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Current microbial cell factory methods for producing chemicals from renewable resources primarily rely on (fed-)batch production systems, leading to the accumulation of the desired product. Industrially relevant chemicals like 2-phenylethanol (2PE), a flavor and fragrance compound, can exhibit toxicity at low concentrations, inhibit the host activity, and negatively impact titer, rate, and yield. Batch liquid-liquid (L-L) In Situ Product Removal (ISPR) was employed to mitigate inhibition effects, but was not found sufficient for industrial-scale application. Here, we demonstrated that continuous selective L-L ISPR provides the solution for maintaining the productivity of de novo produced 2PE at an industrial pilot scale. A unique bioreactor concept called "Fermentation Accelerated by Separation Technology" (FAST) utilizes hydrostatic pressure differences to separate aqueous- and extractant streams within one unit operation, where both production and product extraction take place - allowing for the control of the concentration of the inhibiting compound. Controlled aqueous 2PE levels (0.43 ± 0.02 g kg -1 ) and extended production times (>100 h) were obtained and co-inhibiting by-product formation was reduced, resulting in a twofold increase of the final product output of batch L-L ISPR approaches. This study establishes that continuous selective L-L ISPR, enabled by FAST, can be applied for more economically viable production of inhibiting products., (© 2024 The Author(s). Biotechnology and Bioengineering published by Wiley Periodicals LLC.)

Fermentation and hydrothermal methods were tested to reduce the phytic acid (PA) content of oat bran, and the effects of these methods on the dietary fiber (DF) and total phenolic (TP) contents as well as the antioxidant activity (AA) were also investigated. Fermentation with 6% yeast and for 6 h resulted in 88.2% reduction in PA content, while it only resulted in 32.5% reduction in the sample incubated for 6 h without yeast addition. The PA loss in autoclaved oat bran sample (1.5 h, pH 4.0) was 95.2% while it was 41.8% at most in the sample autoclaved without pH adjustment. In both methods, soluble, insoluble, and total DF contents of samples were remarkably higher than the control samples. Also for TP in the oat bran samples, both processes led to 17% and 39% increases, respectively, while AA values were 8% and 15%, respectively. Among all samples, the autoclaving process resulted in the lowest PA and the greatest amount of bioactive compounds.

Background: In this study we examine the integrity of the cell wall during scale up of a yeast fermentation process from laboratory scale (10 L) to industrial scale (10,000 L). In a previous study we observed a clear difference in the volume fraction occupied by yeast cells as revealed by wet cell weight (WCW) measurements between these scales. That study also included metabolite analysis which suggested hypoxia during scale up. Here we hypothesize that hypoxia weakens the yeast cell wall during the scale up, leading to changes in cell permeability, and/or cell mechanical resistance, which in turn may lead to the observed difference in WCW. We tested the cell wall integrity by probing the cell wall sensitivity to Zymolyase. Also exometabolomics data showed changes in supply of precursors for the glycosylation pathway., Results: The results show a more sensitive cell wall later in the production process at industrial scale, while the sensitivity at early time points was similar at both scales. We also report exometabolomics data, in particular a link with the protein glycosylation pathway. Significantly lower levels of Man6P and progressively higher GDP-mannose indicated partially impaired incorporation of this sugar nucleotide during co- or post-translational protein glycosylation pathways at the 10,000 L compared to the 10 L scale. This impairment in glycosylation would be expected to affect cell wall integrity. Although cell viability from samples obtained at both scales were similar, cells harvested from 10 L bioreactors were able to re-initiate growth faster in fresh shake flask media than those harvested from the industrial scale., Conclusions: The results obtained help explain the WCW differences observed at both scales by hypoxia-triggered weakening of the yeast cell wall during the scale up.

In the present study, office waste paper was employed as feedstock for bioethanol production. Lignocellulosic material was pre-treated with dilute sulphuric acid (5 %) to release monomeric sugars. Acid pretreatment of waste papers was carried out at different ratios of 10, 15, and 20 ml for each 1 gm of raw material to obtain the best yield of hydrolysate. After the pH adjustment of each paper hydrolysate, the hydrolysate was subjected to fermentation and distillation processes respectively. The fermentation process was performed using Saccharomyces Cerevisiae to convert the released sugars to bio-ethanol as a main product. The highest bio-ethanol yield (28.3%) was obtained at a high concentration from the yeast fermentation using waste paper pretreated with acid at a ratio of 10:1 ml/gm (liquid to solid). Economically, office waste paper is a suitable raw material for sustainable bio-ethanol production. Furthermore, bioethanol obtained was blended with pure gasoline at increasingly higher concentrations. A gasohol was homogenously mixed with four formulated fuels such as gasoline blend (E0), gasoline–5% bio-ethanol blend (E5), gasoline–10% bio-ethanol blend (E10), and gasoline–15% bio-ethanol blend (E15). It is critical to investigate the effect of various bio-ethanol blends on the characteristics and performance of internal combustion fuel. These binary mixtures were tested using density, Ried vapor pressure (RVP), and Research Octane Number (RON) tester according to the ASTM-D4052, ASTM-D6378, and ASTM-D2699 respectively under selected operating conditions. The results obtained revealed that the addition of gasoline–bioethanol blend decreases the RVP value of the fuel blend, whereas the RON and density increase because bioethanol has a high octane rating compared to conventional gasoline, resulting in enhanced gasoline’s performance in internal combustion engines. Overall, the RON of gasohol was enhanced remarkably with the increase in ethanol ratio. [ABSTRACT FROM AUTHOR]

Copyright of China Brewing is the property of China Brewing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Brewing is the property of China Brewing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective To establish a new fermentation process for Zhizhen Recipe by using bi-directional solid fermentation method of traditional Chinese medicine. Methods ① Candidate strains for fermentation were primarily recruited through literature research. Then plate incorporation assay of candidate strains were conducted to investigate the growth compatibility between the strains. CCK-8 cell proliferation assay was used to compare the half proliferation inhibitory concentration of the products obtained under different fermentation conditions against human colorectal cancer cell line HCT-8. The advantages of different fermentation systems were evaluated and the key fermentation parameters including strains and incubation periods were determined, which gave rise to the establishment of the optimal fermentation process for Zhizhen Recipe. ② In vitro pharmacological effects were compared between the fermented and unfermented Zhizhen Recipe by measuring proliferation inhibition of HCT-8 cells，as well as NO release and phagocytic activity of RAW264.7 cells. Results The results showed that Aspergillus niger/Saccharomyces cerevisiae was the optimal combination of strains，and the optimal fermentation time is 4 days. Under optimized conditions，the half inhibitory concentration (IC50) of the fermentation group on HCT-8 cells was 67.41 µg·mL-1, while IC50 value of the unfermented Zhizhen Recipe was 1 032 µg·mL-1. Compared with unfermented preparation, the fermented preparation exhibited significant effects on inhibiting the release of inflammatory factor NO of macrophages RAW264.7 cells and obviously enhanced their phagocytic activity. Conclusion In this present study，we established a new bi-directional solid fermentation process for Zhizhen Recipe. Under this fermentation system, the anti-colorectal cancer activity, anti-inflammatory activity and pro-immune activity of Zhizhen Recipe in vitro were significantly improved. [ABSTRACT FROM AUTHOR]

Copyright of Food Research & Development is the property of Food Research & Development Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The initial concentration and composition of yeast assimilable nitrogen (YAN) can affect cider fermentation kinetics and hydrogen sulfide production by Saccharomyces cerevisiae. The aim of this study was to investigate how initial YAN concentration affects hydrogen sulfide (H2S) production and fermentation kinetics in cider fermentation. The initial YAN concentration was adjusted by adding diammonium phosphate, and the yeast fermented cider at low (86 mg N/L), medium (208 mg N/L), and high (433 mg N/L) concentrations. The fermentation characteristics, amount of H2S released, and four types of nitrogen-derived compounds were measured. There is a complex relationship between the initial YAN concentration and H2S release (release change and total amount). The highest H2S release was obtained with the medium concentration treatment, which was 288.25 μg/100 mL, whereas the lowest H2S release was obtained in the high concentration treatment, at 44.13 μg/100 mL. Only under low concentration treatment conditions did the fermentation rate [3.84 g/(d·L)] have a markedly significant effect on the H2S production rate [31.68 μg/(d·100 mL)] (R²=0.95, P<0.000 1). The absorption and release patterns of four different types of YAN components differed during the fermentation process. The results of this study confirm that the initial concentration of YAN has a strong influence on the production, kinetics, and uptake profile of each type of YAN, suggesting that the use of diammonium phosphate as a nitrogen is an effective way to avoid H2S release during cider fermentation. [ABSTRACT FROM AUTHOR]

During the fermentation process, yeast cells face different stresses, and their survival and fermentation efficiency depend on their adaptation to these challenging conditions. Yeast cells must tolerate not only a single stress but also multiple simultaneous and sequential stresses. However, the adaptation and cellular response when cells are sequentially stressed are not completely understood. To explore this, we exposed a multi-stress-tolerant strain (BT0510) to different consecutive stresses to globally explore a common response, focusing on the genes induced in both stresses. Gene Ontology, pathway analyses, and common transcription factor motifs identified many processes linked to this common response. A metabolic shift to the pentose phosphate pathway, peroxisome activity, and the oxidative stress response were some of the processes found. The SYM1, STF2, and HSP genes and the transcription factors Adr1 and Usv1 may play a role in this response. This study presents a global view of the transcriptome of a multi-resistance yeast and provides new insights into the response to sequential stresses. The identified response genes can indicate future directions for the genetic engineering of yeast strains, which could improve many fermentation processes, such as those used for bioethanol production and beverages. [ABSTRACT FROM AUTHOR]

The present work sought to implement a model different from the more traditional ones for the fermentation process of ethanol production by the action of the fungus Saccharomyces cerevisiae, using a relevant metabolic network based on the glycolytic Embden–Meyerhof–Parnas route, also called "EMP". We developed two models to represent this phenomenon. In the first model, we used the simple and unbranched EMP route, with a constant concentration of microorganisms throughout the process and glucose as the whole substrate. We called this first model "SR", regarding the Portuguese name "sem ramificações", which means "no branches". We developed the second model by simply adding some branches to the SR model. We called this model "CR", regarding the Portuguese name "com ramificações", which means "with branches". Both models were implemented in MATLABTM software considering a constant temperature equal to 32 °C, similar to that practiced in sugar and ethanol plants, and a wide range of substrate concentrations, ranging from 30 to 100 g/L, and all the enzymes necessary for fermentation were already expressed in the cells so all the enzymes showed a constant concentration throughout the fermentation. The addition of common branches to the EMP route resulted in a considerable improvement in the results, especially predicting ethanol production closer to what we saw experimentally. Therefore, the results obtained are promising, making adjustments consistent with experimental data, meaning that all the models proposed here are a good basis for the development of future metabolic models of discontinuous fermentative processes. [ABSTRACT FROM AUTHOR]

ABSTRACT Cachaça is the second most consumed alcoholic beverage in Brazil, obtained by distilling wine from fermented sugarcane must, and has an alcohol content of 38 to 48% (v/v) at 20 ºC. The quality of the drink is affected by the raw material used, the treatment of the juice, the type of yeast and the distillation process. The aim of this study was to evaluate the performance of two types of yeast (selected and pressed) and the prior physical and chemical treatment of the sugarcane juice on the quality of the cachaça. The experimental design was completely randomised with 9 replications. The primary treatment was represented by the must (obtained from clarified and non-clarified juice) and the secondary treatment by the types of yeast (CA-11 and pressed biological). The microbiological behaviour of the yeast during fermentation was evaluated together with the chemical composition of the wine and cachaça. The use of selected strains and the prior treatment of the juice resulted in better performance of the fermenting yeasts, producing distillates of suitable physical and chemical standards and quality.

Alcoholic fermentation is fundamentally an adaptation process, in which the yeast Saccharomyces cerevisiae outperforms its competitors and takes over the fermentation process itself. Although wine yeast strains appear to be adapted to the stressful conditions of alcoholic fermentation, nitrogen limitations in grape must cause stuck or slow fermentations, generating significant economic losses for the wine industry. One way to discover the genetic bases that promote yeast adaptation to nitrogen-deficient environments are selection experiments, where a yeast population undergoes selection under conditions of nitrogen restriction for a number of generations, to then identify by sequencing the molecular characteristics that promote this adaptation. In this work, we carried out selection experiments in bioreactors imitating wine fermentation under nitrogen-limited fermentation conditions (SM60), using the heterogeneous SGRP-4X yeast population, to then sequence the transcriptome and the genome of the population at different time points of the selection process. The transcriptomic results showed an overexpression of genes from the NA strain (North American/YPS128), a wild, non-domesticated isolate. In addition, genome sequencing and allele frequency results allowed several QTLs to be mapped for adaptation to nitrogen-limited fermentation. Finally, we validated the ECM38 allele of NA strain as responsible for higher growth efficiency under nitrogen-limited conditions. Taken together, our results revealed a complex pattern of molecular signatures favouring adaptation of the yeast population to nitrogen-limited fermentations, including differential gene expression, allele frequency changes and loss of the mitochondrial genome. Finally, the results suggest that wild alleles from a non-domesticated isolate (NA) may have a relevant role in the adaptation to the assayed fermentation conditions, with the consequent potential of these alleles for the genetic improvement of wine yeast strains.

Copyright of China Brewing is the property of China Brewing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Brewing is the property of China Brewing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Ciência Agronômica is the property of Revista Ciencia Agronomica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• Vermicompost leachate was used as nutrient supplement for the ethanologenic yeast Saccharomyces cerevisiae. • Dehydration of Ataulfo mango pulp allowed to increase the concentration of fermentable sugars in the fermentation process. • All tested Ataulfo dehydrated mango pulp treatments with vermicompost leachate showed bioethanol production. • Moderate concentration of added vermicompost leachate has a positive effect on bioethanol yield. Mango fruits are easily damaged by knocking during harvest and transport, producing agro-industrial waste with high content of fermentable sugars. The aim of this work was to assess the production of bioethanol from residual Ataulfo (Mangifera indica L.) mango pulp, using vermicompost leachate as a nutritional supplement for ethanologenic yeast Saccharomyces cerevisiae during the fermentation process. Mango pulp was subjected to a dehydration process at 60 °C in order to preserve fermentable sugars. Moisture and ash content, total soluble solids (TSS), titratable acidity (TA), pH and total reducing sugar (TRS) concentration of the Ataulfo mango pulp were determined. Five treatments with different vermicompost leachate concentration (0%, 10%, 20%, 50% and 100%) were tested. The fermentation progress was evaluated by physicochemical characterization analysis (TSS and TRS) and accumulated production of CO 2. Initial and final concentration of bioethanol was determined by HPLC. The highest bioethanol concentration of 44.67 ± 1.6 g/L was reached for treatment with 50% of vermicompost leachate. This result represents a viable option for using mango waste and vermicompost leachate as a renewable alternative for bioethanol production. [ABSTRACT FROM AUTHOR]

Alcoholic fermentation is fundamentally an adaptation process, in which the yeast Saccharomyces cerevisiae outperforms its competitors and takes over the fermentation process itself. Although wine yeast strains appear to be adapted to the stressful conditions of alcoholic fermentation, nitrogen limitations in grape must cause stuck or slow fermentations, generating significant economic losses for the wine industry. One way to discover the genetic bases that promote yeast adaptation to nitrogen-deficient environments are selection experiments, where a yeast population undergoes selection under conditions of nitrogen restriction for a number of generations, to then identify by sequencing the molecular characteristics that promote this adaptation. In this work, we carried out selection experiments in bioreactors imitating wine fermentation under nitrogen-limited fermentation conditions (SM60), using the heterogeneous SGRP-4X yeast population, to then sequence the transcriptome and the genome of the population at different time points of the selection process. The transcriptomic results showed an overexpression of genes from the NA strain (North American/YPS128), a wild, non-domesticated isolate. In addition, genome sequencing and allele frequency results allowed several QTLs to be mapped for adaptation to nitrogen-limited fermentation. Finally, we validated the ECM38 allele of NA strain as responsible for higher growth efficiency under nitrogen-limited conditions. Taken together, our results revealed a complex pattern of molecular signatures favouring adaptation of the yeast population to nitrogen-limited fermentations, including differential gene expression, allele frequency changes and loss of the mitochondrial genome. Finally, the results suggest that wild alleles from a non-domesticated isolate (NA) may have a relevant role in the adaptation to the assayed fermentation conditions, with the consequent potential of these alleles for the genetic improvement of wine yeast strains. [ABSTRACT FROM AUTHOR]

The present work sought to implement a model different from the more traditional ones for the fermentation process of ethanol production by the action of the fungus Saccharomyces cerevisiae, using a relevant metabolic network based on the glycolytic Embden–Meyerhof–Parnas route, also called “EMP”. We developed two models to represent this phenomenon. In the first model, we used the simple and unbranched EMP route, with a constant concentration of microorganisms throughout the process and glucose as the whole substrate. We called this first model “SR”, regarding the Portuguese name “sem ramificações”, which means “no branches”. We developed the second model by simply adding some branches to the SR model. We called this model “CR”, regarding the Portuguese name “com ramificações”, which means “with branches”. Both models were implemented in MATLABTM software considering a constant temperature equal to 32 °C, similar to that practiced in sugar and ethanol plants, and a wide range of substrate concentrations, ranging from 30 to 100 g/L, and all the enzymes necessary for fermentation were already expressed in the cells so all the enzymes showed a constant concentration throughout the fermentation. The addition of common branches to the EMP route resulted in a considerable improvement in the results, especially predicting ethanol production closer to what we saw experimentally. Therefore, the results obtained are promising, making adjustments consistent with experimental data, meaning that all the models proposed here are a good basis for the development of future metabolic models of discontinuous fermentative processes.

Copyright of China Brewing is the property of China Brewing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Brewing is the property of China Brewing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Food Research & Development is the property of Food Research & Development Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Microbial lipid and bio-ethanol were co-generated by an integrated process using corn cob bagasse as raw material. After pretreatment, the acid hydrolysate was used as substrate for microbial lipid fermentation, while the solid residue was further enzymatic hydrolysis for bio-ethanol production. The effect of acid loading and pretreatment time on microbial lipid and ethanol production were evaluated. Under the optimized condition for ethanol production, ∼131.3 g of ethanol and ∼11.5 g of microbial lipid were co-generated from 1 kg raw material. On this condition, ∼71.6% of the overall fermentable sugars in corn cob bagasse could be converted into valuable products. At the same time, at least 33% of the initial COD in the acid hydrolysate was depredated. [ABSTRACT FROM AUTHOR]

Background Scale-up to industrial production level of a fermentation process occurs after optimization at small scale, a critical transition for successful technology transfer and commercialization of a product of interest. At the large scale a number of important bioprocess engineering problems arise that should be taken into account to match the values obtained at the small scale and achieve the highest productivity and quality possible. However, the changes of the host strain's physiological and metabolic behavior in response to the scale transition are still not clear. Results Heterogeneity in substrate and oxygen distribution is an inherent factor at industrial scale (10,000 L) which affects the success of process up-scaling. To counteract these detrimental effects, changes in dissolved oxygen and pressure set points and addition of diluents were applied to 10,000 L scale to enable a successful process scale-up. A comprehensive semiquantitative and time-dependent analysis of the exometabolome was performed to understand the impact of the scale-up on the metabolic/physiological behavior of the host microorganism. Intermediates from central carbon catabolism and mevalonate/ergosterol synthesis pathways were found to accumulate in both the 10 L and 10,000 L scale cultures in a time-dependent manner. Moreover, excreted metabolites analysis revealed that hypoxic conditions prevailed at the 10,000 L scale. The specific product yield increased at the 10,000 L scale, in spite of metabolic stress and catabolic-anabolic uncoupling unveiled by the decrease in biomass yield on consumed oxygen. Conclusions An optimized S. cerevisiae fermentation process was successfully scaled-up to an industrial scale bioreactor. The oxygen uptake rate (OUR) and overall growth profiles were matched between scales. The major remaining differences between scales were wet cell weight and culture apparent viscosity. The metabolic and physiological behavior of the host microorganism at the 10,000 L scale was investigated with exometabolomics, indicating that reduced oxygen availability affected oxidative phosphorylation cascading into down- and upstream pathways producing overflow metabolism. Our study revealed striking metabolic and physiological changes in response to hypoxia exerted by industrial bioprocess up-scaling [ABSTRACT FROM AUTHOR]

Abstract: Simple genetic algorithms have been investigated aiming to improve the algorithm convergence time. Because of the stochastic nature of genetic algorithms, several runs have to be performed in order to achieve representative results. A procedure for purposeful genesis concerning intervals of variations of model parameters is proposed for a standard simple genetic algorithm, aiming to improve significantly the algorithm effectiveness. Such a stepwise methodology is applied to parameter identification of fed-batch cultivation of S. cerevisiae. The procedure is further validated to a modified simple genetic algorithm with changed sequence of main genetic algorithm operators, namely mutation, crossover and selection, proven to be faster than the standard one. Results obtained from both applications show significant improvement of the algorithm convergence time while saving the model accuracy. [Copyright &y& Elsevier]

Various approaches have been applied to optimize biological product fermentation processes and define design space. In this article, we present a stepwise approach to optimize a Saccharomyces cerevisiae fermentation process through risk assessment analysis, statistical design of experiments (DoE), and multivariate Bayesian predictive approach. The critical process parameters (CPPs) were first identified through a risk assessment. The response surface for each attribute was modeled using the results from the DoE study with consideration given to interactions between CPPs. A multivariate Bayesian predictive approach was then used to identify the region of process operating conditions where all attributes met their specifications simultaneously. The model prediction was verified by twelve consistency runs where all batches achieved broth titer more than 1.53 g/L of broth and quality attributes within the expected ranges. The calculated probability was used to define the reliable operating region. To our knowledge, this is the first case study to implement the multivariate Bayesian predictive approach to the process optimization for the industrial application and its corresponding verification at two different production scales. This approach can be extended to other fermentation process optimizations and reliable operating region quantitation. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 28: 1095-1105, 2012 [ABSTRACT FROM AUTHOR]

Abstract: A tight and robust yeast fermentation controller is usually difficult to achieve because of the inherent uncertainty, nonlinear, and time-varying characteristics of the yeast fermentation dynamic process. This paper presented an alternative method for yeast fermentation process control by hybrid reinforcement learning algorithm and fuzzy logic. The fuzzy logic was used to adjust the weighting gain of control action adaptively from reinforcement learning. It led to faster tracking and helped to alleviate the overshoot of the controller. The improved multi-step action Q-learning control algorithm was developed and demonstrated through studies on ethanol concentration control of the yeast fermentation process. Experimental results show that the improved multi-step action Q-learning controller has much lower overshoot, faster tracking, shorter transition, and smoother control signal than the advanced PID controller. [Copyright &y& Elsevier]

Abstract: This study endeavored to investigate the variability of bacteria and fungi present during the fermentation process of the light-fragranced distilled liquor known as Fen liquor. To accomplish this, we used a combination of clone libraries of 16S rRNA genes, bar-coded pyrosequencing of the internal transcribed spacer region 1 (ITS1), and quantitative real-time PCR (qPCR). Fifteen families of bacteria and six families of fungi were detected. More than 91% of 16S rRNA gene sequences could be assigned to the family Lactobacillaceae, which were then classified to eight different operational taxonomic units (OTUs), based on a 3% cut-off. The most abundant OTU which contributed to 51% of the total 16S rRNA gene sequences was affiliated with Lactobacillus acetotolerans and had a significantly similar variation trend with the chemical constituents detected. Sixty percent of the fungal ITS1 region sequences were affiliated with the family Saccharomycetaceae. The most abundant OTU was very similar to Issatchenkia orientalis, which displayed notable similarities with respect to the change trends in both ethanol and organic acid contents. The sequences of the second most abundant OTU were closest to Saccharomyces cerevisiae, an important species in the process of ethanol production. Furthermore, about one fourth of the ITS1 region sequences belonged to the family Saccharomycopsidaceae. Conversely, very few sequences could be grouped together with filamentous fungi. The results of qPCR showed that the content of bacteria was increased while that of fungi was more stable in the fermentation process. It is very important to simultaneously investigate bacterial and fungal variations in food-fermentation processes. [Copyright &y& Elsevier]

An important purpose of the scientific investigation in the oenological domain is the isolation of the yeasts strains that are in a viticulture area, the identification of those strains and their integration regarding the taxonomic level, testing their oenological aptitudes and the strains selection that correspond very well to the requires of a managed grape fermentation (1). The modem procedures for obtaining different types of wine in continuo's and discontinuous systems involve the substitution of the spontaneous micro biota or its association with the selection yeasts in order to dominate and favors the start and the regularization of the fermentative process as well as the efficiency and the quality of the final product (2). The selection yeasts are recommended in current wine production, especially when the grapes production is of inferior quality and the must bisulfate, or when the grapes are excessively washed by rains and poor in yeasts cells. The biological material study was represented by a Saccharomyces oviformis strains isolated from the must that is a fermentation process, the Riesling Italian wine with 9% vol. of alcohol and 35,6g/l residual sugar. Used in the conditions of a 246,8 g/l sugar concentration of the must, the strains SOBM 16 rapidly determined the alcoholic fermentation at a temperature of 18°C of the ambient environment, phenomenon which cannot be observed in the case of natural fermentation, where there are great delays in the fermentation start. The obtained alcohol was 12,9% vol. in comparison to 11,0% vol. in case natural fermentation residual sugar having a 26g/l concentration for the selection strains and 49,3g/l in the case of natural fermentation. The period of time was almost the same, except that the natural fermentation was stopped before all sugars metabolize. In conclusion, the SOBM16 strains can be used with success by the wine producers, having all the necessary characteristics for a selection strains included in Oenological Codex. [ABSTRACT FROM AUTHOR]