Immobilization Of Microorganisms Research Articles

Enhancing Se(IV) bioremediation efficiency via immobilization of filamentous fungi and yeasts in eco-friendly alginate bead hydrogels.

The immobilization of microorganisms in polymeric hydrogel has gained attention as a potential method for applications in various fields, offering several advantages over traditional cell free-living technologies. The present study aims to compare the efficiency of selenium (Se) bioremediation and biorecovery by two different fungal types, both in their free and immobilized forms using alginate hydrogels. Our results demonstrated an improvement in the amount of Se(IV) removed from the hydrogels of Aspergillus ochraceus (∼97%) and Rhodotorula mucilaginosa (∼43%) compared to that of the planktonic cultures (∼57% and ∼9-17%). In both cases, most of the Se(IV) is enzymatically reduced by the cells to amorphous Se(0) nanospheres, which are retained throughout the alginate hydrogels. The extensive growth, colonization and distribution of the cells throughout the highly porous hydrogel, along with their ability to maintain viability over long periods and the preservation of the structural integrity of the hydrogel, demonstrated the enormous biotechnological potential of the studied system for practical applications. The results reported show that the immobilization of fungi in alginate hydrogels is an efficient and environmentally friendly alternative for bioremediation and biorecovery of Se nanoparticles, which are of significant industrial and medical interest within the framework of a circular economy.

Acclimatisation process of biogas production from tofu industrial wastewater using biofilter in anaerobic baffled reactor (ABR)

A biofilter is a simple technology used in an anaerobic baffled reactor (ABR) to keep biological solids (inoculum) from being easily carried by the inlet substrate and to shorten the hydraulic retention time (HRT). The principle of a biofilter is to form a biofilm on the packed bed of the biofilter in ABR so that it contains immobilised microorganisms. This study aims to know the performance of the biofilter reactor on biogas production during the acclimatisation process. The results show biofilters shorten the HRT and effectively remove pollutants, increasing biogas production and methane quality. The total solid content decreases by around 44 %, from 0.38 % to 0.17 %. The biogas production during acclimatisation was 1806.41 L and COD removal was 95 %. The biogas composition of CH4 was 58.05 %, CO2 38.23 %, and N2 3.2 %. This study provides preliminary findings for further studies on the use of tofu wastewater as a biogas feedstock with different concentrate substrates, which is very useful for sustainability activities and improving the industry to become green.

Microorganisms immobilized hydroxyethyl cellulose/luffa composite sponge for selective adsorption and biodegradation of oils in wastewater

The highly efficient removal of oils such as oils or dyes from wastewater has aroused wide concern and is of great significance for clean production and environmental remediation. The synthesis of a novel aerogel (designated as HEC/LS) is reported herein, achieved through a sol-gel method followed by freeze-drying utilizing loofa and hydroxyethyl cellulose as the raw materials. The new HEC/LS aerogel exhibits excellent porosity and specific surface area, with a porosity of 88.70 %, a total pore area of 0.607 m2 g−1, and a specific surface area of 230 m2 g−1. The prepared HEC/LS aerogel exhibits exceptional hydrophilicity and self-floatability, facilitating its rapid absorption of water up to 21 times its own weight within a mere 3 s. Additionally, it demonstrates good adsorption performance for methylene blue (MB), with a maximum adsorption capacity of 83.30 mg g−1. Subsequently, a new hydrophobic microorganisms-loaded composite aerogel (namely, Bn-HEC/LS) was obtained by doping microorganisms into the as-prepared HEC/LS in multiple enrichment followed by a hydrophobic and oleophilic surface modification. Based on its rich porous structure and oleophilic wettability, the as-synthesized Bn-HEC/LS exhibits excellent selective adsorption and degradation properties for the oil contamination, the diesel oil could be selectively absorbed in the Bn-HEC/LS and degraded by the loaded microorganisms. Among them, B5-HEC/LS displays the highest removal efficiency of 94.50 % within 180 h, while free microorganisms and HEC/LS aerogels show degradation efficiencies of only 21.70 % and 48.10 %, respectively. The fixation of microorganisms in the aerogel increases their number within the material and enhances the relative microorganisms removal capacity. The hydrophobic and lipophilic modifications improve the selective adsorption performance of the aerogel on diesel oil, resulting in a significantly high removal rate of Bn-HEC/LS for diesel oil. The results indicate that the immobilization of microorganisms into aerogel improves the activity of microorganisms, and the hydrophobic and oleophilic modification enhances the selective adsorption performance of aerogel to diesel oil, thus resulting in a very high removal rate of Bn-HEC/LS for diesel oil. This study is expected to provide a now possibility for the green and efficient bioremediation of oils.

Granular activated carbon supported polyethylene glycol modified nano-zero-valent iron immobilized microbial removal of 2,4-dichlorophenol in water

In recent years, the remediation of 2,4-DCP pollution using immobilized microbial technology has attracted increasing attention. Using granular activated carbon (GAC), polyethylene glycol 4000 (PEG-4000), ferrous sulfate, and sodium borohydride as raw materials, granular activated carbon loaded polyethylene glycol modified nano zero-valent iron composite material (PEG-nZVI/GAC) was prepared via a liquid-phase reduction method. Bacillus marisflavi, capable of degrading phenolic compounds, was immobilized on PEG-nZVI/GAC using an adsorption method to prepare immobilization of microorganisms by granular activated carbon loaded polyethylene glycol modified nano zero-valent iron (PEG-nZVI/GAC@B) for 2,4-DCP removal. Characterization analysis of immobilized microbes was conducted using transmission electron microscopy (TEM) and other methods to determine their physicochemical properties. Response surface methodology (RSM) was employed to optimize the conditions for 2,4-DCP removal, and the performance and mechanism of 2,4-DCP removal by PEG-nZVI/GAC@B were studied. The results indicate that nanoscale zero-valent iron (nZVI) was uniformly distributed in granular activated carbon, Bacillus marisflavi was successfully loaded onto PEG-nZVI/GAC, PEG-nZVI/GAC@B had a higher content of oxygen-containing groups on its surface, and exhibits good dispersibility, stability, and reusability. When the immobilized microbial dosage was 270.32 mg/L, the initial concentration of 2,4-DCP was 50.51 mg/L, and pH was 6.58, the predicted removal rate of 2,4-DCP was 96.53 %. Under these conditions, the actual removal rate of 2,4-DCP was 94.68 %. The removal of 2,4-DCP by PEG-nZVI/GAC@B involved adsorption by granular activated carbon, reductive dechlorination by nanoscale zero-valent iron, and degradation by Bacillus marisflavi. In conclusion, PEG-nZVI/GAC@B is an excellent immobilized microorganism for the removal of 2,4-DCP.

Immobilization: the promising technique to protect and increase the efficiency of microorganisms to remove contaminants

AbstractBiodegradation of pollutants is one of the most economical methods for their removal and usually is accompanied by no production of toxic by‐products. In general, this approach is favored over others because it offers reduced expenses and the potential for complete mineralization. In order to enhance the viability and longevity of the bioremediation agents within polluted areas, it becomes necessary to immobilize the cells. Cell immobilization refers to the procedure of confining intact cells to specific areas within a device or material, without compromising their essential biological functions. A wide variety of carriers and approaches have been used for the restriction of various cells. Immobilization techniques, such as microencapsulation, have opened up new possibilities in biotechnology by facilitating the development of artificial organs, cell therapies and drug delivery systems. Researchers have found promising outcomes in various applications through the immobilization of microorganisms. This approach enhances stability, reusability and catalytic efficiency, making immobilization a valuable strategy for biocatalysis, bioremediation and other biotechnological processes. Notably, the use of immobilized microorganisms has led to significant improvements in the removal of pollutants, with some studies achieving 100% efficiency. When comparing the degradation of pollutants between free and immobilized microorganisms over the same time period, the results demonstrated that immobilized microorganisms achieved a removal efficiency >21% more than that of free microbial consortia. The primary objective of this review is to give an overview of the key scientific aspects related to bioremediation of various pollutants using immobilized cells, with a particular focus on the techniques used to entrap the cells. © 2024 Society of Chemical Industry (SCI).

Effectiveness of biogeosorbents based on mineral carriers for treatment oil-contaminated soil

Methods for cleaning oil-contaminated areas include the use of sorbents, the effectiveness of which is enhanced by the immobilization of hydrocarbon-oxidizing microorganisms on their surface. Biogeosorbents are obtained on the basis of mineral raw materials (analcime- and glauconite-containing rocks and thermally activated vermiculite) and hydrocarbon-oxidizing bacteria of the genera Pseudomonas and Microbacterium extracted from contaminated soils of the Murmansk region. The number of immobilized bacteria on the studied carriers remains high throughout 9 months of storage, and the bacterial film on the surface of mineral carriers persists for 12 months of storage in an air-dry state. When storing biogeosorbents, no special conditions or additional preparation are required before use. Mineral carriers have a stimulating effect on the height of seedlings and the length of roots of test plants. When biogeosorbents are added, the number of bacteria capable of microbiological transformation of petroleum products increases, and the degree of soil purification from petroleum hydrocarbons at the initial stage (during the first 30 days) increases. The most effective is the introduction of thermally activated vermiculite and glauconite-containing rock with immobilized hydrocarbon-oxidizing bacteria. The use of a biogeosorbent based on thermally activated vermiculite can reduce the cleaning time to 20–22 months, and based on glauconite-containing rock – up to 17 months, while without treatment this period will be at least 29 months.

Remediation potential of an immobilized microbial consortium with corn straw as a carrier in polycyclic aromatic hydrocarbons contaminated soil

Polycyclic aromatic hydrocarbons (PAHs) are widespread in soils and threaten human health seriously. The immobilized microorganisms (IM) technique is an effective and environmentally sound approach for remediating PAH-contaminated soil. However, the knowledge of the remedial efficiency and the way IM operates using natural organic materials as carriers in complex soil environments is limited. In this study, we loaded a functional microbial consortium on corn straw to analyze the effect of IM on PAH concentration and explore the potential remediation mechanisms of IM in PAH-contaminated soil. The findings revealed that the removal rate of total PAHs in the soil was 88.25% with the application of IM after 20 days, which was 39.25% higher than the control treatment, suggesting that IM could more easily degrade PAHs in soil. The findings from high-throughput sequencing and quantitative PCR revealed that the addition of IM altered the bacterial community structure and key components of the bacterial network, enhanced cooperative relationships among bacteria, and increased the abundance of bacteria and functional gene copies such as nidA and nahAc in the soil, ultimately facilitating the degradation of PAHs in the soil. This study enhances our understanding of the potential applications of IM for the treatment of PAH-contaminated soil.

Recent insight into the advances and prospects of microbial lipases and their potential applications in industry.

Enzymes play a crucial role in various industrial sectors. These biocatalysts not only ensure sustainability and safety but also enhance process efficiency through their unique specificity. Lipases possess versatility as biocatalysts and find utilization in diverse bioconversion reactions. Presently, microbial lipases are gaining significant focus owing to the rapid progress in enzyme technology and their widespread implementation in multiple industrial procedures. This updated review presents new knowledge about various origins of microbial lipases, such as fungi, bacteria, and yeast. It highlights both the traditional and modern purification methods, including precipitation and chromatographic separation, the immunopurification technique, the reversed micellar system, the aqueous two-phase system (ATPS), and aqueous two-phase flotation (ATPF), moreover, delves into the diverse applications of microbial lipases across several industries, such as food, vitamin esters, textile, detergent, biodiesel, and bioremediation. Furthermore, the present research unveils the obstacles encountered in employing lipase, the patterns observed in lipase engineering, and the application of CRISPR/Cas genome editing technology for altering the genes responsible for lipase production. Additionally, the immobilization of microorganisms' lipases onto various carriers also contributes to enhancing the effectiveness and efficiencies of lipases in terms of their catalytic activities. This is achieved by boosting their resilience to heat and ionic conditions (such as inorganic solvents, high-level pH, and temperature). The process also facilitates the ease of recycling them and enables a more concentrated deposition of the enzyme onto the supporting material. Consequently, these characteristics have demonstrated their suitability for application as biocatalysts in diverse industries.

A Review of the Strategic Use of Sodium Alginate Polymer in the Immobilization of Microorganisms for Water Recycling.

In the quest for advanced and environmentally friendly solutions to address challenges in the field of wastewater treatment, the use of polymers such as sodium alginate (Na-Alg) in combination with immobilized microorganisms (IMs) stands out as a promising strategy. This study assesses the potential of Na-Alg in immobilizing microorganisms for wastewater treatment, emphasizing its effectiveness and relevance in environmental preservation through the use of IMs. Advances in IMs are examined, and the interactions between these microorganisms and Na-Alg as the immobilization support are highlighted. Additionally, models for studying the kinetic degradation of contaminants and the importance of oxygen supply to IMs are detailed. The combination of Na-Alg with IMs shows promise in the context of improving water quality, preserving ecological balance, and addressing climate change, but further research is required to overcome the identified challenges. Additional areas to explore are discussed, which are expected to contribute to the innovation of relevant systems.

Application potential of modified waste-lignin as microbial immobilization carriers for improve soil fertility

The immobilized microorganism technology is used to load the functional microorganism on a suitable carrier to maintain its biological activity, resist the impact of adverse environment. In this study, chemical modification of lignin side chain phenolic hydroxyl groups was carried out to increase the content of amide functional groups and enhance their adsorption and fixation effects on microorganisms due to the numerous active sites in the structure of discarded lignin, and studied its impact on microbial activity and crop growth. The results show that the modified lignin could be effectively combined with functional microorganisms, and the proposed bio-composite material was an effective method for cell protection. In addition, it was shown that functional microorganisms maintained high biological activity by immobilization of modified lignin, which was 34.3–41.0% higher than that of CK. Moreover, the technology could increase the total nitrogen content and available phosphorus content in soil by 70.8% and 64.4%, respectively, compared with CK. Therefore, it could increase eventually wheat growth indices and biomass. The completed research opens new perspectives for the effective immobilization of microorganisms and utilization of wasted lignin of significant economic importance.

Statistical optimization of cell-hydrogel interactions for green microbiology - a tutorial review.

In this tutorial mini-review, we explore the application of Design of Experiments (DOE) as a powerful statistical tool in biotechnology. Specifically, we review the optimization of hydrogel materials for diverse microbial applications related to green microbiology, the use of microbes to promote sustainability. Hydrogels, three-dimensional polymers networks with high water retention capabilities, are pivotal in the immobilization of microorganisms and provide a customizable environment essential for directing microbial fate. We focus on the application of DOE to precisely tailor hydrogel compositions for a range of fungi and bacteria either used for the sustainable production of chemical compounds, or the elimination of hazardous substances. We examine a variety of DOE design strategies such as central composite designs, Box-Behnken designs, and optimal designs, and discuss their strategic implementation across diverse hydrogel formulations. Our analysis explores the integral role of DOE in refining hydrogels derived from a spectrum of polymers, including natural and synthetic polymers. We illustrate how DOE facilitates nuanced control over hydrogel properties that cannot be achieved using a standard one factor at a time approach. Furthermore, this review reveals a conserved finding across different materials and applications: there are significant interactions between hydrogel parameters and cell behavior. This highlights the intricacies of cell-hydrogel interactions and the impact on hydrogel material properties and cellular functions. Lastly, this review not only highlights DOE's efficacy in streamlining the optimization of cell-hydrogel processes but also positions it as a critical tool in advancing our understanding of cell-hydrogel dynamics, potentially leading to innovative advancements in biotechnological applications and bioengineering solutions.

Clay-polymer hybrid hydrogels in the vanguard of technological innovations for bioremediation, metal biorecovery, and diverse applications.

Polymeric hydrogels are among the most studied materials due to their exceptional properties for many applications. In addition to organic and inorganic-based hydrogels, "hybrid hydrogels" have been gaining significant relevance in recent years due to their enhanced mechanical properties and a broader range of functionalities while maintaining good biocompatibility. In this sense, the addition of micro- and nanoscale clay particles seems promising for improving the physical, chemical, and biological properties of hydrogels. Nanoclays can contribute to the physical cross-linking of polymers, enhancing their mechanical strength and their swelling and biocompatibility properties. Nowadays, they are being investigated for their potential use in a wide range of applications, including medicine, industry, and environmental decontamination. The use of microorganisms for the decontamination of environments impacted by toxic compounds, known as bioremediation, represents one of the most promising approaches to address global pollution. The immobilization of microorganisms in polymeric hydrogel matrices is an attractive procedure that can offer several advantages, such as improving the preservation of cellular integrity, and facilitating cell separation, recovery, and transport. Cell immobilization also facilitates the biorecovery of critical materials from wastes within the framework of the circular economy. The present work aims to present an up-to-date overview on the different "hybrid hydrogels" used to date for bioremediation of toxic metals and recovery of critical materials, among other applications, highlighting possible drawbacks and gaps in research. This will provide the latest trends and advancements in the field and contribute to search for effective bioremediation strategies and critical materials recovery technologies.

Microorganism Immobilization Device Using Artificial Siderophores

Inspired by the mechanism by which microorganisms utilize siderophores to ingest iron, four different FeIII complexes of typical artificial siderophore ligands containing catecholate and/or hydroxamate groups, K3[FeIII-LC3], K2[FeIII-LC2H1], K[FeIII-LC1H2], and [FeIII-LH3], were prepared. They were modified on an Au substrate surface (Fe-L/Au) and applied as microorganism immobilization devices for fast, sensitive, selective detection of microorganisms, where H6LC3, H5LC2H1, H4LC1H2, and H3LH3 denote the tri-catecholate, biscatecholate-monohydroxamate, monocatecholate-bishydroxamate, and tri-hydroxamate type of artificial siderophores, respectively. Their adsorption properties for the several microorganisms were investigated using scanning electron microscopy (SEM), quartz crystal microbalance (QCM), and electric impedance spectroscopy (EIS) methods. The artificial siderophore-iron complexes modified on the Au substrates Fe-LC3/Au, Fe-LC2H1/Au, Fe-LC1H2/Au, and Fe-LH3/Au showed specific microorganism immobilization behavior with selectivity based on the structure of the artificial siderophores. Their specificities corresponded well with the structural characteristics of natural siderophores that microorganisms release from the cell and/or use to take up an iron. These findings suggest that release and uptake are achieved through specific interactions between the artificial siderophore-FeIII complexes and receptors on the cell surfaces of microorganisms. This study revealed that Fe-L/Au systems have specific potential to serve as effective immobilization probes of microorganisms for rapid, selective detection and identification of a variety of microorganisms.

Analysis of the Use of Modified Coal Bottom Ash as a Media for Immobilization of Microorganisms for the Production of Biogas from Macroalgae

Biofuel from macroalgae is referred to as the third generation biofuel because it does not require fertile land in the production process. Therefore, it is not included in the debate on the food sector. One of the process engineering in biogas production is the addition of immobilization media in anaerobic reactors. Coal combustion produces bottom ash solid waste containing 39.70% carbon (C) and 46.99% silica dioxide (SiO2) as well as other trace metals that have the potential to be used as absorbent materials or immobilization media in anaerobic decomposition. The purpose of this study was to determine the effect of the use of coal bottom ash-based immobilization media in the production of macroalgae biogas Spadina sp. The fixed variable in this study was the use of immobilization media of 30 grams, 40 grams, and 50 grams. Test parameters in the form of sCOD, VFA, biogas volume, and methane levels were used in this study. The production of macroalgae biogas Spadina sp is carried out in a fixed bed reactor with a capacity of 2000 mL with semi-batch conditions. The results showed that the highest biogas production was 204.8 mL/day with the use of immobilization media of 40 grams. The lowest biogas production is 20.5 mL/day with the use of 50 grams of immobilization media. The use of 50 grams of immobilization media is the best media to produce biogas with a high level of purity with an average of 57.48% followed by the use of 40 grams of immobilization media with an average of 41.35%, and the use of 30 grams of immobilization media with an average of 21.96%.

A bidirectional kinetic reaction model to predict uranium distribution in permeable reactive bio-barrier with high-sulfate environment

The use of permeable reactive bio-barriers (Bio-PRBs) is a developing method for remediation of uranium groundwater pollution. However, some remediation effects are difficult to estimate when because of the subsurface environment. Advanced knowledge of uranium migration and reactions in Bio-PRBs is crucial for successful practical application. In this study, a bidirectional kinetic reaction model was developed for predicting uranium reduction in a Bio-PRB system. The research demonstrates that the model is able to predict the uranium migration and rapidly evaluate the Bio-PRBs performance. The results show that contact period and microbial growth are the key factors that affect the remediation performance of Bio-PRBs. Microbial growth could lead to a decrease in hydraulic conductivity (K). The hydraulic conductivity loss in the free microorganisms (FM) group was 0.8–2.3 m/d, which was significantly smaller than the immobilized microorganism (IM) group (0.8–5.2 m/d). Compared to the IM group, the simulation results reveal that longer contact reaction period improves the remediation performance of SO42− and uranium by 32.6% and 21.7%, respectively. The bidirectional reaction between microorganisms and pollutants leads to a decrease in the remediation efficiency. In addition, the model can be used to design standard Bio-PRBs for real field of uranium contanminated groundwater. To meet the remediation goal of groundwater, the width of IM group needs to be increased to 250 cm while 500 cm for FM group. Therefore, IM-PRBs save costs significantly. The model has successfully optimized Bio-PRBs and predicted uranium contaminant-plume evolution and microbial growth inhibition in different Bio-PRBs.

Effect of fiber type and content on mechanical properties of microbial solidified sand

Fibers are applied to construction works to improve the strength and brittle failure of the soil. In this paper, fibers with a length of 6 mm are added to the microbial cemented sand, and fiber types and content are research variable. Unconfined compressive strength (UCS), permeability coefficient, water absorption rate, dry density, and calcium carbonate precipitation of the solidified sand were tested. The physical and mechanical properties of fiber types and content on the immobilization of microorganisms were also analyzed from the micro–macro perspective. Results are presented as follows. The UCS of the Microbial induced calcium carbonate precipitation (MICP) treated sand increases first and then decreases with the increasing fiber content. This phenomenon is due to the promotion of calcium carbonate precipitation by short fiber reinforcement, the limited movement of the sand particles caused by the formed network between the fibers, and the enhanced strength of the microbial solidified sand. However, the agglomeration caused by additional fibers leads to the uneven distribution of calcium carbonate and the reduction in strength. The optimum fiber contents of polypropylene, glass, polyvinyl alcohol, and basalt fibers are 0.4%, 0.2%, 0.2%, and 0.1%, respectively.

Bioutilization of the distillery stillage of different grain species from bioethanol production

Wastewater from bioethanol plants is classified as highly concentrated in terms of organic pollution precisely due to distillery stillage. The main problem in the disposal of distillery stillage is the processing of the liquid phase, the volume of which is up to 92% of all wastewater from a bioethanol plant. The existing wastewater treatment technologies of a bioethanol plant can be conditionally divided into four types: evaporation, aerobic biological treatment with fodder yeast production, anaerobic stillage treatment with biogas production, combined schemes. The aim of our work was to study a combined method for cleaning grain stillage by the anaerobic-aerobic method with the immobilization of microorganisms on a fibrous carrier. Physicochemical parameters of grain stillage and purified methane mash were determined according to generally accepted methods for analyzing wastewater from distilleries. Under anaerobic conditions, biogas was formed from distillery stillage, including low molecular weight organic compounds – methane, carbon dioxide, organic acids. After the first anaerobic stage of treatment, the pollution of wastewater decreased by 8-10 times, after which it was fed to the aerobic stage of post-treatment, which was carried out by microorganisms immobilized on a fixed carrier, which reduced the removal of biomass with the flow of purified water and improved treatment performance. The chemical oxygen demand (COD) of methane mash after the 1st stage of anaerobic fermentation was 1360 mg/dm3 compared to the initial COD of grain stillage of 15800 mg/dm3, which ensured a purification efficiency of 91.4%. The purification efficiency according to biochemical oxygen demand in five days (BOD5) was 97.5%. After the aerobic stage, the purification efficiency was 98.2% in terms of COD and 99.8% in terms of BOD5. The values of the content of total phosphorus also decreased by almost 20 times, nitrogen – by 9 times, sulfates – by 5 times. The advantages of the proposed method of wastewater treatment of bioethanol plants over existing ones are the ability to treat wastewater with any concentration of pollutants and additional obtaining of fuel – biogas, which can be used to replace natural gas, solving the problem of removing the biomass of microorganisms from the purification zone due to their fixation on a fibrous fixed carrier.

Novel 3D-Printed Biocarriers from Aluminosilicate Materials

The addition of biocarriers can improve biological processes in bioreactors, since their surface allows for the immobilization, attachment, protection, and growth of microorganisms. In addition, the development of a biofilm layer allows for the colonization of microorganisms in the biocarriers. The structure, composition, and roughness of the biocarriers’ surface are crucial factors that affect the development of the biofilm. In the current work, the aluminosilicate zeolites 13X and ZSM-5 were examined as the main building components of the biocarrier scaffolds, using bentonite, montmorillonite, and halloysite nanotubes as inorganic binders in various combinations. We utilized 3D printing to form pastes into monoliths that underwent heat treatment. The 3D-printed biocarriers were subjected to a mechanical analysis, including density, compression, and nanoindentation tests. Furthermore, the 3D-printed biocarriers were morphologically and structurally characterized using nitrogen adsorption at 77 K (LN2), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The stress–strain response of the materials was obtained through nanoindentation tests combined with the finite element analysis (FEA). These tests were also utilized to simulate the lattice geometries under compression loading conditions to investigate their deformation and stress distribution in relation to experimental compression testing. The results indicated that the 3D-printed biocarrier of 13X/halloysite nanotubes was endowed with a high specific surface area of 711 m2/g and extended mesoporous structure. Due to these assets, its bulk density of 1.67 g/cm3 was one of the lowest observed amongst the biocarriers derived from the various combinations of materials. The biocarriers based on the 13X zeolite exhibited the highest mechanical stability and appropriate morphological features. The 13X/halloysite nanotubes scaffold exhibited a hardness value of 45.64 MPa, which is moderate compared to the rest, while it presented the highest value of modulus of elasticity. In conclusion, aluminosilicate zeolites and their combinations with clays and inorganic nanotubes provide 3D-printed biocarriers with various textural and structural properties, which can be utilized to improve biological processes, while the most favorable characteristics are observed when utilizing the combination of 13X/halloysite nanotubes.

Immobilization on Polyethylenimine and Chitosan Sorbents Modulates the Production of Valuable Fatty Acids by the Chlorophyte Lobosphaera sp. IPPAS C-2047

Green microalgae, including those from the genus Lobosphaera, are exploited in various fields of biotechnology to obtain valuable fatty acids (e.g., arachidonic acid (C20:4, ARA)) for the production of infant formulae, food and feed additives. In nature, microalgae frequently exist in naturally immobilized state (as biofilms) with a limited cell division rate and increased stress resilience. In the fields of biotechnology, immobilization of microalgae on artificial cell carriers simplifies biomass harvesting and increases culture robustness and productivity. The choice of a suitable cell carrier is central to biotechnology involving immobilized cultures. Cell carriers based on the natural amine-containing polymer chitosan and synthetic polyethylenimine (PEI) are promising candidates for immobilization of phototrophic microorganisms. This is the first report on the effects of immobilization on PEI and chitosan on the accumulation and composition of polyunsaturated fatty acids, including ARA, in Lobosphaera sp. IPPAS C-2047. Immobilization on PEI increased the ARA percentage in the total fatty acids and ARA accumulation by 72% and 81% compared to the suspended cells cultured in complete or nitrogen-deprived medium 14 days, respectively. Immobilization of Lobosphaera sp. on the chitosan-based carrier reduced the ARA percentage but increased oleic and α-linoleic acid percentages. The mechanisms of the effects of immobilization on the fatty acid profiles of the microalgae are discussed.

Study on modified SA-H3BO3 immobilization microorganism method for wastewater treatment in seawater recirculating aquaculture system

The sodium alginate-H3BO3 (SA-H3BO3) is traditionally used as bioremediation method for wastewater treatment in recirculating aquaculture system. Even though this method has many advantages (e.g., high cell loading) for immobilization, the remove of ammonium is not very effective. In this study, a modified method was built by adding polyvinyl alcohol and activated carbon into SA solution, and then crosslinked with saturated H3BO3–CaCl2 solution for creating new beads. Moreover, response surface methodology was utilized for optimizing the immobilization based on Box-Behnken design. The removal rate of ammonium in 96 h was taken as the primary performance criterion to characterize the biological activity of immobilized microorganisms (i.e., Chloyella pyrenoidosa, Spirulina platensis, Nitrifying bacteria, and Photosynthetic bacteria). Based on the results, the optimal parameter of immobilization as follows: the concentration of SA was 1.46%, the concentration of polyvinyl alcohol was 0.23%, the concentration of activated carbon was 0.11%, the crosslinking time was 29.33 h, and the pH was 6.6.