ABSTRACT
L-glutamic acid is the world's largest bulk amino acid product that is widely used in the food, pharmaceutical and chemical industries. Using Corynebacterium glutamicum G01 as the starting strain, the fermentation by-product alanine content was firstly reduced by knocking out the gene encoding alanine aminotransferase (alaT), a major by-product related to alanine synthesis. Secondly, since the α-ketoglutarate node carbon flow plays an important role in glutamate synthesis, the ribosome-binding site (RBS) sequence optimization was used to reduce the activity of α-ketoglutarate dehydrogenase and enhance the glutamate anabolic flow. The endogenous conversion of α-ketoglutarate to glutamate was also enhanced by screening different glutamate dehydrogenase. Subsequently, the glutamate transporter was rationally desgined to improve the glutamate efflux capacity. Finally, the fermentation conditions of the strain constructed using the above strategy were optimized in 5 L fermenters by a gradient temperature increase combined with a batch replenishment strategy. The glutamic acid production reached (135.33±4.68) g/L, which was 41.2% higher than that of the original strain (96.53±2.32) g/L. The yield was 55.8%, which was 11.6% higher than that of the original strain (44.2%). The combined strategy improved the titer and the yield of glutamic acid, which provides a reference for the metabolic modification of glutamic acid producing strains.
Subject(s)
Glutamic Acid , Corynebacterium glutamicum/genetics , Ketoglutaric Acids , Metabolic Engineering , AlanineABSTRACT
ABSTRACT This study aimed to verify if coal ash, a residue from thermal power plants, could act as a granulation nucleus, cations source, and abrasive element to favor granules formation and stability in aerobic granular sludge (AGS) systems. Two simultaneous fill/draw sequencing batch reactors (SBRs) (R1 and R2) were operated with 6-h cycles, i.e., the filling and drawing phases occurred simultaneously, followed by the reaction and settling phases. R1 was maintained as control, while R2 was supplemented with coal ash (1 g·L-1) on the first day of operation. Granulation was achieved in both reactors, and no significant differences were observed in terms of settleability, biomass retention, morphology, resistance to shear, and composition of the EPS matrix. However, the ash addition did not change the settleability, biomass retention, granule morphology, shear resistance, and extracellular polymeric substances (EPS) content significantly. COD removal was high (≥ 90%), while nitrogen (~50%) and phosphorus (~40%) removals were low, possibly due to the presence of nitrate during the anaerobic phase. With granulation, microbial population profile was altered, mainly at the genus level. In general, the operational conditions had a more considerable influence over granulation than the ash addition. The possible reasons are because the ash supplementation was performed in a single step, the low sedimentation rate of this particular residue, and the weak interaction between the ash and the EPS formed in the granular sludge. These factors appear to have decreased or prevented the action of the ash as granulation nucleus, source of cations, and abrasive element.
RESUMO O objetivo deste estudo foi verificar se a cinza de carvão mineral, um resíduo de usinas termelétricas, poderia atuar como núcleo de granulação, fonte de cátions e elemento abrasivo em sistemas de lodo granular aeróbio (LGA) para favorecer a formação e estabilidade dos grânulos. Dois reatores em batelada sequencial (RBS) (R1 e R2) foram operados em regime de alimentação/descarte simultâneos com ciclos de 6 h, ou seja, as fases de alimentação e descarte do efluente ocorreram simultaneamente, seguidas das fases de reação e de decantação. O R1 foi mantido como controle, enquanto o R2 foi suplementado com as cinzas (1 g·L-1) no primeiro dia de operação. A granulação foi alcançada em ambos os reatores, não havendo diferenças marcantes em termos de sedimentabilidade, retenção de biomassa, morfologia do grânulo, resistência ao cisalhamento e conteúdo de substâncias poliméricas extracelulares (SPE). A remoção de DQO foi alta (≥ 90%), enquanto as remoções de nitrogênio (~50%) e fósforo (~40%) foram baixas, possivelmente pela presença de nitrato na fase anaeróbia. Após a granulação, o perfil da comunidade microbiana mudou, especialmente em termos de gênero. Globalmente, as condições operacionais tiveram maior influência sobre a granulação do que a adição das cinzas, possivelmente porque elas só foram adicionadas uma vez e possuem baixa velocidade de sedimentação, bem como devido a uma fraca interação das cinzas com a matriz de SPE formada no lodo aeróbio. Esses fatores podem ter diminuído, ou mesmo impedido, a ação das cinzas como núcleo de grânulo, fonte de cátions ou elemento abrasivo.
ABSTRACT
This study engineered β-carotene ketolase CrtW and β-carotene hydroxylase CrtZ to improve biosynthesis of astaxanthin in Escherichia coli. Firstly, crtW was randomly mutated to increase CrtW activities on conversion from β-carotene to astaxanthin. A crtW* mutant with A6T, T105A and L239M mutations has improved 5.35-fold astaxanthin production compared with the wild-type control. Secondly, the expression levels of crtW* and crtZ on chromosomal were balanced by simultaneous modulation RBS regions of their genes using RBS library. The strain RBS54 selected from RBS library, directed the pathway exclusively towards the desired product astaxanthin as predominant carotenoid (99%). Lastly, the number of chromosomal copies of the balanced crtW-crtZ cassette from RBS54 was increased using a Cre-loxP based technique, and a strain with 30 copies of the crtW*-crtZ cassette was selected. This final strain DL-A008 had a 9.8-fold increase of astaxanthin production compared with the wild-type control. Fed-batch fermentation showed that DL-A008 produced astaxanthin as predominant carotenoid (99%) with a specific titer of 0.88 g·L without addition of inducer. In conclusion, through constructing crtW mutation, balancing the expression levels between crtW* and crtZ, and increasing the copy number of the balanced crtW*-crtZ cassette, the activities of β-carotene ketolase and β-carotene hydroxylase were improved for conversion of β-carotene to astaxanthin with higher efficiency. The series of conventional and novel metabolic engineering strategies were designed and applied to construct the astaxanthin hetero-producer strain of E. coli, possibly offering a general approach for the construction of stable hetero-producer strains for other natural products.
ABSTRACT
Background: Random blood sugar (RBS) is a commonly performed screening test for type 2 diabetes in both programmatic as well as clinical settings. Previous calorie intake is known to affect the results of RBS. So, present study was conducted to assess the effect of previous calorie intake on sensitivity, specificity, positive and negative predictive values (NPV) and accuracy of RBS.Methods: A cross sectional study was done in 317 patients of 30 years or more using systematic random sampling in a general outpatient department of a district hospital. All the patients underwent RBS measurement. History of calorie intake in past 1-2 hours before undergoing RBS was taken. Screening test parameters of RBS was evaluated using oral glucose tolerance test as clinical reference.Results: This study found that calorie consumption of 200 kcal or more significantly affected the screening test result of RBS. When patient had consumed 200 kcal or more in last 1-2 hours, the sensitivity of RBS is 90.0%, specificity is 57.4%, positive predictive value (PPV) is 26.9% and NPV is 97.1%. Whereas, these parameters are 63.3%. 78.5%, 43.6% and 88.9% respectively when patient had consumed less than 200 kcal in last 1-2 hours before RBS.Conclusions: Sensitivity and NPV of RBS is higher if patient had consumed more than 200 kcal 1-2 hours prior to RBS whereas specificity and PPV is higher if patient had consumed less than 200 kcal. Taking history of quantity and time of last meal would be helpful to better interpret the screening test results of RBS.
ABSTRACT
Background: To study the health and efficiency of the more up to date oral hypoglycemic specialist sitagliptin in the executives of sort 2 diabetes mellitus patients. In our examination authors have enlisted 250 patients who met our investigation criteria of which authors ordered dependent on age and lab information, most of patients in the age bunch between 45-55 years (n=97, 39.2%), the RBS was diminished to Comparatively estimations of RBS, FBS, PPBS, HbA1C were decreased in follow up than benchmark esteem.Methods: This simultaneous observational investigation was done when all is said in done department of General Medicine of Hi-Tech Medical College and Hospital, Bhubaneswar, Odisha for a time of 6 months in which type 2 diabetes mellitus patients were enrolled dependent on incorporation and avoidance criteria and were pursued to assess the adequacy and security of sitagliptin. Information was dissected by utilizing chart cushion crystal understudy T-test.Results: Authors can presume that sitagliptin use was not related with any dangers and is compelling in the board of Type 2 diabetics, treatment with sitagliptin gave clinically significant decreases in HbA1C, RBS, FBS, PPBS by utilizing this investigation authors realize that gliptins are considerably more protected and powerful in the treatment of sort 2 diabetes mellitus.Conclusion: Treatment with sitagliptin provided clinically meaningful reductions in HbA1C, RBS, FBS, PPBS by using this study authors know that sitagliptins are much more safe and effective in the treatment of type 2 diabetes mellitus.
ABSTRACT
Introduction: Diabetes is an important public health problem,one of our priority non communicable diseases (NCDs)targeted for action by world leaders. Both the number of casesand the prevalence of diabetes have been steadily increasingover the past few decades. The global prevalence of diabeteshas nearly doubled in year 2014 since 1980, rising from 4.7%to 8.5% in the adult population. Study objective was to findout risk factors for Type 2 Diabetes Mellitus among 40 yearand above in rural areas of Varanasi.Material and methods: A community based cross sectionalstudy was conducted in rural areas of Varanasi covering 40year and above. WHO, STEP approach was used for datacollection in this study. RBS and FBS blood sugar measuredand diagnosis was confirmed by WHO criteria. χ2 test wasapplied to find significant association.Results: The mean ±SD age of the study subject was55.19+11.92 years. The prevalence of smoking, alcoholintake, fruits consumption, vegetables consumption andphysical activity was 18.3%, 22.7%, 48.1%, 99.8% and 28.8%respectively. The overall prevalence of diabetes was 6.1%.The prevalence of overweight and obesity was found 15.5%and 32.5% respectively, while prevalence of hypertension was29%.Conclusion: Study showed that the association betweenphysiological risk factors such as obesity and hypertensionwith diabetes was statistically significant (p<0.05), whilebehavioural risk factors mentioned above were not statisticallysignificant (p>0.05).
ABSTRACT
Realgar is a naturally occurring arsenic sulfide (or Xionghuang, in Chinese). It contains over 90% tetra-arsenic tetrasulfide (As4S4). Currently, realgar has been confirmed the antitumor activities, both in vitro and in vivo, of realgar extracted using Acidithiobacillus ferrooxidans (A. ferrooxidans). Bioleaching, a new technology to greatly improve the use rate of arsenic extraction from realgar using bacteria, is a novel methodology that addressed a limitation of the traditional method for realgar preparation. The present systematic review reports on the research progress in realgar bioleaching and its antitumor mechanism as an anticancer agent. A total of 93 research articles that report on the biological activity of extracts from realgar using bacteria and its preparation were presented in this review. The realgar bioleaching solution (RBS) works by inducing apoptosis when it is used to treat tumor cells in vitro and in vivo. When it is used to treat animal model organisms in vivo, such as mice and Caenorhabditis elegans, tumor tissues grew more slowly, with mass necrosis. Meanwhile, the agent also showed obvious inhibition of tumor cell growth. Bioleaching technology greatly improves the utilization of realgar and is a novel methodology to improve the traditional method.
Subject(s)
Humans , Arsenicals/pharmacology , Sulfides/pharmacology , Acidithiobacillus thiooxidans/metabolism , Antineoplastic Agents/pharmacology , Arsenicals/metabolism , Arsenicals/chemistry , Sulfides/metabolism , Sulfides/chemistry , Apoptosis/drug effects , K562 Cells , Cell Line, Tumor , Cell Proliferation/drug effects , Drug Synergism , Toxicological Phenomena , Antineoplastic Agents/chemistryABSTRACT
O objetivo deste trabalho foi estudar o tratamento biológico de efluente de indústria de vegetais congelados em Reator em Batelada Sequencial (RBS), verificando o efeito da concentração de Sólidos Suspensos Voláteis (SSV), Demanda Química de Oxigênio inicial (DQOi) e aeração na remoção biológica de carbono e nitrogênio, a fim de obter um efluente tratado que atenda aos padrões de lançamento recomendados pela legislação ambiental brasileira. Nesta pesquisa, o tratamento dos efluentes foi feito em um RBS, utilizando concentração de SSV variando entre 2000 mg.L-1 e 4000 mg.L-1, DQOi variando entre 300 mg.L-1 e 600 mg.L-1, e quantidade de aeração variando entre 3 L.min-1 e 6 L.min-1. Os resultados mostram que a maior eficiência de remoção para DQO foi de 88%, e para nitrogênio total Kjeldahl (NTK) foi de 74,9%. As condições otimizadas para remoção de DQO e NTK do efluente estudado foram: DQO inicial de 600 mg.L-1, aeração de 4,5 L.min-1 e concentração de SSV de 2000 mg.L-1 .
The objective of this work was to study the biological wastewater treatment from frozen vegetables industry in sequential batch reactor (SBR), verifying the effect of the volatile suspended solids (VSS) concentration, initial Chemical Oxygen Demand (iCOD) and aeration to remove organic carbon and nitrogen in order to obtain a treated wastewater that meets discharge standards recommended by the Brazilian environmental legislation. In this study, the treatment of wastewaters was done in an SBR using VSS concentration ranging from 2000 mg L-1 and 4000 mg.L-1, iCOD ranging from 300 mg.L-1 and 600 mg.L-1, and aeration ranging between 3 L.min-1 and 6 L.min-1. The results show that the major removal efficiency for COD was 88%, and for Total Kjeldahl Nitrogen (TKN) was 74,9%. The optimized conditions for COD and TKN removal of the studied wastewater were: initial COD of 600 mg.L-1, aeration of 4.5 L.min-1 and VSS concentration of 2000 mg.L-1 .