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1.
Electron. j. biotechnol ; 46: 55-64, jul. 2020. tab, graf
Article in English | LILACS | ID: biblio-1223246

ABSTRACT

BACKGROUND: Ethanol concentration (PE), ethanol productivity (QP) and sugar consumption (SC) are important values in industrial ethanol production. In this study, initial sugar and nitrogen (urea) concentrations in sweet sorghum stem juice (SSJ) were optimized for high PE (≥10%, v/v), QP, (≥2.5 g/L·h) and SC (≥90%) by Saccharomyces cerevisiae SSJKKU01. Then, repeated-batch fermentations under normal gravity (NG) and high gravity (HG) conditions were studied. RESULTS: The initial sugar at 208 g/L and urea at 2.75 g/L were the optimum values to meet the criteria. At the initial yeast cell concentration of ~1 × 108 cells/mL, the PE, QP and SC were 97.06 g/L, 3.24 g/L·h and 95.43%, respectively. Repeated-batch fermentations showed that the ethanol production efficiency of eight successive cycles with and without aeration were not significantly different when the initial sugar of cycles 2 to 8 was under NG conditions (~140 g/L). Positive effects of aeration were observed when the initial sugar from cycle 2 was under HG conditions (180­200 g/L). The PE and QP under no aeration were consecutively lower from cycle 1 to cycle 6. Additionally, aeration affected ergosterol formation in yeast cell membrane at high ethanol concentrations, whereas trehalose content under all conditions was not different. CONCLUSION: Initial sugar, sufficient nitrogen and appropriated aeration are necessary for promoting yeast growth and ethanol fermentation. The SSJ was successfully used as an ethanol production medium for a high level of ethanol production. Aeration was not essential for repeated-batch fermentation under NG conditions, but it was beneficial under HG conditions.


Subject(s)
Saccharomyces cerevisiae/metabolism , Sorghum/chemistry , Ethanol/metabolism , Saccharomyces cerevisiae/growth & development , Urea , Yeasts/growth & development , Aeration , Sorghum/microbiology , Ethanol/analysis , Sugars , Juices , Fermentation , Gravitation , Nitrogen
2.
Braz. j. med. biol. res ; 53(4): e9200, 2020. tab, graf
Article in English | LILACS | ID: biblio-1089350

ABSTRACT

The consumption of alcoholic beverages influences carbohydrate and lipid metabolism, although it is not yet clear whether metabolism during physical exercise at different intensities is also affected. This was the objective of the present study. Eight young and healthy volunteers performed a treadmill test to identify the running speed corresponding to a lactate concentration of 4 mM (S4mM). At least 48 h later, they were subjected to two experimental trials (non-alcohol or alcohol) in which they performed two 1-km running sessions at the following intensities: 1) S4mM; 2) 15% above S4mM. In both trials, blood lactate, triglycerides, and glucose concentrations were measured before and after exercise. The acute alcohol intake increased triglycerides, but not lactate concentration under resting conditions. Interestingly, alcohol intake enhanced the exercise-induced increase in lactate concentration at the two intensities: S4mM (non-alcohol: 4.2±0.3 mM vs alcohol: 4.8±0.9 mM; P=0.003) and 15% above S4mM trial (P=0.004). When volunteers ingested alcohol, triglycerides concentration remained increased after treadmill running (e.g., at S4mM - at rest; non-alcohol: 0.2±0.5 mM vs alcohol: 1.3±1.3 mM; P=0.048). In contrast, glucose concentration was not modified by either alcohol intake, exercise, or their combination. We concluded that an acute alcohol intake changed lactate and lipid metabolism without affecting blood glucose concentration. In addition, the increase in lactate concentration caused by alcohol was specifically observed when individuals exercised, whereas augmented triglycerides concentration was already observed before exercise and was sustained thereafter.


Subject(s)
Humans , Male , Adult , Young Adult , Physical Endurance/drug effects , Blood Glucose/metabolism , Alcohol Drinking/blood , Lactic Acid/blood , Ethanol/metabolism , Alcoholic Beverages/analysis , Physical Endurance/physiology , Triglycerides/blood , Blood Glucose/analysis , Exercise Test , Athletic Performance/physiology
3.
Electron. j. biotechnol ; 42: 16-22, Nov. 2019. graf, tab
Article in English | LILACS | ID: biblio-1087350

ABSTRACT

Background: Fuels and chemicals from renewable feedstocks have a growing demand, and acetone, butanol and ethanol (ABE) are some relevant examples. These molecules can be produced by the bacterial fermentation process using hydrolysates generated from lignocellulosic biomass as sugarcane bagasse, one of the most abundant sources of lignocellulosic biomass in Brazil. It originates as a residue in mills and distilleries in the production of sugar and ethanol. Results: In the present work, two strategies to generate hydrolysates of sugarcane bagasse were adopted. The fermentation of the first hydrolysate by Clostridium acetobutylicum DSM 6228 resulted in final concentrations of butanol, acetone and ethanol of 6.4, 4.5 and 0.6 g/L, respectively. On the other hand, the second hydrolysate presented better results (averages of 9.1, 5.5 and 0.8 g/L, respectively), even without the need for nutrient supplementation, since key elements were already present in the medium. The productivity (QP) and yield (YP/S) of the solvents with second hydrolysate were 0.5 g/L•h-1 and 0.4 g/g, respectively. Conclusions: The results described herein open new perspectives for the production of important molecules from residual lignocellulosic biomass for the fuel and chemical industries within the context of second-generation biorefinery.


Subject(s)
Acetone/metabolism , Cellulose/metabolism , Saccharum/metabolism , Ethanol/metabolism , Butanols/metabolism , Brazil , Cellulose/chemistry , Saccharum/chemistry , Clostridium acetobutylicum/metabolism , Biofuels , Fermentation
4.
Electron. j. biotechnol ; 41: 1-8, sept. 2019. tab, ilus, graf
Article in English | LILACS | ID: biblio-1053552

ABSTRACT

Background: The bioethanol produced from biomass is a promising alternative fuel. The lignocellulose from marginal areas or wasteland could be a promising raw material for bioethanol production because it is present in large quantities, is cheap, renewable and has favorable environmental properties. Despite these advantages, lignocellulosic biomass is much more difficult to process than cereal grains, due to the need for intensive pretreatment and relatively large amounts of cellulases for efficient hydrolysis. Therefore, there is a need to develop an efficient and cost-effective method for the degradation and fermentation of lignocellulosic biomass to ethanol. Results: The usefulness of lignocellulosic biomass from wasteland for the production of bioethanol using pretreatment with the aid of ionic liquids of 1-ethyl-3-methylimidazolium acetate and 1-ethyl-3-methylimidazolium chloride was evaluated in this study. The pretreatment process, enzymatic hydrolysis and alcoholic fermentation lasted a total of 10 d. The largest amounts of bioethanol were obtained from biomass originating from agricultural wasteland, in which the dominant plant was fireweed (Chamaenerion angustifolium) and from the field where the common broom (Cytisus scoparius) was the dominant. Conclusions: The plants such as fireweed, common broom, hay and goldenrod may be useful for the production of liquid biofuels and it would be necessary in the further stage of research to establish and optimize the conditions for the technology of ethyl alcohol producing from these plant species. Enzymatic hydrolysis of biomass from agricultural wastelands results in a large increase in fermentable sugars, comparable to the enzymatic hydrolysis of rye, wheat, rice or maize straw.


Subject(s)
Soil/chemistry , Biomass , Ethanol/metabolism , Biodegradation, Environmental , Cellulases/analysis , Enzymes/metabolism , Ionic Liquids , Biofuels , Hydrolysis , Lignin/analysis
5.
Electron. j. biotechnol ; 41: 13-21, sept. 2019. ilus, graf, tab
Article in English | LILACS | ID: biblio-1053560

ABSTRACT

Background: Sugars from sweet sorghum stalks can be used to produce ethanol and also to grow oleaginous yeasts. Instead of two separate processes, in this paper we propose a different route producing ethanol and microbial oil in two consecutive fermentation steps. Results: Three yeasts were compared in the first ethanol producing step. In the second step four different oleaginous yeasts were tested. Sweet sorghum juice was first clarified and concentrated. High gravity ethanol fermentation was carried out with concentrated juice with 23.7 g/100 mL of total sugars and without added nutrients. Total sugars were 2.5 times more than the original clarified juice. One yeast gave the best overall response over the two other tested; relative high ethanol productivity, 1.44 g ethanol/L•h−1 , and 90% of sugar consumption. Aeration by flask agitation produced superior results than static flasks for all yeasts. Microbial oil production was done employing the residual liquid left after ethanol separation. The pooled residual liquid from the ethanol distillation contained 7.08 g/mL of total carbohydrates, rich in reducing sugars. Trichosporon oleaginosus and Lipomyces starkeyi produced higher dry biomass, total sugar consumption and oil productivity than the other two oleaginous yeasts tested; with values around 25 g/L, 80%, and 0.55 g oil/L•h−1 respectively. However, the biomass oil content in all yeasts was relatively low in the range of 14 to 16%. Conclusion: The two step process is viable and could be considered an integral part of a consolidated biorefinery from sweet sorghum.


Subject(s)
Sorghum/chemistry , Ethanol/metabolism , Fruit and Vegetable Juices , Saccharomyces cerevisiae , Yeasts , Trichosporon , Sugars , Juices , Lipomyces , Biofuels/microbiology , Fermentation
6.
Electron. j. biotechnol ; 41: 95-99, sept. 2019. graf, tab, ilus
Article in English | LILACS | ID: biblio-1087252

ABSTRACT

Background: Pretreatment is the critically important step for the production of ethanol from lignocelluloses. In this study, hardwood birch (Betula pendula) and softwood spruce (Norway spruce) woods were pretreated with a newly synthesized morpholinium ionic liquid, 1-H-3-methylmorpholinium chloride ([HMMorph][Cl]), followed by enzymatic hydrolysis and fermentation to ethanol. Results: [HMMorph][Cl] was synthesized using inexpensive raw materials, i.e., hydrochloric acid and N-methyl morpholine, following a simple process. The influence of pretreatment time (2, 3, 5, and 8 h) and temperature (120 and 140°C) in terms of hydrolysis efficiency was investigated. Glucose yields from enzymatic hydrolysis were improved from 13.7% to 45.7% and 12.9% to 51.8% after pretreatment of birch and spruce woods, respectively, under optimum pretreatment conditions (i.e., at 140°C for 3 h) as compared to those from pristine woods. Moreover, the yields of ethanol production from birch and spruce were increased to 34.8% and 44.2%, respectively, while the yields were negligible for untreated woods. Conclusions: This study demonstrated the ability of [HMMorph][Cl] as an inexpensive agent to pretreat both softwood and hardwood.


Subject(s)
Betula/metabolism , Ethanol/metabolism , Ethanol/chemical synthesis , Lignin/metabolism , Cellulose/metabolism , Pretreatment , Chlorides/chemistry , Abies , Biofuels , Fermentation , Hydrolysis
7.
Braz. j. microbiol ; 49(2): 378-391, Apr.-June 2018. tab, graf
Article in English | LILACS | ID: biblio-889229

ABSTRACT

Abstract High potential, thermotolerant, ethanol-producing yeasts were successfully isolated in this study. Based on molecular identification and phylogenetic analysis, the isolated thermotolerant yeasts were clustered in the genera of Pichia kudriavzevii, Candida tropicalis, Candida orthopsilosis, Candida glabrata and Kodamea ohmeri. A comparative study of ethanol production using 160 g/L glucose as a substrate revealed several yeast strains that could produce high ethanol concentrations at high temperatures. When sugarcane bagasse (SCB) hydrolysate containing 85 g/L glucose was used as a substrate, the yeast strain designated P. kudriavzevii RZ8-1 exhibited the highest ethanol concentrations of 35.51 g/L and 33.84 g/L at 37 °C and 40 °C, respectively. It also exhibited multi-stress tolerance, such as heat, ethanol and acetic acid tolerance. During ethanol fermentation at high temperature (42 °C), genes encoding heat shock proteins (ssq1 and hsp90), alcohol dehydrogenases (adh1, adh2, adh3 and adh4) and glyceraldehyde-3-phosphate dehydrogenase (tdh2) were up-regulated, suggesting that these genes might play a crucial role in the thermotolerance ability of P. kudriavzevii RZ8-1 under heat stress. These findings suggest that the growth and ethanol fermentation activities of this organism under heat stress were restricted to the expression of genes involved not only in heat shock response but also in the ethanol production pathway.


Subject(s)
Ethanol/metabolism , Hot Temperature , Pichia/metabolism , Biotransformation , Candida/classification , Candida/isolation & purification , Candida/metabolism , Pichia/classification , Pichia/isolation & purification , Plant Extracts/metabolism , Saccharum/metabolism , Stress, Physiological
8.
Braz. j. microbiol ; 49(1): 162-168, Jan.-Mar. 2018. tab, graf
Article in English | LILACS | ID: biblio-889200

ABSTRACT

ABSTRACT For the implementation of cellulosic ethanol technology, the maximum use of lignocellulosic materials is important to increase efficiency and to reduce costs. In this context, appropriate use of the pentose released by hemicellulose hydrolysis could improve de economic viability of this process. Since the Saccharomyces cerevisiae is unable to ferment the pentose, the search for pentose-fermenting microorganisms could be an alternative. In this work, the isolation of yeast strains from decaying vegetal materials, flowers, fruits and insects and their application for assimilation and alcoholic fermentation of xylose were carried out. From a total of 30 isolated strains, 12 were able to assimilate 30 g L-1 of xylose in 120 h. The strain Candida tropicalis S4 produced 6 g L-1 of ethanol from 56 g L-1 of xylose, while the strain C. tropicalis E2 produced 22 g L-1 of xylitol. The strains Candida oleophila G10.1 and Metschnikowia koreensis G18 consumed significant amount of xylose in aerobic cultivation releasing non-identified metabolites. The different materials in environment were source for pentose-assimilating yeast with variable metabolic profile.


Subject(s)
Pentoses/metabolism , Xylose/metabolism , Yeasts/metabolism , Vegetables/microbiology , Xylitol/metabolism , Yeasts/isolation & purification , Yeasts/classification , Yeasts/genetics , Ethanol/metabolism , Fermentation
9.
Electron. j. biotechnol ; 31: 61-66, Jan. 2018. graf, ilus, tab
Article in English | LILACS | ID: biblio-1022044

ABSTRACT

Background: Study of correlation between pretreatment of yeast with ultraviolet radiation and efficiency of further fermentation of wort made of ultrafine grain particles to ethanol. Results: We investigated three races of industrial yeast Saccharomyces cerevisiae (native and irradiated by ultraviolet). Physiological properties during fermentation of starchy wort were tested in all variants. It was shown that activation of the yeast by ultraviolet radiation allows to further increase the ethanol yield by 25% on average compared with the native yeast races when using thin (up to micro- and nano-sized particles) or standard grain grinding. Conclusions: Using mechanical two-stage grinding of starchy raw materials and ultraviolet pretreatment of yeast, the efficiency of saccharification of starch and fermentation of wort to ethanol was increased.


Subject(s)
Saccharomyces cerevisiae/radiation effects , Ultraviolet Rays , Yeasts/radiation effects , Ethanol/radiation effects , Saccharomyces/metabolism , Starch , Temperature , Yeasts/metabolism , Enzyme Stability , Ethanol/metabolism , Fermentation , Glucose , Amylases
10.
Electron. j. biotechnol ; 31: 67-54, Jan. 2018. ilus, tab, graf
Article in English | LILACS | ID: biblio-1022118

ABSTRACT

Background: Pretreatment of lignocellulosic biomass is essential for using it as a raw material for chemical and biofuel production. This study evaluates the effects of variables in the chemical pretreatment of the Arundo biomass on the glucose and xylose concentrations in the final enzymatic hydrolysate. Three pretreatments were tested: acid pretreatment, acid pretreatment followed by alkaline pretreatment, and alkaline pretreatment. Results: The amounts of glucose and xylose released by the enzymatic hydrolysis of the Arundo biomass obtained from acid pretreatment ranged from 6.2 to 19.1 g/L and 1.8 to 3.1 g/L, respectively. The addition of alkaline pretreatment led to a higher yield from the enzymatic hydrolysis, with the average glucose concentration 3.5 times that obtained after biomass hydrolysis with an acid pretreatment exclusively. The use of an alkaline pretreatment alone resulted in glucose and xylose concentrations similar to those obtained in the two-step pretreatment: acid pretreatment followed by alkaline pretreatment. There was no significant difference in 5-hydroxymethylfurfural, furfural, or acetic acid concentrations among the pretreatments. Conclusion: Alkaline pretreatment was essential for obtaining high concentrations of glucose and xylose. The application of an alkaline pretreatment alone resulted in high glucose and xylose concentrations. This result is very significant as it allows a cost reduction by eliminating one step.


Subject(s)
Ethanol/metabolism , Poaceae/chemistry , Acids/chemistry , Xylose/analysis , Cellulose/chemistry , Biomass , Biofuels , Glucose/analysis , Hydrolysis , Lignin
11.
Braz. j. microbiol ; 49(supl.1): 140-150, 2018. tab, graf
Article in English | LILACS | ID: biblio-974343

ABSTRACT

Abstract Ethanol production from sweet sorghum juice (SSJ) using the thermotolerant Saccharomyces cerevisiae strain DBKKUY-53 immobilized in an alginate-loofah matrix (ALM) was successfully developed. As found in this study, an ALM with dimensions of 20 × 20 × 5 mm3 is effective for cell immobilization due to its compact structure and long-term stability. The ALM-immobilized cell system exhibited greater ethanol production efficiency than the freely suspended cell system. By using a central composite design (CCD), the optimum conditions for ethanol production from SSJ by ALM-immobilized cells were determined. The maximum ethanol concentration and volumetric ethanol productivity obtained using ALM-immobilized cells under the optimal conditions were 97.54 g/L and 1.36 g/L h, respectively. The use of the ALM-immobilized cells was successful for at least six consecutive batches (360 h) without any loss of ethanol production efficiency, suggesting their potential application in industrial ethanol production.


Subject(s)
Saccharomyces cerevisiae/metabolism , Industrial Microbiology/methods , Sorghum/microbiology , Ethanol/metabolism , Saccharomyces cerevisiae/chemistry , Cells, Immobilized/metabolism , Cells, Immobilized/chemistry , Sorghum/metabolism , Sorghum/chemistry , Ethanol/analysis , Alginates/chemistry , Fermentation
12.
Braz. j. microbiol ; 49(supl.1): 151-159, 2018. tab, graf
Article in English | LILACS | ID: biblio-974324

ABSTRACT

Abstract To reduce the cost of obtaining bacterial cellulose, acidic by-products of the alcohol and dairy industries were used without any pretreatment or addition of other nitrogen sources. Studies have shown that the greatest accumulation of bacterial cellulose (6.19 g/L) occurs on wheat thin stillage for 3 days of cultivation under dynamic conditions, which is almost 3 times higher than on standard Hestrin and Schramm medium (2.14 g/L). The use of whey as a nutrient medium makes it possible to obtain 5.45 g/L bacterial cellulose under similar conditions of cultivation. It is established that the pH of the medium during the growth of Gluconacetobacter sucrofermentans B-11267 depends on the feedstock used and its initial value. By culturing the bacterium on thin stillage and whey, there is a decrease in the acidity of the waste. It is shown that the infrared spectra of bacterial cellulose obtained in a variety of environments have a similar character, but we found differences in the micromorphology and crystallinity of the resulting biopolymer.


Subject(s)
Waste Products/analysis , Industrial Microbiology/methods , Cellulose/biosynthesis , Gluconacetobacter/metabolism , Waste Products/economics , Triticum/metabolism , Triticum/microbiology , Industrial Microbiology/economics , Food Industry , Culture Media/economics , Culture Media/metabolism , Gluconacetobacter/growth & development , Ethanol/metabolism
13.
Braz. j. microbiol ; 48(4): 648-655, Oct.-Dec. 2017. tab, graf
Article in English | LILACS | ID: biblio-889169

ABSTRACT

ABSTRACT Producing biofuels such as ethanol from non-food plant material has the potential to meet transportation fuel requirements in many African countries without impacting directly on food security. The current shortcomings in biomass processing are inefficient fermentation of plant sugars, such as xylose, especially at high temperatures, lack of fermenting microbes that are able to resist inhibitors associated with pre-treated plant material and lack of effective lignocellulolytic enzymes for complete hydrolysis of plant polysaccharides. Due to the presence of residual partially degraded lignocellulose in the gut, the dung of herbivores can be considered as a natural source of pre-treated lignocellulose. A total of 101 fungi were isolated (36 yeast and 65 mould isolates). Six yeast isolates produced ethanol during growth on xylose while three were able to grow at 42 °C. This is a desirable growth temperature as it is closer to that which is used during the cellulose hydrolysis process. From the yeast isolates, six isolates were able to tolerate 2 g/L acetic acid and one tolerated 2 g/L furfural in the growth media. These inhibitors are normally generated during the pre-treatment step. When grown on pre-treated thatch grass, Aspergillus species were dominant in secretion of endo-glucanase, xylanase and mannanase.


Subject(s)
Animals , Ethanol/metabolism , Fungi/isolation & purification , Fungi/metabolism , Manure/microbiology , Biofuels/analysis , Biofuels/microbiology , Fermentation , Fungi/classification , Fungi/genetics , Herbivory , Lignin/metabolism , Manure/analysis , Plants/metabolism , Xylose/metabolism
14.
Electron. j. biotechnol ; 30: 77-82, nov. 2017. tab, graf
Article in English | LILACS | ID: biblio-1021550

ABSTRACT

Background: Mucor indicus is a dimorphic fungus used in the production of ethanol, oil, protein, and glucosamine. It can ferment different pentoses and hexoses; however, the yields of products highly depend on the nutrients and cultivation conditions. In this study, the effects of different morphologic forms, cultivation time and temperature, presence or absence of oxygen, carbon sources, and concentration of nitrogen source on the products of M. indicus were investigated. Results: The fungus with all morphologies produced high yields of ethanol, in the range of 0.32­0.43 g/g, on glucose. However, the fungus with filamentous morphology produced higher amounts of oil, protein, phosphate, and glucosamine together with ethanol, compared with other morphologies. A higher amount of oil (0.145 g/g biomass) was produced at 28°C, while the best temperature for protein and glucosamine production was 32 and 37°C, respectively. Although ethanol was produced at a higher yield (0.44 g/g) under anaerobic conditions compared with aerobic conditions (yield of 0.41 g/g), aerobic cultivation resulted in higher yields of protein (0.51 g/g biomass), glucosamine (0.16 g/g alkali insoluble material, AIM), and phosphate (0.11 g/g AIM). Conclusions: It is not possible to have the maximum amounts of the products simultaneously. The fermentation conditions and composition of culture media determine the product yields. Carbon source type and the addition of nitrogen source are among the most influencing factors on the product yields. Moreover, all measured products were made with higher yields in cultivation on glucose, except glucosamine, which was produced with higher yields on xylose.


Subject(s)
Ethanol/metabolism , Mucor/metabolism , Temperature , Time Factors , Oils/metabolism , Carbon/metabolism , Biomass , Aerobiosis , Culture Media , Fermentation , Glucosamine/metabolism , Glucose , Anaerobiosis , Nitrogen/metabolism
15.
Electron. j. biotechnol ; 30: 64-70, nov. 2017. ilus, graf, tab
Article in English | LILACS | ID: biblio-1021461

ABSTRACT

Background: The development of a potential single culture that can co-produce hydrogen and ethanol is beneficial for industrial application. Strain improvement via molecular approach was proposed on hydrogen and ethanol co-producing bacterium, Escherichia coli SS1. Thus, the effect of additional copy of native hydrogenase gene hybC on hydrogen and ethanol co-production by E. coli SS1 was investigated. Results: Both E. coli SS1 and the recombinant hybC were subjected to fermentation using 10 g/L of glycerol at initial pH 7.5. Recombinant hybC had about 2-fold higher cell growth, 5.2-fold higher glycerol consumption rate and 3-fold higher ethanol productivity in comparison to wild-type SS1. Nevertheless, wild-type SS1 reported hydrogen yield of 0.57 mol/mol glycerol and ethanol yield of 0.88 mol/mol glycerol, which were 4- and 1.4-fold higher in comparison to recombinant hybC. Glucose fermentation was also conducted for comparison study. The performance of wild-type SS1 and recombinant hybC showed relatively similar results during glucose fermentation. Additional copy of hybC gene could manipulate the glycerol metabolic pathway of E. coli SS1 under slightly alkaline condition. Conclusions: HybC could improve glycerol consumption rate and ethanol productivity of E. coli despite lower hydrogen and ethanol yields. Higher glycerol consumption rate of recombinant hybC could be an advantage for bioconversion of glycerol into biofuels. This study could serve as a useful guidance for dissecting the role of hydrogenase in glycerol metabolism and future development of effective strain for biofuels production.


Subject(s)
Ethanol/metabolism , Escherichia coli/metabolism , Hydrogen/metabolism , Hydrogenase/metabolism , Recombination, Genetic , Biodegradation, Environmental , Culture Media , Escherichia coli/enzymology , Alkalinization , Fermentation , Glucose/metabolism , Glycerol/metabolism , Hydrogenase/genetics
16.
Electron. j. biotechnol ; 30: 118-124, nov. 2017. tab, ilus, graf
Article in English | LILACS | ID: biblio-1021652

ABSTRACT

Background: Zymomonas mobilis is a Gram-negative microaerophilic bacterium with excellent ethanol-producing capabilities. The RecET recombination system provides an efficient tool for direct targeting of genes in the bacterial chromosome by PCR fragments. Results: The plasmids pSUZM2a-RecET and pSUZM2a-RecE588T were first developed to co-express RecE or RecE588 and RecT for homologous recombination. Thereafter, the PCR fragments of the tetracycline resistance marker gene flanked by 60 bp of adhA (alcohol dehydrogenase I) or adhB (alcohol dehydrogenase II) homologous sequences were electroporated directly into ZM4 cells harboring pSUZM2a-RecET or pSUZM2a-RecE588T. Both adhA and adhB were replaced by the tetracycline resistance gene in ZM4, yielding two mutant strains, Z. mobilis ZM4 ΔadhA and Z. mobilis ZM4 ΔadhB. These two mutants showed varying extent of reduction in ethanol production, biomass generation, and glucose metabolism. Furthermore, enzyme activity of alcohol dehydrogenase II in Z. mobilis ZM4 ΔadhB exhibited a significant reduction compared to that of wild-type ZM4. Conclusion: This approach provided a simple and useful method for introducing mutations and heterologous genes in the Z. mobilis genome.


Subject(s)
Zymomonas/genetics , Homologous Recombination , Plasmids , Recombination, Genetic , Alcohol Dehydrogenase/metabolism , Zymomonas/enzymology , Electroporation , Ethanol/metabolism , Gene Knockout Techniques , Mutation
17.
Int. j. morphol ; 35(3): 942-949, Sept. 2017.
Article in English | LILACS | ID: biblio-893078

ABSTRACT

Prolonged alcohol consumption has consequences on the liver, producing necrotic precipitates and fibrosis, on the pancreas, causing the pancreatic acini to atrophy and destroying insulin-producing cells, and on the central nervous system (CNS), causing the gray and white matter in the frontal lobes of the brain and cerebellum to atrophy. Generally, alcohol is metabolized via oxidative pathways, where the enzymes alcohol dehydrogenase and aldehyde dehydrogenase participate during its metabolization in the liver and CNS, or via non-oxidative pathways during its metabolization in the pancreas. Ethanol metabolism can produce oxidative stress and tissue damage mediated by free radicals, causing morphological and functional alterations in the liver. In the pancreas, it can cause progressive and irreversible damage affecting the endocrine and exocrine functions, a result of the activation of the stellate cells, which are activated directly by alcohol, causing pancreatic fibrosis. In the CNS ethanol can bind directly to proteins, nucleic acids and phospholipids to develop its pathogenesis. The effects produced by alcohol can be counteracted by supplementation with antioxidants, which reduce the inflammation and areas of focal necrosis in the liver, inhibit the activation of pancreatic stellate cells, and reduce oxidative stress in the CNS. Additionally, in order to reduce the negative effects associated with alcohol consumption, recent studies have suggested the administration of antioxidants as a treatment strategy.


El consumo prolongado de alcohol tiene consecuencias en hígado, produciendo precipitados necróticos y fibrosis; en páncreas, provocando atrofia del acino pancreático y destrucción de las células productoras de insulina, y en Sistema Nervioso Central (SNC) generando atrofia de la sustancia gris y blanca en lóbulos frontales del cerebro y cerebelo. En general, el metabolismo del alcohol se consigue mediante las vías oxidativas, donde participan las enzimas alcohol-deshidrogenasa y aldehído deshidrogenasa durante su metabolización en hígado y SNC; o bien, mediante las vías no oxidativas durante su metabolización en páncreas. El metabolismo del etanol es capaz de producir estrés oxidativo y daño tisular mediado por radicales libres, causando alteraciones morfológicas y funcionales del hígado; en el páncreas, puede causar daño progresivo e irreversible afectando las funciones endocrinas y exocrinas de este órgano producto de la activación de las células estrelladas que son activadas directamente por el alcohol generando fibrosis pancreática; mientras que, en SNC se puede unir directamente a proteínas, ácidos nucleicos y fosfolípidos para desarrollar su patogenia. Los efectos producidos por el alcohol pueden contrarrestarse mediante la suplementación con antioxidantes, que reducen la inflamación y las zonas de necrosis focal en el hígado, inhiben la activación de células pancreáticas estrelladas, y reducen el estrés oxidativo en SNC. Asimismo, para reducir los efectos negativos asociados al consumo de alcohol, estudios recientes han propuesto la administración de antioxidantes como estrategia terapéutica.


Subject(s)
Humans , Central Nervous System/drug effects , Ethanol/toxicity , Alcoholic Intoxication/drug therapy , Antioxidants/therapeutic use , Pancreas/drug effects , Pancreas/pathology , Central Nervous System/pathology , Oxidative Stress , Ethanol/metabolism , Liver/drug effects , Liver/pathology
18.
Braz. j. microbiol ; 48(3): 403-409, July-Sept. 2017. tab, graf
Article in English | LILACS | ID: biblio-889142

ABSTRACT

Abstract Very high gravity (VHG) technology was employed on industrial scale to produce ethanol from molasses (fermented) as well as by-products formation estimation. The effect of different Brix° (32, 36 and 40) air-flow rates (0.00, 0.20, 0.40, and 0.60 vvm) was studied on ethanol production. The maximum ethanol production was recorded to be 12.2% (v/v) at 40 Brix° with 0.2 vvm air-flow rate. At optimum level aeration and 40 Brix° VHG, the residual sugar level was recorded in the range of 12.5-18.5 g/L, whereas the viable cell count remained constant up to 50 h of fermentation and dry matter production increased with fermentation time. Both water and steam consumption reduced significantly under optimum conditions of Brix° and aeration rate with compromising the ethanol production. Results revealed VHG with continuous air flow is viable technique to reduce the ethanol production cost form molasses at commercial scale.


Subject(s)
Chick Embryo , Ethanol/metabolism , Industrial Microbiology/methods , Molasses/microbiology , Saccharomyces cerevisiae/metabolism , Fermentation , Hypergravity , Industrial Microbiology/instrumentation , Molasses/analysis , Molasses/economics , Saccharomyces cerevisiae/genetics
19.
Braz. j. microbiol ; 48(3): 592-601, July-Sept. 2017. tab, graf
Article in English | LILACS | ID: biblio-889150

ABSTRACT

Abstract The aim of this study was to develop a kefir apple-based vinegar and evaluate this fermentation process using new methodology with Biospeckle Laser. Brazilian kefir grains were inoculated in apple must for vinegar production. In this study, the microbial community present in kefir, and correspondent vinegar, was investigated using Matrix Assisted Laser Desorption/Ionization - Time of Flight Mass Spectrometry (MALDI-TOF MS) technique. Saccharomyces cerevisiae, Lactobacillus paracasei, Lactobacillus plantarum, Acetobacter pasteurianus and Acetobacter syzygii were the microbial species identified. S. cerevisiae, L. plantarum, A. pasteurianus and A. syzygii were found in smaller quantities at the beginning of the alcoholic fermentation, but were found throughout the alcoholic and acetic fermentation. Kefir grains were able to utilize apple must as substrate to produce ethanol, and acetic acid. Acetate, volatile alcohols and aldehydes in the vinegar-based kefir were also produced. The yield of acetic acid in the kefir vinegars was ∼79%. The acetic acid concentration was ∼41 g L-1, reaching the required standard for the Brazilian legislation accepts it as vinegar (4.0% acetic acid). Kefir vinegar showed good acceptance in the sensory analysis. The technology proposed here is novel by the application of immobilized-cell biomass (kefir grains) providing a mixed inocula and eliminating the use of centrifuge at the end of the fermentative process. This step will save energy demand and investment. This is the first study to produce apple vinegar using kefir grains.


Subject(s)
Humans , Alcoholic Beverages/microbiology , Kefir/analysis , Malus/microbiology , Acetic Acid/analysis , Acetic Acid/metabolism , Acetobacter/isolation & purification , Acetobacter/metabolism , Biodiversity , Brazil , Ethanol/analysis , Ethanol/metabolism , Fermentation , Food Handling , Kefir/microbiology , Lactobacillus/isolation & purification , Lactobacillus/metabolism , Malus/metabolism , Saccharomyces cerevisiae/isolation & purification , Saccharomyces cerevisiae/metabolism , Taste
20.
Braz. j. microbiol ; 48(3): 537-543, July-Sept. 2017. graf
Article in English | LILACS | ID: biblio-889126

ABSTRACT

Abstract Metallothioneins are a superfamily of low-molecular-weight, cysteine (Cys)-rich proteins that are believed to play important roles in protection against metal toxicity and oxidative stress. The main purpose of this study was to investigate the effect of heterologous expression of a rice metallothionein isoform (OsMTI-1b) on the tolerance of Saccharomyces cerevisiae to Cd2+, H2O2 and ethanol stress. The gene encoding OsMTI-1b was cloned into p426GPD as a yeast expression vector. The new construct was transformed to competent cells of S. cerevisiae. After verification of heterologous expression of OsMTI-1b, the new strain and control were grown under stress conditions. In comparison to control strain, the transformed S. cerevisiae cells expressing OsMTI-1b showed more tolerance to Cd2+ and accumulated more Cd2+ ions when they were grown in the medium containing CdCl2. In addition, the heterologous expression of GST-OsMTI-1b conferred H2O2 and ethanol tolerance to S. cerevisiae cells. The results indicate that heterologous expression of plant MT isoforms can enhance the tolerance of S. cerevisiae to multiple stresses.


Subject(s)
Plant Proteins/genetics , Oryza/genetics , Saccharomyces cerevisiae/metabolism , Cadmium/metabolism , Gene Expression , Ethanol/metabolism , Hydrogen Peroxide/metabolism , Metallothionein/genetics , Plant Proteins/metabolism , Saccharomyces cerevisiae/genetics , Oxidative Stress , Protein Isoforms/genetics , Protein Isoforms/metabolism , Metallothionein/metabolism
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