Ilaria Mannazzu - Academia.edu (original) (raw)

Papers by Ilaria Mannazzu

Genetics, Feb 1, 2004

Saccharomyces cerevisiae whi2⌬ cells are unable to halt cell division in response to nutrient lim... more Saccharomyces cerevisiae whi2⌬ cells are unable to halt cell division in response to nutrient limitation and are sensitive to a wide variety of stresses. A synthetic lethal screen resulted in the isolation of siw mutants that had a phenotype similar to that of whi2⌬. Among these were mutations affecting SIW14, FEN2, SLT2, and THR4. Fluid-phase endocytosis is severely reduced or abolished in whi2⌬, siw14⌬, fen2⌬, and thr4⌬ mutants. Furthermore, whi2⌬ and siw14⌬ mutants produce large actin clumps in stationary phase similar to those seen in prk1⌬ ark1⌬ mutants defective in protein kinases that regulate the actin cytoskeleton. Overexpression of SIW14 in a prk1⌬ strain resulted in a loss of cortical actin patches and cables and was lethal. Overexpression of SIW14 also rescued the caffeine sensitivity of the slt2 mutant isolated in the screen, but this was not due to alteration of the phosphorylation state of Slt2. These observations suggest that endocytosis and the organization of the actin cytoskeleton are required for the proper response to nutrient limitation. This hypothesis is supported by the observation that rvs161⌬, sla1⌬, sla2⌬, vrp1⌬, ypt51⌬, ypt52⌬, and end3⌬ mutations, which disrupt the organization of the actin cytoskeleton and/or reduce endocytosis, have a phenotype similar to that of whi2⌬ mutants.

Yeast, 2000

The methylotrophic yeast H. polymorpha is a popular system for the expression of recombinant prot... more The methylotrophic yeast H. polymorpha is a popular system for the expression of recombinant proteins using the strong and regulatable methanol oxidase (MOX) promoter. Here we show that the constitutive PMA1 promoter can programme the expression of two heterologous proteins, glucose oxidase and human serum albumin. A constitutive promoter provides a useful additional facility to the H. polymorpha expression system because it allows a simpli®ed fermentation regime, avoids the use of methanol, which is both toxic and an explosive hazard, and allows more¯exibility for ectopic gene expression during the course of academic studies. A fragment previously isolated in a promoter screen, using glucose oxidase (GOD) as a reporter gene, was shown to consist of the promoter region and the ®rst 659 bp of the H. polymorpha PMA1 gene, encoding the plasma membrane H +-ATPase. When the PMA1 promoter was optimally aligned with the GOD coding region, it produced 185 mg/l glucose oxidase in high cell density fed batch fermentations, whereas in previous experiments using the MOX promoter, a yield of 500 mg/l was recovered. The PMA1 promoter was also used to express recombinant human serum albumin (rHA) in H. polymorpha. In high cell density fermentations the PMA1 promoter produced 460 mg/l rHA, whereas 280 mg/l rHA was obtained using the MOX promoter. Taken together, these experiments show that the HpPMA1 programmes the constitutive expression of recombinant proteins and provides a yield comparable to that from the MOX promoter.

HAL (Le Centre pour la Communication Scientifique Directe), 2014

Encyclopedia of Ecology, 2008

Encyclopedia of Ecology, 2013

Reviews in environmental science and bio-technology/Reviews in environmental science and bio/technology, May 20, 2024

The second cheese whey (SCW) is the liquid fraction that remains after the production of whey-che... more The second cheese whey (SCW) is the liquid fraction that remains after the production of whey-cheeses. SCW appears as a white to yellow/ green opalescent liquid with suspended solids and contains up to 6% lactose and variable amounts of proteins, fats, and mineral salts. Due to its organic load, SCW is characterized by levels of Biochemical Oxygen Demand and Chemical Oxygen Demand that are significantly higher than urban wastewater. Therefore, it poses an environmental challenge and represents a significant cost and a problem for cheese production facilities when it comes to disposal. On the flip side, SCW contains valuable nutrients that make it a cost-effective substrate for bio-based productions including lactose extraction, and the production of lactic acid, bioethanol, eco-friendly bioplastics, biofuels, beverages, bioactive peptides, and microbial starters. A search in Scopus database indicates that despite the numerous potential applications, interest in SCW exploitation is surprisingly limited and, accordingly, sustainable management of SCW disposal remains an unresolved issue. In this review, which marks the first exclusive focus on SCW, with the aim of contributing to increase the interest of both the scientific community and the stakeholders in the exploitation of this by-product, the processes aimed at SCW valorisation will be described, with particular attention to its use in the production of beverages, food and feed, single cell proteins and as a source of biodegradable bioplastics, organic acids and renewable energy. Moreover, to provide valuable insights into its applications and innovations, an overview on patents regarding the exploitation of SCW will be presented.

Applied Microbiology and Biotechnology, Dec 15, 2021

Abstract Red yeasts, mainly included in the genera Rhodotorula , Rhodosporidiobolus , and Sporobo... more Abstract Red yeasts, mainly included in the genera Rhodotorula , Rhodosporidiobolus , and Sporobolomyces , are renowned biocatalysts for the production of a wide range of secondary metabolites of commercial interest, among which lipids, carotenoids, and other isoprenoids. The production of all these compounds is tightly interrelated as they share acetyl-CoA and the mevalonate pathway as common intermediates. Here, T-DNA insertional mutagenesis was applied to the wild type strain C2.5t1 of Rhodotorula mucilaginosa for the isolation of albino mutants with impaired carotenoids biosynthesis. The rationale behind this approach was that a blockage in carotenoid biosynthetic pathway could divert carbon flux toward the production of lipids and/or other molecules deriving from terpenoid precursors. One characterized albino mutant, namely, strain W4, carries a T-DNA insertion in the CAR1 gene coding for phytoene desaturase. When cultured in glycerol-containing medium, W4 strain showed significant decreases in cell density and fatty acids content in respect to the wild type strain. Conversely, it reached significantly higher productions of phytoene, CoQ 10 , and sterols. These were supported by an increased expression of CAR 2 gene that codes for phytoene synthase/lycopene cyclase. Thus, in accordance with the starting hypothesis, the impairment of carotenoids biosynthesis can be explored to pursue the biotechnological exploitation of red yeasts for enhanced production of secondary metabolites with several commercial applications. Key points • The production of lipids, carotenoids, and other isoprenoids is tightly interrelated. • CAR1 gene mutation results in the overproduction of phytoene, CoQ 10 , and sterols. • Albino mutants are promising tools for the production of secondary metabolites. Graphical abstract

Journal of Microbiological Methods, May 1, 2004

Slow growing actinobacteria of the genus Frankia are best known for their nitrogen-fixing mutuali... more Slow growing actinobacteria of the genus Frankia are best known for their nitrogen-fixing mutualism with dicotyledonous host plants called actinorhizal plants. Twenty nine (29) strains obtained from diverse host plants and geographic area, have been studied based on amplified ribosomal DNA restriction analysis (ARDRA) and repetitive element polymorphism-polymerase chain reaction (rep-PCR) DNA fingerprinting using BOX A1R primer. The collection has been classified into 28 ARDRA haplotypes clustered into three genogroups. The first genogroup 1 contains Frankia strains infecting Elaeagnus, genogroup 2 includes strains infecting Casuarina, while Frankia strains infective on Alnus, Comptonia and Myrica were grouped in genogroup 3. The results of BOX-PCR fingerprinting, supported the observation that BOX-PCR seems to be able to discriminate Frankia at strain level but are not useful for assigning strain to their respective genogroups or host infection groups.

Fems Microbiology Letters, Jan 17, 2006

Applied Microbiology and Biotechnology, Sep 2, 2020

Brewers' spent grain (BSG) is the most abundant by-product of brewing. Due to its microbiological... more Brewers' spent grain (BSG) is the most abundant by-product of brewing. Due to its microbiological instability and high perishability, fresh BSG is currently disposed of as low-cost cattle feed. However, BSG is an appealing source of nutrients to obtain products with high added value through microbial-based transformation. As such, BSG could become a potential source of income for the brewery itself. While recent studies have covered the relevance of BSG chemical composition in detail, this review aims to underline the importance of microorganisms from the stabilization/contamination of fresh BSG to its biotechnological exploitation. Indeed, the evaluation of BSG-associated microorganisms, which include yeast, fungi, and bacteria, can allow their safe use and the best methods for their exploitation. This bibliographical examination is particularly focused on the role of microorganisms in BSG exploitation to (1) produce enzymes and metabolites of industrial interest, (2) supplement human and animal diets, and (3) improve soil fertility. Emerging safety issues in the use of BSG as a food and feed additive is also considered, particularly considering the presence of mycotoxins. Key points • Microorganisms are used to enhance brewers' spent grain nutritional value. • Knowledge of brewers' spent grain microbiota allows the reduction of health risks.

Biochimica Et Biophysica Acta - General Subjects, Jul 3, 2000

The mechanisms by which vanadate exerts a toxic effect on living organisms are not completely und... more The mechanisms by which vanadate exerts a toxic effect on living organisms are not completely understood. This is principally due to the variety of intracellular targets of the metal and to the changes in the chemical form and oxidation states that vanadate can undergo, both in the external environment and intracellularly. In order to further elucidate the reasons for vanadate toxicity, and assuming that common detoxification mechanisms can be evoked by a general heavy metal response, we have compared some aspects of the cellular responses to vanadate and copper in the yeast Hansenula polymorpha. By means of 2D electrophoresis we show the existence of common determinants in the responses to vanadate-and copper-induced stresses. Moreover, we demonstrate that both metals induce significant increases in antioxidant enzyme levels, and that there are significant overlaps in the heavy metal and oxidative stress responses. Interestingly, vanadate induces an increase in catalase activity that is much higher than that seen with copper and, unlike copper, does not cause lipid peroxidation of cellular membranes. This suggests that H. polymorpha cells activate a further specific detoxification pathway against vanadate-induced oxidative insults.

Fems Microbiology Letters, Sep 1, 2004

Please note that the name of one of the authors in the above mentioned article should be De Ingen... more Please note that the name of one of the authors in the above mentioned article should be De Ingeniis; the genus and species names for P. anomala and K. wickerhamii should read Pichia anomala and Kluyveromyces wickerhamii; and the genus name Brettanomyces should be italicised throughout.

Biochimica Et Biophysica Acta - General Subjects, Jun 1, 2008

To further elucidate the impact of fermentative stress on Saccharomyces cerevisiae wine strains, ... more To further elucidate the impact of fermentative stress on Saccharomyces cerevisiae wine strains, we have here evaluated markers of oxidative stress, oxidative damage and antioxidant response in four oenological strains of S. cerevisiae, relating these to membrane integrity, ethanol production and cell viability during fermentation in high-sugar-containing medium. The cells were sampled at different fermentation stages and analysed by flow cytometry to evaluate membrane integrity and accumulation of reactive oxygen species (ROS). At the same time, catalase and superoxide dismutase activities, trehalose accumulation, and protein carbonylation and degradation were measured. The results indicate that the stress conditions occurring during hypoxic fermentation in high-sugar-containing medium result in the production of ROS and trigger an antioxidant response. This involves superoxide dismutase and trehalose for the protection of cell structures from oxidative damage, and protein catabolism for the removal of damaged proteins. Cell viability, membrane integrity and ethanol production depend on the extent of oxidative damage to cellular components. This is, in turn, related to the 'fitness' of each strain, which depends on the contribution of individual cells to ROS accumulation and scavenging. These findings highlight that the differences in individual cell resistances to ROS contribute to the persistence of wine strains during growth under unfavourable culture conditions, and they provide further insights into our understanding of yeast behaviour during industrial fermentation.

Frontiers in Microbiology, 2022

This paper reports on a common experiment performed by 17 Research Units of the Italian Group of ... more This paper reports on a common experiment performed by 17 Research Units of the Italian Group of Microbiology of Vine and Wine (GMVV), which belongs to the Scientific Society SIMTREA, with the aim to validate a protocol for the characterization of wine strains of Saccharomyces cerevisiae. For this purpose, two commercial S. cerevisiae strains (EC 1118 and AWRI796) were used to carry out inter-laboratory-scale comparative fermentations using both synthetic medium and grape musts and applying the same protocol to obtain reproducible, replicable, and statistically valid results. Ethanol yield, production of acetic acid, glycerol, higher alcohols, and other volatile compounds were assessed. Moreover, the Fourier transform infrared spectroscopy was also applied to define the metabolomic fingerprint of yeast cells from each experimental trial. Data were standardized as unit of compounds or yield per gram of sugar (glucose and fructose) consumed throughout fermentation, and analyzed throug...