Effects of Xenorhabdus and Photorhabdus (Morganellaceae) on volatile composition of “Tempranillo” must and on Saccharomyces cerevisiae during alcoholic fermentation

The Kei apple is a tree found on the African continent. Limited information exists on the effect of alcoholic and acetous fermentation on the phytochemicals of Kei apple. The fruit has increased concentrations of l-malic, ascorbic, and phenolic acids among other compounds. Juice was co-inoculated with Schizosaccharomyces pombe (Sp) and Saccharomyces cerevisiae (Sc) to induce alcoholic fermentation (AF). Acetous fermentation followed AF, using an acetic acid bacteria (AAB) consortium. Saccharomyces cerevisiae + Sp wines and vinegars had the highest pH. Total acidity, soluble solids and l-malic acid decreased during AF and acetous fermentation, and was highest in Sc wines and vinegars. Volatile acidity (VA) concentration was highest in Sp vinegars but was not significantly different from Sc and Sc + Sp vinegars. Gallic acid was highest in Sp wines and vinegars, whereas syringic acid was highest in Sc wines and vinegars. The Sc + Sp wines were highest in caffeic, p-coumaric, and protocatechuic acids. Schizosaccharomyces pombe vinegars were highest in caffeic and p-coumaric acids. Highest concentrations of ferulic and sinapic acids were found in Sp and Sc wines, respectively. Chlorogenic acid was most abundant phenolic acid in both wines and vinegars. Saccharomyces cerevisiae + Sp and Sc fermentation had a positive effect on most phenolic acids; Sc + AAB had an increased effect on syringic and chlorogenic acids, whereas Sp + AAB resulted in an increase in gallic, caffeic, and p-coumaric acids. The AAB selected had minimal performance with respect to VA production in comparison to commercial vinegars. Acetic acid bacteria selection for acetous fermentation should therefore be reconsidered and the decrease of certain phenolic acids during acetous fermentation needs to be investigated. © 2021 Society of Chemical Industry.

A history of research on yeasts 2: Louis Pasteur and his contemporaries, 1850-1880

Ceri Terengganu (Lepisanthes fruticosa), an underutilized exotic fruit native to Malaysia, has been overlooked due to limited cultivation and low economic value. This study aimed to highlight the potential of Ceri Terengganu by exploring its alcoholic fermentation using Saccharomyces cerevisiae and its acetic fermentation using Acetobacter aceti. The feasibility of using Ceri Terengganu as a substrate in both fermentations was examined, along with the physicochemical, antioxidant activity, and bioactive compound changes during the fermentation process. During alcoholic fermentation, yeast counts increased in the early stage and stabilized by day 3–5, while pH and total soluble solids progressively declined. The highest ethanol yield (6.41%) was recorded on day 8 with 15% sucrose supplementation. Subsequent acetic fermentation with A. aceti led to an increase in acetic acid concentration from 0.62% to 3.43%, accompanied by a decrease in ethanol, pH, and total soluble solids. Notably, acetic fermentation enhanced the total phenolic content of Ceri Terengganu. While the fruit itself is known for its high antioxidant activity, no significant changes in antioxidant activity were observed. However, acetic fermentation improved the flavonoids and phenolic acids content, with epigallocatechin (65.57±4.1 µg/ mL) and protocatechuic acid (12.75±3.2 µg/mL) being the most abundant, respectively. The acetic fermentation product exhibited high levels of acetic acid (56790.56±56.8 µg/ mL) and citric acid (7662.25±64.56 µg/mL). In conclusion, Ceri Terengganu shows promise as a substrate for alcoholic and acetic fermentations, resulting in fermented products enriched with beneficial bioactive compounds. This research sheds light on the potential value and health benefits of this underutilized Malaysian tropical fruit, contributing to its wider recognition and application in the food industry.

Simultaneous saccharification and fermentation of ethanol from potato waste by co-cultures of Aspergillus niger and Saccharomyces cerevisiae in biofilm reactors

In order to produce vinegar, coconut water was fermented through two stages: alcoholic fermentation with baker’s yeast and followed by acetous fermentation with A. aceti TISTR 102 starter powder. The baker’s yeast and the sugar concentration significantly effected on the alcoholic fermentation ( p ≤0.05). Baker’s yeast at 0.4% (w/v) was added to 1,500 mL of coconut water at 12% (w/v) sugar content that adequately produced approximately 6% (v/v) ethanol concentration within 1 day . The ethanol was used as the substrate for acetification with A. aceti TISTR 102 starter powder. The addition of A. aceti TISTR 102 starter powder at 0.5% (w/v) completely produced 6.27±0.02% acetic acid within 18 days, thus attaining 89% fermentation efficiency . In the sensory evaluation test, the coconut water vinegar was rated with acceptable scores for all of the sensorial attributes (appearance, odor, sourness and overall acceptance). Vinegar from coconut water is one considered and application in household scale.

Indonesia's oil production has declined, while demand for derivative products is increasing. Objective of this research are to understand effect of reducing sugar and total nitrogen variation to ethanol production and fermentation efficiency, cell viability, acidity, temperature, dissolved oxygen with molasses by Saccharomyces cerevisiae (SAF Instant). Step of this research consist of determination of reducing sugar, ethanol fermentation, total nitrogen determination, ethanol determination and data analysis. Treatment of reducing sugar (GR) and total nitrogen (N) (g.L-1) that are GR 100 N 0, GR 100 N 6, GR 100 N 10, GR 125 N 0, GR 125 N 6 and GR 125 N 10. Fermentation was carried out for 72 hours with three replications. Observation parameters every 24 hours are ethanol and reducing sugar concentration, temperature, acidity and dissolved oxygen. Highest ethanol resulted from GR 125 N 6 (3.68 g.L-1) and GR 100 N 6 (3.53 g.L-1). Low reducing sugar consumption inhibited by by-product of yeast metabolism and molasses chemical compound, lead leaves high sugar concentration (> 80 g.L-1). GR 100 N 6 and GR 125 N 6 have highest fermentation efficiency (69 and 57 %). There was no increase in temperature and decrease in pH significantly (α>0.05). Dissolved oxygen decreased significantly (α>0.05) at the early of fermentation and decrease until the end of fermentation. Total nitrogen 6 g g.L-1 has the highest fermentation efficiency. Keywords: ethanol, molasses, reducing sugar, Saccharomyces cerevisiae, total nitrogen

New techniques are required to replace the use of sulfur dioxide (SO2) or of sterilizing filtration in wineries, due to those methods’ drawbacks. Pulsed electric fields (PEF) is a technology capable of inactivating microorganisms at low temperatures in a continuous flow with no detrimental effect on food properties. In the present study, PEF technology was evaluated for purposes of microbial decontamination of red wines after alcoholic and malolactic fermentation, respectively. PEF combined with SO2 was evaluated in terms of microbial stability and physicochemical parameters over a period of four months. Furthermore, the effect of PEF on the sensory properties of red wine was compared with the sterilizing filtration method. Results showed that up to 4.0 Log10 cycles of S. cerevisiae and O. oeni could be eradicated by PEF and sublethal damages and a synergetic effect with SO2 were also observed, respectively. After 4 months, wine treated by PEF after alcoholic fermentation was free of viable yeasts; and less than 100 CFU/mL of O. oeni cells were viable in PEF-treated wine added with 20 ppm of SO2 after malolactic fermentation. No detrimental qualities were found, neither in terms of oenological parameters, nor in the sensory parameters of wines subjected to PEF after storage time.

Diacetyl accumulates in wine during alcoholic and malolactic fermentation (MLF). In an effort to understand the factors influencing the final diacetyl content of wine, we followed the changes in diacetyl concentration in Cabernet Sauvignon and Pinot noir wines throughout alcoholic fermentation with the widely used wine yeast <i>Saccharomyces cerevisiae</i> strain EC1118, during MLF with <i>Leuconostoc oenos</i> strain MCW, and during storage. The effect of presence of yeast on the evolution of diacetyl concentration during MLF was investigated using the following treatments: (<i>1</i>) wine; (<i>2</i>) wine plus 60 mg/L sulfur dioxide; (<i>3</i>) sterile filtered wine; (<i>4</i>) wine plus <i>Leuc. oenos</i> strain MCW; and (<i>5</i>) sterile filtered wine plus <i>Leuc. oenos</i> strain MCW. Diacetyl concentrations increased linearly during alcoholic fermentation and then declined. No reduction in diacetyl concentration occurred after sterile filtration of wine or addition of 60 mg/L SO₂ to Pinot noir wine. An increase in diacetyl concentrations was observed two days after inoculation with malolactic cultures. Presence of <i>S. cerevisiae</i> EC1118 in wines inoculated with <i>Leuc. oenos</i> strain MCW resulted in lower diacetyl concentration throughout the course of MLF. Final concentration of diacetyl in MLF wines was brought to a concentration below sensory threshold about 20 days after completion of malolactic fermentation, both in the presence and absence of <i>S. cerevisiae</i>. Utilization of diacetyl by <i>Leuc. oenos</i> strain MCW, as well as other strains, was demonstrated.

Fruity aroma modifications in Merlot wines during simultaneous alcoholic and malolactic fermentations through mixed culture of S. cerevisiae, P. fermentans, and L. brevis

Fermentation is being utilized since ages as a safe process for food preservation. Fermentation in winemaking is the process which converts grapes juice into wine. Alcoholic fermentation is the principle for the manufacturing of alcoholic beverages like wine and beer. Several by-products are produced by the alcoholic fermentation of organic carbon sources by Saccharomyces cerevisiae. The secondary bacterial fermentation is malolactic fermentation which is carried out in most red and some kinds of white wines. Malolactic fermentation causes acid reduction, flavor modification, and also is accountable for microbial stability. The present searching was carried out by the keywords in major indexing systems including PubMed/MEDLINE, Scopus, Institute for Scientific Web of Science and the search engine of Google Scholar. The keywords were alcoholic fermentation, malolactic fermentation, bottle fermentation, carbonic maceration, Saccharomyces, Lactobacillus, Oenococcus oeni, aromatic substances, flavour quality, terpenes, esters, lactones, aldehydes, organic acid, pyrazines, mercaptans, and traditional fermented food. This review was done to highlight the significance, and introduce different kinds of fermentations carried out in wine-making process, specially alcoholic and malolactic fermentation, survey on aromatic substances, flavour quality, and organic acids, and introduce the most notable traditional fermented food in China.

This research is to study the effect of ethanol fermentation aerobic pH on acetic acid product. Anaerobic fermentation uses saccharomyces cerevisiae to produce ethanol, and aerobic fermentation uses acetobacter acetic for acetic acid production. In aerobic ethanol fermentation using pH 3; 3.5; 4 and 5. The ethanol concentration was evaluated using GC ULTRA Scientific Gas Chromatography, DSQ II detector, and MS 220 column. Acetic acid produced was analyzed using an alkalymetric method. Anaerobic fermentation uses Saccharomyces cerevisiae with 1-day log phase, while aerobic fermentation uses acetobacter aceti with a 5-day log phase. Fermentation using saccharomyces cerevisiae within 24 hours so that reduction sugar could stably decrease, optimum ethanol could be got at optimum pH 6 which could decrease 55 % of reducing sugar concentration to produce 8,20583 %v/v ethanol. Fermentation acetate acid content observed in 3 days at pH 6 and 30 ⁰C will produce 6,659 g/l also shows that pH 4-6 at 30 ⁰C will produce 6,605 g/l acetate acid. Aerobic fermentation of acetate acid in 3 days shows that pH 4-6 is highly affected by temperature at 30⁰C. Statistical analysis shows, in ethanol production pH and fermentation time give significant effect, but interaction has no significant effect.

In the studies and production of bioethanol, the preferred fermenting yeast (Saccharomyces cerevisiae) is usually cultured in liquid broth that contains yeast extract and peptone. However, the use of these laboratory and scientific grade chemicals is costly, making them impractical for mass bioethanol production. Therefore, this study was conducted to evaluate the feasibility of glucose ethanolic fermentation by S. cerevisiae using generic fertiliser formulations to provide inorganic nitrogen, phosphorus, potassium and trace elements (NPK-TE). Fermentation media of different generic fertiliser strength at 0.5X, 1.0X and 2.0X Fertiliser Nitrogen Equivalents (FNE), as compared to the conventional Yeast Extract-Peptone (YEP) medium as control, was used as fermentation broth during the ethanolic fermentation of glucose. Based on the results, S. cerevisiae cultured in YEP broth produced the highest cell concentration for both wet (21.93 g/L) and dry cells (3.87 g/L), with rapid increment observed in the first 72 h of fermentation. By the end of the fermentation period, lactic acid (3.14 g/L) and acetic acid (0.96 g/L) levels were recorded to be the lowest in YEP medium while their concentration (lactic acid, 8.08 g/L) and (acetic acid, 2.67 g/L) were highest in 2.0X FNE fertiliser medium. Results indicated that the best theoretical ethanol yield (TEY) among the fertiliser media was achieved when fermentation was performed in the 0.5X FNE fertiliser medium, with a TEY of 86.18%. TEY yields were 78.68% and 51.54% in broth with 1.0X and 2.0X FNE, respectively. In general, all three fertiliser media supported ethanolic fermentation of glucose, with the 0.5X FNE fertiliser broth showing a yield that is significantly close to the conventional YEP medium, as seen in the statistical analysis. Similarities in other fermentation profiles such as acetic acid, lactic acid, and biomass production, as well as glucose utilisation, between the results from the YEP samples and samples from the fertiliser broths (at 0.5X and 1.0X FNE) have also shown that generic fertiliser has the potential to be used as an alternative medium to replace the conventional YEP to produce ethanol at a lower cost.

The alcoholic fermentation is an amphibolic process that allows the formation of ATP at substrate‐level, keeps active the glycolysis through re‐oxidation of NADH, and generate metabolites of biotechnological interest. Saccharomyces cerevisiae is a positive Crabtree, which performs the alcoholic fermentation in oxygen presence, increasing the glycolytic flux accompanied by repression of respiration. However, the molecular mechanism of the Crabtree effect is still not clear. The sucrose non‐fermenting protein‐1 (Snf1p) is a cellular energy sensor that modulates the switch between respiration and alcoholic fermentation. Therefore, Snf1p could be a key piece in the molecular puzzle of the alcoholic fermentation related to the Crabtree effect. For this reason, this work aimed to determine whether the deletion in SNF1 gene affects the alcoholic fermentation at 1% glucose. For this purpose, the BY4742 genetic background was used and its mutant in the SNF1 gene. In this way, it was found: 1) that the absence of SNF1 gene affects growth. 2) A decrease in extracellular acidification rate in SNF1 mutant. 3) NADH/NAD ratio does not have any change in the strains. However, the amount NAD(P)H showed an increase in SNF1 mutant. 4) Transcription levels of HXK2 gene displayed an increase in SNF1 mutant; while transcription levels of PFK1 gene decrease. 5) The basal respiration and the maximum respiratory capacity diminished in SNF1 mutant. All data suggest that deletion in SNF1 gene favors the formation of the anabolic species NADPH, probably by a transcriptional regulation of glycolysis, not observing an effect in the alcoholic fermentation. Support or Funding Information PRODEP partially funded this work (project number: ITESCH‐EXB‐002). This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .

Hydrogen has received attention as a next-generation renewable energy source; accordingly, sustainable production and safe transportation are crucial for its effective utilization. In this study, we focused on dihydrolevoglucosenone (CyreneTM), which was a biodegradable ketone derived from cellulose, as a renewable organic hydride. Furthermore, hydrogenation using alcoholic fermentation with baker's yeast was proposed for a novel hydrogen storage, wherein water and nicotinamide adenine dinucleotide serve as hydrogen sources. CyreneTM was hydrogenated with baker's yeast to produce 1,6-anhydro-3,4-dideoxy-β-D-threo-hexopyranose (Cyrene-OH). Cyrene-OH stored hydrogen via chemical bonding, and was dehydrogenated by warming in the presence of an iridium complex catalyst to produce hydrogen gas and reproduce CyreneTM. Therefore, this study demonstrated a new sustainable and renewable hydrogen gas production and storage cycle. This cycle, which uses readily available CyreneTM and baker's yeast, enables hydrogen energy production and storage in isolated areas and should contribute to Sustainable Development Goal 7 (Affordable and Clean Energy).

Effect of Propanoic Acid on Ethanol Fermentation by Saccharomyces cerevisiae in an Ethanol-Methane Coupled Fermentation Process