RESUMO
Zymomonas mobilis has long attracted attention owing to its capacity to ferment hexose to ethanol. From a taxonomic viewpoint, Z. mobilis is a unique species of the genus Zymomonas, separated into three subspecies, Z. mobilis subsp. mobilis, Z. mobilis subsp. pomaceae and Z. mobilis subsp. francensis on the basis of physiological tests, which are often unreliable owing to the genetic proximity among these species. Currently, the use of molecular techniques is more appropriate for identification of these bacterial subspecies. In this study, the 32 strains of Z. mobilis present in the UFPEDA bacterial collection were characterized using molecular techniques, such as sequencing of the 16S rDNA gene and its theoretical restriction profile, classifying them as members of the subspecies, Z. mobilis subsp. mobilis. In addition, anaerobic cultivations were performed, which showed the biological diversity of the strains in terms of growth, sugar consumption and ethanol production. From these results, it was possible to identify the strain Z-2-80 as a promising bacterium for use in the fermentation process. SIGNIFICANCE AND IMPACT OF THE STUDY: Zymomonas mobilis is a bacterium of great relevance to biotechnology, owing to its capacity to ferment hexose to ethanol. On a molecular basis, 32 isolates were identified as Z. mobilis subsp. mobilis. However, intraspecific diversity was identified when these were grown under strictly anaerobic conditions. The results obtained from this study suggest a strain of Z. mobilis as an alternative for use in the fermentation process.
Assuntos
Reatores Biológicos/microbiologia , DNA Bacteriano/genética , Etanol/metabolismo , Zymomonas/classificação , Zymomonas/metabolismo , Anaerobiose , Brasil , DNA Ribossômico/genética , Fermentação , Hexoses/metabolismo , RNA Ribossômico 16S/genética , Zymomonas/genética , Zymomonas/isolamento & purificaçãoRESUMO
The E. coli recA gene was introduced into the pso4-1 mutant of S. cerevisiae and transformants were treated with 8-MOP+UVA and 254-nm UV light. The results showed that the recA gene increased the resistance to the toxic effect of 8-MOP+UVA and restored the frequency of reversion of the pso4-1 mutants after both treatments. The presence of the recA gene stimulated expression of the small subunit of the ribonucleotide reductase (Rnr2) in the pso4-1 mutants. Thus the E. coli recA gene is functional in yeast. Moreover, it was shown that the pso4-1 mutant is epistatic to pso1-1 and rad6-1, which belong to a mutagenic repair pathway. We propose here that the PSO4 gene has some role in the control of mutagenic repair in yeast.
Assuntos
Escherichia coli/genética , Genes Bacterianos/genética , Mutagênese , Recombinases Rec A/genética , Saccharomyces cerevisiae/genética , Reparo do DNA , Epistasia Genética , Genes Fúngicos/genética , Metoxaleno/farmacologia , Mutação , Recombinases Rec A/análise , Saccharomyces cerevisiae/efeitos dos fármacos , Saccharomyces cerevisiae/efeitos da radiação , Transformação Genética , Raios UltravioletaRESUMO
We have evaluated the effect of the Saccharomyces cerevisiae pso4-1 mutation in sporulation and DNA repair during meiosis. We have found that pso4-1 cells were arrested in an early step of meiosis, before premeiotic DNA synthesis, and hence did not produce spores. These results suggest that the PSO4 gene may act at the start point of the cell cycle, as do some SPO and CDC genes. The pso4-1 mutant cells are specifically sensitive to 8-MOP- and 3-CPs-photoinduced lesions, and are found to be severely affected in meiotic recombination as well as impaired in the mutagenic response, as previously described for mitosis. This means that the PSO4 gene is important for the repair 8-MOP-photoinduced lesions, mainly double-strand breaks, and the processing of these lesions into recombinogenic intermediates.
Assuntos
Reparo do DNA , Proteínas Fúngicas/genética , Furocumarinas/farmacologia , Genes Fúngicos , Saccharomyces cerevisiae/genética , Esporos Fúngicos , Reparo do DNA/efeitos dos fármacos , Reparo do DNA/efeitos da radiação , DNA Fúngico/biossíntese , DNA Fúngico/efeitos dos fármacos , DNA Fúngico/efeitos da radiação , Meiose , Mutagênese , Recombinação Genética/efeitos dos fármacos , Recombinação Genética/efeitos da radiação , Saccharomyces cerevisiae/efeitos dos fármacos , Saccharomyces cerevisiae/efeitos da radiação , Raios UltravioletaRESUMO
Sm15 and Sm13 are recognized by antibodies from mice protectively vaccinated with tegumental membranes, suggesting a potential role in protective immunity. In order to raise antibodies for immunochemical investigations, the genes for these antigens were expressed in pGEX and pMal vectors so that comparisons could be made among different expression systems and different genes. The fusion proteins corresponding to several parts of the gene for the precursor of Sm15 failed in producing antibodies recognizing the parasite counterpart. On the other hand, antibodies raised against Sm13 MBP-fusion proteins recognized the 13 kDa tegumental protein. Thus the peculiarities of the gene of interest are important and the choice of the expression system must sometimes be decided on an empirical basis.
Assuntos
Antígenos de Helmintos/genética , Escherichia coli/genética , Regulação Bacteriana da Expressão Gênica/genética , Schistosoma mansoni/imunologia , Animais , Clonagem Molecular/métodos , Mucina-1/imunologia , Coelhos , Proteínas Recombinantes de Fusão/imunologiaRESUMO
Industrial ethanol fermentation is a complex microbiological process to which yeast cells must adapt for survival. One of the mechanisms for adaptation is thought to involve chromosome rearrangements. We found that changes in chromosome banding patterns measured by pulsed-field gel electrophoresis can also be produced in laboratory media under simulated industrial conditions. Based on analysis of their generational variation, we found that these chromosome changes were specific to the genetic backgrounds of the initial strains. We conclude that chromosome rearrangements could be one of the factors involved in yeast cell adaptation to the industrial environment.