Haploid recombinants formed as sectors in the intraspecific fusants of Aspergillus niger producing citric acid

Protoplasts of nutritionally complementary strains of Aspergillus niger producing citric acid were treated in a polyethylene glycol solution, plated onto hypertonic minimal medium and the intraspecific fusants were obtained. When transferred and cultivated on minimal medium, almost all fo the fusants continued to grow as heterokaryons. However, some fusant colonies formed sectors of the prototrophic strains (sector strains). Most of these sector strains were haploid recombinants and their properties were genetically stable when subcultivated on both minimal and supplemented media. With respect of morphological features and citric acid productivity, the recombinant strains were like either of the parental strains or an intermediate between both parental strains. The rest of the sector strains that were nonconidiation typw seemed to be haploid recombinants, although they stopped growing on the third subcultivation on both the minimal and supplemented media.     

The isolation of fumB mutants of Escherichia coli

Escherichia coli strains lacking the terminus region of the chromosome (min 29-36) due to an IS10-promoted deletion did not grow well in rich medium; they also did not grow on fumarate minimal medium because fumAC (min 35.7) is deleted. Strains with secondary mutations that partially suppress the deletion phenotype displayed healthier growth on rich medium and grew on minimal fumarate medium. These suppressor mutants had an IS10 insertion just upstream of the fumB structural gene (min 93.4). A strain with a Tn10 insertion at this location was constructed and used to delete nonessential fumB; fumB deletion mutants grew well on both rich and minimal fumarate media.     

Characterization of AAT1: a gene involved in the regulation of amino acid transport in Saccharomyces cerevisiae

A new class of Saccharomyces cerevisiae mutants (aat1 - amino acid transport) has been identified. These mutants are unable to grow on rich medium or on minimal medium supplemented with certain amino acids (isoleucine, methionine, phenylalanine, tyrosine or valine). This phenotype is directly linked to the presence of the leu2 allele in these strains: aat1 LEU2 organisms grow normally on all media tested. Leucine uptake through the leucine-specific permease is inhibited to less than 35% of wild-type levels in aat1 cells preincubated in nonpermissive media, and the activity of the general amino acid permease is also low in these conditions. aat1 cells are therefore unable to grow on rich media because they cannot take up enough leucine to supplement their auxotrophic requirement.     

Glycine dependence of Staphylococcus aureus strains]

Glycine dependent Staphylococcus aureus var. bovis strains (TSCHAPE and RISCHE 1971) were tested for their ability to grow on glycine containing and glycine deprived media. We observed glycine dependence only in minimal media. In complete media the strains grew in absence of glycine. Testing the ability of some glycine precursors we found that in minimal media glycine could be replaced by threonine and in some cases by serine. One mutant (Gly 100 Glyox.r.) was able to metabolize glyoxylate instead of glycine. Aspartic acid was metabolized in presence of glycine. Using 14C-aspartic acid we detected 14C-glycine and 14C-threonine. Presumably the bacteria metabolize aspartic acid to glycine via threonine.     

Chemically defined media for the cultivation of Naegleria: pathogenic and high temperature tolerant species

Chemically defined minimal media for the cultivation of high temperature tolerant and pathogenic Naegleria spp. have been developed. A defined minimal medium, identical for N. fowleri and N. lovaniensis, consists of eleven amino acids (arginine, glycine, histidine, isoleucine, leucine, methionine, phenylalanine, proline, threonine, tryptophan, and valine), six vitamins (biotin, folic acid, hemin, pyridoxal, riboflavin, and thiamine), guanosine, glucose, salts, and metals. Three of the four strains of Naegleria fowleri tested (ATCC 30100, ATCC 30863, and ATCC 30896) and two strains of N. lovaniensis (ATCC 30467 and ATCC 30569) could be cultured beyond ten subcultures on this medium. For N. fowleri ATCC 30894 diaminopimelic acid, or lysine, or glutamic acid was also required. Mean generation time was reduced and population density increased for all strains with the introduction of glutamic acid. Glucose could be eliminated from the minimal medium only if glutamic acid was present. Without glucose, mean generation time increased and population density decreased. Diaminopimelic acid could substitute for lysin for ATCC 30894, indicating that Naegleria species may synthesize their lysine via the DAP pathway. Naegleria fowleri ATCC 30100 could be adapted to grow without serine or glycine in the minimal medium with glutamic acid added, but with mean generation time increased and population density decreased. The strain could be grown in the minimal medium in the absence of metals. For growth of N. australiensis ATCC 30958, modification of the medium by increasing metals ten-fold, substituting guanine for guanosine and adding lysine, glutamic acid, and six vitamins (p-aminobenzoic acid, choline chloride, inositol, vitamin B12, nicotinamide, and Ca pantothenate) was required.     

NUTRITIONAL REQUIREMENTS OF ACETOBACTER SPECIES: INORGANIC AMMONIUM SALTS AS SOURCES OF NITROGEN

SUMMARY: Forty-six strains of Acetobacter , representing twenty species, have been compared on the basis of their respective abilities to proliferate in two defined inorganic media, in which either glucose or ethanol was the sole source of carbon and energy. Twenty-three strains, representing eleven species, grew in either inorganic medium when glucose was present and nine of these strains, representing five species, could grow also in either inorganic medium when ethanol was present. The remaining twenty-three strains, representing eleven species, failed to grow in either medium with either glucose or ethanol. Three organisms grew better with ethanol than with glucose and three were inhibited by ethanol in the presence of glucose.     

Sinorhizobium meliloti cells require biotin and either cobalt or methionine for growth

Sinorhizobium meliloti is usually cultured in rich media containing yeast extract. It has been suggested that some components of yeast extract are also required for growth in minimal medium. We tested 27 strains of this bacterium and found that none were able to grow in minimal medium when methods to limit carryover of yeast extract were used during inoculation. By fractionation of yeast extract, two required growth factors were identified. Biotin was found to be absolutely required for growth, whereas previously the need for this vitamin was considered to be strain specific. All strains also required supplementation with cobalt or methionine, consistent with the requirement for a vitamin B(12)-dependent homocysteine methyltransferase for methionine biosynthesis.     

Standard YPD, even supplemented with extra nutrients, does not always compensate growth defects of Saccharomyces cerevisiae auxotrophic strains

Conventional complex media are routinely used to grow auxotrophic strains under the assumption that they can compensate the latter's nutritional deficiencies. We here demonstrate that this is not always true. This study compares the growth parameters of Saccharomyces cerevisiae (S288C) and its derived auxotrophic strains FY1679-14C and BY4741 in synthetic minimal medium (SD), standard YPD medium from two of the most commonly used suppliers, or modified YPD medium. Maximum specific growth rates of auxotrophic strains were slightly lower than the prototrophic case in all growth conditions tested. Also, the biomass production of auxotrophic strains in synthetic medium was slightly less than the prototrophic case. However in both of the two standard YPD media used, the biomass production of both auxotrophic strains was markedly lower than that of the prototrophic one. The extent of the differences depended on the medium used. Indeed in one of the two YPD media, the lower biomass production of auxotrophic strains was evident even at the diauxic shift. Uracil seems to be the main limiting growth factor for both auxotrophic strains growing in the two standard YPD medium tested. No YPD media or specific supplement was able to compensate for the effect of the auxotrophic mutations in the multiple auxotrophic marker strain BY4741. The fact that auxotrophic strains grew poorly on YPD when compared to their prototrophic counterpart indicates that standard YPD medium is not sufficient to overcome the effect of auxotrophic mutations.     

Avirulent isolates of Corynebacterium fascians that are unable to utilize agmatine and proline.

Growth of a highly virulent strain of the phytopathogen Corynebacterium fascians on rich media at 37 degrees C resulted in a loss of virulence in a majority of the population within 10 generations. Strains retained virulence during cultivation at 30 degrees C on a minimal medium with ammonia as a nitrogen source. Populations of avirulent strains on the surfaces of pea seedlings decreased, whereas the number of cells of the virulent strain increased 1,000-fold during a 3-week period. All avirulent mutants isolated by growth on rich media at 37 degrees C were unable to grow on media containing agmatine or proline as sole sources of nitrogen. The ability of the mutants to grow on pea seedlings and cause fasciation disease appeared to be related to their ability to utilize nitrogen sources available on plant surfaces.     

Avirulent isolates of Corynebacterium fascians that are unable to utilize agmatine and proline

Growth of a highly virulent strain of the phytopathogen Corynebacterium fascians on rich media at 37 degrees C resulted in a loss of virulence in a majority of the population within 10 generations. Strains retained virulence during cultivation at 30 degrees C on a minimal medium with ammonia as a nitrogen source. Populations of avirulent strains on the surfaces of pea seedlings decreased, whereas the number of cells of the virulent strain increased 1,000-fold during a 3-week period. All avirulent mutants isolated by growth on rich media at 37 degrees C were unable to grow on media containing agmatine or proline as sole sources of nitrogen. The ability of the mutants to grow on pea seedlings and cause fasciation disease appeared to be related to their ability to utilize nitrogen sources available on plant surfaces.     

Two chemically defined media for the growth of Acholeplasma laidlawii strain A

A total of 11 tissue culture media and one synthetic medium were screened to determine whether they could support the growth of two strains of Acholeplasma. Two similar chemically defined media were found in which Acholeplasma laidlawii Strain A (Buchanan & Gibbons 1974) could grow. This is the first report of a fully defined medium for the growth of this organism (Greenaway 1981).     

Sinorhizobium meliloti Cells Require Biotin and either Cobalt or Methionine for Growth

Sinorhizobium meliloti is usually cultured in rich media containing yeast extract. It has been suggested that some components of yeast extract are also required for growth in minimal medium. We tested 27 strains of this bacterium and found that none were able to grow in minimal medium when methods to limit carryover of yeast extract were used during inoculation. By fractionation of yeast extract, two required growth factors were identified. Biotin was found to be absolutely required for growth, whereas previously the need for this vitamin was considered to be strain specific. All strains also required supplementation with cobalt or methionine, consistent with the requirement for a vitamin B₁₂-dependent homocysteine methyltransferase for methionine biosynthesis.     

Isolation and Characterization of Glycerol-3-Phosphate Dehydrogenase-Defective Mutants of Neurospora crassa

Three glycerol-nonutilizing mutants deficient in the mitochondrial glycerol-3-phosphate (G3P) dehydrogenase (EC 1.1.99.5) were isolated from inl(ts) derivatives of Neurospora crassa following inositolless death at elevated temperatures on minimal glycerol medium. These mutants failed to grow on glycerol as a sole carbon source, but could grow on acetate, glucose, or mannitol media and were female fertile in genetic crosses, thereby distinguishing them from the previously reported polyol-protoperithecial defective Neurospora mutants. In addition, these glp mutants exhibited a distinct morphological alteration during vegetative growth on sucrose slants and colonial growth on sorbose-containing semicomplete medium. The glp-2 locus was assigned a location between arg-5 and nuc-2 on chromosome IIR on the basis of two-factor crosses and by duplication coverage by insertional translocation ALS176, but not NM177. All mutations were allelic as judged from the absence of both complementation in forced heterokaryons and genetic recombination among glp-2 mutations. The reversion frequency of all three mutations was less than 10(10), indicating probable deletions in these strains. No G3P dehydrogenase activity could be detected in either cytosolic or mitochondrial extracts from mutant strains grown on glycerol, glucose, or galactose media. These results suggest that the glp-2 locus may be the structural gene for both the cytosolic and mitochondrial forms of G3P dehydrogenase or for a cytosolic precursor of the mitochondrial G3P dehydrogenase. The defect is specific for the G3P dehydrogenase since normal activities of the mitochondrial cytochrome oxidase and succinate dehydrogenase and the cytosolic glycerol dehydrogenase and dihydroxyacetone phosphate reductase are detected in mutant extracts. During attempted growth of glp-2 mutants on glycerol media, there was an accumulation of G3P in culture filtrates, a reduction in the mycelial growth rate, and a decreased level of glycerokinase induction.     

Chemically Defined Media for the Cultivation of Naegleria: Pathogenic and High Temperature Tolerant Species

Chemically defined minimal media for the cultivation of high temperature tolerant and pathogenic Naegleria spp. have been developed. A defined minimal medium, identical for N. fowleri and N. lovaniensis, consists of eleven amino acids (arginine, glycine, histidine, isoleucine, leucine, methionine, phenylalanine, proline, threonine, tryptophan, and valine), six vitamins (biotin, folic acid, hemin, pyridoxal, riboflavin, and thiamine), guanosine, glucose, salts, and metals. Three of the four strains of Naegleria fowleri tested (ATCCr?30100, ATCCr?30863, and ATCCr?30896) and two strains of N. lovaniensis (ATCCr?30467 and ATCCr?30569) could be cultured beyond ten subcultures on this medium. For N. fowleri ATCCr?30894 diaminopimelic acid, or lysine, or glutamic acid was also required. Mean generation time was reduced and population density increased for all strains with the introduction of glutamic acid. Glucose could be eliminated from the minimal medium only if glutamic acid was present. Without glucose, mean generation time increased and population density decreased. Diaminopimelic acid could substitute for lysine for ATCCr?30894, indicating that Naegleria species may synthesize their lysine via the DAP pathway. Naegleria fowleri ATCCr?30100 could be adapted to grow without serine or glycine in the minimal medium with glutamic acid added, but with mean generation time increased and population density decreased. The strain could be grown in the minimal medium in the absence of metals. For growth of N. australiensis ATCCr?30958, modification of the medium by increasing metals ten-fold, substituting guanine for guanosine and adding lysine, glutamic acid, and six vitamins (p-aminobenzoic acid, choline chloride, inositol, vitamin B₁₂, nicotinamide, and Ca pantothenate) was required.     

Bacteria--degraders of polycyclic aromatic hydrocarbons, isolated from soil and bottom sediments in salt-mining areas

Fifteen bacterial strains capable of utilizing naphthalene, phenanthrene, and biphenyl as the sole sources of carbon and energy were isolated from soils and bottom sediments contaminated with waste products generated by chemical and salt producing plants. Based on cultural, morphological, and chemotaxonomic characteristics, ten of these strains were identified as belonging to the genera Rhodococcus, Arthrobacter, Bacillus, and Pseudomonas. All ten strains were found to be halotolerant bacteria capable of growing in nutrient-rich media at NaCl concentrations of 1-1.5 M. With naphthalene as the sole source of carbon and energy, the strains could grow in a mineral medium with 1 M NaCl. Apart from being able to grow on naphthalene, six of the ten strains were able to grow on phenanthrene; three strains, on biphenyl; three strains, on octane; and one strain, on phenol. All of the strains were plasmid-bearing. The plasmids of the Pseudomonas sp. strains SN11, SN101, and G51 are conjugative, contain genes responsible for the degradation of naphthalene and salicylate, and are characterized by the same restriction fragment maps. The transconjugants that gained the plasmid from strain SN11 acquired the ability to grow at elevated NaCl concentrations. Microbial associations isolated from the same samples were able to grow at a NaCl concentration of 2.5 M.     

酸性和碱性土壤新分离的放线菌中线型和环型质粒的检测

从湖南、云南采集的19份酸性土壤样品分离到50株放线菌,在pH4.5和pH7.0的培养基上都能生长.从新疆、青海、云南的14份碱性土壤样品中分离到38株放线菌,在pH10.0和pH7.0的培养基上均能生长.因此,这些菌株属于中度嗜酸或中度嗜碱放线菌.利用脉冲电泳技术和普通凝胶电泳在其中12株放线菌中检测到线型质粒,其中3株放线菌中检测到环型质粒.这是首次在中度嗜酸和中度嗜碱的放线菌中报道线型和环型质粒.     

Mutants of Escherichia coli with High Minimal Temperatures of Growth.

O'Donovan, Gerard A. (University of California, Davis), Catherine L. Kearney, and John L. Ingraham. Mutants of Escherichia coli with high minimal temperatures of growth. J. Bacteriol. 90:611-616. 1965.-Three general classes of mutants showing increased minimal temperatures of growth have been isolated from Escherichia coli. These mutants do not grow at temperatures below 20 C, although their parents can grow at temperatures as low as 8 C. The first class of mutants (K-I) cannot grow below 20 C in either complex or minimal medium, but grows at nearly normal rates at 37 C on both types of media. Normal growth rate at 20 C can be conferred on these mutants by infection at a low multiplicity with a transducing phage grown on the parent. The second class of mutants (K-II) fails to grow only in minimal medium at 20 C. These mutants are characterized by their singular response to specific nutrients in minimal medium at 20 C. The third class of mutants (K-III) grows normally in minimal medium at all temperatures with either glucose or glycerol as the carbon source, but does not grow at 20 C with lactose as the carbon source.     

Sporulation of Clostridium acetobutylicum P262 in a Defined Medium

A defined minimal sporulation medium for Clostridium acetobutylicum P262, which produces high levels of solvents, is described. The overall sporulation sequence was similar to that of other endospore-forming bacteria. However, we observed a presporulation stage, during which swollen phase-bright cells which contained large amounts of granulose formed. During sporulation, the initiation of spore coat formation occurred before the onset of cortex formation. Other Clostridium strains tested showed marked variations in ability to grow and sporulate in various minimal media.     

Differentiation of Candida stellatoidea from C. albicans and C. tropicalis by temperature-dependent growth responses on defined media

C. stellatoidea differs from both C. albicans and C. tropicalis in its i) much greater growth differential on minimal and amino acid enriched media and ii) unique inability to grow on minimal medium containing glycerol as carbon source at 37C. The relative responses to amino acid enrichment occur on media containing either fermentative or oxidative carbon sources, at 25C or 37C. Under any given conditions of carbon source and temperature, different assortments of individual amino acids are stimulatory for each of the three species. All assortments include one or more members of the glutamic acid family. However, sulfur amino acids stimulate only C. stellatoidea on all three carbon sources. On minimal-glycerol medium, wild type strains of C. stellatoidea grow prototrophically at 25C but are auxotrophic for amino acids at 37C; the particular auxotrophies expressed vary from strain to strain. Slow growing, mycelial mutants, prototrophic on glycerol at 37C arise spontaneously in wild type strains at frequencies indicating nuclear gene mutation. Such mutants can be induced by both transition and frame shift mutagens. The implications of these observations for the taxonomic relationships between the three Candida species and for identification of C. stellatoidea in particular are discussed.     

Nutritional Requirements of Acinetobacter Strains Isolated from Soil, Water, and Sewage

One hundred five strains of Acinetobacter were isolated from water, soil, and sewage on nonselective complex media, and their nutritional properties were studied. Only one of these strains requires growth factors in order to grow in a mineral medium containing a single carbon source.