The establishment of a marine focused biorefinery for bioethanol production using seawater and a novel marine yeast strain

Current technologies for bioethanol production rely on the use of freshwater for preparing the fermentation media and use yeasts of a terrestrial origin. Life cycle assessment has suggested that between 1,388 to 9,812 litres of freshwater are consumed for every litre of bioethanol produced. Hence, bioethanol is considered a product with a high-water footprint. This paper investigated the use of seawater-based media and a novel marine yeast strain ‘Saccharomyces cerevisiae AZ65’ to reduce the water footprint of bioethanol. Results revealed that S. cerevisiae AZ65 had a significantly higher osmotic tolerance when compared with the terrestrial reference strain. Using 15-L bioreactors, S. cerevisiae AZ65 produced 93.50 g/L ethanol with a yield of 83.33% (of the theoretical yield) and a maximum productivity of 2.49 g/L/h when using seawater-YPD media. This approach was successfully applied using an industrial fermentation substrate (sugarcane molasses). S. cerevisiae AZ65 produced 52.23 g/L ethanol using molasses media prepared in seawater with a yield of 73.80% (of the theoretical yield) and a maximum productivity of 1.43 g/L/h. These results demonstrated that seawater can substitute freshwater for bioethanol production without compromising production efficiency. Results also revealed that marine yeast is a potential candidate for use in the bioethanol industry especially when using seawater or high salt based fermentation media

Anaerobiosis revisited: growth of Saccharomyces cerevisiae under extremely low oxygen availability

The budding yeast Saccharomyces cerevisiae plays an important role in biotechnological applications, ranging from fuel ethanol to recombinant protein production. It is also a model organism for studies on cell physiology and genetic regulation. Its ability to grow under anaerobic conditions is of interest in many industrial applications. Unlike industrial bioreactors with their low surface area relative to volume, ensuring a complete anaerobic atmosphere during microbial cultivations in the laboratory is rather difficult. Tiny amounts of O2 that enter the system can vastly influence product yields and microbial physiology. A common procedure in the laboratory is to sparge the culture vessel with ultrapure N2 gas; together with the use of butyl rubber stoppers and norprene tubing, O2 diffusion into the system can be strongly minimized. With insights from some studies conducted in our laboratory, we explore the question ‘how anaerobic is anaerobiosis?’. We briefly discuss the role of O2 in non-respiratory pathways in S. cerevisiae and provide a systematic survey of the attempts made thus far to cultivate yeast under anaerobic conditions. We conclude that very few data exist on the physiology of S. cerevisiae under anaerobiosis in the absence of the anaerobic growth factors ergosterol and unsaturated fatty acids. Anaerobicity should be treated as a relative condition since complete anaerobiosis is hardly achievable in the laboratory. Ideally, researchers should provide all the details of their anaerobic set-up, to ensure reproducibility of results among different laboratories. A correction to this article is available online at http://eprints.whiterose.ac.uk/131930/ https://doi.org/10.1007/s00253-018-9036-

Impact of oxygen consumption by yeast lees on the autolysis phenomenon during simulation of wine aging on lees

45 ref.International audienc

Oxygen consumption by wine lees: impact on lees integrity during wine ageing

39 ref.International audienc

Morphological Changes in Saccharomyces cerevisiae during the Second Fermentation of Sparkling Wines

This study shows the morphological changes of Saccharomyces cerevisiae EC1118 during the second fermentation of Spanish cava wines, in relation with progression of fermentation and aging. In the first stages of active fermentation, and associated with the increase in viable counts, budding cells and a relative homogeneity in cell size were observed. Close to the moment of sugar exhaustion cells acquired the morphology of stationary phase, to finally enter in a death phase with cell size reduction, and cytoplasm alterations including inhomogeneity, refringency, and detachment of the cell wall. At the beginning of this step structures reminiscent to autophagosomes are observed. This is in accordance with the appearance of molecular markers of autophagy described elsewhere in similar winemaking conditions.This work was funded by the Spanish Ministerio de Ciencia y Tecnología (25506 FUN C FOOD CONSOLIDER-IMAGENIO 2010; AGL2006-02558 and AGL2004-06933-CO2-01/ALI), and the Comunidad Autónoma de Madrid (ALIBIRD-CM S-0505/AGR-0153).Peer reviewe

Wine making by-products

Approximately, 67.1 million tons of grapes were utilized in wine production in 2013 (FAO 2014). This generates a considerable amount of waste because as much as 20% of the weight of processed grapes is not found in the final product (Mazza and Miniati 1993). There is growing interest in the utilization of this waste including its conversion into biofuels and use as nutrient supplements, food ingredients, and animal feeds.The authors acknowledge the funding received from the New Zealand Ministry for Environment (Community Environment Fund & Waste Minimisation Fund, Deed Number 20398) and the Sustainable Farm Fund (Project Number 09/099). This work is part of the New Zealand Grape and Wine Research Program, a joint investment by the Plant and Food Research and NZ Winegrowers