Deoxyribonucleic Acid Base Composition in Yeasts

The deoxyribonucleic acid base composition of 15 species of yeasts was determined to obtain further clues to or supporting evidence for their taxonomic position. Species examined belonged to the genera Saccharomyces, Debaryomyces, Lodderomyces, Metschnikowia, and Candida. The range of moles per cent guanine plus cytosine (GC content) for all yeasts examined extended from 34.9 to 48.3%. The sporogenous species and the asporogenous yeasts spanned the range with 36.6 to 48.3% GC and 34.9 to 48% GC, respectively. Three Saccharomyces species (S. rosei and related species) exhibited significantly higher GC contents than S. cerevisiae, whereas the fermentative species D. globosus revealed a%GC more aligned to the S. rosei group than to the nonfermentative D. hansenii. Similar GC contents were demonstrated by L. elongasporus and its proposed imperfect form C. parapsilosis. The range of GC contents of various strains of three Metschnikowia species studied was 6.1%, with the type strain of M. pulcherrima having the highest GC content (48.3%) of all of the yeasts examined.     

DNA Base composition of soil arthrobacters and other coryneforms from cheese and sea fish

The DNA base composition of 34 coryneforms isolated from different sources, and those of 20 named cultures of the generaArthrobacter, Brevibacterium,Mycobacterium, Corynebacterium andNocardia has been determined. A preliminary study of the morphological and physiological characteristics of the new isolates, and some named cultures, led to a division into three groups:

1. Soil coryneforms identified as arthrobacters, completed with theArthrobacter globiformis strains ATCC 8602 and 8010.
2. Orange coryneforms and one white isolate from cheese, and orange coryneforms including one yellow isolate from sea fish, completed with twoBrevibacterium linens strains ATCC 9174 and 9175.
3. Non-orange cheese coryneforms.

DNA base composition of group (1) ranges from 65.3 to 67.0 molar % GC, suggesting that this group is genetically homogeneous. % GC values of group (2) range from 62.6 to 64.0 except for one isolate (65.6), suggesting that this group is also homogeneous. DNA base composition of group (3) ranges from 65.5 to 66.9 % GC, except for three isolates (56.5, 60.1, 60.6). It is concluded that as far as their % GC is concerned, the strains of group (3), except the threem entioned ones, may be closely related to the arthrobacters of group (1). The strains of group (2) are probably less closely related to those of the groups (1) and (3).     

DNA base composition of planktonic species of Anabaena (Cyanobacteria) and its taxonomic value

Fifty axenic strains of planktonic Anabaena, including 24 strains of the straight form and 26 strains of the coiled form, were examined for their DNA base composition (GC content). The taxonomic value of their GC content at species level was evaluated by comparing their morphological, physiological and biochemical properties. The DNA base composition determined for all fifty strains ranged from 35.9 to 56.4 mol% GC. The straight-form strains were in the range of 35.9-56.4 mol% GC, while coiled forms were in the range of 38.1-50.3 mol% GC. In general, strains assigned to the same species showed similar DNA base composition. However, of three strains of A. affinis Lemmermann that were separated into two categories, two had 40.6-40.9 mol% GC, and the third strain 45.6 mol% GC. It is noteworthy that the DNA base composition of the newly established species A. eucompacta Li et Watanabe was 45.5 mol% GC, which differed from 39.5 mol% GC of the morphologically close species, A. compacta (Nygarrd) Hickel.     

Classification of the genus Humicola Traaen: II. The DNA base composition of some strains within the genus

The base composition of DNA (GC content) of 25 strains, morphologically referred to the genusHumicola Traaen, is studied. The range of GC% variation is about 23 % (from 28,5 % to 51,6). Two prominent groups of strains with similar GC content may be distinguished: one ranging from 28 % to 37 % and the other ranging from 40 % to 49 %. The aleuriospore size is not related to the DNA base composition, but a group of strains with prevalently coloured hyphae, with aleuriospores of similar size and with high GC content is recognized. Several previous literature reports on the taxonomy ofHumicola are discussed.     

Use of Lysostaphin in the Isolation of Highly Polymerized Deoxyribonucleic Acid and in the Taxonomy of Aerobic Micrococcaceae

By use of the staphylolytic enzyme lysostaphin, a method was devised for isolating and purifying highly polymerized deoxyribonucleic acid (DNA) from lysostaphinsusceptible Micrococcaceae. Staphylococcus aureus DNA isolated by this procedure gave an estimated molecular weight of ca. 2 x 10(8) and a residual protein content of 2.3%. The mole percentage of guanine + cytosine (GC) present in the DNA from 21 strains of aerobic Micrococceae was determined by buoyant density in cesium chloride. DNA from 12 biochemically typical members of the genus Staphylococcus gave a mean GC composition of 35.2 +/- 0.5 mole per cent. Four biochemically atypical Staphylococcus strains and one biochemically typical strain of the genus Micrococcus (M. candicans) were found to be susceptible to lysostaphin and gave typical Staphylococcus spp. GC base ratios. One biochemically atypical member of the genus Micrococcus (M. varians) was not susceptible to lysostaphin and gave a typical Micrococcus spp. GC base ratio. Lysostaphin susceptibility is an easy test to perform, and the results of this test appear to correlate with GC base ratio studies of the genera of Micrococcaceae.     

Restriction fragment fingerprint and genome sizes of Staphylococcus species using pulsed-field gel electrophoresis and infrequent cleaving enzymes.

Large restriction fragments of genomic DNA from Staphylococcus species were separated by pulsed-field gel electrophoresis (PFGE). Five different strains of S. aureus (ISP8, SAU3A, PS96, ATCC 6538, ATCC 15564) and three representative strains of S. haemolyticus SM102, S. warneri MCS4, S. cohnii LK478 from human hosts, and one strain of S. aureus (ATCC 8432) from an avian host were used in this study. Since Staphylococcus is A + T rich (approximately 67%), restriction fragments were obtained by digesting chromosomal DNA with endonucleases that recognize GC-rich sequences. Five enzymes Csp I, Sma I, Ecl XI, Ksp I, or Sac II were used for generation of few (7 to 16) distinctly separated fragments, with average sizes in the range of 200-300 kb. The size distribution of restriction fragments for each enzyme for each strain produced a strain-identifying fingerprint, and the genome size of each strain was determined from such restriction fragments separated by PFGE.     

Identification and discrimination of Staphylococcus aureus strains using matrix-assisted laser desorption/ionization-time of flight mass spectrometry

Staphylococcus aureus is an important human pathogen frequently resistant to a wide range of antibiotics. Methicillin-resistant S. aureus (MRSA) strains are common nosocomial pathogens that pose a world-wide problem. Rapid and accurate discrimination between methicillin-sensitive S. aureus (MSSA) and methicillin-resistant S. aureus is essential for appropriate therapeutic management and timely intervention for infection control. We report here the application of matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) for monitoring the bacterial fingerprints expressed by two well characterized S. aureus strains ATCC 29213 (MSSA) and ATCC 43330 (MRSA). Consistent strain-specific data were obtained from subcultures analyzed over a period of three months as well as after changing the growth media from Mueller-Hinton to blood agar indicating the reliability of the method. The bacterial fingerprints of these two strains were compared to independent clinical isolates of S. aureus. A uniform signature profile for MRSA could not be identified. However, the bacterial fingerprints obtained proved to be specific for any given strain. This study demonstrates that MALDI-TOF MS is a powerful method for rapid identification of clonal strains of S. aureus, which might be useful for tracking nosocomial outbreaks of MRSA and for epidemiologic studies of infections diseases in general.     

Antibacterial activity of crude methanolic extract and its fractions of aerial parts of Anthemis tinctoria

The antibacterial activity of the methanolic extract and its fractions of aerial parts of Aniheinis tinctoria (Asteraceae) was investigated against representative gram-positive Staphylococcus aureus (ATCC 25923) and Enterococcus faecalis (ATCC 29212) and gram-negative strains Escherichia coli (ATCC 25922) and Pseudomonas aeruginosa (ATCC 27853). The activity was concentrated mainly in the dichloromethane (DCM) and hexane fractions of crude methanolic extract. The 5 mg of DCM extract per disk produced 15-16 mm of inhibition zone against S. aureus and P. aeruginosa, however, no activity was found against E. faecalis and E. coli. The hexane fraction showed activity against S. aureus, P. aeruginosa and E. faecalis. As DCM fraction showed the highest antibacterial activity in the disk diffusion assay, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of only this fraction was determined against S. aureus and P. aeruginosa. These values were found to be in the range of 1.25 to 10 mg/ml.     

DNA base composition and taxonomy of someAcinetobacter strains

The DNA base composition of a group of numerically analyzed acinetobacters was determined. Seven strains ofAcinetobacter anitratus appear to form a homogeneous group with S>90% and ca. 42.1 % GC.A. Iwoffii is less homogeneous. Most of the strains have around 46.6 % GC and a broad compositional distribution with 2=3.8 C. Two other small groups have a % GC of 44.8±0.3 and 42.1±1 % GC. The DNA characteristics of the latter group are indistinguishable fromA. anitratus-DNA. ThreeAlcaligenes faecalis strains have 58.8 % GC. Numerical analysis suggests that they might be related toBordetella bronchiseptica, but the % GC of the latter (69.5) shows that the relationship is only remote.     

两株新的金黄色葡萄球菌烈性噬菌体的生物学特性和基因组学研究

以金黄色葡萄球菌为宿主菌,从奶牛场废水样品中分离到两株烈性噬菌体,分别命名为phiSA_BS1和phiSA_BS2。电子显微镜观察显示其头部呈多面体对称,有伸缩性尾部。对这两株噬菌体的一步生长曲线、温度耐受性和pH耐受性进行研究,发现两者均裂解3株金黄色葡萄球菌,但不能裂解1株表皮葡萄球菌。进一步分析它们的全基因组序列,发现phiSA_BS1基因组大小为 142 978 bp,GC含量为 29.80%,预测到201个开放读码框(open reading frame,ORF),未预测到tRNA基因;phiSA_BS2基因组大小为 149 230 bp,GC含量为 29.61%,预测到210个ORF和1个tRNA基因。系统发育分析表明,这两株噬菌体同属肌尾噬菌体科,属于新的金黄色葡萄球菌噬菌体,可能为治疗金黄色葡萄球菌相关的奶牛乳腺炎提供新的方法。     

Deoxyribonucleic acid base composition of some micrococci and sarcinae

The strains designated in this paper asMicrococcus lysodeikticus, M. sodonensis, M. flavus, Sarcina flava, S. pelagia, S. variabilis, S. marginata, S. subflava, S. citrea, S. lutea andStaphylococcus afermentans have similar DNA base compositions. The mole % GC (guanine plus cytosine) contents in DNA of these strains ranged from 71.8 to 73.3 as calculated from the denaturation temperature (Tm). They may be, therefore, closely related. However, at variance with Kocur and Martinec (1962) they do not seem to be identical withMicrococcus luteus (Schroeter 1872) Cohn 1872, because the neotype culture of the latter species has a different content of guanine and cytosine in its DNA (GC=66.3%). Sarcina aurantiaca, Micrococcus dentrificans andM. luteus have a similar DNA base composition. However, they are not identical as they differ from each other in several physiological characters. In the strains designated asStaphylococcus roseus andSarcina erythromyxa the content of GC varies within the range 72–72.8%. These species do not differ from each other physiologically. They form a pink pigment, reduce nitrates, do not hydrolyze casein and gelatin, and do not produce urease. They seem, therefore, to be identical, which confirms the conclusion of Kocur and Martinec (1962) who designated them asMicrococcus roseus Flügge 1886. Micrococcus conglomeratus differs significantly in DNA base composition from almost all strains of the groupM. lysodeikticus—Staphylococcus afermentans, also fromMicrococcus luteus, M. roseus andM. denitrificans. It differs fromSarcina aurantiaca only physiologically.     

In vitro effect of some Indian honeys on Staphylococcus aureus from wounds

Staphylococcus aureus is the most frequently isolated pathogen from wounds with multiple resistances to antibiotics. Honey has been demonstrated and reported to be effective antibacterial agent on Gram positive and Gram negative organisms. Hence, the present study was conducted to evaluate the in vitro antibacterial effect of Indian honeys on Staphylococcus aureus obtained from wounds. A total of 123 Staphylococcus aureus isolates along with ATCC 25923 were categorized as sensitive, multi drug resistant (MDR) and non-MDR strains. Out of total nine Indian honeys (three each of unifloral, multifloral and branded marketed honey) used, three unifloral and three multifloral honey samples showed antibacterial activity against all the organisms tested by Agar diffusion method but not the branded marketed honeys. The MIC values of all honey samples for all studied Staphylococcus aureus isolates ranged between 5-15% (v/v). Unifloral honey samples showed higher antibacterial activity than multifloral honey. The single sample of Jambhul honey showed the highest activity. Thus, Indian honeys were found to be effective for their antimicrobial activity on sensitive, non-MDR, MDR and ATCC strains of S. aureus.     

Neutrophil-stimulating activity of staphylococci based on reactive chemiluminescence data

The neutrophil-stimulating properties of 38 S. aureus strains and 32 S. epidermidis strains were studied in the reaction of luminol-mediated chemiluminescence. All S. aureus strains and 29 S. epidermidis strains were found to possess neutrophil-stimulating activity, the mean activity index for S. aureus being significantly higher. The stimulating activity of the strains varied within a wide range (the variation coefficient was 120.0 +/- 21.9%) and did not correlate with the content of protein A in bacterial cells and the degree of their hydrophoby. The opsonization of staphylococci with normal human serum enhanced the neutrophil reaction 1.5- to 100-fold and simultaneously leveled out the chemiluminescence indices in experiments with different strains (the variation coefficient was 8.0 +/- 1.5%). The nature of the neutrophil-stimulating effect of staphylococci and its relationship to the exploratory reactions of phagocytes are discussed.     

Deoxyribonucleic Acid Base Composition of Species in the Yeast Genus Kluyveromyces van der Walt emend. van der Walt

The deoxyribonucleic acid base composition (percent guanine + cytosine [GC]) was determined for 29 strains, representing 18 species of the genus Kluyveromyces. It was concluded that on the basis of GC content (47.4%) and other properties K. veronae occupies an uncertain position in the genus Kluyveromyces. The GC content of the remaining 17 species ranged from 35.3 to 43.4%, and three groups of species were recognized. The GC content of the first ranged from 35.3 to 38.0%; that of the second group from 39.5 to 41.7%; that of the third group from 42.4 to 43.4%. Several species revealed a nearly identical GC content. The GC contents do not correspond in all instances with the five groups of species proposed by van der Walt.     

The DNA of CAENORHABDITIS ELEGANS

Chemical analysis and a study of renaturation kinetics show that the nematode, Caenorhabditis elegans, has a haploid DNA content of 8 x 10(7) base pairs (20 times the genome of E. coli). Eighty-three percent of the DNA sequences are unique. The mean base composition is 36% GC; a small component, containing the rRNA cistrons, has a base composition of 51% GC. The haploid genome contains about 300 genes for 4S RNA, 110 for 5S RNA, and 55 for (18 + 28)S RNA.     

Cutinase production byStreptomyces spp.

Forty-fiveStreptomyces strains, including representatives of the plant pathogensS. acidiscabies, S. scabies, andS. ipomoea, were screened for ability to produce enzymes (cutinases) capable of hydrolyzing the insoluble plant biopolyester cutin. Initially, all strains were tested for production of extracellular esterase in liquid shake (250 rpm) cultures at room temperature in defined (glycerol-asparagine) or complex (tryptone-yeast extract with or without addition of mannitol) broth media supplemented with either tomato or apple cutin. Esterase activity was determined by a spectrophotometric assay utilizing the model substratep-nitrophenyl butyrate. Of the five strains exhibiting highest esterase activity, four (S. acidiscabies ATCC 49003,S. scabies ATCC 15485 and IMRU 3018, andS. badius ATCC 19888) were confirmed to produce enzymes with cutin-degrading activity (cutinases). Confirmation of extracellular cutinase production was accomplished by use of a new high-performance liquid chromatography method for separation and quantification of released cutin monomers. Monomer identification was confirmed by GC/MS analyses. Cutinase production was induced 2- to 17-fold by inclusion of cutin in the media. To our knowledge this constitutes the first report of cutinase production byStreptomyces spp. other thanS. scabies.Reference to any brand or firm name does not constitute endorsement by the U.S. Department of Agriculture over others of a similar nature not mentioned.     

In vitro propagation and chemical and biological studies of the essential oil of Salvia przewalskii Maxim

The procedure of Salvia przewalskii shoot multiplication and the ability of regenerated plants to produce essential oil is reported. The essential oil was obtained by hydrodistillation from leaves and flowering stems of field-grown plants, and their chemical composition was examined by GC, GC-MS and 1H NMR. The differences in yield as well as qualitative and quantitative composition between the oils isolated from in vitro and in vivo plants were observed. S. przewalskii essential oil was tested for its antimicrobial and cytotoxic properties. It was found that cytotoxicity against human leukemia HL-60 cells and antimicrobial activity (especially, against Staphylococcus aureus and S. epidermidis strains) of oils isolated from in vitro plants were higher than those for oils from in vivo S. przewalskii plants.     

Studies on antimicrobial activity, in vitro, of Physalis angulata L. (Solanaceae) fraction and physalin B bringing out the importance of assay determination

Complex physalin metabolites present in the capsules of the fruit of Physalis angulata L. have been isolated and submitted to a series of assays of antimicrobial activity against Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 29213, S. aureus ATCC 25923, S. aureus ATCC 6538P, Neisseria gonorrhoeae ATCC 49226, Escherichia coli ATCC 8739; E. coli ATCC 25922, Candida albicans ATCC 10231 applying different methodologies such as: bioautography, dilution broth, dilution agar, and agar diffusion techniques. A mixture of physalins (pool) containing physalins B, D, F, G inhibit S. aureus ATCC 29213, S. aureus ATCC 25923, S. aureus ATCC 6538P, and N. gonorrhoeae ATCC 49226 at a concentration of 200 mg/microl, using agar dilution assays. The mixture was inactive against P. aeruginosa ATCC27853, E. coli ATCC 8739; E. coli ATCC 25922, C. albicans ATCC 10231 when applying bioautography assays. Physalin B (200 microg/ml) by the agar diffusion assay inhibited S. aureus ATCC 6538P by +/- 85%; and may be considered responsible for the antimicrobial activity.     

Physiologische und biochemische Beiträge zur Taxonomie der Gattungen Ankistrodesmus und Scenedesmus

The base composition of the DNA was found to be a species-specific, taxonomically valuable character also in the genera Ankistrodesmus (21 strains) and Scenedesmus (27 strains). As compared to the genus Chlorella, however, the differences between different species are considerably smaller. The GC content is between 63 and 70% in the genus Ankistrodesmus, and between 52 and 62% in the genus Scenedesmus. Obviously, a few strains with a very much different base composition do not belong to the genus Ankistrodesmus.     

The quick approximation of DNA base composition from absorbancy ratios

The approximate base composition of pure deoxyribonucleic acid (DNA) can be quickly estimated from the absorbancy ratio E₂₆₀/E₂₈₀ in 0.1n acetic acid according to the empirical relation % GC=168.6–87.4 (E₂₆₀/E₂₈₀), valid in the range 40 to 70% GC (molar per cent guanine ... cytosine). The method is only accurate to within + 3% GC. It can be used when a quick, rough estimate of DNA base composition is required, e.g., to check the correct taxonomic position of new isolates or to give an approximation of the melting point T_m or buoyant density of an unknown DNA sample. The method can not be recommended for distinguishing between two genera with closely related % GC values, or for finer distinction within one genus.