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Ruyters S.,Campus Management | Mukherjee V.,Campus Management | Thevelein J.M.,Institute of Botany and Microbiology | Willems K.A.,Campus Management | Lievens B.,Campus Management
Journal of Industrial Microbiology and Biotechnology | Year: 2015

Bioethanol fermentations expose yeasts to a new, complex and challenging fermentation medium with specific inhibitors and sugar mixtures depending on the type of carbon source. It is, therefore, suggested that the natural diversity of yeasts should be further exploited in order to find yeasts with good ethanol yield in stressed fermentation media. In this study, we screened more than 50 yeast isolates of which we selected five isolates with promising features. The species Candida bombi, Wickerhamomyces anomalus and Torulaspora delbrueckii showed better osmo- and hydroxymethylfurfural tolerance than Saccharomyces cerevisiae. However, S. cerevisiae isolates had the highest ethanol yield in fermentation experiments mimicking high gravity fermentations (25 % glucose) and artificial lignocellulose hydrolysates (with a myriad of inhibitors). Interestingly, among two tested S. cerevisiae strains, a wild strain isolated from an oak tree performed better than Ethanol Red, a S. cerevisiae strain which is currently commonly used in industrial bioethanol fermentations. Additionally, a W. anomalus strain isolated from sugar beet thick juice was found to have a comparable ethanol yield, but needed longer fermentation time. Other non-Saccharomyces yeasts yielded lower ethanol amounts. © 2014, Society for Industrial Microbiology and Biotechnology.

Fernandez O.,CNRS Research Unit on Grapevine and Wines in Champagne | Vandesteene L.,Institute of Botany and Microbiology | Feil R.,Max Planck Institute of Molecular Plant Physiology | Baillieul F.,CNRS Research Unit on Grapevine and Wines in Champagne | And 2 more authors.
Planta | Year: 2012

During the last decade, there has been growing interest in the role of trehalose metabolism in tolerance to abiotic stress in higher plants, especially cold stress. So far, this metabolism has not yet been studied in Vitis vinifera L., despite the economic importance of this crop. The goal of this paper was to investigate the involvement of trehalose metabolism in the response of grapevine to chilling stress, and to compare the response in plants bacterised with Burkholderia phytofirmans strain PsJN, a plant growth-promoting rhizobacterium that confers grapevine chilling tolerance, with mock-inoculated plants. In silico analysis revealed that the V. vinifera L. genome contains genes encoding the enzymes responsible for trehalose synthesis and degradation. Transcript analysis showed that these genes were differentially expressed in various plant organs, and we also characterised their response to chilling. Both trehalose and trehalose 6-phosphate (T6P) were present in grapevine tissues and showed a distinct pattern of accumulation upon chilling. Our results suggest a role for T6P as the main active molecule in the metabolism upon chilling, with a possible link with sucrose metabolism. Furthermore, plants colonised by B. phytofirmans and cultivated at 26°C accumulated T6P and trehalose in stems and leaves at concentrations similar to non-bacterised plants exposed to chilling temperatures for 1 day. Overall, our data suggest that T6P and trehalose accumulate upon chilling stress in grapevine and might participate in the resistance to chilling stress conferred by B. phytofirmans. © 2012 Springer-Verlag.

Kong E.F.,University of Maryland, Baltimore | Kucharikova S.,VIB | Kucharikova S.,Institute of Botany and Microbiology | Van Dijck P.,VIB | And 5 more authors.
Infection and Immunity | Year: 2015

The clinical significance of polymicrobial interactions, particularly those between commensal species with high pathogenic potential, remains largely understudied. Although the dimorphic fungal species Candida albicans and the bacterium Staphylococcus aureus are common cocolonizers of humans, they are considered leading opportunistic pathogens. Oral candidiasis specifically, characterized by hyphal invasion of oral mucosal tissue, is the most common opportunistic infection in HIV+ and immunocompromised individuals. In this study, building on our previous findings, a mouse model was developed to investigate whether the onset of oral candidiasis predisposes the host to secondary staphylococcal infection. The findings demonstrated that in mice with oral candidiasis, subsequent exposure to S. aureus resulted in systemic bacterial infection with high morbidity and mortality. Histopathology and scanning electron microscopy of tongue tissue from moribund animals revealed massive C. albicans hyphal invasion coupled with S. aureus deep tissue infiltration. The crucial role of hyphae in the process was demonstrated using a non-hypha-producing and a noninvasive hypha-producing mutant strains of C. albicans. Further, in contrast to previous findings, S. aureus dissemination was aided but not contingent upon the presence of the Als3p hypha-specific adhesion. Importantly, impeding development of mucosal C. albicans infection by administering antifungal fluconazole therapy protected the animals from systemic bacterial disease. The combined findings from this study demonstrate that oral candidiasis may constitute a risk factor for disseminated bacterial disease warranting awareness in terms of therapeutic management of immunocompromised individuals. © 2015, American Society for Microbiology.

Huysmans S.,Institute of Botany and Microbiology | Verstraete B.,Institute of Botany and Microbiology | Smets E.,Institute of Botany and Microbiology | Smets E.,Leiden University | Chatrou L.W.,Wageningen University
Plant Ecology and Evolution | Year: 2010

Background and aims - Orbicules or Ubisch bodies have been recorded in many angiosperm families and although the first observations date back to 1865, their function in the anther remains enigmatic. In flowering plants a general evolutionary trend is observed from common occurrence of orbicules in early diverging lineages towards a more patchy distribution in derived clades of eudicots. Annonaceae was our family of choice for an in depth study of orbicule distribution in early diverging angiosperms since it met the following three criteria: (1) high tapetum diversity, (2) orbicule presence and absence recorded, and (3) recent phylogeny at genus level available. Key results - Our SEM data of eighteen species show that orbicules are more common in Annonaceae than previously perceived. The resulting orbicule distribution pattern on the family topology indicates a consistent absence of orbicules in the 'long branch clade' while orbicules are present in Anaxagorea, the ambavioids, and the 'short branch clade'. Presence of orbicules is the ancestral condition in the family. Morphologically, Annonaceae orbicules are small (< 1 μm), spherical and smooth. Conclusions - The orbicule distribution pattern in Annonaceae reflects the general evolutionary trend in flowering plants. We hypothesize that orbicule presence can be considered as a powerful proxy for nonamoeboid tapetum characterization in Annonaceae. © 2010 National Botanic Garden of Belgium and Royal Botanical Society of Belgium.

Vandesteene L.,Institute of Botany and Microbiology | Ramon M.,Harvard University | Le Roy K.,Institute of Botany and Microbiology | Van Dijck P.,VIB | And 2 more authors.
Molecular Plant | Year: 2010

Higher plants typically do not produce trehalose in large amounts, but their genome sequences reveal large families of putative trehalose metabolism enzymes. An important regulatory role in plant growth and development is also emerging for the metabolic intermediate trehalose-6-P (T6P). Here, we present an update on Arabidopsis trehalose metabolism and a resource for further detailed analyses. In addition, we provide evidence that Arabidopsis encodes a single trehalose-6-P synthase (TPS) next to a family of catalytically inactive TPS-like proteins that might fulfill specific regulatory functions in actively growing tissues.

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