Abstract: Yeast cells are generally used as a model system of eukaryotes due to their complex genetic structure, rapid growth ability in optimum conditions, easy replication and well-defined genetic system properties. Thus, yeast cells increased the knowledge of the principal pathways in humans. During fermentation, carbohydrates (hexoses and pentoses) degrade into some toxic by-products such as 5-hydroxymethylfurfural (5-HMF or HMF) and furfural. HMF influences the ethanol yield, and ethanol productivity; it interferes with microbial growth and is considered as a potent inhibitor of bioethanol production. In this study, yeast single cell behavior under HMF application was monitored by using a continuous flow single phase microfluidic platform. Microfluidic device in operation is fabricated by hot embossing and thermo-compression techniques from cyclo-olefin polymer (COP). COP is biocompatible, transparent and rigid material and it is suitable for observing fluorescence of cells considering its low auto-fluorescence characteristic. The response of yeast cells was recorded through Red Fluorescent Protein (RFP) tagged Nop56 gene product, which is an essential evolutionary-conserved nucleolar protein, and also a member of the box C/D snoRNP complexes. With the application of HMF, yeast cell proliferation continued but HMF slowed down the cell growth, and after HMF treatment the cell proliferation stopped. By the addition of fresh nutrient medium, the yeast cells recovered after 6 hours of HMF exposure. Thus, HMF application suppresses normal functioning of cell cycle but it does not cause cells to die. The monitoring of Nop56 expression phases of the individual cells shed light on the protein and ribosome synthesis cycles along with their link to growth. Further computational study revealed that the mechanisms underlying the inhibitory or inductive effects of HMF on growth are enriched in functional categories of protein degradation, protein processing, DNA repair and multidrug resistance. The present microfluidic device can successfully be used for studying the effects of inhibitory agents on growth by single cell tracking, thus capturing cell to cell variations. By metabolic engineering techniques, engineered strains can be developed, and the metabolic network of the microorganism can thus be manipulated such that chemical overproduction of target metabolite is achieved along with the maximum growth/biomass yield.
Abstract: Lactic acid bacteria (LAB) and some yeast species are common microorganisms found in dairy products and most of them are responsible for the fermentation of foods. Such cultures are isolated and used as a starter culture in the food industry because of providing standardisation of the final product during the food processing. Choice of starter culture is the most important step for the production of fermented food. Isolated LAB and yeast cultures which have the ability to create a biofilm layer can be preferred as a starter in the food industry. The biofilm formation could be beneficial to extend the period of usage time of microorganisms as a starter. On the other hand, it is an undesirable property in pathogens, since biofilm structure allows a microorganism become more resistant to stress conditions such as antibiotic presence. It is thought that the resistance mechanism could be turned into an advantage by promoting the effective microorganisms which are used in the food industry as starter culture and also which have potential to stimulate the gastrointestinal system. Development of the biofilm layer is observed in some LAB and yeast strains. The resistance could make LAB and yeast strains dominant microflora in the human gastrointestinal system; thus, competition against pathogen microorganisms can be provided more easily. Based on this circumstance, in the study, 10 LAB and 10 yeast strains were isolated from various dairy products, such as cheese, yoghurt, kefir, and cream. Samples were obtained from farmer markets and bazaars in Bursa, Turkey. As a part of this research, all isolated strains were identified and their ability of biofilm formation was detected with two different methods and compared with each other. The first goal of this research was to determine whether isolates have the potential for biofilm production, and the second was to compare the validity of two different methods, which are known as “Tube method” and “96-well plate-based method”. This study may offer an insight into developing a point of view about biofilm formation and its beneficial properties in LAB and yeast cultures used as a starter in the food industry.
Abstract: Kefir is a traditional fermented refreshing beverage which is known for its valuable and beneficial properties for human health. Mainly yeast species, lactic acid bacteria (LAB) strains and fewer acetic acid bacteria strains live together in a natural matrix named “kefir grain”, which is formed from various proteins and polysaccharides. Different microbial species live together in slimy kefir grain and it has been thought that synergetic effect could take place between microorganisms, which belong to different genera and species. In this research, yeast and LAB were isolated from kefir samples obtained from Uludag University Food Engineering Department. The cell morphology of isolates was screened by microscopic examination. Gram reactions of bacteria isolates were determined by Gram staining method, and as well catalase activity was examined. After observing the microscopic/morphological and physical, enzymatic properties of all isolates, they were divided into the groups as LAB and/or yeast according to their physicochemical responses to the applied examinations. As part of this research, the antagonistic/synergistic efficacy of the identified five LAB and five yeast strains to each other were determined individually by disk diffusion method. The antagonistic or synergistic effect is one of the most important properties in a co-culture system that different microorganisms are living together. The synergistic effect should be promoted, whereas the antagonistic effect is prevented to provide effective culture for fermentation of kefir. The aim of this study was to determine microbial interactions between identified yeast and LAB strains, and whether their effect is antagonistic or synergistic. Thus, if there is a strain which inhibits or retards the growth of other strains found in Kefir microflora, this circumstance shows the presence of antagonistic effect in the medium. Such negative influence should be prevented, whereas the microorganisms which have synergistic effect on each other should be promoted by combining them in kefir grain. Standardisation is the most desired property for industrial production. Each microorganism found in the microbial flora of a kefir grain should be identified individually. The members of the microbial community found in the glue-like kefir grain may be redesigned as a starter culture regarding efficacy of each microorganism to another in kefir processing. The main aim of this research was to shed light on more effective production of kefir grain and to contribute a standardisation of kefir processing in the food industry.
Abstract: Biofuel is one of the renewable energy sources adapted by the Philippine government in order to lessen the dependency on foreign fuel and to reduce carbon dioxide emissions. Rain tree pods were seen to be a promising source of bioethanol since it contains significant amount of fermentable sugars. The study was conducted to establish the complete procedure in processing rain tree pods for village level hydrous bioethanol production. Production processes were done for village level hydrous bioethanol production from collection, drying, storage, shredding, dilution, extraction, fermentation, and distillation. The feedstock was sundried, and moisture content was determined at a range of 20% to 26% prior to storage. Dilution ratio was 1:1.25 (1 kg of pods = 1.25 L of water) and after extraction process yielded a sugar concentration of 22 0Bx to 24 0Bx. The dilution period was three hours. After three hours of diluting the samples, the juice was extracted using extractor with a capacity of 64.10 L/hour. 150 L of rain tree pods juice was extracted and subjected to fermentation process using a village level anaerobic bioreactor. Fermentation with yeast (Saccharomyces cerevisiae) can fasten up the process, thus producing more ethanol at a shorter period of time; however, without yeast fermentation, it also produces ethanol at lower volume with slower fermentation process. Distillation of 150 L of fermented broth was done for six hours at 85 °C to 95 °C temperature (feedstock) and 74 °C to 95 °C temperature of the column head (vapor state of ethanol). The highest volume of ethanol recovered was established at with yeast fermentation at five-day duration with a value of 14.89 L and lowest actual ethanol content was found at without yeast fermentation at three-day duration having a value of 11.63 L. In general, the results suggested that rain tree pods had a very good potential as feedstock for bioethanol production. Fermentation of rain tree pods juice can be done with yeast and without yeast.
Abstract: Colorectal cancer (CRC) is one of the most prevalent cancers and intestinal microbial community plays an important role in colorectal tumorigenesis. Probiotics have recently been assessed as effective anti-proliferative agents and thus this study was performed to examine whether CRC undergo apoptosis by treating with isolated Iranian native dairy yeast, Kluyveromyces marxianus YAS, secretion metabolites. The cytotoxicity assessments on cells (HT-29, Caco-2) were accomplished through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay as well as qualitative DAPI (4',6-diamidino-2-phenylindole staining) and quantitative (flow cytometry assessments) evaluations of apoptosis. To evaluate the main mechanism of apoptosis, Real time PCR method was applied. Kluyveromyces marxianus YAS secretions (IC50) showed significant cytotoxicity against HT-29 and Caco-2 cancer cell lines (66.57 % and 66.34 % apoptosis) similar to 5-Fluorouracil (5-FU) while apoptosis only was developed in 27.57 % of KDR normal cells. The prophylactic effects of Kluyveromyces marxianus (PTCC 5195), as a reference yeast, was not similar to Kluyveromyces marxianus YAS indicating strain dependency of bioactivities on CRC disease prevention. Based on real time PCR results, the main cytotoxicity is related to apoptosis phenomenon and the core related mechanism is depended on the overexpression of BAX, CASP 9, CASP 8 and CASP 3 inducing apoptosis genes. However, several investigations should be conducted to precisely determine the effective compounds to be used as anticancer therapeutics in the future.
Abstract: Toddy sediment (TS) was cultured in a PDA medium
to determine initial yeast load, and also it was undergone sun, shade,
solar, dehumidified cold air (DCA) and hot air oven (at 400, 500 and
60oC) drying with a view to preserve viability of yeast. Thereafter,
this study was conducted according to two factor factorial design in
order to determine best preservation method. Therein the dried TS
from the best drying method was taken and divided into two portions.
One portion was mixed with 3: 7 ratio of TS: rice flour and the
mixture was divided in to two again. While one portion was kept
under in house condition the other was in a refrigerator. Same
procedure was followed to the rest portion of TS too but it was at the
same ratio of corn flour. All treatments were vacuum packed in triple
laminate pouches and the best preservation method was determined
in terms of leavening index (LI). The TS obtained from the best
preservation method was used to make foods (bread and hopper) and
organoleptic properties of it were evaluated against same of ordinary
foods using sensory panel with a five point hedonic scale.
Results revealed that yeast load or fresh TS was 58×106 CFU/g.
The best drying method in preserving viability of yeast was DCA
because LI of this treatment (96%) is higher than that of other three
treatments. Organoleptic properties of foods prepared from best
preservation method are as same as ordinary foods according to Duo
trio test.
Abstract: In this work, two fermentations at different
temperatures (25 and 30ºC), with cell recycling, were accomplished
to produce ethanol, using a mix of commercial substrates, xylose
(70%) and glucose (30%), as organic source for Scheffersomyces
stipitis. Five consecutive fermentations of 80 g L-1 (1º, 2º and 3º
recycles), 96 g L-1 (4º recycle) and 120 g L-1 (5º recycle)reduced
sugars led to a final maximum ethanol concentration of 17.2 and 34.5
g L-1, at 25 and 30ºC, respectively. Glucose was the preferred
substrate; moreover xylose startup degradation was initiated after a
remaining glucose presence in the medium. Results showed that yeast
acid treatment, performed before each cycle, provided improvements
on cell viability, accompanied by ethanol productivity of 2.16 g L-1 h-
1 at 30ºC. A maximum 36% of xylose was retained in the
fermentation medium and after five-cycle fermentation an ethanol
yield of 0.43 g ethanol/g sugars was observed. S. stipitis fermentation
capacity and tolerance showed better results at 30ºC with 83.4% of
theoretical yield referenced on initial biomass.
Abstract: The aim of this study was to select the best strains of
Saccharomyces cerevisiae able to resist lead and cadmium. Ten
strains were screened on the basis of their resistance at different
concentrations of 0, 2, 4, 8, 12, 16, 20 and 24 ppm for Pb and 0, 0.5,
1, 2, 4, 6, 8 and 10 ppm for Cd. The properties of baker's yeast
quality were decreased by the increase of Pb or Cd in growth
medium. The slope values of yield, total viable cells and gassing
power of produced baker's yeast were investigated as an indicator of
metal resistant. In addition, concentrations of Pb and Cd in produced
baker's yeast were determined. The strain of S. cerevisiae FH-620
had the highest resistance against Pb and Cd and had the minimum
levels of both two investigated metals in produced baker's yeast.
Abstract: Natural antimicrobials are used to preserve foods that
can be found in plants, animals, and microorganisms. Antimicrobial
substances are natural or artificial agents that produced by
microorganisms or obtained semi/total chemical synthesis are used at
low concentrations to inhibit the growth of other microorganisms.
Food borne pathogens and spoilage microorganisms are inactivated
by the use of antagonistic microorganisms and their metabolites.
Yeasts can produce toxic proteins or glycoproteins (toxins) that cause
inhibition of sensitive bacteria and yeast species. Antimicrobial
substance producing phenotypes belonging different yeast genus
were isolated from different sources. Toxins secreted by many yeast
strains inhibiting the growth of other yeast strains. These strains show
antimicrobial activity, inhibiting the growth of mold and bacteria.
The effect of antimicrobial agents produced by yeasts can be
extremely fast, and therefore may be used in various treatment
procedures. Rapid inhibition of microorganisms is possibly caused by
microbial cell membrane lipopolysaccharide binding and in
activation (neutralization) effect. Antimicrobial agents inhibit the
target cells via different mechanisms of action.
Abstract: The biomass-based fuels have become great concern in order to replace the petroleum-based fuels. Biofuels are a wide range of fuels referred to liquid, gas and solid fuels produced from biomass. Recently, higher chain alcohols such as 3-methyl-1-butanol and isobutanol have become a better candidate compared to bioethanol in order to replace gasoline as transportation fuel. Therefore, in this study, 3-methyl-1-butanol was produced through a fermentation process by yeast. Several types of yeast involved in this research including Saccharomyces cerevisiae, Kluyveromyces lactis GG799 and Pichia pastoris (KM71H, GS115 and X33). The result obtained showed that K. lactis GG799 gave the highest concentration of 3-methyl-1-butanol at 274 mg/l followed by S. cerevisiae, P. pastoris GS115, P. pastoris KM71H and P. pastoris X33 at 265 mg/l, 190 mg/l, 182 mg/l and 174 mg/l respectively. Based on the result, it proved that yeast have a potential in producing 3-methyl-1-butanol naturally.
Abstract: The hydrolysis of lactose using β-galactosidase is one of the most promising biotechnological applications, which has wide range of potential applications in food processing industries. However, due to intracellular location of the yeast enzyme, and expensive extraction methods, the industrial applications of enzymatic hydrolysis processes are being hampered. The use of permeabilization technique can help to overcome the problems associated with enzyme extraction and purification of yeast cells and to develop the economically viable process for the utilization of whole cell biocatalysts in food industries. In the present investigation, standardization of permeabilization process of novel yeast isolate was carried out using a statistical model approach known as Response Surface Methodology (RSM) to achieve maximal b-galactosidase activity. The optimum operating conditions for permeabilization process for optimal β-galactosidase activity obtained by RSM were 1:1 ratio of toluene (25%, v/v) and ethanol (50%, v/v), 25.0 oC temperature and treatment time of 12 min, which displayed enzyme activity of 1.71 IU /mg DW.
Abstract: Nowadays there is a growing interest in biofuel production in most countries because of the increasing concerns about hydrocarbon fuel shortage and global climate changes, also for enhancing agricultural economy and producing local needs for transportation fuel. Ethanol can be produced from biomass by the hydrolysis and sugar fermentation processes. In this study ethanol was produced without using expensive commercial enzymes from sugarcane bagasse. Alkali pretreatment was used to prepare biomass before enzymatic hydrolysis. The comparison between NaOH, KOH and Ca(OH)2 shows NaOH is more effective on bagasse. The required enzymes for biomass hydrolysis were produced from sugarcane solid state fermentation via two fungi: Trichoderma longibrachiatum and Aspergillus niger. The results show that the produced enzyme solution via A. niger has functioned better than T. longibrachiatum. Ethanol was produced by simultaneous saccharification and fermentation (SSF) with crude enzyme solution from T. longibrachiatum and Saccharomyces cerevisiae yeast. To evaluate this procedure, SSF of pretreated bagasse was also done using Celluclast 1.5L by Novozymes. The yield of ethanol production by commercial enzyme and produced enzyme solution via T. longibrachiatum was 81% and 50% respectively.
Abstract: This experiment was conducted to investigate the
effect of different levels of dietary chromium yeast (Cr-yeast) on
thigh meat quality of broiler chicks reared under heat stress
condition. Two hundred and forty Ross male chickens in heat stress
condition (33±3°C) were allocated to five treatments in a completely
randomized design. Treatments were supplemented with 0 (control),
200, 400, 800 and 1200 μg kg-1 Cr in the form of Cr yeast. Twelve
chicks from each treatment were slaughtered at 42 d, to evaluate
moisture, protein, lipid, pH and lipid oxidation of thigh meat.
Protein, moisture, lipid and pH of thigh meat were not affected by
supplemental Cr. Thigh meat lipid tended to decrease in broilers
received 1200 μg kg-1. Storage time increased lipid oxidation of
meat (P
Abstract: This paper describes a novel approach for deriving
modules from protein-protein interaction networks, which combines
functional information with topological properties of the network.
This approach is based on weighted clustering coefficient, which
uses weights representing the functional similarities between the
proteins. These weights are calculated according to the semantic
similarity between the proteins, which is based on their Gene
Ontology terms. We recently proposed an algorithm for identification
of functional modules, called SWEMODE (Semantic WEights for
MODule Elucidation), that identifies dense sub-graphs containing
functionally similar proteins. The rational underlying this approach is
that each module can be reduced to a set of triangles (protein triplets
connected to each other). Here, we propose considering semantic
similarity weights of all triangle-forming edges between proteins. We
also apply varying semantic similarity thresholds between
neighbours of each node that are not neighbours to each other (and
hereby do not form a triangle), to derive new potential triangles to
include in module-defining procedure. The results show an
improvement of pure topological approach, in terms of number of
predicted modules that match known complexes.
Abstract: The effects of commercial or bovine yeasts on the
performance and blood variables of broiler chickens intoxicated with
aflatoxin were investigated in broilers. Four hundred eighty broilers
(Arbor Acres; 3-wk-old) were randomly assigned to 4 groups. Each
group (120 broiler chickens) was further randomly divided into 6
replicates of 20 chickens. The treatments were control diet without
additives (treatment 1), 250 ppb AFB1 (treatment 2), commercial
yeast, Saccharomyces cerevisiae, (CY 2.5 x 107 CFU/g) + 250 ppb
AFB1 (treatment 3) and bovine yeast, Saccharomyces cerevisiae,
(BY 2.5 x 107 CFU/g + 250 ppb AFB1 (treatment 4). Complete
randomized design (CRD) was used in the experiment. Feed
consumption and body weight were recorded at every five-day
period. On day 42, carcass compositions were determined from 30
birds per treatment. While chicks were sacrificed, 3-4 ml blood
sample was taken and stored frozen at (-20°C) for serum chemical
analysis to determine effects of consumption of diets on blood
chemistry (total protein, albumin, glucose, urea, cholesterol and
triglycerides). There were no significant differences in ADFI among
the treatments(P>0.05). However, BWG, FCR and mortality were
highly significantly different (P
Abstract: UK breweries generate extensive by products in the
form of spent grain, slurry and yeast. Much of the spent grain is
produced by large breweries and processed in bulk for animal feed.
Spent brewery grains contain up to 20% protein dry weight and up to
60% fiber and are useful additions to animal feed. Bulk processing is
economic and allows spent grain to be sold so providing an income
to the brewery. A proportion of spent grain, however, is produced by
small local breweries and is more variably distributed to farms or
other users using intermittent collection methods. Such use is much
less economic and may incur losses if not carefully assessed for
transport costs. This study reports an economic returns of using wet
brewery spent grain (WBSG) in animal feed using the Co-product
Optimizer Decision Evaluator model (Cattle CODE) developed by
the University of Nebraska to predict performance and economic
returns when byproducts are fed to finishing cattle. The results
indicated that distance from brewery to farm had a significantly
greater effect on the economics of use of small brewery spent grain
and that alternative uses than cattle feed may be important to
develop.
Abstract: Understanding the cell's large-scale organization is an interesting task in computational biology. Thus, protein-protein interactions can reveal important organization and function of the cell. Here, we investigated the correspondence between protein interactions and function for the yeast. We obtained the correlations among the set of proteins. Then these correlations are clustered using both the hierarchical and biclustering methods. The detailed analyses of proteins in each cluster were carried out by making use of their functional annotations. As a result, we found that some functional classes appear together in almost all biclusters. On the other hand, in hierarchical clustering, the dominancy of one functional class is observed. In the light of the clustering data, we have verified some interactions which were not identified as core interactions in DIP and also, we have characterized some functionally unknown proteins according to the interaction data and functional correlation. In brief, from interaction data to function, some correlated results are noticed about the relationship between interaction and function which might give clues about the organization of the proteins, also to predict new interactions and to characterize functions of unknown proteins.
Abstract: The zinc and iron environments in different growth
stages have been studied with EXAFS and XANES with Brookhaven
Synchrotron Light Source. Tissue samples included meat, organ,
vegetable, leaf, and yeast. The project studied the EXAFS and
XANES of tissue samples using Zn and Fe K-edges. Duck embryo
samples show that brain and intestine would contain shorter EXFAS
determined Zn-N/O bond; as with the cases of fresh yeast versus
reconstituted live yeast and green leaf versus yellow leaf. The
XANES Fourier transform characteristic-length would be useful as a
functionality index for selected types of tissue samples in various
physical states. The extension to the development of functional
synchrotron imaging for tissue engineering application based on
spectroscopic technique is discussed.
Abstract: Compared to oil production from microorganisms, little work has been performed for mixed culture of microalgae and yeast. In this article it is aimed to show high oil accumulation potential of mixed culture of microalgae Chlorella sp. KKU-S2 and oleaginous yeast Torulaspora maleeae Y30 using sugarcane molasses as substrate. The monoculture of T. maleeae Y30 grew faster than that of microalgae Chlorella sp. KKU-S2. In monoculture of yeast, a biomass of 6.4g/L with specific growth rate (m) of 0.265 (1/d) and lipid yield of 0.466g/L were obtained, while 2.53g/L of biomass with m of 0.133 (1/d) and lipid yield of 0.132g/L were obtained for monoculture of Chlorella sp. KKU-S2. The biomass concentration in the mixed culture of T. maleeae Y30 with Chlorella sp. KKU-S2 increased faster and was higher compared with that in the monoculture and mixed culture of microalgae. In mixed culture of microalgae Chlorella sp. KKU-S2 and C. vulgaris TISTR8580, a biomass of 3.47g/L and lipid yield of 0.123 g/L were obtained. In mixed culture of T. maleeae Y30 with Chlorella sp. KKU-S2, a maximum biomass of 7.33 g/L and lipid yield of 0.808g/L were obtained. Maximum cell yield coefficient (YX/S, 0.229g/L), specific yield of lipid (YP/X, 0.11g lipid/g cells) and volumetric lipid production rate (QP, 0.115 g/L/d) were obtained in mixed culture of yeast and microalgae. Clearly, T. maleeae Y30 and Chlorella sp. KKU-S2 use sugarcane molasses as organic nutrients efficiently in mixed culture under mixotrophic growth. The biomass productivity and lipid yield are notably enhanced in comparison with monoculture.
Abstract: Understanding the cell's large-scale organization is an
interesting task in computational biology. Thus, protein-protein
interactions can reveal important organization and function of the
cell. Here, we investigated the correspondence between protein
interactions and function for the yeast. We obtained the correlations
among the set of proteins. Then these correlations are clustered using
both the hierarchical and biclustering methods. The detailed analyses
of proteins in each cluster were carried out by making use of their
functional annotations. As a result, we found that some functional
classes appear together in almost all biclusters. On the other hand, in
hierarchical clustering, the dominancy of one functional class is
observed. In brief, from interaction data to function, some correlated
results are noticed about the relationship between interaction and
function which might give clues about the organization of the
proteins.