Improvement of Torulaspora delbrueckii Genome Annotation: Towards the Exploitation of Genomic Features of a Biotechnologically Relevant Yeast

Adaptive Laboratory Evolution Uncovers Potential Role of a DNA Helicase Mutation in Torulaspora delbrueckii Increased Sulphite Resistance

Wine industry has faced pressure to innovate its products. Saccharomyces cerevisiae has been the traditional yeast for producing alcoholic beverages, but interest has shifted from the conventional S. cerevisiae to non-Saccharomyces yeasts for their biotechnological potential. Among these, Torulaspora delbrueckii is particularly notable for its ability to enrich wine with novel flavours. During winemaking, sulphites are added to suppress spoilage microorganisms, making sulphite tolerance a valuable characteristic of wine yeasts. Adaptive laboratory evolution in liquid and solid media improved sulphite resistance in two T. delbrueckii strains, achieving, in the best case, a fourfold increase from 0.50 to 2.00 mM of sodium metabisulphite, highlighting the potential of these evolve strains for winemaking applications. Genomic analysis revealed SNPs/InDels in all the strains, including a novel unique missense mutation common to the four evolved isolates, but absent from the parental strains, located in chromosome VIII (protein TDEL0H03170, homologue of S. cerevisiae MPH1). These genes code for a protein catalogued as an ATP-dependent DNA helicase, known for its role in maintaining genome stability by participating in DNA repair pathways. We propose that this valine-to-serine mutation, common to all the evolved isolates, helps the evolved strains repair sulphite-induced DNA damage more effectively.

A review: Effects of microbial fermentation on the structure and bioactivity of polysaccharides in plant-based foods

Fermented plant-based foods that catering to consumers' diverse dietary preferences play an important role in promoting human health. Recent exploration of their nutritional value has sparked increasing interest in the structural and bioactive changes of polysaccharides during fermentation, the essential components of plant-based foods which have been extensively studied for their structures and functional properties. Based on the latest key findings, this review summarized the dominant fermented plant-based foods in the market, the involved microbes and plant polysaccharides, and the corresponding modification in polysaccharides structure. Further microbial utilization of these polysaccharides, influencing factors, and the potential contributions of altered structure to the functions of polysaccharides were collectively illustrated. Moreover, future research trend was proposed, focusing on the directional modification of polysaccharides and exploration of the mechanisms underlying structural changes and enhanced biological activity during fermentation.

Metagenomic reconstructions of caecal microbiome in Landes, Roman and Zhedong White geese

1. The caecal microbiota in geese play a crucial role in determining the host's health, disease status and behaviour, as evidenced by extensive epidemiological data. The present investigation conducted 10× metagenomic sequencing of caecal content samples obtained from three distinct goose species, namely Landes geese, Roman geese and Zhedong White geese (n = 5), to explore the contribution of the gut microbiome to carbohydrate metabolism.2. In total, 337GB of Illumina data were generated, which identified 1,048,575 complete genes and construction of 331 metagenomic bins, encompassing 78 species from nine phyla. Firmicutes, Bacteroidetes, Actinobacteria, Proteobacteria and Bacteria were identified as the dominant phyla while Prevotella, Bacteroides, Streptococcus, and Subdoligranulum were the most abundant genera in the caecum of geese.3. The genes were allocated to 375 pathways using the Kyoto Encyclopedia of Genes and Genome (KEGG) analysis. The most abundant classes in the caecum of geese were confirmed to be glycoside hydrolases (GHs), glycosyl transferases (GTs), as identified through the carbohydrate-active enzyme (CAZyme) database mapping. Subdoligranulum variabile and Mediterraneibacter glycyrrhizinilyticus were discovered to potentially facilitate carbohydrate digestion in geese.4. Notwithstanding, further investigation and validation are required to establish a connection between these species and CAZymes. Based on binning analysis, Mediterraneibacter glycyrrhizinilyticus and Ruminococcus sp. CAG:177 are potential species in LD geese that contribute to the production of fatty liver.

Gene coexpression network during ontogeny in the yellow fever mosquito, Aedes aegypti

BACKGROUND

The behaviors and ontogeny of Aedes aegypti are closely related to the spread of diseases caused by dengue (DENV), chikungunya (CHIKV), Zika (ZIKV), and yellow fever (YFV) viruses. During the life cycle, Ae. aegypti undergoes drastic morphological, metabolic, and functional changes triggered by gene regulation and other molecular mechanisms. Some essential regulatory factors that regulate insect ontogeny have been revealed in other species, but their roles are still poorly investigated in the mosquito.

RESULTS

Our study identified 6 gene modules and their intramodular hub genes that were highly associated with the ontogeny of Ae. aegypti in the constructed network. Those modules were found to be enriched in functional roles related to cuticle development, ATP generation, digestion, immunity, pupation control, lectins, and spermatogenesis. Additionally, digestion-related pathways were activated in the larvae and adult females but suppressed in the pupae. The integrated protein‒protein network also identified cilium-related genes. In addition, we verified that the 6 intramodular hub genes encoding proteins such as EcKinase regulating larval molt were only expressed in the larval stage. Quantitative RT‒PCR of the intramodular hub genes gave similar results as the RNA-Seq expression profile, and most hub genes were ontogeny-specifically expressed.

CONCLUSIONS

The constructed gene coexpression network provides a useful resource for network-based data mining to identify candidate genes for functional studies. Ultimately, these findings will be key in identifying potential molecular targets for disease control.

Torulaspora delbrueckii Phenotypic and Metabolic Profiling towards Its Biotechnological Exploitation

Wine is a particularly complex beverage resulting from the combination of several factors, with yeasts being highlighted due to their fundamental role in its development. For many years, non-Saccharomyces yeasts were believed to be sources of spoilage and contamination, but this idea was challenged, and many of these yeasts are starting to be explored for their beneficial input to wine character. Among this group, Torulaspora delbrueckii is gaining relevance within the wine industry, owing to its low volatile acidity production, increased release of aromatic compounds and enhanced color intensity. In addition, this yeast was also attracting interest in other biotechnological areas, such as bread and beer fermentation. In this work, a set of 40 T. delbrueckii strains, of varied geographical and technological origins, was gathered in order to characterize the phenotypic behavior of this species, focusing on different parameters of biotechnological interest. The fermentative performance of the strains was also evaluated through individual fermentations in synthetic grape must with the isolates’ metabolic profile being assessed by HPLC. Data analysis revealed that T. delbrueckii growth is significantly affected by high temperature (37 °C) and ethanol concentrations (up to 18%), alongside 1.5 mM SO₂, showing variable fermentative power and yields. Our computation models suggest that the technological origin of the strains seems to prevail over the geographical origin as regards the influence on yeast properties. The inter-strain variability and profile of the products through the fermentative processes reinforce the potential of T. delbrueckii from a biotechnological point of view.

Whole-Genome Sequencing and Annotation of the Yeast Clavispora santaluciae Reveals Important Insights about Its Adaptation to the Vineyard Environment

Clavispora santaluciae was recently described as a novel non-Saccharomyces yeast species, isolated from grapes of Azores vineyards, a Portuguese archipelago with particular environmental conditions, and from Italian grapes infected with Drosophila suzukii. In the present work, the genome of five Clavispora santaluciae strains was sequenced, assembled, and annotated for the first time, using robust pipelines, and a combination of both long- and short-read sequencing platforms. Genome comparisons revealed specific differences between strains of Clavispora santaluciae reflecting their isolation in two separate ecological niches—Azorean and Italian vineyards—as well as mechanisms of adaptation to the intricate and arduous environmental features of the geographical location from which they were isolated. In particular, relevant differences were detected in the number of coding genes (shared and unique) and transposable elements, the amount and diversity of non-coding RNAs, and the enzymatic potential of each strain through the analysis of their CAZyome. A comparative study was also conducted between the Clavispora santaluciae genome and those of the remaining species of the Metschnikowiaceae family. Our phylogenetic and genomic analysis, comprising 126 yeast strains (alignment of 2362 common proteins) allowed the establishment of a robust phylogram of Metschnikowiaceae and detailed incongruencies to be clarified in the future.

Biotechnological Importance of Torulaspora delbrueckii: From the Obscurity to the Spotlight

Torulaspora delbrueckii has attracted interest in recent years, especially due to its biotechnological potential, arising from its flavor- and aroma-enhancing properties when used in wine, beer or bread dough fermentation, as well as from its remarkable resistance to osmotic and freezing stresses. In the present review, genomic, biochemical, and phenotypic features of T. delbrueckii are described, comparing them with other species, particularly with the biotechnologically well-established yeast, Saccharomyces cerevisiae. We conclude about the aspects that make this yeast a promising biotechnological model to be exploited in a wide range of industries, particularly in wine and bakery. A phylogenetic analysis was also performed, using the core proteome of T. delbrueckii, to compare the number of homologous proteins relative to the most closely related species, understanding the phylogenetic placement of this species with robust support. Lastly, the genetic tools available for T. delbrueckii improvement are discussed, focusing on adaptive laboratorial evolution and its potential.

Cold Adaptation Strategies and the Potential of Psychrophilic Enzymes from the Antarctic Yeast, Glaciozyma antarctica PI12

Psychrophilic organisms possess several adaptive strategies which allow them to sustain life at low temperatures between −20 to 20 °C. Studies on Antarctic psychrophiles are interesting due to the multiple stressors that exist on the permanently cold continent. These organisms produce, among other peculiarities, cold-active enzymes which not only have tremendous biotechnological potential but are valuable models for fundamental research into protein structure and function. Recent innovations in omics technologies such as genomics, transcriptomics, proteomics and metabolomics have contributed a remarkable perspective of the molecular basis underpinning the mechanisms of cold adaptation. This review critically discusses similar and different strategies of cold adaptation in the obligate psychrophilic yeast, Glaciozyma antarctica PI12 at the molecular (genome structure, proteins and enzymes, gene expression) and physiological (antifreeze proteins, membrane fluidity, stress-related proteins) levels. Our extensive studies on G. antarctica have revealed significant insights towards the innate capacity of- and the adaptation strategies employed by this psychrophilic yeast for life in the persistent cold. Furthermore, several cold-active enzymes and proteins with biotechnological potential are also discussed.