- Volume 129, Issue 11, 1983
Volume 129, Issue 11, 1983
- Physiology And Growth
-
-
-
Reversion of Yeast Protoplasts in Media containing Polyethylene Glycol
A. Svoboda and D. PiedraLiquid medium supplemented with 35% (w/v) PEG supported regeneration of the cell wall in protoplasts of Saccharomyces cerevisiae. The regeneration was followed by reversion to normal cells. Both these morphogenetic processes were similar to those described previously in gelatin media. The frequency of reversion was estimated to be 20 to 30%. The regeneration medium with PEG also induced protoplast fusion. When complementary auxotrophs were used for fusion only the fused products proliferated, giving first regenerated protoplasts and then hybrid cells.
-
-
-
-
Effect of Chloramphenicol and Streptomycin on Developmental Stages of Phytophthom infestans
More LessChloramphenicol and streptomycin inhibited vegetative growth and sporulation of wild-type isolates of Phytophthora infestans (B.25, C1234, respectively) but not the corresponding resistant isolates (Cr, Sr), or a streptomycin-dependent mutant (Sd); in the latter streptomycin was stimulatory. Chloramphenicol inhibited zoospore release in B.25 and Cr but direct sporangial germination of Cr was reduced only at high concentrations. Streptomycin inhibited zoospore release and direct sporangial germination equally in wild-type and Sr. Chloramphenicol was fungistatic, whereas streptomycin was fungistatic or fungicidal, depending on its concentration and length of incubation with the fungus. Delayed addition of antibiotics to liquid cultures of the wild-type isolates reduced growth inhibition.
-
-
-
Zinc Uptake and Toxicity in the Yeasts Sporobolomyces roseus and Saccharomyces cerevisiae
More LessSporobolomyces roseus and Saccharomyces cerevisiae accumulated zinc from zinc-containing medium. Uptake was biphasic and consisted of an initial, rapid, metabolism-independent binding of zinc to cell surfaces which was followed by slower, metabolism-dependent intracellular uptake of zinc. Spor. roseus could bind approximately eight times more zinc, per unit surface area, than could S. cerevisiae. Metabolism-dependent zinc uptake followed Michaelis-Menten kinetics with K m values of 0·09 and 5·00 mm-Zn2+ for Spor. roseus and S. cerevisiae, respectively; corresponding V max values were 0·51 and 9·09 nmol Zn2+ (mg dry wt)−1 min−1. Zinc uptake by viable cells was not accompanied by potassium release in either yeast, but zinc levels which affected viability in S. cerevisiae caused this yeast to release K+. No efflux of K+ was observed for Spor. roseus despite its greater sensitivity to zinc.
-
-
-
Lipoperoxidation and Aflatoxin Biosynthesis by Aspergillus parasiticus and A. flavus
More LessThe amount of aflatoxin produced by Aspergillus flavus and Aspergillus parasiticus grown on various aged and non-aged seeds, kept at suitable conditions of temperature and moisture, is particularly related to the peroxide numbers of the seed oils. The addition of synthetic hydroperoxides to the cultures greatly increased aflatoxin production.
-
-
-
Yeast Water Relations: Physiological Changes Induced by Solute Stress in Saccharomyces cerevisiae and Saccharomyces rouxii
More LessA comparison was made of the xerotolerant yeast Saccharomyces rouxii and its non-tolerant counterpart S. cerevisiae when fully adapted to growth media of high and low water activity (a w), and during the period of adaptation from a high aw to a medium containing NaCl (10%, w/v). Comparisons of the fully adapted yeasts were confined to levels of activity of phosphofructo-kinase and sn-glycerol-3-phosphate dehydrogenase. The results confirmed our previous findings obtained with different assay procedures that growth at diminished a w dramatically increased the level of glycerol phosphate dehydrogenase in S. cerevisiae but had little or no effect in that respect on S. rouxii. Simultaneously phosphofructokinase activity was about doubled in S. cerevisiae and about halved in S. rouxii. Differences between the two yeasts were even more conspicuous during the period of response to salt stress. Saccharomyces rouxii apparently adapted fully to the salt broth within 6 h (at 30 °C) inasmuch as viability was unaffected by the transfer and glycerol content reached its maximum by then. On the other hand, S. cerevisiae took about 140 h to adapt by a process that could be resolved into two stages. Stage 1 was marked by a catastrophic drop in apparent viability and widely different counts on three plating media. Stage 2 was identified by similar counts on all three plating media and a progressive increase in viability up to the level of the original inoculum. Glycerol phosphate dehydrogenase activity increased during this stage but glycerol accumulation began in both species immediately after transfer. Throughout the entire adaptation period, S. cerevisiae consumed glucose much more slowly than did S. rouxii. The complexity of the response of S. cerevisiae to salt stress has focused attention on this species as a reference for studying yeast water relations in general.
-
-
-
Alginate Biosynthesis by Pseudomonas mendocina
More LessExopolysaccharide-synthesizing variants of Pseudomonas mendocina NCIB 10541 were isolated on media containing carbenicillin. The exopolysaccharide was identified as alginic acid with a mannuronic acid:guluronic acid ratio of 1:2. These strains lost the ability to produce alginate at a high frequency, but more stable mutants which produced increased amounts of polysaccharide could be isolated by subsequent mutagenesis. High concentrations of polysaccharide (approximately 20 g 1−1) were obtained in nitrogen-limited continuous culture with a minimal glucose medium. In common with other bacterial alginates, the polymer is acetylated and has similar rheological properties to alginate from brown algae. An alginate lyase activity was present in cultures at sufficient specific activities to result in a low molecular weight, low viscosity polymer with rheology similar to printing grade alginate. This degradation was overcome by incorporation of a proteolytic enzyme into the growth medium without adverse effects on bacterial or polysaccharide yields. As an organism for the study of alginate biosynthesis. P. mendocina possesses advantages over Azotobacter vinelandii or Pseudomonas aeruginosa in terms of yield, strain stability, and absence of known pathogenicity.
-
-
-
Nitrogen Fixation in Obligate Methanotrophs
More LessA number of representative species of obligate methane-oxidizing bacteria were surveyed for their ability to fix N2 by growth experiments and the acetylene reduction test. Although all strains exhibited growth on nitrogen-free plates, only type II organisms and the type X methanotroph Methylococcus capsulatus (Bath) grew well in nitrogen-free liquid medium and were capable of active acetylene reduction. N2-fixation in type II methanotrophs was less senstive to O2 than in the type X methanotroph Methylococcus capsulatus (Bath) and batch cultures of type II organisms could be established at pO2 values of up to 0·2 bar. N2-fixation in Methylococcus capsulatus (Bath) was inhibited at pO2 values above 0·15 bar and the ‘switch-off’ of nitrogenase activity by ammonia was also observed in this organism.
-
-
-
In vivo Studies of Primary Alcohols, Aldehydes and Carboxylic Acids as Electron Donors for the Methane Mono-oxygenase in a Variety of Methanotrophs
More LessC2 to C4 primary alcohols and their corresponding aldehydes were oxidized by type I, type II and type X obligate methanotrophs. Reducing equivalents from each oxidation step could be utilized, in vivo, to stimulate methane mono-oxygenase activity. As neither oxidation step produces NADH directly, these observations are presented as evidence for reverse electron transport in methanotrophs. In type II methanotrophs, 5 mm-acetate, propionate and butyrate also stimulate methane mono-oxygenase activity apparently by inducing the breakdown of poly-β-hydroxybutyrate. subsequent metabolism of β-hydroxybutyrate giving rise to NADH.
-
- Short Communication
-
-
-
Reclassification of Corynebacterium flaccumfaciens, Corynebacterium betae, Corynebacterium oortii and Corynebacterium poinsettiae in the genus Curtobacterium, as Curtobacterium flaccumfaciens comb. nov
More LessThe phytopathogens Corynebacterium flaccumfaciens (Hedges), Corynebacterium betae (Keyworth, Howell & Dowson), Corynebacterium oortii (Saaltink & Maas Geesteranus) and Corynebacterium poinsettiae (Starr & Pirone) differ to such an extent from the type species of Corynebacterium, Corynebacterium diphtheriae (Lehimann & Neumann), that they cannot be retained in this genus. On the basis of biochemical, chemical and genetic data it is proposed that Cor. flaccumfaciens. Cor. betae, Cor. oortii and Cor. poinsettiae be reclassified in the genus Curtobacterium (Yamada & Komagata), as Curtobacterium flaccumfaciens (Hedges) comb. nov.
-
-
- Taxonomy
-
-
-
Streptococcus garvieae sp. nov. and Streptococcus plantarum sp. nov
More LessBiochemical and chemotaxonomical studies were performed on some streptococci from frozen peas and bovine mastitis in an attempt to clarify their taxonomy. The results of the present and earlier studies indicate the pea and mastitis isolates represent two new species of the genus Streptococcus. The isolates from frozen peas are named Streptococcus plantarum sp. nov. and those from mastitis, Streptococcus garvieae sp. nov. The type strains are NCDO 1869 and NCDO 2155, respectively.
-
-
-
-
Molecular-genetic and Chemotaxonomic Studies on Actinomadura and Nocardiopsis
More LessThe relationships of 24 strains of 13 species of Actinomadura and 4 strains of Nocardiopsis dassonvillei were determined by nucleic acid hybridization studies. DNA-rRNA cistron similarity and DNA homology values reveal that Actinomadura is genetically heterogeneous. One cluster contained the type species Actinomadura madurae, Actinomadura pelletieri, Actinomadura verrucosospora, Actinomadura malachitica, Actinomadura citrea and Actinomadura kijaniata. A second cluster embraced Actinomadura pusilla, Actinomadura roseoviolacea, Actinomadura libanotica, Actinomadura roseola and Actinomadura ferruginea. The internal homogeneity of the two Actinomadura clusters was demonstrated by a high similarity in the m menaquinone and fatty acid composition of the strains enclosed. Actinomadura spadix, Actinomadura spiralis, and two strains of Actinomadura madurae were found to be unrelated to each other and could not be allocated to one of the two major Actinomadura clusters. Nocardiopsis dassonvillei was genetically and phenotypically clearly separated from all Actinomadura species investigated.
-
Volumes and issues
-
Volume 170 (2024)
-
Volume 169 (2023)
-
Volume 168 (2022)
-
Volume 167 (2021)
-
Volume 166 (2020)
-
Volume 165 (2019)
-
Volume 164 (2018)
-
Volume 163 (2017)
-
Volume 162 (2016)
-
Volume 161 (2015)
-
Volume 160 (2014)
-
Volume 159 (2013)
-
Volume 158 (2012)
-
Volume 157 (2011)
-
Volume 156 (2010)
-
Volume 155 (2009)
-
Volume 154 (2008)
-
Volume 153 (2007)
-
Volume 152 (2006)
-
Volume 151 (2005)
-
Volume 150 (2004)
-
Volume 149 (2003)
-
Volume 148 (2002)
-
Volume 147 (2001)
-
Volume 146 (2000)
-
Volume 145 (1999)
-
Volume 144 (1998)
-
Volume 143 (1997)
-
Volume 142 (1996)
-
Volume 141 (1995)
-
Volume 140 (1994)
-
Volume 139 (1993)
-
Volume 138 (1992)
-
Volume 137 (1991)
-
Volume 136 (1990)
-
Volume 135 (1989)
-
Volume 134 (1988)
-
Volume 133 (1987)
-
Volume 132 (1986)
-
Volume 131 (1985)
-
Volume 130 (1984)
-
Volume 129 (1983)
-
Volume 128 (1982)
-
Volume 127 (1981)
-
Volume 126 (1981)
-
Volume 125 (1981)
-
Volume 124 (1981)
-
Volume 123 (1981)
-
Volume 122 (1981)
-
Volume 121 (1980)
-
Volume 120 (1980)
-
Volume 119 (1980)
-
Volume 118 (1980)
-
Volume 117 (1980)
-
Volume 116 (1980)
-
Volume 115 (1979)
-
Volume 114 (1979)
-
Volume 113 (1979)
-
Volume 112 (1979)
-
Volume 111 (1979)
-
Volume 110 (1979)
-
Volume 109 (1978)
-
Volume 108 (1978)
-
Volume 107 (1978)
-
Volume 106 (1978)
-
Volume 105 (1978)
-
Volume 104 (1978)
-
Volume 103 (1977)
-
Volume 102 (1977)
-
Volume 101 (1977)
-
Volume 100 (1977)
-
Volume 99 (1977)
-
Volume 98 (1977)
-
Volume 97 (1976)
-
Volume 96 (1976)
-
Volume 95 (1976)
-
Volume 94 (1976)
-
Volume 93 (1976)
-
Volume 92 (1976)
-
Volume 91 (1975)
-
Volume 90 (1975)
-
Volume 89 (1975)
-
Volume 88 (1975)
-
Volume 87 (1975)
-
Volume 86 (1975)
-
Volume 85 (1974)
-
Volume 84 (1974)
-
Volume 83 (1974)
-
Volume 82 (1974)
-
Volume 81 (1974)
-
Volume 80 (1974)
-
Volume 79 (1973)
-
Volume 78 (1973)
-
Volume 77 (1973)
-
Volume 76 (1973)
-
Volume 75 (1973)
-
Volume 74 (1973)
-
Volume 73 (1972)
-
Volume 72 (1972)
-
Volume 71 (1972)
-
Volume 70 (1972)
-
Volume 69 (1971)
-
Volume 68 (1971)
-
Volume 67 (1971)
-
Volume 66 (1971)
-
Volume 65 (1971)
-
Volume 64 (1970)
-
Volume 63 (1970)
-
Volume 62 (1970)
-
Volume 61 (1970)
-
Volume 60 (1970)
-
Volume 59 (1969)
-
Volume 58 (1969)
-
Volume 57 (1969)
-
Volume 56 (1969)
-
Volume 55 (1969)
-
Volume 54 (1968)
-
Volume 53 (1968)
-
Volume 52 (1968)
-
Volume 51 (1968)
-
Volume 50 (1968)
-
Volume 49 (1967)
-
Volume 48 (1967)
-
Volume 47 (1967)
-
Volume 46 (1967)
-
Volume 45 (1966)
-
Volume 44 (1966)
-
Volume 43 (1966)
-
Volume 42 (1966)
-
Volume 41 (1965)
-
Volume 40 (1965)
-
Volume 39 (1965)
-
Volume 38 (1965)
-
Volume 37 (1964)
-
Volume 36 (1964)
-
Volume 35 (1964)
-
Volume 34 (1964)
-
Volume 33 (1963)
-
Volume 32 (1963)
-
Volume 31 (1963)
-
Volume 30 (1963)
-
Volume 29 (1962)
-
Volume 28 (1962)
-
Volume 27 (1962)
-
Volume 26 (1961)
-
Volume 25 (1961)
-
Volume 24 (1961)
-
Volume 23 (1960)
-
Volume 22 (1960)
-
Volume 21 (1959)
-
Volume 20 (1959)
-
Volume 19 (1958)
-
Volume 18 (1958)
-
Volume 17 (1957)
-
Volume 16 (1957)
-
Volume 15 (1956)
-
Volume 14 (1956)
-
Volume 13 (1955)
-
Volume 12 (1955)
-
Volume 11 (1954)
-
Volume 10 (1954)
-
Volume 9 (1953)
-
Volume 8 (1953)
-
Volume 7 (1952)
-
Volume 6 (1952)
-
Volume 5 (1951)
-
Volume 4 (1950)
-
Volume 3 (1949)
-
Volume 2 (1948)
-
Volume 1 (1947)