Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 3.882
Filtrar
1.
J Agric Food Chem ; 67(44): 12228-12236, 2019 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-31638826

RESUMO

Zeaxanthin is a value-added carotenoid with wide applications. This study aims to manipulate a generally recognized as safe and carotenoid-producing bacterium, Sphingobium sp., for enhanced production of zeaxanthin and exopolysaccharides. First, whole-genome sequencing and analysis of pathway genes were applied to define the carotenoid pathway in Sphingobium sp. Second, a Sphingobium transformation system was established to engineer metabolite flux into zeaxanthin. By a combination of chemical mutagenesis and removal of bottlenecks of carotenoid biosynthesis via overexpression of three rate-limiting enzymes, the genetically modified Sphingobium DIZ strain produced 21.26 mg/g dry cell weight of zeaxanthin, which was about 4-fold higher than the wild type. Upon optimization of culture conditions, the DIZ strain produced 479.5 mg/L of zeaxanthin with the productivity of 4.99 mg/L/h and 21.9 g/L of exopolysaccharides using a fed-batch fermentation strategy. This study represents the first genetic manipulation of Sphingobium sp., a biotechnologically important bacterium, for high-yield production of value-added metabolites.


Assuntos
Proteoglicanas/biossíntese , Sphingomonadaceae/genética , Sphingomonadaceae/metabolismo , Zeaxantinas/biossíntese , Técnicas de Cultura Celular por Lotes , Meios de Cultura/metabolismo , Fermentação , Engenharia Metabólica
2.
J Microbiol ; 57(9): 759-768, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31376108

RESUMO

The cultivation of microbial species remains a primary challenge in microbiology and obtaining pure cultures is essential for the study of microbial physiology and function. When isolating microorganisms from aquaculture environments, Vibrio are the most dominate isolates on the media that are commonly used. In order to expand our ability to study microbial species, an easy-operation and low-cost medium that can reduce the interference of Vibrio strains and increase the cultivability of other bacteria is urgently needed. We compared viable cell counts on conventional media (CM; including Marine Agar 2216 and LB media) and diluted media (DM; including 1/10-Marine Agar 2216, 1/10-LB). We also assessed the diversity of cultivable microorganisms under high and low nutrient conditions by a plate-wash strategy coupled with high-throughput sequencing of the V4 hypervariable region of the 16S rRNA gene. The results show that microbial communities from DM, especially 1/10-Marine Agar 2216, are more diverse than those obtained from CM. Vibrio isolates were reduced on DM. PICRUSt analysis revealed that nutrient composition is a significant contributor to the diversity and function of the cultivable microbial communities. Bacteria grown on CM possess more pathogenic characteristics, whereas DM favors the growth of bacteria that have multiple metabolic functions. Collectively, our data provide strong evidence that dilution of CM influences the cultivability of bacteria from aquaculture seawater. It also supports that DM can expand the range of microbial species that can be cultivated. This study also provides insights for media design in microbial cultivation from aquaculture systems.


Assuntos
Meios de Cultura/metabolismo , Água do Mar/microbiologia , Vibrio/crescimento & desenvolvimento , Bactérias/classificação , Bactérias/genética , Bactérias/crescimento & desenvolvimento , Bactérias/isolamento & purificação , Meios de Cultura/química , DNA Bacteriano/genética , Filogenia , RNA Ribossômico 16S/genética , Vibrio/genética , Vibrio/isolamento & purificação , Vibrio/metabolismo
3.
J Basic Microbiol ; 59(8): 775-783, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31259432

RESUMO

We unearthed some interesting microecological discoveries while selecting for the most beneficial bacterial strains to be used as probiotics in Lecane inermis rotifer mass culture. For 3 years, we maintained the cultures of L. inermis, with selection for the highest growth rate and resistance to potential contamination. Then, we conducted further selection and isolation in two groups: rotifers inoculated with the bacterial consortium isolated from the rotifer cultures, and rotifers fed with a commercial bioproduct. Selection was conducted in demanding conditions, with particulate matter suspended in spring water as a substrate, without aeration and under strong consumer pressure, and led to selection of two cultivable strains isolated from the optimal rotifers culture. According to molecular analysis, these strains were Aeromonas veronii and Pseudomonas mosselii. Biolog® ECO plate tests showed that both investigated bacterial communities metabolized wide but similar range of substrates. Therefore, intensely selective conditions led to considerable reduction in bacterial community regarding taxonomy, but not in metabolic activity, showing a functional composition decoupling. Aside from this result, our novel selection method dedicated to the sustainable culture of two trophic levels, a directed selection procedure (DSC), could potentially lead to the development of biotechnologically valuable strains with high metabolic activity and the ability to metabolize different sorts of substrate without harmful impact on higher trophic levels.


Assuntos
Biodiversidade , Consórcios Microbianos , Rotíferos/microbiologia , Animais , Bactérias/classificação , Bactérias/genética , Bactérias/isolamento & purificação , Bactérias/metabolismo , Meios de Cultura/metabolismo , Nutrientes/metabolismo , Filogenia , Rotíferos/crescimento & desenvolvimento , Esgotos/microbiologia
4.
J Basic Microbiol ; 59(8): 784-791, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31259434

RESUMO

Laccases are multicopper oxidases with high potential for industrial applications. Several basidiomycete fungi are natural producers of this enzyme; however, the optimization of production and selection of inducers for increased productivity coupled with low costs is necessary. Lignocellulosic residues are important lignin sources and potential inducers for laccase production. Pinus taeda, a dominant source of wood-based products, has not been investigated for this purpose yet. The aim of this study was to evaluate the production of laccase by the basidiomycete fungus Ganoderma lucidum in the presence of different inducers in submerged and solid-state fermentation. The results of submerged fermentation in presence of 5 µM CuSO 4 , 2 mM ferulic acid, 0.1 g/L P. taeda sawdust, or 0.05 g/L Kraft lignin indicated that although all the tested inducers promoted increase in laccase activity in specific periods of time, the presence of 2 mM ferulic acid resulted in the highest value of laccase activity (49 U/L). Considering the submerged fermentation, experimental design following the Plackett-Burman method showed that the concentrations of ferulic acid and P. taeda sawdust had a significant influence on the laccase activity. The highest value of 785 U/L of laccase activity on submerged fermentation was obtained on the seventh day of cultivation. Finally, solid-state fermentation cultures in P. taeda using ferulic acid or CuSO 4 as inducers resulted in enzymatic activities of 144.62 and 149.89 U/g, respectively, confirming the potential of this approach for laccase production by G. lucidum.


Assuntos
Fermentação , Lacase/biossíntese , Reishi/metabolismo , Sulfato de Cobre/metabolismo , Ácidos Cumáricos/metabolismo , Meios de Cultura/metabolismo , Lacase/metabolismo , Lignina/metabolismo , Pinus/metabolismo , Reishi/enzimologia , Fatores de Tempo
5.
Int J Food Microbiol ; 306: 108268, 2019 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-31352303

RESUMO

Bacterial production of exopolysaccharides (EPS) is of increasing interest near food manufacturers, biotechnology industries and nutritionists because of their different roles. Several analytical methods are available for recovery, quantification and characterization of EPS from lactic acid bacteria (LAB) in food. However, direct screening method for production of EPS is still based on the visual observation of filamentous texture of the colonies developed on supplemented solid growth media. To overcome weaknesses of many currently used screening methods, we propose adopting impedance microbiology to evaluate the EPS production from LAB in milk. In this work we have proven that the peculiar shape of capacitance curve of Lactobacillus delbrueckii subsp. bulgaricus 2214, measured in milk by means of a BacTrac 4300® system, is due to production of EPS. Besides the pH measurement, the amounts of EPS evaluated after 0, 8, 13 and 55 h of incubation in milk, were in agreement with the evaluation of gene expression and confirmed by the observations by confocal laser scanning microscopy and by transmission electron microscopy. With the aim to verify the applicability of the proposed method, the drop entity of the capacitance curve (ΔE%) of 22 EPS-producing (EPS+) LAB strains and one negative (EPS-) control was evaluated both in broth medium and in milk. The positive ΔE% value found for all of the strains cultivated in the clear broth medium allowed to confirm the EPS production, simply observing a strain-dependent amount of EPS on surface of the measurement electrodes of the device. When the same EPS+ strains were cultivated in milk, the obtained ΔE% values showed that only a few of them were able to produce EPS in this environment, supporting their diversified ability to utilize lactose for this purpose. Results obtained by this multidisciplinary study demonstrate that impedance microbiology represents a suitable method to overcome the limits of the most commonly used methods to screen LAB for EPS production in milk. Moreover, these results also open a door to the application to other food and beverages, in which the EPS produced in situ could be of great interest for food industry.


Assuntos
Impedância Elétrica , Lactobacillus delbrueckii/metabolismo , Lactose/metabolismo , Leite/microbiologia , Polissacarídeos Bacterianos/isolamento & purificação , Animais , Meios de Cultura/metabolismo , Fermentação , Microscopia Confocal , Microscopia Eletrônica de Transmissão , Polissacarídeos Bacterianos/metabolismo
6.
J Food Sci ; 84(7): 1776-1783, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31218715

RESUMO

Citrus pectin hydrolysates (Citrus paradisi [Mafc.]) from "Foster," "Red Shambar," "Tangelo Orlando," and "Citrumelo Swingle" cultivars were obtained by partial chemical hydrolysis and their properties as culture media (sole carbon/nutrient source) and encapsulating agents of Lactobacillus plantarum CIDCA 83114 were evaluated. The concentration of neutral sugars was maximal after 2-hour hydrolysis. All hydrolysates were rich in glucose >xylose >galactose >galacturonic acid >mannose >arabinose. "Citrumelo Swingle" cultivar was the one with the highest concentration of xylose. After 24 hr of fermentation with L. plantarum CIDCA 83114, bacterial viability increased from 6.76 ± 0.14 to almost 9 log CFU/mL, and lactic acid concentration, from 2.63 ± 0.41 to 7.82 ± 0.15 mmol/L in all hydrolysates. Afterwards, bacteria were entrapped in pectate-calcium beads by ionotropic gelation. Bacterial viability did not significantly decrease after freeze-drying and storage the beads at 4 °C for 45 days. PRACTICAL APPLICATION: Pectin hydrolysates were adequate culture media for microorganisms, as determined by the viabililty and lactic acid production. Considering that citrus peels are agro-wastes obtained in large quantities, their use as encapsulating materials provides a solution to overcome the environmental problem they entail.


Assuntos
Citrus paradisi/química , Meios de Cultura/metabolismo , Lactobacillus plantarum/química , Pectinas/química , Citrus paradisi/metabolismo , Meios de Cultura/química , Fermentação , Liofilização , Hidrólise , Ácido Láctico/análise , Ácido Láctico/metabolismo , Lactobacillus plantarum/classificação , Lactobacillus plantarum/crescimento & desenvolvimento , Lactobacillus plantarum/metabolismo , Pectinas/metabolismo , Açúcares/análise , Açúcares/metabolismo
7.
J Basic Microbiol ; 59(8): 820-833, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31232462

RESUMO

During production and characterization of exopolysaccharides (EPS) of Ochrobactrum pseudintermedium C1, it was observed that an experimental change in the basic hydrocarbon type of substrate for bacterial utilization led to elicitation of different surface-active properties in the EPS produced. In the sugar substrate, it elicited surfactant property, while in oil substrates it elicited emulsifying property, which indicated that the EPS might be different. Consequently, attention was focused on a detailed analysis of this substrate-specific EPS. Utilizing waste sugar, edible, and mineral oil substrates, EPS produced in each situation was characterized. Besides estimating surface activity and thermostability, each substrate-specific EPS was analyzed by Fourier-transform infrared spectroscopy, gas chromatography-mass spectroscopy, 1 H-nuclear magnetic resonance, and matrix-assisted laser desorption/ionization-time of flight mass spectroscopy to find any structural difference. The results were significantly contrasting although the similarity in molecular mass suggested a basic similarity in polysaccharide structure. Morphological differences were also evident both macroscopically and microscopically with scanning electron microscopy. As the surface-active property of EPS was dependent on the substrate utilized, their structural differences might account for it. These diverse surface activities of EPS produced by a single bacterial strain simply by changing the nature of substrate would also augment their bioapplications. Moreover, utilization of waste and easily available substrates should make such applications convenient, ecofriendly, and cost-worthy.


Assuntos
Hidrocarbonetos/metabolismo , Ochrobactrum/química , Polissacarídeos Bacterianos/química , Meios de Cultura/metabolismo , Microscopia Eletrônica de Varredura , Peso Molecular , Ochrobactrum/crescimento & desenvolvimento , Ochrobactrum/metabolismo , Polissacarídeos Bacterianos/biossíntese , Polissacarídeos Bacterianos/ultraestrutura , Solubilidade , Propriedades de Superfície , Temperatura Ambiente
8.
Int J Food Microbiol ; 305: 108254, 2019 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-31238194

RESUMO

Pathogens in viable but nonculturable (VBNC) state can escape traditional detection methods based on culturable ability, thus bringing risks to food safety and human health. Considering Staphylococcus aureus as a kind of primary foodborne pathogen, this study attempted to investigate whether citric acid, a food additive commonly used, can force S. aureus into VBNC state along with low temperature. Treated with citric acid solution (pH 4.0) at 4 °C, S. aureus was confirmed to enter into VBNC state after induction for 18 days. Meanwhile, resuscitation was achieved in culture medium rather than in nutrition-free saline solution. In VBNC cells, ATP concentration still maintained at a high level, as about two-thirds of exponential-phase cells. For survival, intracellular structure of VBNC cells changed remarkably, including irregular cell shape, denser cytoplasm, space between cell wall and cell membrane, and decreased density of nuclear region. Notably, resistance of VBNC cells to simulated gastric fluid improved when compared with exponential-phase cells. What are noted above suggests that VBNC state adopted by S. aureus might be a survival strategy to the adverse environment (acidity stress and low temperature). In conclusion, our study sounds an alarm for the safety of citric acid-containing foods.


Assuntos
Ácido Cítrico/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Temperatura Baixa , Meios de Cultura/química , Meios de Cultura/metabolismo , Staphylococcus aureus/crescimento & desenvolvimento
9.
Ecotoxicol Environ Saf ; 181: 481-490, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31228824

RESUMO

Peroxidases and catalases are well-known antioxidant enzymes produced in almost all living organisms for the elimination of reactive oxygen species (ROS) and thus they prevent the occurrence of oxidative stress. In our study we focused on two soil fungi of the family Chaetomiaceae (mesophilic Chaetomium cochliodes and its thermophilic counterpart C. thermophilum var. dissitum) in order to explore the presence of peroxidase and catalase genes, formation of their native transcripts and protective effect of corresponding translation products in a case study. Predicted genes of our interest were confirmed by genomic PCR and their inducible transcripts by RT-PCR. We were able to quantify the expression levels of newly discovered fungal heme peroxidases and catalases with the reverse-transcription quantitative real-time PCR method. We compared obtained quantitative levels of mRNA production with the level of corresponding extracellular protein occurrence as detected with monitoring their specific peroxidase and catalase activities directly in the cultivation media at optimal growth temperatures. The presence of secretory Catalase 2 from C. thermophilum var. dissitum was detected and identified with mass spectrometry approach directly in the growth medium. This unique catalase is phylogenetically closely related with a previously described catalase-phenol oxidase thus representing an effective and versatile antioxidant in the environment of the fungal mycelia also involved in the catabolism of recalcitrant phenolic substances.


Assuntos
Ascomicetos/metabolismo , Catalase/metabolismo , Espaço Extracelular/enzimologia , Estresse Oxidativo , Peroxidases/metabolismo , Antioxidantes/metabolismo , Ascomicetos/classificação , Ascomicetos/enzimologia , Ascomicetos/genética , Catalase/genética , Meios de Cultura/metabolismo , Espaço Extracelular/metabolismo , Oxirredução , Peroxidases/genética , Filogenia , Temperatura Ambiente
10.
J Agric Food Chem ; 67(22): 6263-6274, 2019 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-31088055

RESUMO

The development of commercial poly-γ-glutamic acid (γ-PGA) production by glutamate-dependent strains requires understanding the glutamate dependence mechanism in the strains. Here, we first systematically analyzed the response pattern of Bacillus subtilis to glutamate addition by comparative transcriptomics. Glutamate addition induced great changes in intracellular metabolite concentrations and significantly upregulated genes involved in the central metabolic pathways. Subsequent gene overexpression experiments revealed that only the enhancement of glutamate synthesis pathway successfully led to γ-PGA accumulation without glutamate addition, indicating the key role of intracellular glutamate for γ-PGA synthesis in glutamate-dependent strains. Finally, by a combination of metabolic engineering targets, the γ-PGA titer reached 10.21 ± 0.42 g/L without glutamate addition. Exogenous glutamate further enhanced the γ-PGA yield (35.52 ± 0.26 g/L) and productivity (0.74 g/(L h)) in shake-flask fermentation. This work provides insights into the glutamate dependence mechanism in B. subtilis and reveals potential molecular targets for increasing economical γ-PGA production.


Assuntos
Bacillus subtilis/genética , Bacillus subtilis/metabolismo , Proteínas de Bactérias/genética , Ácido Glutâmico/metabolismo , Ácido Poliglutâmico/análogos & derivados , Proteínas de Bactérias/metabolismo , Meios de Cultura/metabolismo , Perfilação da Expressão Gênica , Ácido Poliglutâmico/biossíntese
11.
J Sci Food Agric ; 99(10): 4772-4780, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-30953365

RESUMO

BACKGROUND: Monascus, a filamentous fungus, produces many bioactive substances. However, in the process of fermentation, Monascus also produces the mycotoxin citrinin. Owing to the presence of citrinin, the safety of Monascus products has been questioned and their wide application limited. Using soybean isoflavones (SI) as exogenous additives, alterations in citrinin production by Monascus aurantiacus Li AS3.4384 (MALA) in different media used for liquid state fermentation were investigated. RESULTS: Results showed that the citrinin concentration was 95.98% lower than that of the control group after 16-days fermentation when 20.0 g L-1 SI were added to rice powder and inorganic salt medium. Citrinin production was reduced by 97.24% after 12-days fermentation with 10.0 g L-1 SI in starch inorganic salt medium; 82.52% after 20-days fermentation with 20.0 g L-1 SI in starch peptone medium with high starch content; 45.07% after 14-days fermentation with 5.0 g L-1 SI in starch peptone medium with low starch content; and 82.21% after 14-days fermentation with 20.0 g L-1 SI in yeast extract sucrose medium. CONCLUSION: The developed method of removing citrinin is simple, safe, and effective, and it can be applied to reduce the citrinin content of Monascus products. © 2019 Society of Chemical Industry.


Assuntos
Citrinina/metabolismo , Meios de Cultura/metabolismo , Microbiologia de Alimentos/métodos , Isoflavonas/metabolismo , Monascus/metabolismo , Soja/metabolismo , Citrinina/análise , Meios de Cultura/química , Fermentação , Oryza/química , Oryza/metabolismo , Soja/química
12.
Prep Biochem Biotechnol ; 49(5): 521-528, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31017522

RESUMO

Staphylococcus aureus, among other staphylococcal species, developed multidrug resistance and causes serious health risks that require complex treatments. Therefore, the development of novel and effective strategies to combat these bacteria has been gaining importance. Since Staphylococcus simulans lysostaphin is a peptidoglycan hydrolase effective against staphylococcal species, the enzyme has a significant potential for biotechnological applications. Despite promising results of lysostaphin as a bacteriocin capable of killing staphylococcal pathogens, it is still not widely used in healthcare settings due to its high production cost. In this study, medium engineering techniques were applied to improve the expression yield of recombinant lysostaphin in E. coli. A new effective inducible araBAD promoter system and different mediums were used to enhance lysostaphin production. Our results showed that the composition of autoinduction media enhanced the amount of lysostaphin production 5-fold with the highest level of active lysostaphin at 30 °C. The production cost of 1000 U of lysostaphin was determined as 4-fold lower than the previously proposed technologies. Therefore, the currently developed bench scale study has a great potential as a large-scale fermentation procedure to produce lysostaphin efficiently.


Assuntos
Proteínas de Bactérias/biossíntese , Meios de Cultura/metabolismo , Lisostafina/biossíntese , Engenharia Metabólica/métodos , Proteínas Recombinantes/biossíntese , Arabinose/farmacologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/isolamento & purificação , Meios de Cultura/química , Indução Enzimática/efeitos dos fármacos , Estabilidade Enzimática , Escherichia coli/genética , Fermentação , Lisostafina/isolamento & purificação , Engenharia Metabólica/economia , Regiões Promotoras Genéticas/efeitos dos fármacos , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Staphylococcus/química , Staphylococcus/metabolismo , Temperatura Ambiente , Fatores de Tempo
13.
J Sci Food Agric ; 99(11): 5122-5130, 2019 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-30993725

RESUMO

BACKGROUND: The ability of Coriolus versicolor medicinal mushroom to accumulate and transform selenium from selenourea and sodium selenite into an organic form - l-selenomethionine - during growth in liquid medium is examined in this paper. Additionally, the impact of supplementation on biological activity of the selenated mushroom methanol extracts, as well as their chemical composition, is studied. RESULTS: Selenium accumulation was more efficient with sodium selenite application, but biomass yield was significantly lower (1.89 g DW L-1 ) compared to samples enriched with selenourea (4.48 g DW L-1 ). Mushroom sample obtained after growing in liquid medium with selenourea had significantly higher l-selenomethionine content compared to the sample grown in medium with sodium selenite. Selenium-enriched methanol extracts of C. versicolor mushroom showed improved antimicrobial and antioxidant activities compared to non-enriched extract. CONCLUSION: Our results suggest that C. versicolor mushroom cultivated in liquid culture enriched with selenourea can be used for the production of novel food supplements with improved selenium bioavailability. More than 30% of total accumulated selenium from selenourea is transformed into l-selenomethionine. Differences in biological activity of methanol extracts can be explained not only by different selenium content but also by the differences in chemical composition of extracts. © 2019 Society of Chemical Industry.


Assuntos
Agaricales/crescimento & desenvolvimento , Agaricales/metabolismo , Selênio/metabolismo , Agaricales/química , Disponibilidade Biológica , Meios de Cultura/química , Meios de Cultura/metabolismo , Suplementos Nutricionais/análise , Compostos Organosselênicos/análise , Compostos Organosselênicos/metabolismo , Selênio/análise , Selenometionina/análise , Selenometionina/metabolismo , Ureia/análogos & derivados , Ureia/análise , Ureia/metabolismo
14.
J Sci Food Agric ; 99(11): 5187-5194, 2019 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-31032927

RESUMO

BACKGROUND: Sprouting is known to improve cereal and pulse nutritional properties. However, several outbreaks of illness have been reported after raw sprout consumption. This research aimed to improve wheat sprout hygienic properties through the use of zinc diacetate. Sprouting conditions (sprouting temperature, soaking time and zinc diacetate solution concentration) were optimized to decrease total plate count, coliforms, and molds and yeasts using a factorial design approach and a desirability function. RESULTS: Based on the responses, the effects of variables were calculated and the interactions between them were determined. Optimal conditions were defined as follows: sprouting temperature 18 °C, soaking time 0.66 h and zinc diacetate concentration 400 mg L-1 . These conditions led to the elimination of coliforms and a decrease in total flora count by 2 log. Interestingly, zinc sprouting increased the zinc content of sprouts and improved their nutritional properties. CONCLUSION: Results showed that the use of zinc solution is a useful tool to improve sprout hygienic and nutritional properties. © 2019 Society of Chemical Industry.


Assuntos
Contaminação de Alimentos/prevenção & controle , Manipulação de Alimentos/métodos , Sementes/crescimento & desenvolvimento , Triticum/crescimento & desenvolvimento , Zinco/farmacologia , Bactérias/crescimento & desenvolvimento , Meios de Cultura/química , Meios de Cultura/metabolismo , Manipulação de Alimentos/instrumentação , Fungos/crescimento & desenvolvimento , Higiene , Valor Nutritivo , Sementes/química , Sementes/microbiologia , Triticum/química , Triticum/microbiologia , Zinco/análise
15.
J Microbiol Biotechnol ; 29(2): 256-267, 2019 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-30866181

RESUMO

The use of low-cost substrates represents one key issue to make single cell oil production sustainable. Among low-input crops, Arundo donax L. is a perennial herbaceous rhizomatous grass containing both C5 and C6 carbohydrates. The scope of the present work was to investigate and optimize the production of lipids by the oleaginous yeast Cutaneotrichosporon curvatus from undetoxified lignocellulosic hydrolysates of steam-pretreated A. donax. The growth of C. curvatus was first optimized in synthetic media, similar in terms of sugar concentration to hydrolysates, by applying the response surface methodology (RSM) analysis. Then the bioconversion of undetoxified hydrolysates was investigated. A fed-batch process for the fermentation of A. donax hydrolysates was finally implemented in a 2-L bioreactor. Under optimized conditions, the total lipid content was 64% of the dry cell weight and the lipid yield was 63% of the theoretical. The fatty acid profile of C. curvatus triglycerides contained 27% palmitic acid, 33% oleic acid and 32% linoleic acid. These results proved the potential of lipid production from A. donax, which is particularly important for their consideration as substitutes for vegetable oils in many applications such as biodiesel or bioplastics.


Assuntos
Basidiomycota/metabolismo , Biocombustíveis/microbiologia , Lipídeos/biossíntese , Poaceae/química , Basidiomycota/crescimento & desenvolvimento , Biocombustíveis/economia , Biomassa , Reatores Biológicos/microbiologia , Conservação dos Recursos Naturais , Meios de Cultura/química , Meios de Cultura/metabolismo , Ácidos Graxos/química , Fermentação , Hidrólise , Lignina/metabolismo
16.
J Agric Food Chem ; 67(11): 3134-3139, 2019 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-30827102

RESUMO

Three novel compounds, erinachromanes A and B (1, 2) and erinaphenol A (3), along with eight known compounds (4-11), were isolated from the culture broth of Hericium erinaceus. The structures of 1-3 were determined by the interpretation of spectroscopic data. Although compounds 4 and 9 had been synthesized, they were isolated from a natural source for the first time. In the bioassay examining plant-growth regulatory activity, all of the compounds suppressed the growth of lettuce.


Assuntos
Basidiomycota/química , Fatores Biológicos/química , Meios de Cultura/química , Basidiomycota/crescimento & desenvolvimento , Basidiomycota/metabolismo , Fatores Biológicos/metabolismo , Meios de Cultura/metabolismo , Estrutura Molecular
17.
Nat Commun ; 10(1): 1279, 2019 03 20.
Artigo em Inglês | MEDLINE | ID: mdl-30894528

RESUMO

A classic problem in microbiology is that bacteria display two types of growth behavior when cultured on a mixture of two carbon sources: the two sources are sequentially consumed one after another (diauxie) or they are simultaneously consumed (co-utilization). The search for the molecular mechanism of diauxie led to the discovery of the lac operon. However, questions remain as why microbes would bother to have different strategies of taking up nutrients. Here we show that diauxie versus co-utilization can be understood from the topological features of the metabolic network. A model of optimal allocation of protein resources quantitatively explains why and how the cell makes the choice. In case of co-utilization, the model predicts the percentage of each carbon source in supplying the amino acid pools, which is quantitatively verified by experiments. Our work solves a long-standing puzzle and provides a quantitative framework for the carbon source utilization of microbes.


Assuntos
Aminoácidos/metabolismo , Bacillus subtilis/metabolismo , Carbono/metabolismo , Escherichia coli/metabolismo , Redes e Vias Metabólicas/genética , Bacillus subtilis/genética , Bacillus subtilis/crescimento & desenvolvimento , Meios de Cultura/química , Meios de Cultura/metabolismo , Escherichia coli/genética , Escherichia coli/crescimento & desenvolvimento , Cinética , Óperon Lac , Modelos Biológicos
18.
J Agric Food Chem ; 67(12): 3389-3399, 2019 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-30816043

RESUMO

This study describes the use of alternative operational strategies in the solid-state fermentation of the agro-industrial leftover sugar cane bagasse (SCB) supplemented with l-phenylalanine, for bioproducing natural 2-phenylethanol (2-PE) and 2-phenethyl acetate (2-PEA) using K. marxianus. Here, fed-batch and sequential-batch have been assessed at two scales (1.6 and 22 L) as tools to increase the production, as well as to enhance the sustainability of this residue-based process. While in the reference batch strategy a maximum of 17 mg of 2-PE+2-PEA per gram of added SCB was reached at both scales, the implementation of fed-batch mode induced a production increase of 11.6% and 12.5%, respectively. Also, the production was increased by 16.9% and 2.4% as compared to the batch when a sequential-batch mode was used. Furthermore, the use of these strategies was accompanied by lower consumption of key resources like the inoculum, air, and time, promoting savings between 22% and 76% at both scales.


Assuntos
Acetatos/metabolismo , Técnicas de Cultura Celular por Lotes/métodos , Celulose/metabolismo , Kluyveromyces/metabolismo , Álcool Feniletílico/análogos & derivados , Álcool Feniletílico/metabolismo , Saccharum/metabolismo , Meios de Cultura/metabolismo , Fermentação , Fenilalanina/metabolismo , Saccharum/microbiologia
19.
J Agric Food Chem ; 67(16): 4595-4602, 2019 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-30907589

RESUMO

Aflatoxin B1 (AFB1), is a type I carcinogen that is one of the strongest naturally occurring aflatoxins and can be injurious to humans and livestock upon ingestion, inhalation, or skin contact, with carcinogenic and mutagenic effects. It causes significant hazardous effects to the food- and animal-production industries. We found a bacterial strain, 3J2MO, that degraded AFB1 well, and here we tested and characterized its AFB1-degradation ability. The strain degraded about 93.82% of the AFB1 after incubation for 48 h in Luria-Bertani (LB) medium at 37 °C with a final concentration of 100 ppb and an inoculation quantity of 1 × 107 cfu/mL. High-performance liquid chromatography-fluorescence detection (HPLC-FLD) was used to determine AFB1 amounts. The maximum degradation rates were 89.23% at pH 8.5; 55.78% at an inoculation quantity of 1 × 108 cfu/mL; and 71.50 and 71.21% at 34 and 37 °C, respectively. Treatment with sucrose and soluble starch as carbon sources and beef extract and ammonium acetate as nitrogen sources stimulated the degradation rate. Mg2+ and Ca2+ ions were activators for AFB1 degradation; however, Mn2+, Fe3+, Zn2+, and Cu2+ were strong inhibitors. This bacterial strain has potential in bioremediation and the detoxification of aflatoxin contamination for biocontrol strategies in both agricultural products and food-industry matrices.


Assuntos
Aflatoxina B1/metabolismo , Flavobacteriaceae/metabolismo , Aflatoxina B1/análise , Biodegradação Ambiental , Cromatografia Líquida de Alta Pressão , Meios de Cultura/química , Meios de Cultura/metabolismo , Flavobacteriaceae/química , Concentração de Íons de Hidrogênio , Sacarose/análise , Sacarose/metabolismo
20.
Methods Mol Biol ; 1922: 357-368, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30838590

RESUMO

Caries lesions result from the interaction between dental biofilm and sugars. Since the biofilm is an important component in the etiology of the disease, biofilm models have been developed to study the cariogenicity of dietary sugars, as well as the anticaries effect of substances. Two of such models, termed as "static" or "continuous flow," are described in details here together with their advantages, limitations, and applications.


Assuntos
Biofilmes , Cárie Dentária/microbiologia , Streptococcus mutans/fisiologia , Animais , Técnicas Bacteriológicas/instrumentação , Técnicas Bacteriológicas/métodos , Bovinos , Técnicas de Cultura de Células/instrumentação , Técnicas de Cultura de Células/métodos , Meios de Cultura/química , Meios de Cultura/metabolismo , Cárie Dentária/metabolismo , Esmalte Dentário/microbiologia , Desenho de Equipamento , Humanos , Boca/microbiologia , Açúcares/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA