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Saccharification of cellulosic material is crucial before utilizing it as the feedstock of fermentation processes. This study focuses on developing of robust catalysts for enzymatic hydrolysis of paper waste. Cellulase enzyme was immobilized on Fe3O4 magnetic nanoparticles (MNPs) via multi-covalent bonds. Therefore, the attachments of MNPs were performed by three approaches (3-aminopropyl)triethoxysilane (APTES) (Method I), polyethyleneimine (PEI) (Method II), and both monolayer molybdenum disulfide and PEI (MoS2-PEI) (Method III). The biocatalysts were characterized using Fourier transform infrared (FTIR) and thermogravimetric analysis (TGA). The immobilization yield and loading efficiency of cellulase were determined at 38.65% and 162 mg g−1 in Method I, 13.33% and 31 mg g−1 in Method II, and 14.38% and 33 mg g−1 in Method III. The specification of the biocatalysts was determined for the hydrolysis of filter paper, carboxymethylcellulose (CMC), microcrystalline cellulose, and cellobiose. The total cellulase activity was 2.77, 0.943, 1.38, and 2.02 µmolGlucose mgEnzyme−1 h−1for free-cellulase and the immobilized biocatalysts prepared by Method I, II, and III, respectively. The prepared biocatalyst in Method I maintained 54.54% of its original activity after five cycles, which was more robust than Method II (20.25%) and Method III (12.33%). Further studies were performed on the saccharification of paper waste. The results showed the biocatalyst obtained by Method II resulted in 5.8 folds of higher glucose than the free-cellulase. The highest glucose recovery of about 72.47% was achieved after 48 h using the immobilized biocatalyst prepared by Method II. [ABSTRACT FROM AUTHOR]

LL-37 can inhibit the growth of K562 cancer cells when it is conjugated with iron oxide nanoparticles. In this study, Fe3O4 nanoparticles were synthesized using the co-precipitation method and then modified with the LL-37 peptide through an NH2 bridge. The accuracy of the synthesis process was confirmed through various analytical tests, including FTIR, XRD, FESEM, and EDX. To assess the treatment's effectiveness, a viability test was carried out on K562 leukemia cells and normal peripheral blood mononuclear cells. In addition, flow cytometry and Hoechst staining were used to investigate the mechanism of action of the drug. The expression levels of the Bcl-2, Bax, and TP53 genes in the treated cells and the control group were measured using qRT-PCR. The results indicated that the size of the nanoparticles ranged between 34 and 40 nm. The NH2@LL-37@Fe3O4 nanoparticles more effectively inhibited the growth of cancer cells in a concentration-dependent manner, as compared to Fe3O4 alone. Further analysis revealed that apoptosis occurred through increased expression of TP53 and Bax genes compared to the Bcl-2 gene. Therefore, induction of apoptosis and inhibition of growth in K562 cells was attributed to the impact of iron oxide magnetic nanoparticles conjugated with the LL-37 peptide through the TP53/Bax/Bcl-2 pathway. [ABSTRACT FROM AUTHOR]

Hydrocarbons are considered as one of the most common and harmful environmental pollutants affecting human health and the environment. Bioremediation as an environmentally friendly, highly efficient, and cost-effective method in remediating oil-contaminated environments has been interesting in recent decades. In this study, hydrocarbon degrader bacterial strains were isolated from the highly petroleum-contaminated soils in the Dehloran oil field in the west of Iran. Out of 37 isolates, 15 can grow on M9 agar medium that contains 1.5 g L−1 of crude oil as the sole carbon source. The morphological, biochemical, and 16SrRNA sequencing analyses were performed for the isolates. The choosing of the isolates as the hydrocarbon degrader was examined by evaluating the efficacy of their crude oil removal at a concentration of 10 g L−1 in an aqueous medium. The results showed that five isolates belonging to Pseudomonas sp., Pseudomonas oryzihabitans, Roseomonas aestuarii, Pantoea agglomerans, and Arthrobacter sp. had a hyper hydrocarbon-degrading activity and they could remove more than 85% of the total petroleum hydrocarbon (TPH) after 96 h. The highest TPH removal of about 95.75% and biodegradation rate of 0.0997 g L−1 h−1 was observed for P. agglomerans. The gas chromatography–mass spectroscopy (GC–MS) analysis was performed during the biodegradation process by P. agglomerans to detect the degradation intermediates and final products. The results confirmed the presence of intermediates such as alcohols and fatty acids in the terminal oxidation pathway of alkanes in this biodegradation process. A promising P. agglomerans NB391 strain can remove aliphatic and aromatic hydrocarbons simultaneously. [ABSTRACT FROM AUTHOR]

Sophorolipid (SL) production by Candida catenulata from sunflower fatty acids was studied in a bubble column reactor (BCR). The specific oxygen uptake rate was 0.021 mg gcell−1 min−1 which indicates the importance of aeration in SL biosynthesis. The measurement of oxygen transfer rate (OTR) in the BCR showed a satisfactory OTR value of about 0.093 min−1 in the system. However, further SL production was stopped after 30 h in the BCR mainly due to the product accumulation in the culture and its inhibitory effects on cell growth and SL synthesis. Since an extensive foam was generated in the BCR under the absence of an antifoam agent, the development of an in situ foam recovery system provided the integration of production and separation of SL to handle the problem. The application of the foam recovery system enhanced biomass and titer SL concentration by 38.5 and 28.2% in comparison with the conventional BCR, respectively. Further studies in the system were performed by monitoring the size of bubbles and their effects on the biomass and SL enrichment in the foam stream at different aeration rates where the SL enrichment varied from 900 to 100% at 12 and 50 h of the fermentation. [ABSTRACT FROM AUTHOR]

The application of industrial wastes in the fermentation process could significantly reduce the cost of biological products. In this study, the sunflower and soybean oil soap stocks as the inherent by-products of refinery vegetable oil manufacturers treated by a degumming process to purify the free fatty acids (FFAs). The obtained sunflower fatty acids (SFFA) and soybean fatty acids (SBFA) were used as hydrophobic carbon sources of C. catenulata cells to produce a beneficial biosurfactant namely sophorolipids (SLs). The results showed the test cell grows faster on the SFFA and SBFA versus refined sunflower oil (RSFO) and refined soybean oil (RSBO) as hydrophobic carbon sources and produced higher SLs after the late logarithmic growth. The highest specific growth rate and the volumetric SL production were obtained at 0.0475 h−1 and 0.101 g L−1 h−1 for the SFFA system, respectively. The emulsification capacity of the produced SLs was examined to form a water-soybean oil microemulsion. The emulsification index (E24%) was 70.0 and 63.3% at 500 g L−1 of the SLs obtained from SFFA and SBFA, respectively. The measurement of surface tension at different SL concentrations showed a critical micelle concentration of about 220 mg L−1 and 230 mg L−1 for these SLs. Highlights: Comparing soap stock degumming methods including acidulation and solvent extraction to select a best condition for recovering FFAs. Application FFAs obtained from sunflower and soybean soap stocks versus refinery vegetable oils in sophorolipid production. Sophorolipid production using the FFAs as hydrophobic carbon sources of a new isolate of Candida catenulata. Analyzing the emulsification capacity of the sophorolipids by emulsification index and surface tension measurements. [ABSTRACT FROM AUTHOR]

Chitosan is commonly obtained from shrimp and crab shell chitin by deacetylation; however, such supplies appear limitation. An alternative source of chitosan is cell wall in certain fungi. In this study, chitosan production through submerged fermentation of Aspergillus terreus on apple waste extract as sole carbon source was investigated. Monod equation with a maximum specific growth rate of 0.083 h−1 and half-saturation constant of 6.67 w/v% was best described the kinetic of growth. Results of response surface methodology showed the highest chitosan to substrate yield of 49.32 mg gsubstrate−1, chitosan to fungal biomass yield of 140.9 mg gcell−1, and fungal biomass to substrate yield of 0.387 gcell gsubstrate−1 were simultaneously obtained at temperature 30.0 °C, initial pH 5.98, and ammonium nitrate concentration 5.0 g L−1. The chitosan produced at the optimum condition was characterized by FTIR, TGA, and DSC analysis, and degree of deacetylation was 88.2%. [ABSTRACT FROM AUTHOR]

The biodesulfurization of dibenzothiophene (DBT) by growing and resting cells of Rhodococcus erythropolis PTCC 1767 was studied in this work. The effects of Tween 80 on cell growth and its DBT desulfurization ability were investigated in both aqueous and two-phase systems. The growth-supportive behavior of Tween 80 along with its role in increasing the DBT solubility provided an effective biocatalytic activity in the resting cells assay. The desulfurization capability was also dependent on the hydrocarbon fraction phase and the initial concentration of DBT. Three oil phase fractions of 25, 50, and 75%v/v were tested to evaluate the influence of oil phase presence on DBT desulfurization efficiency. A further decrease in desulfurization ability was occurred at higher oil phase ratios mainly due to a higher mass transfer limitation and lower DBT bioavailability. In the biphasic system, the increment of DBT desulfurization yield was followed by increasing DBT concentration up to 3.5 mM, and thereafter, the cessation of increasing trend occurred. Maximum specific production rate of 2-hydroxybiphenyl (2-HBP) with oil phase fraction of 25%v/v was obtained 0.0055 mmol g−1 h−1 at initial DBT and Tween 80 concentrations of 3.5 and 6 mM, respectively. Finally, kinetics of DBT desulfurization by growing cells in aqueous and biphasic systems were best fitted by the Haldane and Michaelis–Menten equations, respectively. The desulfurization activity of R. erythropolis was not repressed in the biphasic system for DBT concentration up to 7.13 mM, while product inhibition was observed at DBT concentration higher than 0.45 mM in the aqueous system. [ABSTRACT FROM AUTHOR]

The present study highlights the apoptotic activity of magnetic Fe3O4 nanoparticulates functionalized by glutamic acid and 2-pyridinecarboxaldehyde thiosemicarbazone (PTSC) toward human lung epithelial carcinoma A549 cell line. To this aim, the Fe3O4 nanoparticulates were prepared using co-precipitation method. Then, the glutamic acid and Fe3O4 nanoparticulates were conjugated to each other. The product was further functionalized with bio-reactive PTSC moiety. In addition, the synthesized Fe3O4@Glu/PTSC nanoparticulates were characterized by physico-chemical techniques including scanning electron microscope (SEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD), Fourier-transform infrared (FT–IR) spectroscopy and zeta potential analysis. The effects of in vitro cell viability in Fe3O4@Glu/PTSC nanoparticulate indicated the anti-proliferative properties in a dose-dependent manner (IC50 = 135.6 µM/mL). The high selectivity for tumor cells and far below of activity in HEK293 non-tumorigenic cells is considered as an important feature for this complex (SI, 3.48). Based on the results, PTSC failed to reveal any activity against A549 cells alone. However, Fe3O4 nanoparticulates had some effects in inhibiting the growth of lung cancer cell. Furthermore, Bax and Bcl-2 gene expressions were quantified by real-time PCR method. The expression of Bax increased 1.62-fold, while the expression of Bcl-2 decreased 0.76-fold at 135.6 µM/mL concentration of Fe3O4@Glu/PTSC compared to untreated A549 cells. Furthermore, the Fe3O4@Glu/PTSC nanoparticulate-inducing apoptosis properties were evaluated by Hoechst 33258 staining, Caspase-3 activation assay and Annexin V/propidium iodide staining. The results of the present study suggest that Fe3O4@Glu/PTSC nanoparticulates exhibit effective anti-cancer activity against lung cancer cells. [ABSTRACT FROM AUTHOR]

In this work, lipase from Candida rugosa was bound with the multi-covalent bonds attachment to the amino-functionalized magnetic Fe3O4 nanoparticles by glutaraldehyde as a coupling agent. The protein assay showed that the enzyme binding efficiency was 77.65% in the immobilization process. The catalytic activity of the immobilized lipase was compared with the free lipase in enzymatic epoxidation of free fatty acids. The results showed that the immobilized enzyme had better stability than the free system during the reaction in the presence of hydrogen peroxide, as an inactivating substrate, especially at extreme conditions of temperature and pH. The statistical study on effects of temperature and pH by response surface methodology specified that the highest epoxidation activity for the immobilized system was observed at temperature 52.2 °C and pH of 6.7. At the optimum condition, the immobilized lipase showed a good reusability, where 100% and 80.97% of origin catalytic epoxidation activity were, respectively, maintained after sixth and tenth cycles. Also, the storage stability of the immobilized lipase was investigated in room temperate and 4 °C. The experiments revealed that the immobilized lipase had an excellent long-term storage stability after 152 and 203 days at 4 °C after being bound to magnetic nanoparticles. [ABSTRACT FROM AUTHOR]

This study focuses on continuous formaldehyde (FA) biodegradation by Ralstonia eutropha immobilized on polyurethane foam in a semi-pilot-scale plug flow packed-bed bioreactor. The stepwise increasing of the influent FA concentration from 43.9 to 1325.1 mg L−1 was studied in the bioreactor during 70 days of operation. A complete removal of FA was achieved for inlet concentration up to 425.5 mg L−1 and the initial specific biodegradation rate reached to its maximum value about 44.3 mg gcell−1 h−1 at 425.5 mg L−1. However, further increase of inlet concentration resulted in decrease of the biodegradation performance of the immobilized cells due to the inhibitory effect of FA on the enzymatic system involved in the biodegradation process. Based on kinetic modeling results, the Luong equation with the following constants could best describe the behavior of the bio-system: maximum specific FA biodegradation rate (qmax) of 124 mg gcell−1 h−1, half-saturation constant (KS) of 337.2 mg L−1, maximum degradable FA concentration (Smax) of 1582 mg L−1, and shape factor (n) of 1.49. Also, three-dimensional simulation of the bioreactor was performed using an integrated computational fluid dynamics (CFD) approach that takes into account both the biokinetic constants of the immobilized system as well as the fluid properties under steady-state condition. Eulerian computations successfully anticipated the concentration gradients through the reactor for different inlet FA concentrations, and uniform vertical velocity pathlines and non-dispersed plug flow inside the reactor were verified by the presented velocity distribution and flow streamlines. [ABSTRACT FROM AUTHOR]

Abstract: This work reports bioconversion of unsaturated free fatty acids present in soapstock, inherent waste of edible oil manufacture, to the epoxidized fatty acids using Candida rugose lipase in a micro-reactor. Activation energy of the epoxidation reaction was found to be 32.27 kJ mol−1 while the enzyme deactivation was observed at higher temperature than 35 °C with an activation energy of 91.18 kJ mol−1. The low hydrodynamic retention time in the micro-reactor provides a proper condition to measure of initial rates of the enzymatic reaction. The kinetics study was performed at ten different molar ratios of H2O2/C=C, and constants of the Ping-Pong bi bi model were estimated as follows: the maximum specific enzyme activity (Vmax) of 1.453 × 105 mM min−1 genzyme−1, dissociation constant for enzyme-FFA complex (KA) of 58.83 mM genzyme−1, Michaelis constant for FFAs (KmA) of 1.382 × 103 mM genzyme−1, Michaelis constant for hydrogen peroxide (KmB) of 3.279 × 106 mM genzyme−1, and the deactivation constant due to hydrogen peroxide (KIB) of 59.25 mM genzyme−1. The cross-linked enzyme aggregate technology provided a simple method to produce the robust biocatalyst for this bioconversion where more than 89% of original activity was maintained after 9 cycles in the micro-reactor.Graphical Abstract: [ABSTRACT FROM AUTHOR]

The potential of Ralstonia eutropha as a biocatalyst for desulfurization of dibenzothiophene (DBT) was studied in growing and resting cell conditions. The results of both conditions showed that sulfur was removed from DBT which accompanied by the formation of 2-hydroxybiphenyl (2-HBP). In growing cell experiments, glucose was used as an energy supplying substrate in initial concentrations of 55 mM (energy-limited) and 111 mM (energy-sufficient). The growing cell behaviors were quantitatively described using the logistic equation and maintenance concept. The results indicated that 2-HBP production was higher for the energy-sufficient cultures, while the values of the specific growth rate and the maintenance coefficient for these media were lower than those of the energy-limited cultures. Additionally, the kinetic studies showed that the half-saturation constant for the energy-limited cultures was 2 times higher than the energy-sufficient ones where the inhibition constant (0.08 mM) and the maximum specific DBT desulfurization rate (0.002 mmol g h) were almost constant. By defining desulfurizing capacity ( D ) including both the biomass concentration and time to reach a particular percentage of DBT conversion, the best condition for desulfurizing cell was determined at 23% g L h which corresponded with the resting cells that were harvested at the mid-exponential growth phase. [ABSTRACT FROM AUTHOR]

The ability of the Ralstonia eutropha cells to utilize formaldehyde (FA) as the only source of carbon and energy was studied in the kissiris-immobilized cell bioreactor (KICB) in batch-recirculation and continuous modes of operation. In batch-recirculation experiments, the test bacterium could tolerate concentrations of FA up to 1,400 mg/L at 30°C and aeration rate equal to 0.75 vvm ( r = 7.25 mg/L/h, q S = 0.019 g/g/h). However, further increase of initial FA concentration resulted in degradation reaction of FA to stop at 1,600 mg/L. Results of continuous mode experiments showed that the biodegradation performance of the KICB was dependent on both feed flow rate and inlet FA concentration parameters. The optimum feed flow rate which corresponded to the highest biodegradation rate ( r = 240.3 mg/L/h) was observed at Q = 18 mL/min when KICB did not operate under the external mass transfer limiting regime. Substrate inhibition kinetics (Edwards and Luong equations) were used to describe the experimental specific degradation rates data. According to the Luong model, the values of the maximum specific degradation rate ( q), half-saturation coefficient ( K), the maximum allowable FA concentration ( S), and the shape factor (n) were 0.178 g/g/h, 250.9 mg/L, 1,600 mg/L, and 1.86, respectively. [ABSTRACT FROM AUTHOR]

Relying on native microorganisms is crucial for bioremediating petroleum-contaminated soils within this oil field. This study aimed to isolate native bacteria and investigate their ability to degrade petroleum hydrocarbons in contaminated soils. Flame ionization detector gas chromatography analyzed the capacity of Indigenous bacterial isolates to break down diesel fuel in an aquatic environment. Soil samples were collected from the Naft-Shahr area. Initially, 126 bacterial isolates were obtained from these soils, of which only 48 species could grow on a diesel-containing medium. Further analysis identified the top 8 isolates with high diesel removal potential. Results showed that the diesel removal percentage ranged from 26 to 76% at an initial diesel concentration of 3.7 g. L -  1 after 48 h, without adding any supplementary surface-active agent. Four top isolates were selected based on their degradation activity, removal yield, and biodegradation rate and were identified using 16S rRNA gene sequencing and phylogenetic analysis. Sequence alignment revealed that isolates B11Pet, B19Pet, B27Pet, and B48Pet belong to Staphylococcus gallinarum, Paenarthrobacter nitroguajacolicus, Arthrobacter citreus, and Bacillus thuringiensis, respectively. Among these, Bacillus thuringiensis (B48Pet), with a specific growth rate of 0.211 h⁻ 1 , could uniformly remove all diesel hydrocarbon fractions at 58.81 mg. L⁻ 1 . h⁻ 1 . This strain, alone or in consortia, represents a promising strategy for the bioremediation of petroleum-contaminated soils., Competing Interests: Declarations Ethics approval and consent to participate Our manuscript does not report on or involve animals, humans, human data, human tissue, or plants. Consent for publication We give my consent for the publication of identifiable details, which can include photographs and/or videos and/or details within the text to be published in the article. Competing interests The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)