Specific Growth Rate Of Yeast Research Articles

STUDY OF THE PROLIFERATIVE ACTIVITY OF SACCHAROMYCES CEREVISIAE IN YEAST BIOTECHNOLOGY AND PHYSICO-CHEMICAL METHODS OF ITS DETERMINATION

The article discusses the solution of issues related to increasing the efficiency of technological processes and ensuring the release of high-quality finished products, relevant for production based on the use of S. cerevisiae yeast. The paper identifies major reasons for the need to regulate yeast culture metabolism, considers existing practice and proposes methods of changing its metabolic activity. The purpose of the research is to create the classification of the supplements / preparations from different origin to improve yeast vital activity by adjusting its culture medium composition with the use of complex hierarchical faceted method.
 The proliferative processes taking place in the yeast cell are quite easily regulated. Therefore, knowing the dependence between the specific conditions of the environment and certain aspects of the yeast culture's vital activity, it is possible to purposefully change its growth, development and metabolism. Creating and maintaining certain conditions for the cultivation of yeast allows you to control the course of the fermentation process.
 The influence of biologically active substances on the proliferative activity of S. cerevisiae cells was investigated. Concentrations were determined and the regulatory effect of succinic and folic acid preparations on the proliferative activity of yeast cells was proven. A comparative analysis of influence of different concentrations of exogenous substances on microorganisms culture growth was carried out. The most optimal concentrations of drugs for activation of yeast cell division were determined: succinic acid/ascorbic acid – 0.0015/0.0002 mg/ml; folic acid – 0.006 mg/ml.
 Specific growth rate of yeast during cultivation in 20 % sucrose solution with succinic/ascorbic and folic acid preparations was calculated. It was established that the highest specific rate of cell growth was observed in the complex preparation, which included three organic acids. It was established that the specific rate of yeast reproduction in the complex preparation increased by an average of 30–35 % relative to the control sample. Increase in specific growth rate by 20–25 % of yeast was also observed in the medium with folic acid, the addition of succinic/ascorbic acids did not significantly increase specific rate (by approximately 10 %) of the growth of the S. cerevisiae yeast culture. It has been established that biologically active substances have certain concentrations that activate cell division and contribute to their active development and critical limits at which the development and growth of yeast cells are inhibited.

Factors that cause replacement of shochu yeast by wild yeast upon Sashi-moto repetition

In shochu-making, a small amount of fermenting moromi is added to a koji/water mixture instead of yeast culture to initiate fermentation. This is a characteristic process called Sashi-moto. It is known that shochu yeast is replaced by wild yeast upon repetition of Sashi-moto. The shochu yeast strains Kagoshima No. 2 (K2), Kagoshima No. 4 (C4), and Kagoshima No. 5 (H5), but not Kagoshima No. 6 (A6), were replaced by wild yeast (strain No. S5-g). K2 and C4 were easily replaced compared to H5, and the specific growth rates of K2 and C4 were lower than that of S5-g under higher osmotic pressure. Although the specific growth rate of H5 was higher than that of S5-g, its yeast population at the stationary phase was smaller than S5-g. On the other hand, both the specific growth rate and yeast population of A6 were higher than those of S5-g. The specific growth rate of yeast would be affected by osmotic tolerance and specific characters of the yeast strain.

Development of the innovative biotechnological methods of the biological preparations production for feed purposes

The aim of this study was the production of the biological preparations based on the hydrolyzed pea flour and the yeast biomass. The research objects were Saccharomyces cerevisiae Y-1218 yeast with glucoamylase activity, pea flour, and Celloviridin S20X and Amyloprotoorizin S20X enzyme preparations (EP). The specific growth rate of the yeast was determined by the calculation method, protein content – via Kjeldahl and Lowry methods, reducing substances content – by Somogyi-Nelson assay, the amine nitrogen content – by the formol titration method, the number of living yeast cells – by sowing of dilutions. The amino acid content was measured on the KNAUER (Germany) high-performance liquid chromatograph. As the result of the studies, enzyme preparations for the fermentative processing of pea flour were selected. The cultivation conditions of the Saccharomyces cerevisiae Y-1218 yeast were opted. Under these chosen growing parameters the produced biomass contained 2.4×109 CFU/cm3 and specific growth rate of yeast was 0.264 h-1. The resulting biomass contained a high amount of essential amino acids. The biopreparations production based on the described ingredient is perspective. These biopreparations with increased biological value could be used for feed purposes.

Investigation of the possibility of culturing aerobic yeast with oxygen nanobubble addition and evaluation of the results of batch and semi-batch cultures of Saccharomyces cerevisiae

Nanobubble dispersions have been intensively studied in recent years. Their expanding applications include a wide range of industrial and biochemical processes. Nanobubble-saturated water intensifies the growth of bacteria, animal cell lines, plants, and animals. However, their influence on yeast growth has not been investigated. Yeast is an important microorganism in the biotechnology and food industries. Intensified growth of yeasts would be beneficial for basic and industrial purposes. In this study, the possibility of culturing Saccharomyces cerevisiae with oxygen nanobubbles as the sole source of oxygen was investigated. Batch, sequential batch, and semi-batch cultures were grown with the addition of oxygen nanobubbles, along with classical aeration of the bioreactor. The results were compared to batch cultures without nanobubble addition. Biomass, substrate, and oxygen profiles were determined throughout the time of culture. The Monod and Tsao–Hanson models were used to describe yeast growth. The balance of the bioreactor culture was determined using MATLAB software. The comparison of balance and kinetic parameters demonstrated a higher maximum specific growth rate of yeast in nanobubble cultures than in cultures without nanobubble addition.

Relationship between pH and Medium Dissolved Solids in Terms of Growth and Metabolism of Lactobacilli andSaccharomyces cerevisiaeduring Ethanol Production

The specific growth rates of four species of lactobacilli decreased linearly with increases in the concentration of dissolved solids (sugars) in liquid growth medium. This was most likely due to the osmotic stress exerted by the sugars on the bacteria. The reduction in growth rates corresponded to decreased lactic acid production. Medium pH was another factor studied. As the medium pH decreased from 5.5 to 4.0, there was a reduction in the specific growth rate of lactobacilli and a corresponding decrease in the lactic acid produced. In contrast, medium pH did not have any significant effect on the specific growth rate of yeast at any particular concentration of dissolved solids in the medium. However, medium pH had a significant (P < 0.001) effect on ethanol production. A medium pH of 5.5 resulted in maximal ethanol production in all media with different concentrations of dissolved solids. When the data were analyzed as a 4 (pH levels) by 4 (concentrations of dissolved solids) factorial experiment, there was no synergistic effect (P > 0.2923) observed between pH of the medium and concentration of dissolved solids of the medium in reducing bacterial growth and metabolism. The data suggest that reduction of initial medium pH to 4.0 for the control of lactobacilli during ethanol production is not a good practice as there is a reduction (P < 0.001) in the ethanol produced by the yeast at pH 4.0. Setting the mash (medium) with > or =30% (wt/vol) dissolved solids at a pH of 5.0 to 5.5 will minimize the effects of bacterial contamination and maximize ethanol production by yeast.

Combined effects of molasses sucrose and reactive dye on the growth and dye bioaccumulation properties of Candida tropicalis

The combined effects of molasses sucrose and Remazol Blue or Remazol Black B reactive dye on the growth and dye bioaccumulation properties of adapted Candida tropicalis yeast was investigated in a batch system as a function of initial dye and sucrose concentrations. At a constant sucrose concentration, although the increase in initial dye concentration up to approximately 1000 mg l −1 increased the dye bioaccumulation capacity of yeast for both the dyes, all dye concentrations tested inhibited the growth of C. tropicalis. The cell and bioaccumulated dye concentrations and uptake yields increased with increasing sucrose concentration up to 15 g l −1 at a constant dye concentration for each of the dyes. In 10 g l −1 sucrose and about 1000 mg l −1 dye containing medium the dye adapted yeast was capable of accumulating of Remazol Black B and Remazol Blue dyes with a maximum uptake capacity of 167.5 and 163.3 mg dye per g of dry cells, respectively. The inhibition effect of dye anions on the specific growth rate of yeast was expressed by the non-competitive inhibition model (assuming the dye anions as the toxic inhibitory component) and model parameters were determined by graphical method.

Optimal production of glutathione by controlling the specific growth rate of yeast in fed‐batch culture

The optimal of the specific growth rate was obtained with simple mathematical model in a yeast fed-batch cultures. The model was based on the mass balance around the fed-batch system and the relationship between the specific growth rate, mu, and the specific production rate of glutathione, rho(G). The optimal profile of mu was calculated as a bang-bang type, That is mu, should start from the maximum value, mu(max) and should be kept at mu(max); then mu should be switched to mu(c), which gives a maximum value of rho(G). It was proven from the maximum principle that switching was needed only once, with the switching time from mu(max) to mu(c) depending on the final required glutathione content. Finally, this ideal profile of mu for the maximum production of glutathione was realized by manipulating the substrates feed rate in the fed-batch culture. Using the extended Kalman filter and a programmed-controller/feedback-compensator (PF) system, mu could be controlled at the optimal profile obtained. As a result, the maximum production of glutathione was accomplished fairly successfully. However, further improvement in the controller performance for mu is desired. The control strategy employed here can be applied to other batch reaction processes.

Alcoholic fermentation of beet molasses: effects of lactic acid on yeast fermentation parameters

Industrial beet molasses worts for alcoholic fermentation are also good substrates for the growth of some bacteria, especially lactic acid bacteria. Among microbial metabolites, lactic acid is a major component. This inhibitor of alcoholic fermentation affects the specific growth rate of yeast and the specific rate of alcohol production in different ways depending on the osmotic pressure of the worts; yeast growth is the most altered parameter. The use of a large inoculum of yeast leads to a decrease in the observed inhibition phenomena.