A Mixture of “Cheats” and “Co-Operators” Can Enable Maximal Group Benefit

It is commonly assumed that the world would be best off if everyone co-operates. Experimental and mathematical analysis of “co-operation” in yeast show why this isn't always the case

Two approaches in the design of an asymptotic observer for a fermentative process described by partial differential equations [Dos enfoques en el diseño de un observador asintético para un proceso fermentativo descrito por ecuaciones diferenciales parciales]

In this study, the phylogenetic relationships between cachaña strains of Saccharomyces cerevisiae isolated from different geographical areas in Brazil were obtained on the basis of sequences of one mitochondrial (COX2) and three nuclear (EGT2, CAT8, and BRE5) genes. This analysis allowed us to demonstrate that different types of strains coexist in cachaña fermentations: wine strains, exhibiting alleles related or identical to those present in European wine strains; native strains, containing alleles similar to those found in strains isolated from traditional fermentations from Latin America, North America, Malaysian, Japan, or West Africa; and their intraspecific hybrids or 'mestizo' strains, heterozygous for both types of alleles. Wine strains and hybrids with high proportions of wine-type alleles predominate in southern and southeastern Brazil, where cachaña production coexists with winemaking. The high frequency of 'wine-type' alleles in these regions is probably due to the arrival of wine immigrant strains introduced from Europe in the nearby wineries due to the winemaking practices. However, in north and northeastern states, regions less suited or not suited for vine growing and winemaking, wine-type alleles are much less frequent because 'mestizo' strains with intermediate or higher proportions of 'native-type' alleles are predominant. " 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.",,,,,,"10.1111/1567-1364.12108",,,"http://hdl.handle.net/20.500.12104/45509","http://www.scopus.com/inward/record.url?eid=2-s2.0-84896117498&partnerID=40&md5=f613b6cdd7e3306fef9f5029eb8196bc",,,,,,"2",,"FEMS Yeast Research",,"28

Two interbreeding populations of Saccharomyces cerevisiae strains coexist in cachaça fermentations from Brazil

In this study, the phylogenetic relationships between cachaça strains of Saccharomyces cerevisiae isolated from different geographical areas in Brazil were obtained on the basis of sequences of one mitochondrial (COX2) and three nuclear (EGT2, CAT8, and BRE5) genes. This analysis allowed us to demonstrate that different types of strains coexist in cachaça fermentations: wine strains, exhibiting alleles related or identical to those present in European wine strains; native strains, containing alleles similar to those found in strains isolated from traditional fermentations from Latin America, North America, Malaysian, Japan, or West Africa; and their intraspecific hybrids or 'mestizo' strains, heterozygous for both types of alleles. Wine strains and hybrids with high proportions of wine-type alleles predominate in southern and southeastern Brazil, where cachaça production coexists with winemaking. The high frequency of 'wine-type' alleles in these regions is probably due to the arrival of wine immigrant strains introduced from Europe in the nearby wineries due to the winemaking practices. However, in north and northeastern states, regions less suited or not suited for vine growing and winemaking, wine-type alleles are much less frequent because 'mestizo' strains with intermediate or higher proportions of 'native-type' alleles are predominant. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved

Physiological and molecular characterisation of Saccharomyces cerevisiae cachaça strains isolated from different geographic regions in Brazil

In this work, 74 Saccharomyces cerevisiae strains isolated from cachaça fermentation of six different geographic regions in Brazil were characterized by mitochondrial DNA restriction fragment length polymorphism (mtDNA-RFLP) and by their ability to grow on stress conditions occurring during the cachaça fermentation process. Cachaça S. cerevisiae strains showed high mtDNA-RFLP polymorphism with the occurrence of 32 different molecular patterns. The S. cerevisiae strains presenting prevalent mtDNA were able to grow better in the stress conditions than strains represented by infrequent patterns. The principal coordinate analysis on 17 stress conditions revealed that the major source of growth variation were high ethanol concentrations and low temperatures. These results indicate that the stress conditions occurring in the fermentation process influence the prevalence of the most adapted S. cerevisiae strains in each distillery. The physiological tests used in our study can be used as a criterion for rapidly selecting autochthonous yeast strains for further purposes such as the selection of fermentative starters of S. cerevisiae strains. © 2009 Springer Science+Business Media B.V

Two interbreeding populations of Saccharomyces cerevisiae strains coexist in cachaca fermentations from Brazil

In this study, the phylogenetic relationships between cachaca strains of Saccharomyces cerevisiae isolated from different geographical areas in Brazil were obtained on the basis of sequences of one mitochondrial (COX2) and three nuclear (EGT2, CAT8, and BRE5) genes. This analysis allowed us to demonstrate that different types of strains coexist in cachaca fermentations: wine strains, exhibiting alleles related or identical to those present in European wine strains; native strains, containing alleles similar to those found in strains isolated from traditional fermentations from Latin America, North America, Malaysian, Japan, or West Africa; and their intraspecific hybrids or mestizo' strains, heterozygous for both types of alleles. Wine strains and hybrids with high proportions of wine-type alleles predominate in southern and southeastern Brazil, where cachaca production coexists with winemaking. The high frequency of wine-type' alleles in these regions is probably due to the arrival of wine immigrant strains introduced from Europe in the nearby wineries due to the winemaking practices. However, in north and northeastern states, regions less suited or not suited for vine growing and winemaking, wine-type alleles are much less frequent because mestizo' strains with intermediate or higher proportions of native-type' alleles are predominant

Foliar mycoendophytome of an endemic plant of the Mediterranean biome (Myrtus communis) reveals the dominance of basidiomycete woody saprotrophs

The true myrtle, Myrtus communis, is a small perennial evergreen tree that occurs in Europe, Africa, and Asia with a circum-Mediterranean geographic distribution. Unfortunately, the Mediterranean Forests, where M. communis occurs, are critically endangered and are currently restricted to small fragmented areas in protected conservation units. In the present work, we performed, for the first time, a metabarcoding study on the spatial variation of fungal community structure in the foliar endophytome of this endemic plant of the Mediterranean biome, using bipartite network analysis as a model. The local bipartite network of Myrtus communis individuals and their foliar endophytic fungi is very low connected, with low nestedness, and moderately high specialization and modularity. Similar network patterns were also retrieved in both culture-dependent and amplicon metagenomics of foliar endophytes in distinct arboreal hosts in varied biomes. Furthermore, the majority of putative fungal endophytes species were basidiomycete woody saprotrophs of the orders Polyporales, Agaricales, and Hymenochaetales. Altogether, these findings suggest a possible adaptation of these wood-decaying fungi to cope with moisture limitation and spatial scarcity of their primary substrate (dead wood), which are totally consistent with the predictions of the viaphytism hypothesis that wood-decomposing fungi inhabit the internal leaf tissue of forest trees in order to enhance dispersal to substrates on the forest floor, by using leaves as vectors and as refugia, during periods of environmental stress.Comissión Interministerial de Ciencia y Tecnología (CICYT): AGL2008-00572. Coordenação de Aperfeiçoamento de Pessoal de Nível Superior: 2330-10-5/CAPES. CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico of Brazil). Consejo Superior de Investigaciones Científicas (CSIC) and the European Social Funds

Virome analyses of Hevea brasiliensis using small RNA deep sequencing and PCR techniques reveal the presence of a potential new virus

Abstract Background Hevea brasiliensis is an important commercial crop due to the high quality of the latex it produces; however, little is known about viral infections in this plant. The only virus described to infect H. brasiliensis until now is a Carlavirus, which was described more than 30 years ago. Virus-derived small interfering RNA (vsiRNAs) are the product of the plant’s antiviral defense triggered by dsRNA viral intermediates generated, during the replication cycle. These vsiRNAs are complementar to viral genomes and have been widely used to identify and characterize viruses in plants. Methods In the present study, we investigated the virome of leaf and sapwood samples from native H. brasiliensis trees collected in two geographic areas in the Brazilian Amazon. Small RNA (sRNA) deep sequencing and bioinformatic tools were used to assembly, identify and characterize viral contigs. Subsequently, PCR amplification techniques were performed to experimentally verify the presence of the viral sequences. Finally, the phylogenetic relationship of the putative new virus with related viral genomes was analyzed. Results Our strategy allowed the identification of 32 contigs with high similarity to viral reference genomes, from which 23 exhibited homology to viruses of the Tymoviridae family. The reads showed a predominant size distribution at 21 nt derived from both strands, which was consistent with the vsiRNAs profile. The presence and genome position of the viral contigs were experimentally confirmed using droplet digital PCR amplifications. A 1913 aa long fragment was obtained and used to infer the phylogenetic relationship of the putative new virus, which indicated that it is taxonomically related to the Grapevine fleck virus, genus Maculavirus. The putative new virus was named Hevea brasiliensis virus (HBrV) in reference to its host. Conclusion The methodological strategy applied here proved to be efficient in detecting and confirming the presence of new viral sequences on a ‘very difficult to manage’ sample. This is the second time that viral sequences, that could be ascribed as a putative novel virus, associated to the rubber tree has been identified

Switching the mode of sucrose utilization by <it>Saccharomyces cerevisiae</it>

<p>Abstract</p> <p>Background</p> <p>Overflow metabolism is an undesirable characteristic of aerobic cultures of <it>Saccharomyces cerevisiae </it>during biomass-directed processes. It results from elevated sugar consumption rates that cause a high substrate conversion to ethanol and other bi-products, severely affecting cell physiology, bioprocess performance, and biomass yields. Fed-batch culture, where sucrose consumption rates are controlled by the external addition of sugar aiming at its low concentrations in the fermentor, is the classical bioprocessing alternative to prevent sugar fermentation by yeasts. However, fed-batch fermentations present drawbacks that could be overcome by simpler batch cultures at relatively high (e.g. 20 g/L) initial sugar concentrations. In this study, a <it>S. cerevisiae </it>strain lacking invertase activity was engineered to transport sucrose into the cells through a low-affinity and low-capacity sucrose-H⁺symport activity, and the growth kinetics and biomass yields on sucrose analyzed using simple batch cultures.</p> <p>Results</p> <p>We have deleted from the genome of a <it>S. cerevisiae </it>strain lacking invertase the high-affinity sucrose-H⁺symporter encoded by the <it>AGT1 </it>gene. This strain could still grow efficiently on sucrose due to a low-affinity and low-capacity sucrose-H⁺symport activity mediated by the <it>MALx1 </it>maltose permeases, and its further intracellular hydrolysis by cytoplasmic maltases. Although sucrose consumption by this engineered yeast strain was slower than with the parental yeast strain, the cells grew efficiently on sucrose due to an increased respiration of the carbon source. Consequently, this engineered yeast strain produced less ethanol and 1.5 to 2 times more biomass when cultivated in simple batch mode using 20 g/L sucrose as the carbon source.</p> <p>Conclusion</p> <p>Higher cell densities during batch cultures on 20 g/L sucrose were achieved by using a <it>S. cerevisiae </it>strain engineered in the sucrose uptake system. Such result was accomplished by effectively reducing sucrose uptake by the yeast cells, avoiding overflow metabolism, with the concomitant reduction in ethanol production. The use of this modified yeast strain in simpler batch culture mode can be a viable option to more complicated traditional sucrose-limited fed-batch cultures for biomass-directed processes of <it>S. cerevisiae</it>.</p