Allomyces anomalus, Aqualinderella fermentans, Nowakowskiella elegans, Blastocladiopsis parva and Dictyuchus sterilis.
Effect of acetic acid on xylose fermentation to xylitol by Candida guilliermondii
Authors: Felipe Maria G. A. , Vieira Délia C. , Vitolo Michele , Silva Silvio S. , Roberto Ines C. , Manchilha Ismael M. 
Published: February 2007

AbstractThe effect of acetic acid concentration on xylose fermentation to xylitol by Candida guilliermondii FTI 20037 was evaluated in semisynthetic medium containing different concentrations of the acid. Increasing acetic acid concentration up to 1.0 g/1 favored xylitol yield and productivity, with maximum values of 0.82 g/g and 0.57 g/.h1, respectively. The presence of acetic acid reduced cell production at all concentration. Furthermore, acetic acid was assimilated by the yeast together with the sugars and was depleted from the medium at concentrations of less than 3.0 g/1. The ability of this yeast to assimilate acetic acid suggests that these cells act as agents of medium detoxification. This behavior may lead to a viable microbiological process of xylitol production by C. guilliermondii FTI 20037 using xylose‐rich lignocel‐lulosic hydrolysates in which acetic acid is commonly present, causing inhibition of fermentative activity.
Improved contrast by a simplified post‐staining procedure for ultrathin sections of resin‐embedded bacterial cells: Application of ruthenium red
Authors: Vogt Beate , Berker Ruth , Mayer Frank 
Published: February 2007

AbstractHigh contrast can be obtained in ultrathin sections of bacterial cells embedded in the low‐temperature resin Lowieryl by post‐staining of the sections on an aqueous ruthenium red solution. Post‐staining with lead citrate can be omitted. Combination with post‐staining with uranyl acetate results in further improvement of contrast. This is shown for Gram‐positive, Gram‐negative, and methanogenic bacteria. Improved visibility is demonstrated for wall layers including slime and capsule, cytoplasmic membrane, nucleoid, envelope of PHB inclusion bodies, polyphosphate, and intracellular defective bacteriophages. The procedure is suited as post‐staining for immunocytochemical analyses.
The effects of culture media on the production of xyIan‐degrading enzymes by Streptomyces chattanoogensis UAH 23
Authors: Fernández C. L. López , Rodríguez J. , Soliveri J. , Copa‐Patiño J. L. , Pérez‐Leblic M. I. , Arias M. E. 
Published: February 2007

AbstractThe production of 4 extracellular xylanolytic enzymes, arabinofuranosidase, endoxylanase, β‐xylosidase and acetyl esterase during the growth of Streptomyces chattanoogensis UAH 23 in basal salts media containing different carbon sources was examined. The highest enzyme activities were generally detected when arabinoxylan was used as the carbon source, with the exception of acetyl‐esterase where greatest activity was detected when ball‐milled straw was used as carbon source. A comparison of enzyme activities revealed that the specific activity of endoxylanase (3.15 U/mg protein) was greater than those of the other three enzyme activities (44.11,5.77 and 2.04 mU/mg protein for acetyl‐esterase, a‐L‐arabinofuranosidase and β‐xylosidase, respectively). Cellulase activity could not be detected throughout the studyCharacterization of the endoxylanase activity revealed that two optima pH could be detected (7.0 and 8.0) and was stable at alkaline pH values between 6.5 and 8.5. The optimum temperature was 55°C with the enzyme stable for one hour at 60°C. Activity staining of non denatured polyacrylamide gels containing culture supernatants revealed the presence of two active endoxylanase bands. The result suggest that two endoxylanase enzymes with different pH optimas are secreted by Streptomyces chattanoogensis UAH 23.