RESUMO
Based on morphological characteristics the taxa included in the Aspergillus aggregate can hardly be differentiated. For that reason the phylogeny of this genus was revised several times as different criteria, from morphological to later molecular, were used. We found, comparing nucleotide sequences of the ITS-region, that the strain Aspergillus niger (DSM 823) which is claimed to be identical to the strains ATCC 10577, IMI 027809, NCTC 7193 and NRRL 2322 can be molecularly classified as Aspergillus tubingensis, exhibiting 100% identity with the A. tubingensis CBS strains 643.92 and 127.49. We amplified, cloned and sequenced a new glucoamylase gene (glaA) from this strain of A. tubingensis (A. niger DSM 823) using primers derived from A. niger glucoamylase G1. The amplified cDNA fragment of 2013 bp contained an open reading frame encoding 648 amino acid residues. The calculated molecular mass of the glucoamylase, deduced from the amino acid sequence, was 68 kDa. The nucleotide sequence of glaA showed 99% similarity with glucoamylases from Aspergillus kawachii and Aspergillus shirousami, whereas the similarity with the glucoamylase G1 from A. niger was 92%
Assuntos
Aspergillus niger/classificação , Aspergillus niger/enzimologia , Glucana 1,4-alfa-Glucosidase/genética , Sequência de Aminoácidos , Aspergillus niger/genética , Sequência de Bases , Clonagem Molecular , DNA Fúngico/química , DNA Fúngico/genética , DNA Espaçador Ribossômico/química , DNA Espaçador Ribossômico/genética , Genes Fúngicos , Glucana 1,4-alfa-Glucosidase/química , Dados de Sequência Molecular , Peso Molecular , Fases de Leitura Aberta , Filogenia , Análise de Sequência de DNA , Homologia de Sequência de AminoácidosRESUMO
Microorganisms were isolated from lignite freshly excavated in the Záhorie coal mine (southwestern Slovakia) under conditions excluding contamination with either soil or air-borne microorganisms. The isolates represented both Prokarya and Eukarya (fungi). All were able to grow on standard media, although some microorganisms were unstable and became extinct during storage of coal samples. Bacteria belonged to the genera Bacillus, Staphylococcus, and Rhodococcus, according to both morphological criteria and ITS sequences. Several bacterial isolates were resistant to antibiotics. The presence of anaerobic bacteria was also documented, although they have not yet been identified. Fungal isolates were typified by using their ITS sequences. They belonged to the genera Trichoderma (Hypocrea), Penicillium, Epicoccum, Metarhizium (Cordyceps), and Cladosporium. Several fungi produced compounds with antibiotic action against standard bacterial strains. The evidence for the presence of microorganisms in native lignite was obtained by means of fluorescence microscopy, scanning electron microscopy, and electron microprobe analysis. Results demonstrated that microorganisms were able to survive in the low-rank coal over a long time period.
Assuntos
Bactérias/classificação , Bactérias/isolamento & purificação , Carvão Mineral/microbiologia , Fungos/classificação , Fungos/isolamento & purificação , Mineração , Antibacterianos/biossíntese , Antibacterianos/farmacologia , Antibiose , Bacillus/classificação , Bacillus/isolamento & purificação , Bactérias Anaeróbias/isolamento & purificação , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/química , DNA Ribossômico/genética , DNA Espaçador Ribossômico/química , DNA Espaçador Ribossômico/genética , Resistência Microbiana a Medicamentos , Microanálise por Sonda Eletrônica , Microscopia Eletrônica de Varredura , Microscopia de Fluorescência , Dados de Sequência Molecular , Rhodococcus/classificação , Rhodococcus/isolamento & purificação , Análise de Sequência de DNA , Eslováquia , Staphylococcus/classificação , Staphylococcus/isolamento & purificaçãoRESUMO
The expression of glutamic acid decarboxylase gene and the laccase activity were measured during the development of surface-cultivated Trichoderma viride mycelia in order to examine their up-regulation by light. The results show that the changes in activity of GAD induced by light observed previously are caused by transcriptional regulation of gad gene expression in both submerged mycelia and aerial mycelia after photoinduction. The expression of tga gene encoding a T. viride G(alpha) protein was found not to be up-regulated by light and was also present in the non-conidiating mutant of T. viride suggesting that this protein is not involved in the regulation of conidiation in this fungus, or that it plays a role is in later stages of conidia development. The activity of laccase was also not light-inducible and may be related to the maturation of conidia.
Assuntos
Regulação Fúngica da Expressão Gênica , Glutamato Descarboxilase/genética , Trichoderma/enzimologia , Sequência de Bases , DNA Fúngico/química , DNA Fúngico/genética , Subunidades alfa de Proteínas de Ligação ao GTP/genética , Lacase/análise , Luz , Dados de Sequência Molecular , Micélio/enzimologia , RNA Fúngico/análise , RNA Mensageiro/análise , Análise de Sequência de DNA , Transcrição Gênica , Trichoderma/genética , Trichoderma/crescimento & desenvolvimentoRESUMO
Hortaea acidophila is a pigmented, yeast-like ascomycete that is able to grow at a pH as low as 0.6. This study presents evidence that H. acidophila possesses at least two functional laccases that seem to be involved in melanin synthesis. This evidence is supported by PCR amplification of laccase-specific gene fragments by using primers derived from conserved copper-binding-regions and by Southern Blot analysis. Due to their low pH optimum the laccases may be of special interest for biotechnological use.
