| 1. |
- Tiukova, Ievgeniia, et al.
(författare)
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Transcriptome of the Alternative Ethanol Production Strain Dekkera bruxellensis CBS 11270 in Sugar Limited, Low Oxygen Cultivation
- 2013
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:3, s. e58455-
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Tidskriftsartikel (refereegranskat)abstract
- Dekkera bruxellensis can outcompete Saccharomyces cerevisiae in environments with low sugar concentrations. It is usually regarded as a spoilage yeast but has lately been identified as an alternative ethanol production organism. In this study, global gene expression in the industrial isolate D. bruxellensis CBS 11270 under oxygen and glucose limitation was investigated by whole transcriptome sequencing using the AB SOLiD technology. Among other observations, we noted expression of respiratory complex I NADH-ubiquinone reductase although D. bruxellensis is a Crabtree positive yeast. The observed higher expression of NADH-generating enzymes compared to NAD(+)-generating enzymes might be the reason for the previously observed NADH imbalance and resulting Custer effect in D. bruxellensis. Low expression of genes involved in glycerol production is probably the molecular basis for high efficiency of D. bruxellensis metabolism under nutrient limitation. No D. bruxellensis homologs to the genes involved in the final reactions of glycerol biosynthesis were detected. A high number of expressed sugar transporter genes is consistent with the hypothesis that the competitiveness of D. bruxellensis is due to a higher affinity for the limiting substrate.
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| 2. |
- Berglund, Eva C., et al.
(författare)
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Genome dynamics of Bartonella grahamii in micro-populations of woodland rodents
- 2010
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Ingår i: BMC Genomics. - : Springer Science and Business Media LLC. - 1471-2164. ; 11, s. 152-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Rodents represent a high-risk reservoir for the emergence of new human pathogens. The recent completion of the 2.3 Mb genome of Bartonella grahamii, one of the most prevalent blood-borne bacteria in wild rodents, revealed a higher abundance of genes for host-cell interaction systems than in the genomes of closely related human pathogens. The sequence variability within the global B. grahamii population was recently investigated by multi locus sequence typing, but no study on the variability of putative host-cell interaction systems has been performed. Results: To study the population dynamics of B. grahamii, we analyzed the genomic diversity on a whole-genome scale of 27 B. grahamii strains isolated from four different species of wild rodents in three geographic locations separated by less than 30 km. Even using highly variable spacer regions, only 3 sequence types were identified. This low sequence diversity contrasted with a high variability in genome content. Microarray comparative genome hybridizations identified genes for outer surface proteins, including a repeated region containing the fha gene for filamentous hemaggluttinin and a plasmid that encodes a type IV secretion system, as the most variable. The estimated generation times in liquid culture medium for a subset of strains ranged from 5 to 22 hours, but did not correlate with sequence type or presence/absence patterns of the fha gene or the plasmid. Conclusion: Our study has revealed a geographic microstructure of B. grahamii in wild rodents. Despite near-identity in nucleotide sequence, major differences were observed in gene presence/absence patterns that did not segregate with host species. This suggests that genetically similar strains can infect a range of different hosts.
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| 3. |
- Lantz, Henrik, et al.
(författare)
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Xerochrysium gen. nov. and Bettsia, genera encompassing xerophilic species of Chrysosporium
- 2013
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Ingår i: IMA fungus. - : Springer Science and Business Media LLC. - 2210-6340 .- 2210-6359. ; 4, s. 229-241
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Tidskriftsartikel (refereegranskat)abstract
- On the basis of a study of ITS sequences, Vidal et al. (Rev. Iber. Micol. 17: 22, 2000) recommended that the genus Chrysosporium be restricted to species belonging to Onygenales. Using nrLSU genes, we studied the majority of clades examined by Vidal et al. and showed that currently accepted species in Chrysosporium phylogenetically belong in six clades in three orders. Surprisingly, the xerophilic species of Chrysosporium, long thought to be a single grouping away from the majority of Chrysosporium species, occupy two clades, one in Leotiales, the other in Eurotiales. Species accepted in Leotiales are related to the sexual genus Bettsia. One is the type species B. alvei, and related asexual strains classified as C. farinicola, the second is C. fastidium transferred to Bettsia as B. fastidia. Species in the Eurotiales are transferred to Xerochrysium gen. nov., where the accepted species are X. xerophilum and X. dermatitidis, the correct name for C. inops on transfer to Xerochrysium. All accepted species are extreme xerophiles, found in dried and concentrated foods.
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| 4. |
- Leong, Su-lin L., et al.
(författare)
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The extreme xerophilic mould Xeromyces bisporus : Growth and competition at various water activities
- 2011
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Ingår i: International Journal of Food Microbiology. - Amsterdam, Netherlands : Elsevier. - 0168-1605 .- 1879-3460. ; 145:1, s. 57-63
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Tidskriftsartikel (refereegranskat)abstract
- Little is known about the mould, Xeromyces bisporus, unique in its strong xerophilicity and ability to grow at water activity (a(w)) 0.62, lower than for any other known organism. The linear growth rates of one fast and one slow-growing strain of X. bisporus were assessed at 20, 25, 30 and 37 degrees C on solid agar media containing a mixture of glucose and fructose to reduce a(w) to 0.94, 0.88, 0.84, 0.80, 0.76 and 0.66. Growth rates of xerophilic species closely related to X. bisporus, viz. Chrysosporium Mops, C. xerophilum and Monascus eremophilus, were also assessed. Optimal conditions for growth of both X. bisporus strains were approx. 0.84 a(w) and 30 degrees C, despite FRR 2347 growing two- to five-fold faster than CBS 185.75. X. bisporus FRR 2347 even grew well at 0.66 a(w) (0.48 mm/day). C. Mops and C xerophilurn were more tolerant of high a(w) than X. bisporus. and could be differentiated from each other based on: the faster growth of C. xerophilum; its preference for temperatures >= 30 degrees C and a(w) >= 0.94 (c.f. <= 25 degrees C and similar to 0.88 a(w) for C Mops); and its ability to grow at 0.66 a(w), which is the lowest a(w) reported to date for this species. M. eremophilus grew slowly (max. 0.4 mm/day) even in its optimal conditions of similar to 0.88 a(w) and 25 degrees C. To investigate the competitive characteristics of X. bisporus at low a(w), both X. bisporus strains were grown in dual-culture with xerotolerant species Aspergillus flavus and Penicillium roqueforti, and xerophilic species A. penicillioides, C. Mops, C. xerophilum and Eurotium chevalieri, on glucose-fructose agar plates at 0.94, 0.84, 0.80 and 0.76 a(w) and at 25 degrees C. Growth rates and types of interactions were assessed. Excretion of inhibitory substances acting over a long-range was not observed by any species; inhibitors acting over a short-range that temporarily slowed competitors' growth or produced a protective zone around the colony were occasionally observed for A. penicillioides, C. Mops and C. xerophilum. Instead, rapid growth relative to the competitor was the most common means of dominance. The xerotolerant species. A. flavus and P. roqueforti were dominant over X. bisporus at 0.94 a(w). E. chevalieri was often dominant due to its rapid growth over the entire a(w) range. At a(w) < 0.80, X. bisporus was competitive because it grew faster than the other species examined. This supports the concept that its ideal environmental niche is sugary foods with low a(w).
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| 5. |
- Nguyen, Phuong, et al.
(författare)
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Identification of Colletotrichum species associated with anthracnose disease of coffee in Vietnam
- 2010
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Ingår i: European Journal of Plant Pathology. - : Springer Science and Business Media LLC. - 0929-1873 .- 1573-8469. ; 127:1, s. 73-87
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Tidskriftsartikel (refereegranskat)abstract
- Twenty-three isolates of Colletotrichum gloeosporioides, five isolates of C. acutatum, two isolates of C. capsici and six isolates of C. boninense associated with anthracnose disease on coffee (Coffea spp.) in Vietnam were identified based on morphology and DNA analysis. Phylogenetic analysis of DNA sequences from the internal transcribed spacer region of nuclear rDNA and a portion of mitochondrial small subunit rRNA were concordant and allowed good separation of the taxa. We found several Colletotrichum isolates of unknown species and their taxonomic position remains unresolved. The majority of Vietnamese isolates belonged to C. gloeosporioides and they grouped together with the coffee berry disease (CBD) fungus, C. kahawae. However, C. kahawae could be distinguished from the Vietnamese C. gloeosporioides isolates based on ammonium tartrate utilization, growth rate and pathogenicity. C. gloeosporioides isolates were more pathogenic on detached green berries than isolates of the other species, i.e. C. acutatum, C capsici and C. boninense. Some of the C. gloeosporioides isolates produced slightly sunken lesions on green berries resembling CBD symptoms but it did not destroy the bean. We did not find any evidence of the presence of C. kahawae in Vietnam.
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| 6. |
- Vinnere Pettersson, Olga, et al.
(författare)
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Fungal Xerophiles (Osmophiles)
- 2011
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Ingår i: Encyclopedia of Life Sciences. - : Wiley.
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 7. |
- Vinnere Pettersson, Olga, et al.
(författare)
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Phylogeny and intraspecific variation of the extreme xerophile, Xeromyces bisporus
- 2011
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Ingår i: Fungal Biology. - Oxon, United Kingdom : Elsevier. - 1878-6146 .- 1878-6162. ; 115:11, s. 1100-1111
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Tidskriftsartikel (refereegranskat)abstract
- The filamentous ascomycete Xeromyces bisporus is an extreme xerophile able to grow down to a water activity of 0.62. We have inferred the phylogenetic position of Xeromyces in relation to other xerophilic and xerotolerant fungi in the order Eurotiales. Using nrDNA and betatubulin sequences, we show that it is more closely related to the xerophilic food-borne species of the genus Chrysosporium, than to the genus Monascus. The taxonomy of X. bisporus and Monascus is discussed. Based on physiological, morphological, and phylogenetic distinctiveness, we suggest that Xeromyces should be retained as a separate genus.
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| 8. |
- Vinnere Pettersson, Olga, et al.
(författare)
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The Amsterdam Declaration on Fungal Nomenclature
- 2011
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Ingår i: IMA fungus. - : Springer Science and Business Media LLC. - 2210-6340 .- 2210-6359. ; 2, s. 105-112
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Tidskriftsartikel (refereegranskat)abstract
- The Amsterdam Declaration on Fungal Nomenclature was agreed at an international symposium convened in Amsterdam on 19-20 April 2011 under the auspices of the International Commission on the Taxonomy of Fungi (ICTF). The purpose of the symposium was to address the issue of whether or how the current system of naming pleomorphic fungi should be maintained or changed now that molecular data are routinely available. The issue is urgent as mycologists currently follow different practices, and no consensus was achieved by a Special Committee appointed in 2005 by the International Botanical Congress to advise on the problem. The Declaration recognizes the need for an orderly transitition to a single-name nomenclatural system for all fungi, and to provide mechanisms to protect names that otherwise then become endangered. That is, meaning that priority should be given to the first described name, except where that is a younger name in general use when the first author to select a name of a pleomorphic monophyletic genus is to be followed, and suggests controversial cases are referred to a body, such as the ICTF, which will report to the Committee for Fungi. If appropriate, the ICTF could be mandated to promote the implementation of the Declaration. In addition, but not forming part of the Declaration, are reports of discussions held during the symposium on the governance of the nomenclature of fungi, and the naming of fungi known only from an environmental nucleic acid sequence in particular. Possible amendments to the Draft BioCode (2011) to allow for the needs of mycologists are suggested for further consideration, and a possible example of how a fungus only known from the environment might be described is presented.
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