Fluorescent tracers have been used to measure solute transport, but transport kinetics have not been evaluated by comparison of radiolabeled tracers. Using Streptococcus equinus JB1 and other bacteria, the objective of this study was to determine if a fluorescent analogue of glucose (2-NBDG) would be transported with the same kinetics and transporters as [ 14 C]glucose. We uniquely modified a technique for measuring transport of radiolabeled tracers so that transport of a fluorescent tracer (2-NBDG) could also be measured. Deploying this technique for S. equinus JB1, we could detect 2-NDBG transport quantitatively and within 2 s. We found the V max of 2-NBDG transport was 2.9-fold lower than that for [ 14 C]glucose, and the K m was 9.9-fold lower. Experiments with transport mutants suggested a mannose phosphotransferase system (PTS) was responsible for 2-NBDG transport in S. equinus JB1 as well as Escherichia coli. Upon examination of strains from 12 species of rumen bacteria, only the five that possessed a mannose PTS were shown to transport 2-NBDG. Those five uniformly transported [ 14 C]mannose and [ 14 C]deoxyglucose (other glucose analogues at the C-2 position) at high velocities. Species that did not transport 2-NBDG at detectable velocities did not possess a mannose PTS, though they collectively possessed several other glucose transporters. These results, along with retrospective genomic analyses of previous 2-NBDG studies, suggest that only a few bacterial transporters may display high activity toward 2-NBDG. Fluorescent tracers have the potential to measure solute transport qualitatively, but their bulky fluorescent groups may restrict (i) activity of many transporters and (ii) use for quantitative measurement.
ResumoFibra alimentar, ou fibra dietética, pode ser classificada, de acordo com sua funcionalidade, em solúvel e insolúvel. Fibras insolúveis apresentam porosidade, baixa densidade, capacidade de aumentar a produção fecal, devido à hidratação desta, e promover os movimentos intestinais regulares. Em contrapartida, a fração solúvel caracteriza-se por formar gel, atuar como emulsificante e sofrer fermentação. Em virtude da viscosidade e da fermentação, a fibra solúvel apresenta maior relevância à saúde, pois atua na redução dos níveis de colesterol sanguíneo, manutenção da glicemia, colabora com o sistema imunológico, previne doenças (entre elas o câncer) e contribui com a diminuição do esvaziamento gástrico. As fibras solúveis podem ser incorporadas em maior quantidade sem alterar a textura e o sabor dos alimentos quando comparadas com as frações insolúveis, neste sentido, vários estudos são conduzidos com intuito de avaliar a adição de diferentes fibras em produtos cárneos. Carnes e derivados são reconhecidos pela alta composição lipídica indesejada à saúde, tal atributo aliado às características reológicas e funcionais das fibras, permite a substituição de gordura por carboidratos não digestíveis. Destaca-se ainda vantagens como o aumento da capacidade de retenção de água, incremento da estabilidade de emulsão que auxilia o rendimento do produto, além da elaboração de um produto funcional sem modificar sua aceitabilidade.Palavras -chave: alimento funcional, β-glicana, carne, fibra dietética, produto enriquecido. AbstractDietary fiber can be classified according to their functionality in soluble and insoluble. Insoluble dietary fibers have porosity, low density, ability to increase fecal bulk due to the hydration there of and to be higher and transit time enhances bowel. In contrast, the soluble fraction is characterized by forming gel, acting as an emulsifier and suffers fermentation. Due to the viscosity and fermentation, soluble fiber has greater relevance to health as it acts in reducing blood cholesterol levels, blood glucose control helps with the immune system, prevent diseases, among these cancer, and contributes to the decrease of hollowing stomach. Soluble fiber can be incorporated in a larger quantity without changing the texture and tastes of food when compared with the insoluble fractions, in this sense, several studies are conducted in order to assess the addition of fiber in meat products. Meat and meat products are recognized by high lipid composition unwanted health, such combined rheological and functional characteristics of the fibers, attribute allows the replacement of fat by non-digestible carbohydrates.Another highlight advantages such as increased water retention capacity, increased emulsion stability that helps product yield , besides the development of a functional product without changing its acceptability.
This study aimed to evaluate the use of supplementary feed with different percentages of urea and mineral salt for crossbred milk cows. Ten animals were used, mean body weight 480 kg ± 9,7, distributed in a 5 x 5 double Latin square, with treatments of supplements with different urea and mineral salt percentages, namely, 10:10; 10:20; 20:10 and 20:20, completed to 100% with corn meal. Data underwent statistical analysis by SAS at 0.05 significance level. The use of supplements increased (p < 0.05) the total dry matter (DM) intake of diet. The increase in the level of urea in the supplement decreased DM intake of supplement. The use of supplements increased (p < 0.05) DM digestibility. The treatments with presence of supplement showed higher (p < 0.05) milk production. Supplemented diets may be used to correct nutritional deficiencies of sugar cane, with higher intake, digestibility and milk production. Treatments with 20% urea in the composition of the supplement caused a lower DM consumption with the same performance in the animals. The above-mentioned treatments had the best efficiency.
When given excess carbohydrate, certain microbial species respond by storing energy (synthesizing reserve carbohydrate), but other species respond by dissipating the energy as heat (spilling energy). To determine the importance of these responses in the rumen microbial community, this study quantified the responses of mixed ciliate protozoa vs bacteria to glucose. We hypothesized that ciliates would direct more glucose to synthesis of reserve carbohydrate (and less to energy spilling) than would bacteria. Ciliates and bacteria were isolated from rumen fluid using filtration and centrifugation, resuspended in nitrogen-free buffer to limit growth, and dosed with 5 mM glucose. Compared with bacteria, ciliates consumed glucose >3-fold faster and synthesized reserve carbohydrate 4-fold faster. They incorporated 53% of glucose carbon into reserve carbohydrate-nearly double the value (27%) for bacteria. Energy spilling was not detected for ciliates, as all heat production (104%) was accounted by synthesis of reserve carbohydrate and endogenous metabolism. For bacteria, reserve carbohydrate and endogenous metabolism accounted for only 68% of heat production, and spilling was detected within 11 min of dosing glucose. These results suggest that ciliates alter the course of ruminal carbohydrate metabolism by outcompeting bacteria for excess carbohydrate, maximizing reserve carbohydrate synthesis, and minimizing energy spilling.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.