Yeast species utilizing uric acid,adenine,n-alkylamines or diamines as sole source of carbon and energy

Yeast strains utilizing uric acid, adenine, monoamines or diamines as sole source of carbon and energy were isolated from several soil samples by the enrichment culture method. The most common species wasTrichosporon cutaneum. Strains ofCandida catenulata, C. famata, C. parapsilosis, C. rugosa, Cryptococcus laurentii, Stephanoascus ciferrii andTr. adeninovorans were also isolated. All strains utilizing uric acid as sole carbon source utilized some primaryn-alkyl-l-amines hydroxyamines or diamines as well. The ascomycetous yeast strains showing these characteristics all belonged to species known to assimilate hydrocarbons. Type strains of hydrocarbon-positive yeast species which were not found in the enrichment cultures generally assimilated putrescine, some type strains also butylamine or pentylamine, but none assimilated uric acid. Methanol-positive species were not isolated. Type strains of methanol-positive and of hydrocarbon-negative species did not assimilate uric acid, butylamine or putrescine. Assimilation of putrescine as sole source of carbon and energy may be a valuable diagnostic criterion in yeast taxonomy.     

The effect of growth conditions on production and excretion of extracellular antigens by three ascomycetous yeasts

Ascomycetous yeasts produce extracellular antigens that are almost specific for the species. The antigen production by Hansenula wickerhamii and Stephanoascus ciferrii was independent of the carbon source and was proportional to the final cell density of the cultures. The same was true of chemostat cultures of Stephanoascus ciferrii, irrespective of the dilution rate and whether glucose or ammonia was the limiting nutrient. In cultures of Saccharomyces cerevisiae, however, antigen excretion mainly took place in the late exponential growth phase. Large amounts of antigen were extracted from the cell wall of Saccharomyces cerevisiae. A small amount was detected in the cytoplasm.     

Relation between phylogeny and physiology in some ascomycetous yeasts

The question of whether yeasts with similar physiological properties are closely related has been examined using recently published phylogenetic analyses of 26S domain D1/D2 rDNA nucleotide sequences from all currently recognized ascomycetous yeasts. When apparently unique metabolic pathways are examined, some relationships between physiology and rDNA phylogeny are evident. Most Candida and Pichia species that are able to assimilate methanol as the sole carbon source are in a clade delimited by C. nanospora and C. boidinii. Exceptions are P. capsulata and P. pastoris which are phylogenetically separated from the other methanol-assimilating yeasts. Yeasts subject to the petite mutation, resulting in respiratory deficiency, belong to three different clades, viz. a Saccharomyces clade delimited by S. cerevisiae and S. rosinii,the Dekkera/Brettanomyces clade, and some Schizosaccharomyces species (‘Archiascomycete’ clade). However, petite mutants were also found in Zygosaccharomyces fermentati and some other more distantly related species. Yeasts able to assimilate n-hexadecane, uric acid or amines as sole carbon source are broadly distributed over the ascomycetous phylogenetic tree. However, species that assimilate adenine as sole carbon source are closely related. Most of these species also assimilated glycine, uric acid, n-hexadecane, putrescine and branched-chain aliphatic compounds such as isobutanol, leucine and isoleucine. Among the Saccharomycetales, species utilizing all or the great majority of these eight compounds are in the Stephanoascus/Arxula/Blastobotrys clade. Candida blankii, which is distantly related to this clade, proved to be an exception and assimilated six of eight of these compounds. This revised version was published online in June 2006 with corrections to the Cover Date.     

Growth of three fungi on poultry fat or beef tallow

Aspergillus niger, Geotrichum candidum and Mucor miehei, when grown on a medium containing beef tallow or poultry fat for 5 days at 28°C, in Roux bottles, shake-flasks or fermenters, synthesized from 0.4 to 3.2 g lipids/I. The degree of fat utilization varied from 15 to 70%. The type of fat in the medium, the species of fungi and its cultivation method all influenced the fatty acid composition of fats remaining in the medium, as well as the intracellular lipids of the fungi.     

Inhibition of purine utilization by adenine in Alcaligenes eutrophus H16

With 0.5% substrate present in mineral medium, cells of Alcaligenes eutrophus H 16 were able to grow heterotrophically at the expense of guanine, hypoxanthine and xanthine, but not of adenine as sole sources of carbon and nitrogen. An increase in cell counts, however, was observed at lower adenine concentrations (0.1%). Similarly, adenine was only respired if present at low concentrations. Higher amounts of adenine were inhibitory to the utilization of adenine, guanine, hypoxanthine, xanthine, allantoin and glyoxylate, but not to that of fructose or glycerate. The adenine-dependent inhibition of adenine utilization was not overcome by the addition of thiamine, uridine or cytidine. The enzyme glyoxylate carboligase, usually formed in presence of metabolisable purines and of allantoin, was synthesized only at low adenine concentrations. Higher amounts were inhibitory even with allantoin present as additional substrate. According to these resutls, the utilization of purine derivatives and of allantoin as sources of carbon and energy is repressed by adenine in cells of A. eutrophus H 16.     

Microbiology of pozol,a Mexican fermented maize dough

Mexican fermented maize dough, pozol, including traditional banana leaf-wrapped samples and material in plastic bags, was purchased. All samples were pH 4.7 to 5.7 approx. 12 h after preparation, pH declining to 3.6 to 3.9 after 6 to 9 days storage at ambient temperature. These latter samples had dry matter contents of 31% to 48% (w/w), 0.35% to 0.75% titratable acidity as lactic acid and lactic acid bacteria as predominant microbial flora at about 10⁸ c.f.u./ml. The lactic acid bacteria included strains of Leuconostoc mesenteroides, Lactobacillus plantarum, Lactobacillus confusus, Lactococcus lactis and Lactococcus raffinolactis. Fungi were not found in the samples stored in plastic bags. The samples wrapped in banana leaf, however, developed a large surface mycoflora within 2 days. This included Geotrichum candidum, yeasts and moulds. The majority of the lactic acid bacteria and approx. 50% of yeasts hydrolysed starch to some extent. No Geotrichum isolate hydrolysed starch. Lactate was assimilated by all the Geotrichum isolates and by 17 of 39 yeast strains.     

Protoplast Fusion between Geotrichum candidium and Phanerochaete chrysosporium to Produce Fusants for Corn Stover Fermentation

Lignin impedes the digestion of corn stover when used as an animal feed. Phanerochaete chrysosporium is an efficient lignindegrader. Geotrichum candidum can be used to produce single-cell protein. In this study, protoplasts of the two fungi were prepared and fused. After screening, one of the fusants, Fusant R1, was selected for corn stover fermentation. It decreased lignin from 109 to 54 g/kg and increased protein from 48 to 67 g/kg in corn stover. Comparison with their parental strains indicated that the fusant obtained the lignin-degrading ability from P. chrysosporium and the protein-accumulating ability from G. candidium.     

Oxidative degradation of purines by the faculative phototrophic bacterium Rhodopseudomonas capsulata

The mechanism of purine degradation was studied in the facultative phototrophic bacterium Rhodopseudomonas capsulata. Using tungstate as an inhibitor of synthesis of an active xanthine dehydrogenase it could be shown in growth experiments that purine compounds are transformed to uric acid as central purine intermediate prior to ring cleavage. Because of its rapid degradation, the mechanism of uric acid conversion was investigated using 1-methyluric acid as substrate. The analogue was partially degraded by whole cells yielding 3-methylallantoin and methylurea. This implicated an oxidative degradation of 1-methyluric acid analogous to oxidation of uric acid to allantoin suggesting uric acid degradation via allantoin. In cell-free extracts, allantoinase, allantoicase, ureidoglycolase and urease activities degrading allantoin to NH₃, CO₂ and glyoxylic acid were detected. Apparently, purine degradation in R. capsulata proceeds in a manner similar to many aerobic microorganisms. It is peculiar to this bacterium, however, that the pathway evidently operates also under anaerobic conditions. In cell extracts, oxidation of uric acid was observed which could be increased by addition of cytochrome c. The basis of this stimulation is still unknown.     

Fatty acid preference of mycelium-bound lipase from a locally isolated strain of <Emphasis Type="Italic">Geotrichum candidum</Emphasis>

Mycelium-bound lipase (MBL) was prepared using a strain of Geotrichum candidum isolated from local soil. At the time of maximum lipase activity (54 h), the mycelia to which the lipase was bound were harvested by filtration and centrifugation. Dry MBL was prepared by lyophilizing the mycelia obtained. The yield of MBL was 3.66 g/l with a protein content of 44.11 mg/g. The lipase activity and specific lipase activity were 22.59 and 510 U/g protein, respectively. The moisture content of the MBL was 3.85%. The activity of free (extracellular) lipase in the culture supernatant (after removal of mycelia) was less than 0.2 U/ml. The MBL showed selectivity for oleic acid over palmitic acid during hydrolysis of palm olein, indicating that the lipase from G. candidum displayed high substrate selectivity for unsaturated fatty acid containing a cis-9 double bond, even in crude form. This unique specificity of MBL could be a direct, simple and inexpensive way in the fats and oil industry for the selective hydrolysis or transesterification of cis-9 fatty acid residues in natural triacylglycerols.     

Inhibition of Incorporation of l-Alanine into Uridine-diphospho N-acetylmuramic Acid by Glycine

Lipases from Aspergillus niger and Rhizopus delemar hydrolyzed triolein and produced l,2 (2,3)-diolein and 2-monoolein. These two lipases appears to have strong specificity towards the outer chains of the triglyceride. Comparing the proportions of fatty acids in position 1 (3) of cocoa butter with proportions of fatty acids liberated after limited hydrolysis of cocoa butter, it becomes clear that these two lipases do not hydrolyze the ester bond in position 2 of the triglyceride.

On the other hand, lipases from Geotrichum candidum Link and Penicillium cyclopium Westring attacked the fatty acid chains regardless of their positions. Geotrichum candidum lipase liberated oleic acid and palmitic acid in preference to stearic acid from cocoa butter.     

Identification of Geotrichum candidum at the species and strain level: proposal for a standardized protocol

In this study, the M13 primer was used to distinguish Geotrichum candidum from the anamorphic and teleomorphic forms of other arthrospore-forming species (discriminatory power = 0.99). For intraspecific characterization, the GATA4 primer showed the highest level of discrimination for G. candidum among the 20 microsatellite primers tested. A molecular typing protocol (DNA concentration, hybridization temperature and type of PCR machine) was optimized through a series of intra- and interlaboratory trials. This protocol was validated using 75 strains of G. candidum, one strain of G. capitatum and one strain of G. fragrans, and exhibited a discrimination score of 0.87. This method could therefore be used in the agro-food industries to identify and to evaluate biodiversity and trace strains of G. candidum. The results show that the GATA4 primer might be used to differentiate strains according to their ecological niche.     

Utilization of organic compounds as the sole source of nitrogen by Thiobacillus thiooxidans

Thiobacillus thiooxidans DSM 504 was shown to grow with adenine, hypoxanthine, xanthine and uric acid as sole sources of nitrogen. Growth with these compounds was observed after lag periods of varying lengths, unless the cells had been previously grown with the same purine base. The disappearance of adenine was accompanied by a temporary accumulation of hypoxanthine in the medium. The utilization of purines was inhibited by ammonia (1 mM). Guanine, pyrimidines and some other organic compounds were not utilized.Non-standard abbreviation U-¹⁴C uniformly labeled by ¹⁴C     

Degradation of phenanthrene by <Emphasis Type="Italic">Burkholderia</Emphasis> sp. C3: initial 1,2- and 3,4-dioxygenation and <Emphasis Type="Italic">meta</Emphasis>- and <Emphasis Type="Italic">ortho</Emphasis>-cleavage of naphthalene-1,2-diol

Burkholderia sp. C3 was isolated from a polycyclic aromatic hydrocarbon (PAH)-contaminated site in Hilo, Hawaii, USA, and studied for its degradation of phenanthrene as a sole carbon source. The initial 3,4-C dioxygenation was faster than 1,2-C dioxygenation in the first 3-day culture. However, 1-hydroxy-2-naphthoic acid derived from 3,4-C dioxygenation degraded much slower than 2-hydroxy-1-naphthoic acid derived from 1,2-C dioxygenation. Slow degradation of 1-hydroxy-2-naphthoic acid relative to 2-hydroxy-1-naphthoic acid may trigger 1,2-C dioxygenation faster after 3 days of culture. High concentrations of 5,6-␣and 7,8-benzocoumarins indicated that meta-cleavage was the major degradation mechanism of phenanthrene-1,2- and -3,4-diols. Separate cultures with 2-hydroxy-1-naphthoic acid and 1-hydroxy-2-naphthoic acid showed that the degradation rate of the former to naphthalene-1,2-diol was much faster than that of the latter. The two upper metabolic pathways of phenanthrene are converged into naphthalene-1,2-diol that is further metabolized to 2-carboxycinnamic acid and 2-hydroxybenzalpyruvic acid by ortho- and meta-cleavages, respectively. Transformation of naphthalene-1,2-diol to 2-carboxycinnamic acid by this strain represents the first observation of ortho-cleavage of two rings-PAH-diols by a Gram-negative species.     

Antimicrobial effects of three plants (rubia tinctorum, carthamus tinctorius and juglans regia) on some airborne microorganisms

In our study we have detected the antimicrobial effects of the aqueous, methanolic and chloroformic extracts of Rubia tinctorum, Carthamus tinctorius and Juglans regia on some airborne microorganisms; using the usual methods which are used routinely for this purpose in microbiology. Previous investigations have shown that extracts of these plants have antimicrobial effects on some bacteria such as Bacillus subtilis, Bacillus cereus, Bacillus mycoides, and also on some fungi specially Aspergillus niger, Penicillium expansum and Geotrichum candidum.The antimicrobial effects we have detected are 'microbicidal'. The aqueous and the chloroformic extracts had the most and the least microbicidal effects, respectively. The aqueous extracts of Carthamus tintorious and Juglans regia had the most and the least microbicidal effects respectively. This revised version was published online in June 2006 with corrections to the Cover Date.     

Degradation of low rank coal by Trichoderma atroviride ES11

A new isolate of Trichoderma atroviride has been shown to grow on low rank coal as the sole carbon source. T. atroviride ES11 degrades ∼82% of particulate coal (10 g l⁻¹) over a period of 21 days with 50% reduction in 6 days. Glucose (5 g l⁻¹) as a supplemented carbon source enhanced the coal solubilisation efficiency of T. atroviride ES11, while 10 and 20 g l⁻¹ glucose decrease coal solubilisation efficiency. Addition of nitrogen [1 g l⁻¹ (NH₄)₂SO₄] to the medium also increased the coal solubilisation efficiency of T. atroviride ES11. Assay results from coal-free and coal-supplemented cultures suggested that several intracellular enzymes are possibly involved in coal depolymerisation processes some of which are constitutive (phenol hydroxylase) and others that were activated or induced in the presence of coal (2,3-dihydrobiphenyl-2,3-diol dehydrogenase, 3,4-dihydro phenanthrene-3,4-diol dehydrogenase, 1,2-dihydro-1,2-dihydroxynaphthalene dehydrogenase, 1,2-dihydro-1,2-dihydroxyanthracene dehydrogenase). GC-MS analysis of chloroform extracts obtained from coal degrading T. atroviride ES11 cultures showed the formation of only a limited number of specific compounds (4-hydroxyphenylethanol, 1,2-benzenediol, 2-octenoic acid), strongly suggesting that the intimate association between coal particles and fungal mycelia results in rapid and near-quantitative transfer of coal depolymerisation products into the cell. An erratum to this article can be found at     

Production and characterization of polygalacturonase fromGeotrichum candidum

An extracellular polygalacturonase (EC 3.2.1.15) fromGeotrichum candidum ATCC 34614 grown onsauerkraut brine was produced and characterized. Polygalacturonic acid markedly increased the enzyme yield in the brine. The fungus produced the highest activity (290 U/l) in brine with 0.3% (w/v) polygalacturonic acid. The pH and temperature optima of the enzymes were 4.5 to 5.0 and 30°C, respectively. It was stable from pH 4.0 to 5.8 and at 30°C but lost its activity at higher temperatures. The K_m and V_max values for polygalacturonic acid were 4.2 mg/ml and 0.19mm galacturonic acid/min, respectively. The enzyme was not substrate inhibited.     

Oxidation of amines by yeasts grown on 1-aminoalkanes or putrescine as the sole source of carbon,nitrogen and energy

The maximum growth rate of Trichosporon cutaneum CBS 8111 in chemostat cultures was 0.185 h^-1 on ethylamine and 0.21 h^-1 on butylamine, that of Candida famata CBS 8109 was 0.32 h^-1 on putrescine.The amine oxidation pattern of the ascomycetous strains studied, viz. Candida famata CBS 8109, Stephanoascus ciferrii CBS 4856 and Trichosporon adeninovorans CBS 8244 was independent of the amine that had been used as the growth substrate. It resembled that of benzylamine/putrescine oxidase found in other ascomycetous yeasts. However, differences in pH optimum and substrate specificity were observed between the amine-oxidizing systems of these three species.The amine oxidation pattern of cell-free extracts of Trichosporon cutaneum CBS 8111 varied with the amine that was used as growth substrate. The enzyme system produced by Cryptococcus laurentii CBS 7140 failed to oxidize isobutylamine and benzylamine, and showed a high pH optimum.The synthesis of amine oxidase in the four yeast strains studied was not repressed by ammonium chloride and was weakly repressed by glucose but was strongly repressed if both compounds were present in the growth medium.     

Degradation of monohydroxylated benzoates by strain KUFI-6N of the yeast-like fungus Exophiala jeanselmei

Strain KUFI-6N of Exophiala jeanselmei, a cyclohexanol-utilizing yeast-like fungus, was found to grow on 3 isomers of hydroxybenzoate that functioned as the sole carbon sources. Distinct and highly specific hydroxylases converted p- and m-hydroxybenzoate to protocatechuate and o-hydroxybenzoate to catechol.     

Biodegradation of 4-chlorobiphenyl by Micrococcus species

A Micrococcus sp., isolated by enrichment culture, grew on 4-chlorobiphenyl at 2 g/l as sole carbon source and produced 4-chlorobenzoic acid in the culture medium as a dead-end metabolite. The organism degraded 4-chlorobiphenyl by 2,3-dihydroxylation followed by meta-ring cleavage to yield 4-chlorobenzoate and carbon fragments for cell growth.     

Asymmetric synthesis of (R)-2-chloro-1-(m-chlorophenyl)ethanol using acetone powder of Geotrichum candidum

The asymmetric synthesis of (R)-2-chloro-1-(m-chlorophenyl)ethanol, a precursor for a key intermediate of an important class of drugs, was achieved by reduction of the corresponding ketone using an acetone powder of Geotrichum candidum with 98% ee and 94% yield based on the starting amount of ketone.