Effect Of Substrate Concentration Research Articles

Biohydrogen production from lignocellulosic hydrolysate: Unveiling the synergistic impact of substrate concentration and furfural inhibition.

Lignocellulosic biomass offers substantial potential as an ideal feedstock for dark fermentative hydrogen production due to its sustainability and cost-effectiveness. The current study examined the influence of furfural on fermentative hydrogen production using lignocellulosic hydrolysate in the presence of furfural. Synthetic lignocellulosic hydrolysate, consisting primarily of 76% xylose, 10% glucose, 9% arabinose, and a mixture of other sugars such as galactose and mannose (85% pentose sugars and 15% hexose sugars), was employed as the substrate. Various substrate concentrations ranging from 2 to 32g/L were tested, along with furfural concentrations of 0, 1, and 2g/L. The investigation aimed to assess the effects of initial substrate concentration, initial furfural concentration, furfural-to-biomass ratio (F/B), and furfural-to-substrate ratio (F/S) on biohydrogen production yields. The maximum specific substrate utilization rates at different substrate concentrations were effectively characterized using Haldane's substrate inhibition model. Among the tested concentrations, the 16g/L emerged as the optimal substrate concentration. The initial furfural concentration was identified as the most significant parameter impacting biohydrogen production, with complete inhibition observed at a furfural concentration of 2g/L. Higher F/S ratios at substrate concentrations ranging from 2 to 16g/L resulted in reduced maximum specific hydrogen production rates (MSHPR) and hydrogen yields. Substrate inhibition was observed at 24g/L and 32g/L. Lactate was the predominant metabolite in all batches containing 2-g/L furfural, as well as in batches with 1-g/L furfural and substrate concentrations of 24 and 32g/L. Furfural at a concentration of 1g/L was not inhibitory in any of the batches. Overall, the mixed cultures in this study could efficiently produce hydrogen from lignocellulosic hydrolysates and degrade furfural, providing new insights into fermentative hydrogen-producing bacteria with furfural tolerance.

The effect of substrate concentration on the methane-driven interaction network

Methane, the primary substrate for aerobic methanotrophs, regulates the rate of methanotrophic activity and shapes the composition of the methane-oxidizing community. Given that methane-derived carbon may fuel the food web in the soil, methane availability can potentially be a key determinant, structuring the network of the interacting methane-oxidizing community. Here, we determined the response of the methane-driven interaction network to different methane concentrations (∼1.5 %v/v, 3 %v/v, and 7 %v/v), indicative of different levels of energy flow through the soil food web, using a stable isotope probing approach with 13C-methane coupled to a co-occurrence network analysis in a microcosm study. The accumulated 13C-atom fraction in the total carbon content increased from 1.08 % (background level) to an average of 7.2 % in the incubation under 7 %v/v methane, indicating that the carbon-flow via the methanotrophs can significantly contribute to the total carbon in the rice paddy soil. The 13C-enriched 16 S rRNA gene sequencing analysis revealed the predominance of gammaproteobacterial methanotrophs and Methylocystis. The composition of the actively growing (13C-labelled) bacterial community was dissimilar in the incubation under ∼3 %v/v than under 1.5 %v/v and 7 %v/v methane. This was also reflected in the co-occurrence network analysis, where the topological properties indicated a more complex and connected network in the incubation under 3 %v/v methane. It thus appears that moderate methane concentrations fostered closer associations among members of the methane-oxidizing community. Overall, our research findings showed that the methanotrophs can contribute to the total soil carbon, and methane concentrations not only shifted the bacterial community, including the methanotrophic composition, but also affected bacterial interactions.

Development of a model for the ethanol concentration limit as a function of temperature and initial substrate concentration using the yeast Saccharomyces cerevisiae.

In this study, a model was developed to simulate the effect of temperature ( ) and initial substrate concentration ( ) on the ethanol concentration limit ( ) using the yeast Saccharomyces cerevisiae. To achieve this, regressions were performed using data provided by other authors for to establish a model dependent on and capable of predicting results with statistical significance. After constructing the model, a response surface was generated to determine the conditions where reaches higher values: temperatures between 28°C and 32°C and an initial substrate concentration around 200 g/L. Thus, the proposed model is consistent with the observations that increasing temperatures decrease the ethanol concentration obtained, and substrate concentrations above 200 g/L lead to a reduction in ethanol concentration even at low temperatures such as 28°C.

Analyzing the effect of polydopamine cross-linked serine protease on anti-shrinkage finishing of wool using response surface methodology design

The polydopamine-cross-linked serine protease anti-felting process of wool fibers was optimized by response surface methodology to prepare wool fabrics with a low tendency to shrink and high strength. The effects of dopamine substrate concentration, serine protease substrate concentration, and reaction time on the physical properties and surface color of wool were investigated. The experimental data were fitted and analyzed by the polynomial regression model, and the predicted area shrinkage and breaking strength response of wool fabric were obtained. The results were analyzed by variance analysis to determine the important parameters for optimization. Wool fabrics were prepared under the conditions of dopamine substrate concentration of 0.834 g/l, serine protease substrate concentration of 2.5 g/l, and reaction world of 127 min. Scanning electron microscopy images showed that the surface of wool fibers was covered with a large amount of polydopamine and some edge scales were passivated. After 20 cycles of washing, the shrinkage area of wool fabric is from 1.49–7.25%, with good durability. In addition, X-ray photoelectron spectroscopy, and X-ray diffraction analysis results showed that the behavior of polydopamine-coated fibers prevented the excessive hydrolysis of scales by serine protease, and the crystallization index and solubility in alkaline solution increased.

Production of lactulose from lactose using a novel cellobiose 2-epimerase from Clostridium disporicum

Lactulose is a semisynthetic nondigestive sugar derived from lactose, with wide applications in the food and pharmaceutical industries. Its biological production routes which use cellobiose 2-epimerase (C2E) as the key enzyme have attracted widespread attention. In this study, a set of C2Es from different sources were overexpressed in Escherichia coli to produce lactulose. We obtained a novel and highly efficient C2E from Clostridium disporicum (CDC2E) to synthesize lactulose from lactose. The effects of different heat treatment conditions, reaction pH, reaction temperature, and substrate concentrations were investigated. Under the optimum biotransformation conditions, the final concentration of lactulose was up to 1.45 M (496.3 g/L), with a lactose conversion rate of 72.5 %. This study provides a novel C2E for the biosynthesis of lactulose from low-cost lactose.

Regulation Mechanism and Optimization Strategy of Microbial Metabolism in Bioreactor

In this study, the metabolic regulation mechanism of microorganisms in bioreactor was discussed, and a series of optimization strategies were proposed based on this. The key effects of metabolic regulation on the performance of bioreactors were revealed through the overview of microbial metabolic pathways and the analysis of regulatory mechanisms. In view of this, the optimization strategy based on metabolic regulation was proposed from the aspects of metabolic engineering transformation, genetic engineering technology application, metabolic pathway reconstruction and optimization. At the same time, the operating conditions of the reactor, such as temperature, pH value, dissolved oxygen, substrate concentration and mixing effect were optimized in detail. In terms of reactor design and scale-up strategy, the scale effect, reactor configuration and flow field optimization, and heat and mass transfer enhancement technology were mainly considered. This study provides important theoretical and practical guidance for the improvement of bioreactor performance and the progress of biotechnology industry.

Production of fermentable glucose from the hydrolysis process of cellulose algae waste using fungal cellulases

Kappaphycus alvarezii is the most widely cultivated algae species globally because of its main use in carrageenan production. Waste resulting from carrageenan production still contains high levels of cellulose, which is potentially convertible into fermentable sugar. However, the commercial viability of sugar conversion from algae waste is limited by the high cost of the hydrolysis required to break down the algae waste. This study aims to develop a new hydrolysis method, through the adoption of fungal algal cell disruption to produce a fermentable sugar. The fungus Trichoderma reseei was developed as a new pretreatment method. It was chosen for its superior inherent properties, including low chemical input and environmental friendliness. This study develops a method for fungal pretreatment of algae processing waste. We investigated the effects of substrate concentration, inoculum size, and reaction time on sugar production using full factorial design. The results showed that substrate concentration, inoculum size, and reaction time affect sugar production. This study demonstrates that sugar production from algae proccessing waste can reach more than 70% under optimum conditions. These results indicate the potential of microbial cellullase as an economically friendly pretreatment for sugar production from algae processing waste.

Fructooligosaccharides: Production by recombinant fructosyltransferase from Festuca arundinacea in a continuous reactor and kinetic modeling profile

In the quest for maximum conversion of sucrose into 1-kestose using fructosyltransferases in a continuous reactor, consideration of the reversible reactions at competing concentrations of sucrose and 1-kestose is crucial. In this study, a kinetic model based on a combined approach of rapid equilibrium and steady-state kinetics was developed to predict the profile of FOS production using recombinant sucrose: sucrose 1-fructosyltransferase from Festuca arundinacea produced in Pichia pastoris. The purified enzyme selectively converted sucrose into 1-kestose with a final yield of 0.66 g/g sucrose consumed. The reaction rate laws adequately described the kinetic profile of the substrate and the products and accurately predicted the composition of the reaction mixture. The model was fitted to experimental data obtained at three enzyme dosages and three initial sucrose concentrations. The model could predict the effect of substrate concentration on initial rate kinetics, half-saturation constant, and transferase to hydrolase ratio. For the known values of initial sucrose and enzyme concentration, the optimum reaction time and the required dilution rate were predicted for the development of a continuous process to produce 1-kestose-enriched short-chain FOS. A volumetric productivity of ∼110 g/L/h of 1-kestose with 40 % carbohydrate composition in the permeate flux was demonstrated.

Effect of substrate concentration on reactive metabolite assessment in drug discovery research

Effect of substrate concentration on reactive metabolite assessment in drug discovery research

Effect of Fruit Waste Substrate Concentration and pH on Biogas Production by Mixed Culture

Effect of Fruit Waste Substrate Concentration and pH on Biogas Production by Mixed Culture

Effect of Substrate Concentration (Glucose) on Ethanol Fermentation Continue with Immobilized Fixed Bed Fermenter for 2/3 Mesh Pumice Anchoring Size

The need for ethanol which is increasing at all times demands development related to ethanol production, especially those produced through the fermentation process both development in terms of raw materials and processes. Ethanol fermentation process continues to have problems one of them is wash out or the carrying of microorganisms into the product stream which causes the number of microorganisms to continue to decrease in the fermenter. One way to solve the problem of wash out is to tether the microorganism first to the anchoring medium (immobilized cell) and choose the suitable type of fermenter. The purpose of this study was to determine the effect of glucose concentration and the best conditions on the ethanol fermentation process continue with immobilized cell fixed bed fermenter to the value of ethanol concentration and yield ethanol produced as well as the percent of microorganisms still carried into the product streams. Based on the results of the study, the best conditions were obtained with a residence time of 2 days with the ethanol concentration of 1.20%v/v, the yield of fermented ethanol was 37.75%w/w, and % number of cells released was 0.45% at a glucose feed concentration of 150g/L. Fermentation is carried out under conditions of immobilized cell using microorganisms from the type of yeast Saccharomyces cerevisiae. In this study the variables that were considered fixed were the expansion ½ height of 1.47m column height, temperature of 25-30°C, and a pH of 5.5.

Biohydrogen production kinetics from cacao pod husk hydrolysate in dark fermentations: Effect of pretreatment, substrate concentration, and inoculum

This study aims to explore the impact of pretreatment on cacao pod husk (CPH) and investigate the kinetics of biohydrogen production in a dark fermentation (DF) batch reactor with consideration for substrate and inoculum concentration. As the first study focused on biohydrogen production from CPH, the Taguchi orthogonal array was utilized to determine the optimal pretreatment condition for powdered CPH. This study examined different substrate concentrations (3–100 g VS/L) and inoculum concentrations (5 and 10 % v/v). The study showed that biohydrogen production was significantly increased by 74.4 ± 0.1 % by pretreatment with 5.5 % HCl compared to the untreated CPH as control. Furthermore, the optimal performance was achieved by 35 g VS/L of CPH in the mixture with inoculated by 10 % v/v inoculum, resulting in a biohydrogen production and concentration of 257.05 ± 7.97 mL/L and 23.87 ± 0.15 %, respectively. The inoculum's microbial community analysis using Illumina 16S sequencing showed a dominance of the Ethanoligenes (30.4 %), which was positively correlated with the profiles of hydrogen production and the proportion of VFAs. The Aiba model with an exponential substrate concentration and inhibitory constant (R2 of 0.93) was statistically the most precise mathematical model to predict the specific growth rate during the fermentative biohydrogen production by CPH substrate.

Atrazine Degradation by Bacillus safensis Strain BUK_BCH_BTE6 Isolated from Agricultural Land in Northwestern Nigeria

Atrazine herbicide is known to disrupt the endocrine system and is potentially carcinogenic. Consumption of which is devastating. This research aimed to isolate and characterize bacteria with atrazine degrading ability. An enrichment method was adopted to isolate the bacteria on mineral salt media following serial dilution. The isolate was identified molecularly and characterized based on effects of temperature, pH, substrate concentration, incubation time, inoculum size and heavy metals. GC-MS analysis was performed to identify the metabolites and degradation efficiency. The isolate was identified as Bacillus safensis strain BUKˍBCHˍBTE6 based on 16S rRNA gene sequence and molecular phylogenetic analysis. Growth and degradation of atrazine by this bacterium was optimal at 35 °C, pH of 7.5, 400 mgL-1, inoculum size 600 µL after 48 h. The growth of the isolate was inhibited by 2 ppm Hg, Cd, Cr, Pb, Ar and Ni. The degradation efficiency after 120 h was 88.85%. GC-MS analysis detected the formation of Desethyldeisopropylatrazine, Deisopropylatrazine, N-Ethylammelide and Cyanuric acid as metabolites. This isolate can be efficient atrazine degrader, hence may be beneficial for bioremediation of atrazine polluted sites.

Application of OFAT approach for optimizing tannase production under submerged fermentation

Current study reports the optimization of tannase production by Bacillus haynesii SSRY4MN031245 by employing One factor at a Time approach (OFAT). The effects of supplementary carbon sources, nitrogen sources, inoculum size and substrate (Tannic acid) concentration were studied on enzyme production. Tannic acid, when added optimally in the production media along with optimized inoculum size and optimized concentrations of glucose, sodium nitrate resulted in improved tannase production. Optimization of 2.85-fold was achieved by OFAT strategy.

Investigation into Optimal Conditions for Enzymatic Hydrolysis of Cassava Starch to Glucose by Amylase from Rice

The challenge of finding locally available materials in abundance to meet up with the increase in demand for glucose syrup necessitated this study. Enzymatic hydrolysis of cassava starch to glucose using glucose amylase sourced from rice was conducted. A-3 factor with 6 levels factorial viz. substrate concentration (0.5, 1.0, 1.5, 2.0, 2.5 and 3.0% w/v), pH (4, 5, 6, 7, 8 and 9) and temperature (30, 40, 50, 60, 70 and 80 °C) experiment were employed. Rice malt was prepared and enzyme activated. Starch (substrate), buffer solutions, standard glucose solution and its calibration curve were also prepared. Starch was hydrolyzed by α-amylase and tested for presence of reducing sugar using Benedict solution. Time course of the reaction was studied and enzyme activity determined. It was observed that as reaction time increased (t), amount of glucose produced [P] initially increased but soon recorded infinitesimal increase and later assumed constant. The effects of substrate concentration, pH and temperature were found to be essential on glucose production. Statistical analysis on the effect of substrate concentration [S], reaction time and their interactions showed significant impact at probability level of (p) = 0.05.

BIOKINETIC CHARACTERIZATION OF FERROPLASMA ACIDIPHILUM

Abstract. Recently a mixed culture dominated by the iron-oxidizing microorganisms Leptospirillum and Ferroplasma has been used in a large-scale microbial fuel cell for electrical power generation. There are many factors that affect the kinetics of iron oxidation by the mixotroph Ferroplasma acidiphilum. This study investigated the effects of pH, temperature, and substrate and yeast extract concentrations in order to arrive at kinetically favorable operating conditions with minimal jarosite precipitation. Furthermore, F. acidiphilum was cultured with Leptospirillum sp. in order to determine its viability as a species capable of limiting the organic by-products of chemolithotrophic microbial growth. Bacterial characterization in the culture was accomplished using fluorescent in situ hybridization (FISH). It was found that the ferrous iron oxidation was most favorable at yeast extract concentration of 0.02% (w/v), pH of 1.6, temperature of 35 oC and an initial ferrous iron concentration of 1 g/L yielding a maximum specific growth rate of 0.0351-0.042 h-1. Moreover, F. acidiphilum displayed a symbiotic relationship with its chemolithotrophic counterpart, Leptospirillum sp. in that they were able to utilize the metabolic organic products of the chemolithotroph and limit the organic concentration to ~20 ppm total organic carbon (TOC), well below the threshold concentration of 250 ppm for chemolithotroph activity.

The Impact of Process Parameters on 1,3-Propanediol Production and 3-Hydroxypropionaldehyde Accumulation in Fed-Batch Fermentation of Glycerol with Citrobacter freundii AD119

Microbial production of 1,3-propanediol (1,3-PD) has attracted the interest of scientists for decades. Its product offers an environmentally friendly and sustainable alternative to fossil-based raw materials for chemical synthesis. Citrobacter freundii is one of the natural producers of 1,3-PD known for its ability to yield it in significant titers. An efficient bioprocess requires an in-depth understanding of the factors that influence the performance of its biocatalyst. The effects of pH, temperature, stirring rate, and substrate concentration on glycerol fermentation in fed-batch cultures of C. freundii AD119 were investigated in this study. In addition to monitoring the kinetics of substrate utilization and the formation of the final products, the concentration of 3-hydroxypropionaldehyde (3-HPA), an inhibitory intermediate of glycerol bioconversion, was analyzed. When the optimal working conditions were used (pH 7.0, temperature 30 °C, stirring rate of 80 rpm, and glycerol concentration below 15 g/L during the fed-batch phase), 53.44 g/L of 1,3-PD were obtained. When the process was performed at temperatures of 33 °C or higher or in acidic pH (6.5), an elevated concentration of 3-HPA was observed and the process halted prematurely.

Mathematical modeling of dark fermentative hydrogen and soluble by-products generations from water hyacinth

The production of hydrogen and soluble metabolite products from water hyacinth via dark fermentation was modeled. The model was built on the assumption that the substrate exists in two forms (i.e., soluble and particulate) and undergoes two stages (i.e., hydrolysis and acidogenesis) in the dark fermentation process. The modified Michaelis-Menten and surface-limiting models were applied to describe the hydrolysis of soluble and particulate forms, respectively. Meanwhile, the acidogenesis stage was modeled based on the multi-substrate-single-biomass model. The effects of temperature, pH, and substrate concentration were integrated into the model to increase flexibility. As a result, the model prediction agreed with the experimental and literature data of water hyacinth-fed dark fermentation, with high coefficient of determination values of 0.92 – 0.97 for hydrogen and total soluble metabolite products. These results indicate that the proposed model could be further applied to dark fermentation’s downstream and hybrid processes using water hyacinth and other substrates.

Effect of Fructose and Butyric Acid Addition during Electricity Production in Single Chamber Microbial Fuel Cell

The substrate is an important factor for efficient electricity production in Microbial Fuel Cell systems. The substrate is an organic compound that promotes the growth of active microbes. The goal of this study was to investigate the effect of substrate type and concentration on the bioelectricity produced by a single-chamber MFC. Fructose and butyric acid were used as substrates and carbon felt used as an electrode. Types and variations in substrate concentration were applied to the soil media used in the MFC. After 3 weeks of incubation, the optimum power density value achieved by MFC with 90 g/L fructose substrate was 20.5 mW/m2. Whereas, MFC treated with 800 mg/L butyric acid produced a maximum power density of 19.7 mW/m2.Keywords: Substrate, Fructose, Butyric acid, Power density, Microbial Fuel Cell.

Effect of Substrate Concentration and Temperature for Bio-Enzyme Production Using Enterococcus faecalis Isolated from Waste Dump Soil in Sokoto Metropolis, Nigeria

The study evaluated the effect of substrate concentration and temperature on the production of amylase enzyme by Enterococcus faecalis from the wastes dump soil Sokoto Metropolis, Nigeria. Five bacteria species were isolated and biochemically characterized which include E. coli, B. subtilis, S. aureus, E. faecalis and P. aeroginosa. The screening of identified bacteria for amylase production was carried out and all bacteria produced a wide halo on a starch agar. E. faecalis produced highest zone of clearance with 70mm,B.subtilis 50mm,S.aureus 34mm, E. coli 29mm,thenB.cereus with the least zone of clearance of 24mm. proximate analysis of the potato peels sample shows that the potatoes peels has high carbohydrate content with value of 75.737 recorded. The effect of substrate concentration was studied at 5g,10g,15g and 20g. The highest amylase production was recorded (20g) with value of 1.218 and 15g with the least absorbance value of 0.973.The effect of temperature were studied at 25˚C, 35˚C, 45˚C, and 55˚C. The temperature of 45˚C has the highest absorbance value of 1.691. While the least was recorded at55˚C with value of 0.970.These shows that temperature and substrate concentration has a vital role to play in the production of microbial enzymes. It’s concluded in this study that waste dump site is a reservoir of important microorganisms and potato peels is a good substrate for enzyme production and therefore can be utilized instead of dumping it for natural degradation.