Optimum 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.

Extraction, Purification and Characterization of Poly Phenol Oxidase from Potato and Apple and Inhibition of Enzymatic Browning

The purpose of this study was to determine the optimum conditions for the extraction of polyphenol oxidase (PPO) from potato and apple. PPO is found in a variety of fruits and vegetables and is the enzyme that causes browning reactions when handling damaged cells. At 405 nm, the enzyme activity was determined using spectrophotometry. PPO was researched to stop potato and apple from browning, which reduces their marketability. The outcomes showed that using an extraction buffer containing phosphate buffer (0.05 M, pH 6.6) was the optimum condition for the extraction of polyphenol oxidase from potato and apple. In addition, the results showed that as the temperature increased, the (PPO) activity increased, and the activity reached its peak at a temperature of 35 ͦC. The optimum pH value of (PPO) activity was 6.5 and we observed during the research that (PPO) decreased in strong acid condition and alkaline environments. Moreover, the results showed that the highest activity of polyphenol oxidase enzyme extracted from apple and potato was by using (O-dihydroxybenzene) as a substrate. As the concentration of the substrate increased, the (PPO) activity increased, reaching the optimum substrate concentration of 0.8%, and then its activity decreased. Also, we found that when using ascorbic acid, citric acid, and Na2SO3 as inhibitors, the activity of the polyphenol oxidase enzyme decreased with an increase in the concentration of ascorbic acid, citric acid, and Na2SO3. Sodium thiosulfate, 0.01 M ascorbic acid and 0.5% polyethylene glycol were extracted with an extraction ratio of 1:4 (w/v) for three minutes by using a blender. The purpose of study was to determine the optimum conditions for polyphenol oxidase extraction from potato and apple.

Atomically Co-dispersed nitrogen-doped carbon for sensitive electrochemical immunoassay of breast cancer biomarker CA15-3.

The development of an ultrasensitive and precise measurement of a breast cancer biomarker (cancer antigen 15-3; CA15-3) in complex human serum is essential for the early diagnosis of cancer in groups of healthy populations and the treatment of patients. However, currently available testing technologies suffer from insufficient sensitivity toward CA15-3, which severely limits early large-scale screening of breast cancer patients. We report a versatile electrochemical immunoassay method based on atomically cobalt-dispersed nitrogen-doped carbon (Co-NC)-modified disposable screen-printed carbon electrode (SPCE) with alkaline phosphatase (ALP) and its metabolite, ascorbic acid 2-phosphate (AAP), as the electrochemical labeling and redox signaling unit for sensitive detection of low-abundance CA15-3. During electrochemical detection by differential pulse voltammetry (DPV), it was found that the Co-NC-SPCE electrode did not have a current signal response to the AAP substrate; however, it had an extremely favorable response current to ascorbic acid (AA). Based on the above principle, the target CA15-3-triggered immunoassay enriched ALP-catalyzed AAP produces a large amount of AA, resulting in a significant change in the system current signal, thereby realizing the highly sensitive detection of CA15-3. Under the optimal AAP substrate concentration and ALP catalysis time, the Co-NC-SPCE-based electrochemical immunoassay demonstrated a good DPV current for CA15-3 in the assay interval of 1.0 mU/mL to 10,000 mU/mL, with a calculated limit of detection of 0.38 mU/mL. Since Co-NC-SPCE has an excellent DPV current response to AA and employs split-type scheme, the constructed electrochemical immunoassay has the merits of high preciseness and anti-interference, and its clinical diagnostic results are comparable to those of commercial kits.

The Biogas Production Potential and Community Structure Characteristics of the Co-Digestion of Dairy Manure and Tomato Residues

Anaerobic digestion is an important means to turn agricultural waste into resources and an important way to address the challenges in treating vegetable residues in China. In this study, the co-digestion of dairy manure with tomato residue was investigated to clarify the effect of the total solids (TS) of the digestion substrate on methane’s production and mechanism using the self-made anaerobic digestion device. The results showed that all treatments could rapidly ferment methane and that the daily methane production showed a trend of increasing first and then decreasing. The optimal concentrations of the digestion substrate for liquid anaerobic digestion (L-AD), hemi-solid-state anaerobic digestion (HSS-AD), and solid-state anaerobic digestion (SS-AD) were 10%, 18%, and 25%, respectively. Compared with SS-AD and HSS-AD, L-AD gas production peaked 3–6 days earlier. Treatment TS25 had the best cumulative methane production, reaching 117.4 mL/g VS. However, treatment TS6 had acid accumulation and a very unstable system. The cumulative methane production of SS-AD was higher than that of HSS-AD and L-AD. Firmicutes and Bacteroidetes were the dominant flora, and Methanoculleus, Methanosarcina, and Methanobrevibacter were the main archaeal groups. The TS significantly changed the microbial community composition of the digestion system, especially the low TS treatment. The results presented herein indicated that TS significantly changed the bacterial and archaeal community composition of the digestion system, and thus with the increase in TS from 6% to 25%, the methane yield increased.

Development of Amperometric Enzyme Biosensor for Determination of Heavy Metal Ions in aqueous samples

An amperometric urease inhibition-based biosensor was developed to detect Pb2+ and Cr3+ ions in water matrix. The modified GCE/ZnO/urease electrode was developed by immobilizing ZnO nanoparticles and urease using gelatin and glutaraldehyde as crosslinking agent. With urea as a substrate, ZnO catalytic activity was examined through cyclic voltammetry. Working conditions of the biosensing system were optimized in terms of current generated in the presence of substrate (urea) as a function of different variables. Optimal sensor activity (current response) was obtained with a urease loading of 4 µl and ZnONPs concentration of 1.5 mg/L. For solution parameters, optimum pH was in the range of 7.0-7.5, optimum temperature was 35oC, optimal substrate concentration 40 µl. Evaluation of some key biosensing properties revealed relatively stable biosensor activity within the first 7 days, good reproducibility with an RSD of 3.61%. Limits of detection (LOD) for the biosensor ranged from 0.04 - 0.07 while limits of quantitation (LOQ) ranged from 0.22- 0.13 ppm. Applying the developed biosensor to real samples was evaluated by analysing water samples from Kasuwangada River in Mubi North Local Government Area. The system showed good percentage recovery of the added heavy metal standard (0.05 – 0.25 ppm). Percentage recovery within the acceptable range of 98.00% to 103.00% was observed for Pb2+, 92.00% - 102.00 % recovery for Cr3+. Analysis of real samples and assessment of obtained results against a standard method (AAS) showed minimal differences. The developed biosensor showed sufficient sensitivity to the analysed sample and gave quantitative information on the Pb2+ and Cr3+content of the sample. Keywords: Biosensor, Heavy Metals, Urease enzymes, Inhibition studies, Enzyme activity

Efficient production of γ-aminobutyric acid using engineered Escherichia coli whole-cell catalyst

γ-Aminobutyric acid (GABA) has been widely used in the food, feed, pharmaceutical, and chemical industry fields. Previously, we developed a whole-cell catalyst capable of converting L-glutamate (L-Glu) into GABA by overexpressing the glutamate decarboxylase gene (gadz11) from Bacillus sp. Z11 in Escherichia coli BL21(DE3). However, to enhance cell permeability, a freeze-thaw treatment is required, and to enhance GADZ11 activity, pyridoxal 5′-phosphate (PLP) must be added to the reaction system. The aim of this study is to provide a more efficient approach for GABA production by engineering the recombinant E. coli above. First, the inducible expression conditions of the gadz11 in E. coli were optimized to 37 °C for 6 h. Next, an ideal engineered strain was produced via increasing cell permeability by overexpressing sulA and eliminating PLP dependence by constructing a self-sufficient system. Furthermore, an efficient whole-cell biocatalytic process was optimized. The optimal substrate concentration, cell density, and reaction temperature were 1.0 mol/L (the molecular ratio of L-Glu to L-monosodium glutamate (L-MSG) was 4:1), 15 and 37 °C, respectively. Finally, a whole-cell bioconversion procedure was performed in a 3-L bioreactor under optimal conditions. The strain could be reused for at least two cycles with GABA yield, productivity and conversion ratio of 206.2 g/L, 117.8 g/L/h and 100.0%, respectively. This is currently the highest GABA productivity from a mixture of L-Glu and L-MSG reported without the addition of cofactors or additional treatment of cells. This work demonstrates that the novel engineered E. coli strain has the potential for application in large-scale industrial GABA production.

Purification of Glutathione Reductase Enzyme from Whiting Fish Gill Tissue and Investigation of Metal Inhibition

Pollution in the seas basically accumulates in marine organisms. Heavy metal residues in aquatic ecosystems can pass through food and cause toxic effects and accumulations in human health. Glutathione reductase (GR), which is among the basic enzymes, has an important place in the suppression of stress in the cell. In this study, glutathione reductase enzyme from whiting fish gill tissue was partially purified for the first time in the literature and the effects of heavy metal compounds on enzyme activity were determined. The purification process was carried out in three stages as homogenate preparation, ammonium sulfate precipitation and also dialysis. In conclusion the study, optimum level pH 7.0, optimal substrate concentration 2 mM NADPH and optimum buffer 150 mM KH2PO4 were determined. After partial purification, the inhibition effects of Cd2+, Ni2+, Zn2+ as heavy metal ions were investigated. The IC50 levels of heavy metals were calculated as 20.17 µM, 33.7 µM and 59.31 µM, respectively.

Isolation, Identification and Characterization of Thermostable Amylase Producing Bacteria from Budamada Hot Spring, Misrak Badewacho, Hadiya Zone, Southern Ethiopia

Thermophilic microorganisms are microorganisms that are stable over a wide range of harsh environmental conditions. Thermophillic amylase enzyme producing bacteria live at 45°C–80°C. Thermostable microbial amylases are more simplified and economical than other sources. The present research was aimed to isolate, identify and characterize thermostable amylase producing bacterial isolated from Budamada hot spring of Misrak Badawacho woreda. Thirty samples were collected from the source. Totally 18 isolates were isolated and 10 isolates were screened based on their ability to hydrolyze starch. Different biochemical tests were done to identify isolates based on Bergey’s Manual of systematic bacteriology. The results revealed that three enzymes from Bacillus spp. (SED2), Pseudomonas spp. (SED5) and Bacillus spp. (SED7) have maximum activity at 4% starch, 65˚C and pH of 8.5. Lactobacillus spp. (W20-0) and Bacillus cereus (SED12-1) at 8% starch, 75 and 65˚C, 8.5 and 7.5 pH respectively. Bacillus subtilis (W26-2) Bacillus licheniformis (W20-1), Lactobacillus spp. (SED10) at 6%starch; 35, 65, 45˚C; 6.5, 4.5, 4.5 PH., Bacillus spp.(SED8-3)&Bacillus spp. (W9) at 4% & 2%, 55˚C, 8.5 &4.5 pH and have maximum activity at 4% starch, 65˚C and pH of 8.5 and at 8% starch, 75 and 65˚C, 8.5 and 7.5 pH respectively., Lactobacillus spp. (SED10) at 6% starch; 35, 65, 45˚C; 6.5, 4.5, 4.5 PH. Bacillus spp. (SED8-3) and Bacillus spp.(W9) at 4% and 2%, 55˚C, 8.5 &4.5 PH. The amylase produced by bacterial isolates from Budamada hot spring was thermostable and performed from 65oC up to 75˚C. For most of the enzymes the optimum temperature was observed to be 65˚C; whereas optimum substrate concentration and pH for most of them were 4% starch and 8.5pH respectively. They were active at a various starch conditions (2%-10%), pH of 4.5-8.5, and temperature of 35-75°C.Generally, the bacteria isolated were thermophilic and produced thermostable amylase. Therefore, Budamada hot spring could be the source of thermophilic microorganisms and thermozymes as well.

Enhancement of glucose recovery from banana stem by 4-cycle enzymatic hydrolysis

Valorisation of banana waste into value-added products has gained an increasing interest since decades ago. To date, there is still limited information on the rational direction of banana stems, which are conventionally dumped and burnt at the field or disposed into water streams, leading to serious environmental pollution. In this work, we present a novel approach to maximise the recovery of glucose from banana stem. Initially, the effect of substrate load (1%, 3%, 5%, 7% and 9%) on the enzymatic hydrolysis by liquozyme and spirizyme was investigated. Following that, 4-cycle enzymatic hydrolysis was performed and the recovery of glucose was determined for every cycle. The results showed that the optimum substrate concentration for the enzymatic hydrolysis of the banana stem was 1% (w/v) which gave the best hydrolysis yield. Evaluation of one to five cycles of enzymatic hydrolysis showed that the highest hydrolysis yield and rate were achieved during the fourth cycle, which was 2.3-fold and 4.4-fold compared to that achieved in the first cycle. Moreover, the glucose concentration recovered in the fourth cycle was 2.4-fold higher than that attained in the first cycle. Our results clearly showed the advantages of conducting multiple cycles of enzymatic hydrolysis of banana stems. In summary, this work presents a novel approach for maximising the glucose recovery from the banana stem where the method may also be applicable for recovering sugar from other agricultural wastes.

Microbial bioethanol production from locally sourced corncobs through saccharification and fermentation using Aspergillus niger and Saccharomyces cerevisiae


 The utilization of agricultural residues, specifically corncobs, as a renewable feedstock for bioethanol production holds promise in sustainable energy generation. This study investigates the feasibility of microbial bioethanol production from locally sourced corncobs through co-digestion involving Aspergillus niger and Saccharomyces cerevisiae. The process involved washing the corncobs, grinding them, and then hydrolyzing the corncob flour with cultured Aspergillus niger. The resulting sugar syrup was then fermented with Saccharomyces cerevisiae to produce ethanol. The process was optimized to obtain the highest ethanol yield. The results indicated that the process developed achieved a maximum ethanol yield of 33.2, 36.7, and 45.5% from the triplicate digesters used with a percentage purity in the range of 62.06% to 87.69% and a mean volume of ethanol recovery of 145 mL per 400 mL of the fermented product. This yield was obtained when the temperature of the hydrolysis using inoculum and saccharification were maintained at 27 °C. Additionally, the optimal substrate concentration for maximum ethanol yield was found to be 50 % (w/v). The study demonstrates the potential of corncobs obtained from local mashing as a source of fermentable sugars for the microbial production of bioethanol. Additionally, the results provide a basis for the development of an efficient and economically feasible process for production of bioethanol from corncobs obtained from local mashing.

Evaluation of haemolymph phenoloxidase activity from the grub of Zophobas morio as a predictor of immune response.

In insects, enzyme phenoloxidase plays a critical role in cuticular sclerotisation and defensive functions. In the present investigation, haemolymph phenoloxidase activity from the grub of Zophobas morio was attempted to evaluate as a reliable predictor of insect's immunological response. Among the various substrates tested, L-DOPA was chosen as an appropriate substrate due to its high oxidation. The optimum pH and temperature for haemolymph PO activity was found to be 8 and 30°C, respectively. The optimum substrate concentration of L-DOPA was found to be 7.5mM for subsequent PO enzymatic characterisation. Among the various chemical inhibitors and copper chelators, PO activity was significantly reduced in the case of PMSF and thiourea. Preincubation of haemolymph with non-self-molecules showed enhancement of PO activity in the case of LPS from Serratia marcescens. In addition, exogenous proteases like α-chymotrypsin enhanced the PO activity of haemolymph and an increase in PO activity was demonstrated when haemolymph was preincubated with the anionic detergent, SDS and cationic detergent, cetyl pyridium chloride. Alteration of PO activity was observed under agonising conditions of starvation, ligation and microplastics injection at different time intervals. Interestingly, there were no correlation between PO and insect defence under live challenge of microbes. SDS protein profile revealed a significant increase in the 85kDa and 55kDa polypeptides in all the experiments over control after 24h, 48h and 96h. Mass spectrophotometric analysis of the polypeptides revealed their homology to antimicrobial peptides for 55kDa protein and 85kDa protein. A significant increase in 85kDa polypeptide was observed in the haemolymph of the grubs after 72h in the case of starved and microplastics injected groups only. These results demonstrated that PO may not be a reliable benchmark of immunological response in this insect.

Study of some parameters and Partial purification of prolidase from serum women preeclampsia

This study was carried out by partial purification of prolidase from blood serum patients with preeclampsia by ion exchange The degree of purification enzyme (1. 85) fold, enzyme yield (8.82) and specific activity is (8.88) IU/mg .The kinetic studies of partially purified The enzyme technology demonstrated the optimal substrate concentration which was (97) mmol/L and Vmax (71.42 )(U/L),km(1.25) while optimal The optimum temperature was (37°C) and pH (9.2). molecular The weight of the partially purified enzyme was determined by a gel Electrophoresis method, in the presence of polyacrylamide gel and sodium Dodecyl Sulfate (SDS_PAGE) which showed that the approximate. The molecular weight was (54KD). We found a high level of Erythropoietin hormone in Pre-eclampsia patients which was a significant (P≤0.01) increase, (438.47 ) when she was in Control (251.70 ), the value of antidiuretic hormone in the patient was a significant (P≤0.05) increase (7.343) while in Control decrease value (2.155), the value of the ALD hormone in the patient was a significant decrease (P≤0.05) (288.7) and control was (143.6), Nitric Oxide in the patient was a significant (P≤0.05) (30.0) and control was increase (44.2) and vitamin D in the patient was a significant decrease (P≤0.05) (11.04) and control was(15.78) We conclude from the above results that there are some variables that rise with preeclampsia, such as the hormone ADH and the hormone EPO, but other variables such as ALD, vitamin D3 and nitric oxide decrease with increased pregnancy pressure, that is, with preeclampsia, in addition to that the main objective of the research is to purify the prolidease enzyme in the serum of women with preeclampsia and to know the duration of its effect This enzyme on pregnant women and linked it in another study with materials to find a new treatment

Characterization of Guaiacol Peroxidase Enzyme from Carambola Fruit

Carambola is a fruit grown in tropical and subtropical regions of the world. Natural antioxidants including vitamin C, carotenoids, and certain phenolic substances are abundant in carambola fruit. As antioxidants support health by acting as nutraceutical and functional food additives, they help preserve food by preventing oxidation processes. The oxidation of various organic or inorganic substrates by hydrogen peroxide or organic peroxides as terminal oxidants is a process in which peroxidase, which is abundantly present in fruits and vegetables, participates. In this study, guaiacol peroxidase enzyme from carambola fruit was partially purified and characterized. Purification procedure made up the homogenate preparation, ammonium sulfate precipitation, and dialysis. After purification, optimum ionic strength, pH and substrate concentration were investigated. These values were determined as 200 mM Tris, pH: 7.5, 7.5 mM H2O2 and 15 mM guaiacol for carambola fruit guaiacol peroxidase enzyme, respectively.

Purification and Characterization of Glutathione Reductase Enzyme from Arum Maculatum Leaf

Arum species grow in temperate and Mediterranean climates and have been used for hundreds of years for food and medicinal purposes, although they are highly toxic if not cooked using proper techniques. Glutathione reductase (GR) is a member of the pyridine nucleotide disulfide oxidoreductase family of flavoenzymes that catalyzes the reduction of glutathione disulfide (GSSG) to reduced GSH using NADPH or NADH. In this study, GR enzyme was characterized by partial purification processes including homogenate preparation, ammonium sulfate precipitation and dialysis from the leaf of Arum maculatum plant. The highest enzyme activity was found at 40-60% saturation range. Optimum ionic strength, pH and substrate concentration were investigated for GR enzyme from A. maculatum leaf. As a result of the study, these values were found to be 150 mM potassium phosphate buffer, pH 7.00, and 0.18 mM, respectively. The GR enzyme was partially purified from the leaf of the A. maculatum with a specific activity of 1.640 EU mg-1 in 34.9% yield, 1.108-fold. This study is the first study in terms of purification and characterization of GR enzyme from A. maculatum leaf.

Purification and characterisation of glutathione reductase from scorpionfish (scorpaena porcus) and investigation of heavy metal ions inhibition

In the current study, glutathione reductase was purified from Scorpion fish (Scorpaena porcus) liver tissue and the effects of heavy metal ions on the enzyme activity were determined. The purification process consisted of three stages; preparation of the homogenate, ammonium sulphate precipitation and affinity chromatography purification. At the end of these steps, the enzyme was purified 25.9-fold with a specific activity of 10.479 EU/mg and a yield of 28.3%. The optimum pH was found to be 6.5, optimum substrate concentration was 2 mM NADPH and optimum buffer was 300 mM KH2PO4. After purification, inhibition effects of Mn+2, Cd+2, Ni+2, and Cr3+, as heavy metal ions were investigated. IC50 values of the heavy metals were calculated as 2.4 µM, 30 µM, 135 µM and 206 µM, respectively.

Partial Purification of Glutathione S-transferase Enzyme From the Seed of Mallow (Malva Slyvestris L.) and Investigation of the Inhibition Kinetics of Some Heavy Metals.

Glutathione S-Transferase (GST) enzyme is abundant in mammals, insects, fish and microorganisms, as well as in various tissues of these species, particularly in tissues exposed to xenobiotics from the environment. As a result, the enzyme execute detoxifying function by scavenging a diverse range of xenobiotics, such as chemotherapeutic medicines, environmental carcinogens and endogenous compounds. In this study, GST enzyme was partially purified from mallow (Malva slyvestris L.) seed for the first time and the kinetic parameters were determined. The optimum ionic intensity was found in 400 mM Tris-Buffer, optimum pH: 7.0, and optimum substrate concentration was determined as 0.2 mM. One of the biggest reasons for deterioration of ecological balance in nature is heavy metal accumulation in soil, air and water which becomes a major threat to the vital activities of living things. In this study, inhibitory effects of Cd+ 2, Ag+, Zn+ 2 and Fe+ 3 heavy metals, which are common in nature, on mallow seed glutathione S-transferase enzyme were investigated. Each heavy metal showed micromolar inhibitory effects on enzyme activity. IC50 values of the metals were calculated as 60.93, 74.602, 178.22 and 369 µM, respectively.

Partial Purification of Catalase Enzyme from Muscle Tissue of Dusky Spinefoot (Siganus luridus)

Catalase, one of the antioxidant enzymes, decomposes hydrogen peroxide into water and oxygen. From the discovery of catalase, several studies have been carried out to reveal its importance in health, food and cosmetics industries etc., and these studies are still ongoing. In this study, catalase enzyme was partially purified from muscle tissue of Dusky spinefoot (Siganus luridus). Purification procedure consisted of homogenate preparation, ammonium sulfate precipitation and dialysis. The enzyme was precipitated in the range of 40-60 % Ammonium Sulfate concentration. The optimum buffer was determined as 200 mM phosphate buffer, optimum pH 8.0 and optimum substrate concentration 24mM for H₂ and O₂, respectively.

Continuous cultivation of Debaryomyces hansenii (LAF‐3 10 U) on dodecane in synthetic desalter effluent at varying dilution rates on dodecane

AbstractDesalter effluent (DE) is typically discharged into a petroleum wastewater treatment plant, but its high salt concentration deteriorates the biological treatment. This study used various dilution rates to investigate the treatment of a synthetic DE containing dodecane under saline conditions using a halotolerant yeast, Debaryomyces hansenii, to determine the optimum substrate concentration for use in continuous stirred‐tank reactors (CSTRs). A literature review indicated that this study was the first to examine the biological treatment of DE using D. hansenii in a CSTR system. At a low dodecane substrate concentration, DE did not inhibit D. hansenii growth, and the experimental data approached the Monod model, with μmax and Ks selected as 0.08 h−1 and 1575 mg L−1, respectively. The optimum removal of chemical oxygen demand (95.7% and 85%) was obtained at dilution rates of 0.007 and 0.026 d−1. Using D. hansenii in a CSTR system appeared to be a sustainable approach for the biological treatment of DE. Scale‐up of these laboratory findings to the industrial scale is required to confirm that petroleum DE can be treated using equalization and filtration tanks as a continuous bioreactor. Adjusting the dilution rate can provide sufficient time for biodegradation and hydrocarbon removal from high salt DE by halotolerant yeasts like D. hansenii.

Characterization of Catalase Enzyme from Leaf Tissue of Aronia (Aronia melanocarpa) Plant

Aronia is among the most antioxidant containing plants which is found commonly around the world. Aronia cultivation started in Turkey for the first time in 2012 at the Atatürk Central Research Institute of Garden Cultures, and a plantation was constructed in the experimental area. Since antioxidants help to preserve food by blocking oxidation processes and contributing to the health promotion provided by numerous dietary supplements, nutraceutical and functional food additives, antioxidant capacity of these plants should be well characterized. To assess and evaluate the antioxidant content of foods and plant products, many approaches are utilized. In this study, catalase (CAT) enzyme was partially purified from aronia plant leaf tissue and characterization was carried out. Purification process consisted of homogenate preparation, ammonium sulfate precipitation and dialysis. The optimal ionic strength, pH, substrate concentration and enzyme quantity were examined. These values were found to be 300 mM Tris, pH:8.0, 12 mM H2O2 and 75 μl, respectively, for the catalase enzyme of the Aronia plant leaf tissue. This study is the first in the literature dealing with the characterization of antioxidant enzyme from Aronia plant.

Towards enhancement of fungal hydrolytic enzyme cocktail using waste algal biomass of Oscillatoria obscura and enzyme stability investigation under the influence of iron oxide nanoparticles

Development of low-cost and economic cellulase production is among the key challenges due to its broad industrial applications. One of the main topics of research pertaining to sustainable biomass waste based biorefinaries is the development of economic cellulase production strategies. The main cause of the increase in cellulase production costs is the use of commercial substrates; as a result, the cost of any cellulase-based bioprocess can be decreased by employing a productive, low-cost substrate. The goal of the current study is to develop low-cost cellulase using the carbohydrate-rich, renewable, and widely accessible cyanobacteria algae Oscillatoria obscura as the production substrate. Maximum cellulase was produced utilising the fungus Rhizopus oryzae at substrate concentration of 7.0 g among various tested concentrations of algal biomass. Maximum production rates of 22 IU/gds FP, 105 IU/gds BGL, and 116 IU/gds EG in 72 h were possible under optimal conditions and substrate concentration. Further investigations on the crude enzyme's stability in the presence of iron oxide nanoparticles (IONPs) revealed that it was thermally stable at 60 °C for up to 8 h. Additionally, the crude enzyme demonstrated pH stability by maintaining its complete activity at pH 6.0 for 8 h in the presence of the optimal dose of 15 mg IONPs. The outcomes of this research may be used to investigate the possibility of producing such enzymes in large quantities at low cost for industrial use.