Showing papers in "Journal of Basic Microbiology in 1996"
TL;DR: 4 plasmid‐containing strains with an extreme resistance to nickel (up to 20 mM) were Gram‐positive and identified as Arthrobacter spp.
Abstract: The heavy metal-resistant bacterial community of strongly polluted industrial areas was investigated. The bacterial tolerance levels to nickel, chromium and copper depended greatly on the pollution degree of sampling sites. Thirty-six selected strains were tested on their multiple heavy metal resistance, most strains were resistant to high concentrations of nickel as well as of chromate. Remarkably, 4 plasmid-containing strains with an extreme resistance to nickel (up to 20 mM) were Gram-positive and identified as Arthrobacter spp. Nickel resistance is an induced mechanism in 3 strains and is constitutively expressed in one of the 4 strains; nickel resistance is influenced by temperature. This is the first description of extreme nickel resistance in Grampositive bacteria.
48 citations
TL;DR: E. coli susceptibility was shown to vary with growth conditions, whereby cells cultivated either on agar or harvested from the stationary phase of liquid culture were significantly more susceptible to ultrasound than an equivalent population obtained from the exponential phase ofLiquid growth.
Abstract: The effect of continuous-wave ultrasound on the viability of Escherichia coli HB101 was assessed using a 20 kHz ultrasonic processor. A standardised cell suspension of fixed concentration was used to investigate the influence of different physical and environmental conditions on ultrasound susceptibility. Cell viability decreased exponentially with time at different intensities of ultrasound. Increasing intensity caused a decrease in decimal reduction times. Loss of cell viability occurred primarily from the mechanical effects of ultrasound rather than free radical damage. E. coli susceptibility was also shown to vary with growth conditions, whereby cells cultivated either on agar or harvested from the stationary phase of liquid culture were significantly more susceptible to ultrasound than an equivalent population obtained from the exponential phase of liquid growth. The implication of these results is discussed in relation to the use of ultrasound as a novel means of bacterial transformation.
44 citations
TL;DR: The isolates had identical antigenicity to Iriki strain of Akabane virus, but were antigenically more distant to JaGar‐39 and OBE‐1 strain of Akira virus.
Abstract: Nonsuppurative encephalitis in calves aged 4-12 months, cow abortion and fetal deformities were endemic in dairy farms in Taiwan in recent years A virological investigation emphasizing on Arthpodborn virus (Arbovirus) was conducted Total of 11 strains of Akabane virus were isolated from endemic districts between June and July of 1992 Among them, seven viruses were isolated from blood samples of 15 calves showing nervous signs Another 4 Akabane viruses were isolated from clinically healthy calves from three of six dairy farms investigated All the six investigated farms had a recent history of abortion and fetal deformities The isolates caused prominent cytopathic effects in HmLu-1 cells and could reach a high virus titers (5 x 10(6) TCID50/ml) As demonstrated by a cross neutralization test, the isolates had identical antigenicity to Iriki strain of Akabane virus, but were antigenically more distant to JaGar-39 and OBE-1 strain of Akabane virus This is the first report on the isolation of Akabane virus in Taiwan, and also the second report on the isolation of Iriki virus in the world
43 citations
TL;DR: The mycobiota of the sandy soil of Ipanema Beach, Rio de Janeiro, Brazil, was investigated in 144 sand samples collected at four different sites along the sea coast for a period of one year and the largest number of filamentous fungi was isolated during the winter and the smallest number the Summer.
Abstract: The mycobiota of the sandy soil of Ipanema Beach, Rio de Janeiro, Brazil, was investigated in 144 sand samples collected at four different sites along the sea coast, divided into three subsites, for a period of one year. A total of 4285 yeast colonies and of 6956 of colonies filamentous fungi were isolated using conventional media and techniques. Representatives of the filamentous fungi corresponding to a total of 1334 colonies were identified and assigned to 34 genera and 170 species. The genera of highest incidence and their respective numbers of species were as follows: Aspergillus, 30.4%, 32 spp.; Penicillium, 16.2%, 35 spp.; Fusarium, 12,6%, 33 spp.; Trichoderma, 6.4%, 7 spp.; Paecilomyces, 3.7%, 10 spp.; Cladosporium, 3.1%, 8 spp. and Acremonium, 1.0%, 8 spp. Several other genera and species were detected at quite low occurrences. Non-sporulating fungi (18.3%) and Coelomycetes (Sphaeropsidales) (1.9%) were also detected. Most of the genera detected belonged to the Deuteromycotina, with fewer proportions belonging to the Ascomycotina and Zygomycotina. Moniliaceae was represented by the largest number of species and Dematiaceae was represented by the largest number of genera. In terms of seasonal distribution, the largest number of filamentous fungi was isolated during the winter and the smallest number the Summer.
36 citations
TL;DR: A pullulan-degrading enzyme activity was detected in the culture medium after growth of the fungus Aureobasidium pullulans on corn syrup as a carbon source as mentioned in this paper.
Abstract: A pullulan-degrading enzyme activity was detected in the culture medium after growth of the fungus Aureobasidium pullulans on corn syrup as a carbon source. The product of pullulan catabolism by this activity was determined to be glucose. The highest specific activity of this enzyme was found after 7 days of fungal growth. Although α-amylase activity was not detectable, the presence of a glucoamylase activity was indicated. It appeared that the enzyme responsible for pullulan degradation was likely glucoamylase B.
31 citations
TL;DR: A renewable xylose‐xylitol conversion was obtained with 40 h aged inoculum of Candida guilliermondii FTI 20037 grown in a medium containing an initialxylose concentration of 120g/l.
Abstract: The effect of the inoculum age and initial xylose concentration on the activities of xylose reductase (XR) and xylitol dehydrogenase (XD) of Candida guilliermondii FTI 20037 were investigated. Under the experimental conditions used, the XR and XD activities were, respectively. NADPH and NAD or NADP dependent. The NADP/NADPH ratio for XR was not substantially influenced by the age of inoculum or the initial xylose concentration. The Km of XR (0.18 M) was about 4-folds smaller than the Km of XD NAD-dependent. A renewable xylose-xylitol conversion was obtained with 40 h aged inoculum of Candida guilliermondii FTI 20037 grown in a medium containing an initial xylose concentration of 120g/l.
28 citations
TL;DR: Continuous ethanol production by immobilized cells of Saccharomyces cerevisiae HAU‐1 has been studied using synthetic and molasses based medium in column reactors and the diameter of the beads was found to be 3.5 mm for efficient fermentation.
Abstract: Continuous ethanol production by immobilized cells of Saccharomyces cerevisiae HAU-1 has been studied using synthetic and molasses based medium in column reactors. Immobilization of 30% yeast cells biomass (wet) in 1.5% calcium alginate gel resulted in the production of 20.8 g . 1(-1). h(-1) alcohol at a dilution rate of 0.36 h(-1) with approximately 1/3rd volume of the column reactor packed with pal beads. Optimum diameter of the beads was found to be 3.5 mm for efficient fermentation. The size of the column reactor (length to diameter ratio) also affected the productivity and fermentation efficiency due to gas hold-up and mass transfer effects. Molasses could also be fermented by this system but at a lower fermentation efficiency which could be improved, to some extent, by supplementation with nutrients.
26 citations
TL;DR: Two strains of ephiphytes isolated from soybean leaves showed clear antagonistic properties against Escherichia coli and Pseudomonas syringae pv, and under the influences of the antagonists the pathogen multiplied at lower rates and to lower stationary phase population levels, and the development of bacterial blight symptoms was suppressed.
Abstract: The strains 48b/90 and 22d/93 are naturally occurring ephiphytes which were isolated from soybean leaves. On the basis of pheno- and genotypic characteristics 48b/90 was identified as Erwinia herbicola and 22d/93 as Pseudomonas syringae. These two isolates produced biological active substances against different indicator organisms. The E. herbicola strain showed clear antagonistic properties against Escherichia coli and Pseudomonas syringae pv. glycinea, but not against Geotrichum candidum. 22d/93 was active against P. glycinea and G. candidum, but not against E. coli. Strain 48b/90 produced at least two different inhibitors: an antibiotic substance and an inhibitor of the alginate synthesis. Strain 22d/93 produced at least three different compounds inhibitory to P. glycinea and one to G. candidum. Their activities against the bacterial blight pathogen, P. glycinea, can be observed in planta, too. Under the influences of the antagonists the pathogen multiplied at lower rates and to lower stationary phase population levels. The development of bacterial blight symptoms was suppressed.
23 citations
TL;DR: The importance of these air‐borne fungal spores which cause allergy and asthma are emphasized in the paper from the viewpoint of human health.
Abstract: In this research, spore concentrations of Cladosporium, Alternaria, Epicoccum, Botrytis, Leptosphaeria, Polythrincium, ascospores, Aspergillus, Penicillium, basidiospores, uredospores, Ustilago, Torula, Erysiphe, Ganoderma, Hyaline indeterminate and others in the atmosphere have been determined, and comparisons have been made between locations with both low and high spore concentrations. The importance of these air-borne fungal spores which cause allergy and asthma are emphasized in the paper from the viewpoint of human health.
22 citations
TL;DR: Specific activities of extracellular proteinases, assayed under idiophasic (—C or —N) conditions, increased 2—3 fold as compared to those upon nutrient sufficiency, which accompanied a shift to secondary metabolism and onset of ligninolytic activity.
Abstract: The presence of multiple intracellular and extracellular proteolytic activities in trophophasic (nutrientrich) and idiophasic (carbon-or nitrogen-starved) cultures of the white-rot fungi Trametes versicolor and Phlebia radiata was demonstrated by electrophoresis on polyacrylamide gels containing denatured haemoglobin as a substrate. In the trophophasic cultures of T. versicolor, seven electrophoretically distinguishable proteases were defined using mycelial extracts and six (three clear and three less intensive) of secreted proteases. For P. radiata eight bands of intracellular and five bands (one distinct and four less active) of extracellular proteolytic activities were detected. Gel electrophoresis revealed changes in patterns of secreted and mycelial proteinases upon carbon or nitrogen deprivation. The changes were seen both as an increase in activity of certain bands and as the appearance of new proteolytic bands. Specific activities of extracellular proteinases, assayed under idiophasic (—C or —N) conditions, increased 2—3 fold as compared to those upon nutrient sufficiency. These changes accompanied a shift to secondary metabolism and onset of ligninolytic activity.
21 citations
TL;DR: This review is a survey of the works of a large team of chemists, biologists, clinicians, toxicologists and pharmacologists which lead to the development of a new drug of choice and the impact that this drug in particular is having and hopefully other similar ones will have in the field of immunopharmacology.
Abstract: Cyclosporin, a novel drug, exhibiting unique discriminatory action on the activation of helper lymphocytes without the undesirable side effects associated with conventional immunosuppressants, can well be considered as the prototype of a new generation of immunosuppressants. It is probably the first one to demonstrate that an immunopharmacologic approach to the modulation of the immune response by drugs is feasible. This enabled a decisive step forward to be made in transplantation surgery, particularly in the field of heart and kindney transplantation. Cyclosporin A exerts antifungal, antiparasitic and antiinflammatory activities also. There is considerable interest in the prospective value of this drug in the treatment of autoimmune disorders. Accolades are to be given for its role as a tool for studying mechanisms of the immune system. This review is an attempt to look into the various strides it had evolved before attaining the status of a unique drug, and also to assess critically the prospective value of this potent drug. The present modem era of antibiotic research is characterized by advanced screening procedures aiming specifically not only at antibacterials or antifungals but at compounds like enzyme inhibitors, immunomodulators and antitumor drugs. New sources of rare microorganisms are currently under exploitation. Development of microbial products with new medicinal activties has turned out to be a big research area, spearheaded by the success story of small molecular weight immunomodulators. Long accepted as the best way to prevent or treat rejection in patients undergoing organ transplantation, immunosuppressive therapy is attracting increased attention for its ability to treat a variety of diseases. One such potent agent, widely acclaimed as the first of a new generation of remarkable immunosuppressive agents, cyclospofin is being used in novel ways in a wide array of conditions. The cyclosporins are a group of over 25 closely related cyclic undecapeptides produced as secondary metabolites by two strains of fungi imperfecti, Cylindrocarpum lucidum BOOTH and Tolypocladium inflaturn CAMS, isolated from soil samples. Cyclosporin A is the main component of this family of cyclic peptides each containing 11 amino acids. This review is a survey of the works of a large team of chemists, biologists, clinicians, toxicologists and pharmacologists which lead to the development of a new drug of choice and the impact that this drug in particular is having and hopefully other similar ones will have in the field of immunopharmacology.
TL;DR: The secretion of the biologically active enzyme into the medium indicated that the postranslational processing of the PAC molecule, including the excision of a 54 amino acid spacer peptide between the α and β subunit, is not carried out in the periplasmic space, but occurs at the cytoplasmic membrane or autocatalytically.
Abstract: L-form strains of Proteus mirabilis and Escherichia coli lacking the cell wall represent an alternative prokaryotic cell system for the production of recombinant proteins (KLESSEN et al. 1988, LAPLACE et al. 1988a, 1989b). We could demonstrate that they are also able to synthesize the enzyme penicillin G acylase (PAC)1). PAC was processed and secreted into the medium by recombinant L-form strains. The synthesis of PAC was growth-associated and stably regulated. Expression, secretion, and processing were not temperature-dependent and occurred at 26 degrees C, 32 degrees C and even 37 degrees C. The expression vector pHC1 carried the pac gene under the control of the lac UV promotor and a kanamycin resistance gene. It could be maintained in L-form cells, showing low structural as well as segregational instability. The secretion of the biologically active enzyme into the medium indicated that the postranslational processing of the PAC molecule, including the excision of a 54 amino acid spacer peptide between the alpha and beta subunit, is not carried out in the periplasmic space, but occurs at the cytoplasmic membrane or autocatalytically.
TL;DR: Thirty‐four strains of seven species of Trichoderma isolated from various fungal sources were compared for direct mycoparasitic activity, chitinase production and antibiotic activity in order to choose the most appropriate partners for a strain‐breeding programme.
Abstract: Thirty-four strains of seven species of Trichoderma isolated from various fungal sources were compared for direct mycoparasitic activity (MPA), chitinase production and antibiotic activity (ANA) in order to choose the most appropriate partners for a strain-breeding programme. Within species genetic differences were also assesses in T. hamatum, T. harzianum and T. viride by means of random amplification of polymorphic DNA (RAPD). Endochitinase activities of the Trichoderma strains ranged between 20.4 and 1264.5 units/g dry weight of mycelium. The correlation between MPA and chitinase activity was not unambiguous and no correlation existed between MPA and ANA. The RAPD patterns of T. viride strains were highly variable, while isolates of T. harzianum proved to be more uniform; T. hamatum revealed remarkable intraspecific divergence. All these three comprised certain pairs of strains that are promising participants of a strain-improving programme, since their strong genetic affinities offer good changes for combining their contrasted biocontrol traits.
TL;DR: The dimeric nonactic acid (III) was isolated suggesting that III could be an intermediate of nonactin biosynthesis, and displays no antibacterial and antifungal activities supporting the view that cation complex formation by nactin‐type antibiotics requires the entire macrotetrolide ring.
Abstract: The formation of possible intermediates of nonactin (I) biosynthesis by Streptomyces spec. JA 5909-1 was investigated. In addition to monomer nonactic acid (II), the dimeric nonactic acid (III) was isolated suggesting that III could be an intermediate of nonactin biosynthesis. The structure of III was settled by electrospray mass-spectrometry and high-field FT-NMR methods. III displays no antibacterial and antifungal activities supporting the view that cation complex formation by nactin-type antibiotics requires the entire macrotetrolide ring.
TL;DR: Mycobacterium sp.
Abstract: Mycobacterium sp. NRRLB3683 which is capable to convert beta-sitosterol to 1,4-androstadiene-3,17-dione (ADD) was treated with methyl methane sulfonate and two strains with altered sensitivity to various antibiotics were obtained. One of the strain was steroid 1(2)-dehydrogenase negative and the other positive. Efficiency of utilization of sterols followed the order beta-sitosterol > cholesterol > soluble cholesterol. The steroid 1(2)-dehydrogenase negative strain was capable of producing 17KS (AD) from beta-sitosterol and converting AD to testosterone and ADD to AD suggesting the negative role of 1(2)-dehydrogenase in sterol side chain cleavage and decrease in hydrogenase activity by mutation. But this enzyme can perform the reverse reaction under aerobic condition.
TL;DR: Enterococcus faecalis exhibits an extremely high natural resistance to Cadmium which can be even raised by a conditioning treatment at a lower cadmium concentration as well as by a previous exposure to a sublethal temperature.
Abstract: Enterococcus faecalis exhibits an extremely high natural resistance to cadmium which can be even raised by a conditioning treatment at a lower cadmium concentration as well as by a previous exposure to a sublethal temperature By contrast, thermotolerance is not significantly induced by previous exposure to low cadmium concentration The synthesis of several proteins is markedly enhanced by a low concentration of the chemical agent
TL;DR: Twelve isolates of zoosporic fungi belonging to four species (three isolates each) of the genus Saprolegnia were tested for progesterone biotransformation and found that S. hypogyna and S. parasitica have the capacity to perform oxidative splitting of the side chain of progester one with the formation of Δ4 androstene‐3,17 dione, testosterone and testololactone.
Abstract: Twelve isolates of zoosporic fungi belonging to four species (three isolates each) of the genus Saprolegnia were tested for progesterone biotransformation. The three isolates tested of each of S. hypogyna and S. parasitica have the capacity to perform oxidative splitting of the side chain of progesterone with the formation of Δ4 androstene-3,17 dione, testosterone and testololactone. All the isolates tested of S. diclina and S.furcata failed to transform progesterone molecule into another steroid derivative. The chromatographic resolution of the mixture products obtained when S. hypogyna (isolate No. 1008-2) had acted on one gram progesterone revealed the presence of 15 % unchanged progesterone, 25% Δ4-androstene-3,17-dione, 25% testosterone and 35% testololactone.
TL;DR: Signature nucleotides of X. japonicus were identified that distinguish it other members of the family Enterobacteriaceae.
Abstract: Phylogenetic relationships of Xenorhabdus spp. and Photorhabdus sp. were investigated on the basis of 16S rRNA gene sequences. Xenorhabdus spp. and Photorhabdus sp. were grouped together with Proteus vulgaris and Arsenophonus nasoniae. This group was distant from other members of the family Enterobacteriaceae. Xenorhabdus japonicus, previously proposed as a new species, was nearly located to Xenorhabdus nematophilus. Signature nucleotides of X. japonicus were identified that distinguish it other members of the family Enterobacteriaceae.
TL;DR: Maximum cellulase production in Aspergillus terreus was obtained at a temperature of 28 °C, pH 4.0 and a substrate concentration of 1% CMC andVariability in cellulase enzyme production and isozyme polymorphism of endo‐β‐1,4‐glucanase and β‐1‐4-glucosidase was studied in 45 natural isolates of A. ter reus.
Abstract: Maximum cellulase production in Aspergillus terreus was obtained at a temperature of 28 °C, pH 4.0 and a substrate concentration of 1% CMC. Variability in cellulase enzyme production and isozyme polymorphism of endo-β-1,4-glucanase and β-1,4-glucosidase was studied in 45 natural isolates of A. terreus. Different electrophoretic patterns were evident for endoglucanase. Three zones of activity viz EG 1, EG 11 and EG 111 were observed showing different electrophoretic mobilities. Some of the isolates exhibited the presence of null alleles for EG 1. During development EG 1 and EG 11 were observed throughout while EG 111 appeared on the eighth day. For β-1,4-glucosidase two zones of activity viz β-glu 1 and β-glu 11 were observed. β-glu 1 showed variable electrophoretic mobilities. β-glu 1 appeared throughout during development while β-glu 11 appeared on the twelfth day.
TL;DR: Three well characterised lignocellulose‐degrading actinomycetes, Streptomyces viridosporus, StrePTomyces badius and Thermomonospora mesophila were found to be the most efficient at decolorising Poly R, with a maximum decolorisation rate of 0.10 unit per day.
Abstract: The ability of a range of actinomycetes to decolorise the polymeric dye Poly R was investigated Three well characterised lignocellulose-degrading actinomycetes, Streptomyces viridosporus, Streptomyces badius and Thermomonospora mesophila were found to be the most efficient at decolorising Poly R, with a maximum decolorisation rate of 010 unit per day Extracellular fractions taken from S viridosporus grown on a variety lignocellulose-related substrates were also capable of decolorising Poly R, indicating that dye decolorisation was not merely due to biomass uptake The activity of extracellular fractions from straw-grown cultures of S viridosporus was three to six times greater than those from other substrates examined Purification of this dye-decolorising activity from S viridosporus using anion exchange chromatography revealed the presence of a single active fraction This was confirmed using gel permeation chromatography which estimated the molecular mass of the decolorising protein to be approximately 30000 Da
TL;DR: The microbiological status of chicken carcases sampled at three different processing points in a South African Grade B poultry abattoir slaughtering ca.
Abstract: The microbiological status of chicken carcases sampled at three different processing points in a South African Grade B poultry abattoir slaughtering ca 750 birds per hour, was determined Six skin samples and two meat samples were aseptically collected from different sites on each carcase Total bacterial counts were performed at 25 degrees C, 37 degrees C and 43 degrees C and all colonies from plates showing between 30 and 300 cfu were characterised Bacterial counts of the skin samples at 37 degrees C were consistently the highest, followed by those at 25 degrees C and then 43 degrees, but for the two meat samples the highest bacterial counts were found at 37 degrees C and the lowest at 25 degrees C Neck skin counts were marginally higher than bacterial counts of the other skin samples The Gram negative genera Escherichia and Acinetobacter were isolated most frequently at all three incubation temperatures and from all sampling sites, while the dominant Gram positive genera were Staphylococcus and Enterococcus Escherichia isolates predominated on the skin sampling site cranio-dorsal to the pygostyle, whilst Staphylococcus isolates predominated on the skin sampling site caudal to the breastbone Microbiological contamination is a major problem in the abattoir studied and further studies should therefore aim to determine points of maximum contamination in the processing line
TL;DR: Using a simple method of mycelium extraction with 0.1 Triton X‐100, it was possible to obtain about 4‐fold higher amounts of enzyme in the cell free extracts, than those excreted into the post‐culture liquid.
Abstract: Factors affecting the beta-galactosidase production by Penicillium notatum 1 were studied using fermentation media of different chemical composition. The medium containing lactose, salts, peptone and yeast extract with initial pH 2.5 was selected as the best for enzyme production. Monobasic ammonium phosphate (0.9%) was found to be the best inorganic nitrogen source for lactase production. Various extraction media and metabolic inhibitors were examined for effective releasing of beta-galactosidase from the fungal cells. Using a simple method of mycelium extraction with 0.1 Triton X-100, it was possible to obtain about 4-fold higher amounts of enzyme in the cell free extracts, than those excreted into the post-culture liquid.
TL;DR: Cassava wastes — the peel and the root fibre were taken through various pretreatment procedures before being subjected to solid state fermentation with Trichoderma harzianum, finding the best pretreatment found to be 1% NaOH at 120 °C gave the highest production of the Cx, the C1 and xylanase enzymes with the cassava root fibre.
Abstract: Cassava wastes--the peel and the root fibre were taken through various pretreatment procedures before being subjected to solid state fermentation with Trichoderma harzianum. Most of the pretreatment processes increased the cellulose and hemicellulose content of the cassava peel and fibre by as high as 155% while sulfuric acid treatment resulted in 25.3% loss in the peel hemicellulose. The best pretreatment found to be 1% NaOH at 120 degrees C gave the highest production of the Cx, the Cl and xylanase enzymes with the cassava root fibre. Xylanase and cellulase production with the exception of the Cx was found to be affected by age while an improved cassava variety TMS(2) 1425 peel and fibre rated highest in terms of production of the enzymes. Percentage hydrolysis within range of 56.52-67.64% were recorded for the enzymes on sorghum grains.
TL;DR: The most important moulds were: Cladosporium, Alternaria, Penicillium, Aspergillus and yeast, and the peak mould season was early January to early February.
Abstract: Daily mould counts were made using both exposed slides and Petri dishes, from January 1, 1994 to December 31, 1994 in Europe Quarter of Istanbul, Turkey. The most important moulds were: Cladosporium, Alternaria, Penicillium, Aspergillus and yeast. The peak mould season was early January to early February. Some moulds were present all year.
TL;DR: Systematic analysis of the relationship between the DNA content and the cell volume of Azotobacter vinelandii revealed that the cellVolume of the vegetative cells of A. v inelandii is in fact very similar to the cellvolume of E. coli.
Abstract: Previous experiments by other investigators on the DNA content of Azotobacter vinelandii have demonstrated that the DNA content in these cells is several folds higher than that of E. coli. On the basis of this observation, it was hypothesized that A. vinelandii has at least 40 to 80 identical chromosomes per cell. However, the gene dosage analysis in A. vinelandii cells suggested that many genetic operations can be performed in these cells without the constraints expected in a polyploid bacterium. In an attempt to explain this apparent discrepancy, we have done systematic analysis of the relationship between the DNA content and the cell volume of this bacterium. Since a linear correlation is observed between the DNA content and the cell size in many other cell types, we hypothesized that if A. vinelandii is polyploid in nature, it should have a much larger cell volume to accommodate such a large amount of DNA. Our scanning electron microscopic analysis revealed that the cell volume of the vegetative cells of A. vinelandii is about 16 times larger than the cell volume of E. coli. This result is apparently consistent with the concept that the A. vinelandii is a polyploid bacterium. It was also reported that the encysted cells of A. vinelandii contain about 25% of the DNA content of the vegetative cells. This would mean that an encysted cell of A. vinelandii could contain about 10 copies of its chromosome. Since the estimated molecular weight of A. vinelandii chromosome is very similar to that of E. coli chromosome, the DNA content of the encysted cells also should be about 10 times higher than that of E. coli cells. If we assume that the relationship between the DNA content and the cell size is linear, then the encysted cells should have a cell volume larger than that of E. coli and smaller than that of the vegetative cells of A. vinelandii. However our scanning electron microscopic analysis showed that the cell volume of the encysted cells of A. vinelandii is in fact very similar to the cell volume of E. coli.
TL;DR: Vancomycin, an inhibitor of peptidoglycan synthesis, depressed the growth of Mycobacterium sp.
Abstract: Vancomycin, an inhibitor of peptidoglycan synthesis, depressed the growth of Mycobacterium sp. NRRL B 3805 and MB 3683, but not the β-sitosterol side chain degradation and androstane derivatives accumulation. As a result, the specific activity (products formed/cell weight unit × h) increased threefold in the peptidoglycan-deficient cells, indicating faster crossing of the sterol through the cell water barrier.
Cell wall preparations: crude cell wall (CCW), purified cell wall (PCW), and peptidoglycan — enriched PCW — residue (PEPCW) were obtained and analysed in order to find a relationship between the vancomycin — induced chemical changes and the permeation rate of the sterol.
The amounts of CCW, PCW and PEPCW, produced from 8 g lyophilised control cells were 445, 170 and 28 mg respectively. The respective figures were 176, 61, and 4.8 mg for vancomycin — treated cells. In addition to the lower content of the rigid layer, a distinct shift in the molar ratios of the peptidoglycan constituents: alanine, glutamic, diaminopimelic and muramic acids, and glucosamine was observed under the action of the murein inhibitor. The most significant change was that of muramic acid: diaminopimelic acid molar ratio, the compounds which are markers of glycan strands and tetrapeptides, respectively. In control cells it was approximately 1:1, and increased to 1.34–1.43: 1 in the compared preparation, which indicated a marked decrease in the tetrapeptide moieties crosslinking the main glycan strands. Together with the general lower content of murein, this modification may be responsible for the enhanced sterol permeation through the cell wall.
TL;DR: Rarefaction analysis revealed that the bacterial community was more divergent at a polluted location than at clean areas, and the most common OTUs were different in clean locations compared to the polluted site suggesting that both diversity and species composition of theacterial community is greatly affected by pollution.
Abstract: (Received 12 Jutie 1999Accepted 20 November 1995) Diversity of culturable bacteria inhabiting the Baltic sea surface waters was studied in three separate locations. Based on electrophoretically separated whole cell proteins the number of operational taxonomic units (OTU) within each sampling location was high. Most of the OTUs were unique to single locations. Within each sampling location 8-22% of isolates belonged to a single OTU. Rarefaction analysis revealed that the bacterial community was more divergent at a polluted location than at clean areas. Also the most common OTUs were different in clean locations compared to the polluted site suggesting that both diversity and species composition of the bacterial community is greatly affected by pollution. The partial 16s rRNA gene sequences of the isolates of the most common OTUs are unique. lntragroup variation and an OTU-specific bacteriocin system was observed among the isolates of the second common OTU. The bacteriocin activity was linked to restriction fragment length polymorphism grouping, although additional variation correlating to geographic origin of isolates was observed. The metabolic activities camed out by bacterial communities are essential for life in biosphere. Culture independent methods like direct cloning and sequencing of rRNA genes and
TL;DR: An amylolytic yeast strain identified as Saccharomyces cerevisiae was isolated from yam tuber and heavy metal resistance study indicated different levels of resistance to copper, zinc, and manganese ions.
Abstract: An amylolytic yeast strain identified as Saccharomyces cerevisiae was isolated from yam tuber. Studies on the effect of physical agents such as pH and temperature on the activity of the amylase showed that the optimum pH and temperature for the amylase produced by the S. cerevisiae were 5.0 and 60 degrees C, respectively. Heavy metal resistance study on the amylolytic yeast strain indicated different levels of resistance to copper (6.0 mM), zinc (3.0 mM) and manganese (15.0 mM) ions. The results are discussed in relation to the potential use of an amylolytic yeast in the brewing industry in Nigeria.
TL;DR: The NADP‐specific glutamate dehydrogenase of a high β‐lactam producing industrial strain of Penicillium chrysogenum was purified to homogeneity and the N‐terminal sequence of the enzyme was found to be highly homologous to other fungal NADP-specific glutamate dehydration sequences.
Abstract: The NADP-specific glutamate dehydrogenase of a high beta-lactam producing industrial strain of Penicillium chrysogenum was purified to homogeneity. The enzyme (M(r) = 339,000 +/- 34,000) was demonstrated to have a homohexamer quaternary structure with a subunit molecular mass of M(r) = 56,000 +/- 2000. The N-terminal sequence of the enzyme was also determined and was found to be highly homologous to other fungal NADP-specific glutamate dehydrogenase sequences.
TL;DR: Incubation of phenol‐induced cells of the yeast Candida maltosa SBUG 700 with mono‐ and dichlorophenols resulted in the formation of metabolites of the substrate and of further metabolites not related to the degradation pathway of the substrates.
Abstract: Incubation of phenol-induced cells of the yeast Candida maltosa SBUG 700 with mono- and dichlorophenols resulted in the formation of metabolites of the substrates and of further metabolites not related to the degradation pathway of the substrates. These additional compounds, identified as 4-hydroxyphenylacetic acid (4-HPA), phenylacetic acid (PA), indolylacetic acid (IA) and indolylethanol (i.e.) by means of HPLC and GC/MS, were not excreted in incubation experiments with glucose. The excretion of these metabolites of aromatic amino acid metabolism is not caused by toxic effects of the phenol derivatives, but seems to be a result of carbon and nitrogen starvation of yeast cells.