Immobilized Cells Research Articles

Synthetic design of methanotroph co-cultures and their immobilization within polymers containing magnetic nanoparticles to enhance methanol production from wheat straw-based biogas

In this study, various methanotroph co-cultures were designed to enhance methanol production from biogas produced through the anaerobic digestion of wheat straw (WS). Furthermore, whole-cell immobilization was performed using magnetic nanoparticle (MNP)-loaded polymers to develop an efficient bioprocess. The anaerobic digestion of WS by cattle dung yielded 219 L/kg of total solids reduced. Methanol produced was 5.08 and 6.39 mmol/L by pure- and co-cultures from biogas, respectively. The optimization of process parameters enhanced methanol production to 6.82 mmol/L by co-culturing Mithylosinus sporium and Methylocella tundrae. The immobilized co-culture within the MNP-doped polymers exhibited much higher cumulative methanol of up to 70.74 mmol/L than the production of 22.34 mmol/L by free cells after ten cycles of reuse. This study suggests that MNP-doped polymer-based immobilization of methanotrophs is a unique approach for producing renewable fuels from biomass-derived biogas, a greenhouse gas.

Immobilisation of Neuro-2a cells on electrodes and electrochemical detection of MTT formazan crystals to assess their viability

Marine toxins are potent toxic compounds that may reach humans and poison them. Therefore, their detection in seafood is crucial to prevent intoxication cases. Colorimetric cell-based assays (CBAs) have been developed to analyse marine neurotoxins, such as ciguatoxins (CTXs) and tetrodotoxins (TTXs), and are based on the toxicological effect of these toxins on the cells. Cell viability can be quantified by measuring the mitochondrial activity with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). With the purpose of moving forward in the development of cell-based biosensors (CBBs) for neurotoxins, Neuro-2a cells were immobilised on electrodes of different materials (carbon, carbon/polyaniline, carbon/poly-l-lysine, carbon/poly(3,4-ethylenedioxythiophene) and gold) and their presence and viability were assessed by the detection of MTT formazan crystals with cyclic voltammetry (CV). Best results in terms of oxidation potential and current intensity were achieved with carbon and carbon/polyaniline electrodes. Light microscopy also proved the presence of immobilised and living cells on electrodes. Cell density, incubation time and MTT concentration were optimised. Appropriate electrochemical responses were obtained incubating 100,000 cells/electrode for 2 h and using 0.86 mg/mL MTT. The system was able to detect toxicity when exposed to CTX1B and TTX standard solutions as well as Seriola dumerili and Lagocephalus sceleratus fish extracts containing these toxins.

An Alternative Approach to Improve the Butanol Production Efficiency from Sweet Sorghum Stem Juice Using Immobilized Cells Combined with an In Situ Gas Stripping System

The effects of the nitrogen source and buffers used in butanol production with Clostridium beijerinckii TISTR 1461 from sweet sorghum stem juice (SSJ) containing 60 g/L of total sugar were first studied in this paper. Among the various nitrogen sources (dried spent yeast, urea, ammonium acetate, ammonium sulfate), urea was found to be the most suitable for butanol production. SSJ supplemented with urea (0.64 g/L) and cocktail buffers (KH2PO4, 0.5 g/L; K2HPO4, 0.5 g/L; ammonium acetate, 2.2 g/L) gave the highest butanol concentration (PB, 10.13 g/L). Then, the capability of immobilized C. beijerinckii TISTR 1461 cells for butanol fermentation was investigated. Two residual waste materials were examined as immobilized cell carriers. Bamboo chopstick pieces were more appropriate as carriers for cell immobilization than cigarette filter tips. The PB value of the immobilized cells on the bamboo chopstick pieces was ~13% higher than that on the cigarette filter tips. Using the response surface methodology (RSM), 1.9 cm bamboo chopstick pieces with a carrier loading of 1:32 (w/v) were the optimum conditions for cell immobilization for butanol production. Under these conditions, the PB value was 11.62 g/L. To improve the butanol production efficiency, a gas stripping system (GS) was connected to the fermenter. It was found that the PB (14.02 g/L) and butanol productivity (QB, 0.29 g/L·h) values improved by ~21% compared to butanol fermentation using no gas stripping.

Response of mixed bacterial culture towards dibenzothiophene desulfurization under the influence of surfactants and microscopically (SEM and TEM) characterized magnetic Fe3 O4 nanoparticles.

Excessive emission of sulfur dioxides from the combustion of coal and other fossil fuels for thermal and industrial purposes has been associated with serious environmental hazards. Biodesulfisation (BDS) can be an effective approach for reducing the impact of toxic gases to its inbuilt operational feasibility under ambient environmental conditions. In the present research, two strategies for BDS of a standard organosulfur compound such as dibenzothiophene (DBT) were investigated under laboratory conditions. In the first treatment, the role of different surfactants such as Tween-20, Tween-80, SDS, and EDTA on the desulfurization of DBT was investigated by the application of bacterial consortium IQMJ-5. In the second treatment, Iron oxidenanoparticles were synthesized and immobilized on the surface of bacteria cells. Shake flask experiments were conducted with immobilized cells, surfactant amended immobilized cells, and control or noncoated cells. Among different surfactant treatments, Tween-80 was found to be the most effective surfactant, showing maximum desulfurization activity at a concentration of 5g/L. The transmission electron microscopy and X-ray diffraction analysis indicated that produced nanoparticles were spherical in shape with a size of about 46 nm and had a stoichiometric ratio of 55.85% and 44.15% between O and Fe, respectively. The nanoparticle treatment enhanced the DBT desulfurization process up to 11.37% as compared to the control, specifically when immobilized cells were used. Therefore, it was concluded that nanoparticles treatments with immobilization of the bacterial cells enhanced the desulfurization rate of DBT under ambient reaction conditions and provide a sustainable alternative for commercial coal BDS.

An overview on cell and enzyme immobilization for enhanced biohydrogen production from lignocellulosic biomass

Hydrogen gas, a carbon-free energy carrier, can be produced via fossil fuel reforming, coal gasification, water electrolysis, photocatalysis, or biological process. Biohydrogen production from lignocellulosic biomass (LCB) in this regard, appears as an environmental benign, sustainable, non-food competing second generation fuel. LCB serves as the largest potential carbon source for sustainable biohydrogen production with an enormous global annual capacity of more than one trillion tons. Enzymes in this case, are widely used to hydrolyse the LCB into fermentable sugars, and subsequent hydrogen production is carried out by dark fermentation. However, the untapped non-food competing LCB is currently impeded by several critical bottlenecks including sensitivity of cells and enzymes to numerous denaturing conditions, recyclability, and high cost of enzyme. Low productivity of hydrolysis and hydrogen production in this regard, lead to a larger bioreactor and capital expenditures (CAPEX) requirement, which in turn, making this approach to be less competitive in commercial application. These bottlenecks can be overcome by immobilization technique, which enables the recyclability, improves stability and productivity of the enzyme and cells. Current review accommodates for the important outlook and critical insights into the immobilization techniques, providing important guidelines for the operation of immobilization techniques to elevate commercial competitiveness of biohydrogen production from LCB in the future. The effect of geometry, surface charges, and wettability of different type of carriers for cell immobilization to enhance biohydrogen production are discussed. The critical aspects of the immobilization parameters, such as temperature, pH, and duration which could significantly affect the properties of immobilized enzymes are thoroughly examined in this review. Suggestions and future directions of this field are provided to assist the development of an efficient, economic, and sustainable hydrogen production process.

Intracellular connections between basal bodies promote the coordinated behavior of motile cilia.

Hydrodynamic flow produced by multiciliated cells is critical for fluid circulation and cell motility. Hundreds of cilia beat with metachronal synchrony for fluid flow. Cilia-driven fluid flow produces extracellular hydrodynamic forces that cause neighboring cilia to beat in a synchronized manner. However, hydrodynamic coupling between neighboring cilia is not the sole mechanism that drives cilia synchrony. Cilia are nucleated by basal bodies (BBs) that link to each other and to the cell's cortex via BB-associated appendages. The intracellular BB and cortical network is hypothesized to synchronize ciliary beating by transmitting cilia coordination cues. The extent of intracellular ciliary connections and the nature of these stimuli remain unclear. Moreover, how BB connections influence the dynamics of individual cilia has not been established. We show by focused ion beam scanning electron microscopy imaging that cilia are coupled both longitudinally and laterally in the ciliate Tetrahymena thermophila by the underlying BB and cortical cytoskeletal network. To visualize the behavior of individual cilia in live, immobilized Tetrahymena cells, we developed Delivered Iron Particle Ubiety Live Light (DIPULL) microscopy. Quantitative and computer analyses of ciliary dynamics reveal that BB connections control ciliary waveform and coordinate ciliary beating. Loss of BB connections reduces cilia-dependent fluid flow forces.

Efficiency of magnetic immobilization for recombinant Pichia pastoris cells harvesting over consecutive production cycles

ABSTRACT In the current experiment, P. pastoris cells were selected as promising candidate for production of recombinant proteins and were magnetically immobilized by 3-aminopropyltriethoxysilane-coated magnetite nanoparticles (APTES@Fe3O4). The ability of immobilized cells for the production of recombinant human serum albumin (HSA) and the potency of magnetic immobilization for yeast cells recycling was evaluated over three successive batch fermentation cycles. Interestingly, magnetic immobilization resulted in 1.4-fold increase in the HAS production. The productivity was increased from 0.7 mg/mL up to one mg/mL. But, after each production cycle a significant (more than two-fold) reduction in the productivity was recorded in free and immobilized cells. Over consecutive production cycles, efficiency of magnetic immobilization was also reduced. After three production cycles, immobilization efficiency was reduced from 80% down to 64% that was due to appearance of magnetic insensitive cells. Field emission scanning electron microscopy (FESEM) analyses approved that magnetic insensitive cells are nanoparticles free cells. These free cells can be resulted from cell proliferation and detachment of nanoparticles from cells surface. These findings can be considered for development of an efficient immobilization technique to harvest yeast cells over consecutive production cycles.

Development and operation of immobilized cell plug flow bioreactor (PFR) for treatment of textile industry effluent and evaluation of its working efficiency.

The release of untreated/partially treated effluent and solid waste from textile dyeing industries, having un-reacted dyes, their hydrolysed products and high total dissolved solids (TDS) over the period of time had led to the deterioration of ecological niches. In an endeavour to develop a sustainable and effective alternative to conventional approaches, a plug flow reactor (PFR) having immobilized cells of consortium of three indigenous bacterial isolates was developed. The reactor was fed with effluent collected from the equalization tank of a textile processing unit located near city of Amritsar, Punjab (India). The PFR over a period of 3 months achieved 97.98 %, 82.22 %, 87.36%, 77.71% and 68.75% lowering of colour, chemical oxygen demand (COD), biological oxygen demand (BOD), total dissolved solids (TDS) and total suspended solids (TSS) respectively. The comparison of the phytotoxicity and genotoxicity of untreated and PFR-treated output samples using plant and animal models indicated significant lowering of respective toxicity potential. This is a first report, as per best of our knowledge, regarding direct treatment of textile industry effluent without any pre-treatment and with minimal nutritional inputs, which can be easily integrated into already existing treatment plant. The successful implementation of this system will lower the cost of coagulants/flocculants and also lowering the sludge generation.

Effect of passive cell immobilization of co-cultured yeasts on the whey fermentation and alcohols production

Whey is one of the main residues of the dairy industry and its valorization by fermentation is an emergent practice that contributes to the circular economy and sustainable development. Whey fermentation with specialized yeast strains produces value-added biomolecules, such as fusel alcohols of high interest for the pharmaceutic, food and cosmetic industries due to their aromatic and flavor properties. The present study aimed to develop the whey fermentation with the yeasts Kluyveromyces marxianus and Debaryomyces hansenii immobilized on inert support, to increase cell density and 2-phenylethanol (2-PE) production. Biochar synthesized from wood feedstock, perlite and filter Kaldnes plastic rings were used as supports for the cell immobilization. They were selected based on their different nature and physical properties such as porous structure and rough surface, to study the effect of different supports on yeast biofilm development. Also, functional groups such as hydroxyl, carbonyl, siloxane, and aliphatic hydrocarbons were useful for the development of covalent bonds and electrostatic forces between cells-support. The yeast immobilization increased the 2-PE production, especially on the plastic rings and perlite, obtaining 0.56 ± 0.01 g/L of 2-PE for the suspended culture and up to 0.91 ± 0.01 g/L for the immobilized co-culture on filter Kaldnes plastic rings.

Aflatoxin B1 bioremoval by fungal cells immobilised on magnetic nanoparticles

ABSTRACT Aflatoxins are the most potent hepatocarcinogens of all biologically produced toxins found to date. Contaminated food and commodities are one of the most serious problems due to an irreversible damage to health. Taking advantage of biological methods to improve food safety, an aflatoxin B1 (AFB1) bioremoval study was conducted to investigate the potential of arrested fungal cells on magnetic nanoparticles. The favourable results on the degradation of AFB1 indicate a reasonable influence of the carriers on the fungal cells and the degradation process. The efficacy of degradation of AFB1 by free and immobilised fungal cells on four different magnetic nanoparticles (Fe3O4) was investigated. The degradation rate by HPLC analysis exhibited 54.97% for the free cell study, 85.85% for Fe3O4@MTMS@cell, 95.07% for Fe3O4@TEOS@cell, 84.48% for Fe3O4@SiO2-NH2@cell and 96.52% for Fe3O4@BCD@cell for the 3 μg/ml AFB1. The degradation with Fe3O4@ BCD@cell showed remarkable results even for 5 μg/ml AFB1 resulting 93.42%.

Algal immobilization as a green technology for domestic wastewater treatment

wastewater treatment technology is an important issue because of numerous organic and inorganic impurities in municipal, industrial, and agricultural waters. Different systems of wastewater treatment used the microorganisms for the removal of organic materials, most species of algae represent promising biosystems for treating of wastewater by transformation or direct uptake of pollutants and improving the purification performance of bacterial systems. This work aimed to study the efficiency of immobilization technology using immobilized cells of green algae Chlorella vulgaris in the treatment of domestic wastewater. Some physical and chemical characteristics of domestic wastewater were examined and the percentage of treatment efficiency with free and immobilized cells of alga were compared. The results of the study presented high reduction of EC, salinity, TDS, total alkalinity, hardness, calcium, and chloride with slight induction of pH values to the basal side after treatment with free and immobilized algae. After (3,5,7) days of treatment with free microalgae and immobilized microalgae, the recorded value of wastewater had been eliminated to (2.09, 2, 1.8) μs/cm and (2.36, 1.27, 1.07) μs/cm of EC; (689, 580, 520) mg/L and (620,520,489) mg/L of the total hardness; (320, 244, 220) mg/L and (300, 244, 204 ) mg/L of the calcium; (420, 369, 309) mg/L and (400, 340, 289) mg/L of chloride, respectively, while pH value increased to (8.6, 8.7, 8.6) after treated with free microalgae. The results showed high efficiency of mobilized algae compared with free algal cells in reducing many physical and chemical parameters and the immobilized algal cell technique is useful as tools in the treatment process of wastewater.

Sustainable isomaltulose production in Corynebacterium glutamicum by engineering the thermostability of sucrose isomerase coupled with one-step simplified cell immobilization.

Sucrose isomerase (SI), catalyzing sucrose to isomaltulose, has been widely used in isomaltulose production, but its poor thermostability is still resisted in sustainable batches production. Here, protein engineering and one-step immobilized cell strategy were simultaneously coupled to maintain steady state for long-term operational stabilities. First, rational design of Pantoea dispersa SI (PdSI) for improving its thermostability by predicting and substituting the unstable amino acid residues was investigated using computational analysis. After screening mutagenesis library, two single mutants (PdSIV280L and PdSIS499F) displayed favorable characteristics on thermostability, and further study found that the double mutant PdSIV280L/S499F could stabilize PdSIWT better. Compared with PdSIWT, PdSIV280L/S499F displayed a 3.2°C-higher Tm, and showed a ninefold prolonged half-life at 45°C. Subsequently, a one-step simplified immobilization method was developed for encapsulation of PdSIV280L/S499F in food-grade Corynebacterium glutamicum cells to further enhance the recyclability of isomaltulose production. Recombinant cells expressing combinatorial mutant (RCSI2) were successfully immobilized in 2.5% sodium alginate without prior permeabilization. The immobilized RCSI2 showed that the maximum yield of isomaltulose by batch conversion reached to 453.0 g/L isomaltulose with a productivity of 41.2 g/l/h from 500.0 g/L sucrose solution, and the conversion rate remained 83.2% after 26 repeated batches.

Production of the Polysaccharide Pullulan by Aureobasidium pullulans Cell Immobilization

This review examines the immobilization of A. pullulans cells for production of the fungal polysaccharide pullulan. Pullulan is a water-soluble gum that exists structurally as a glucan consisting primarily of maltotriose units, which has a variety of food, non-food and biomedical applications. Cells can be immobilized by carrier-binding or entrapment techniques. The number of studies utilizing carrier-binding as a method to immobilize A. pullulans cells appears to outnumber the investigations using cell entrapment. A variety of solid supports, including polyurethane foam, sponge, diatomaceous earth, ion-exchanger, zeolite and plastic composite, have been employed to immobilize pullulan-producing A. pullulans cells. The most effective solid support that was used to adsorb the fungal cells was polyurethane foam which produced polysaccharide after 18 cycles of use. To entrap pullulan-producing fungal cells, agents such as polyurethane foam, polyvinyl alcohol, calcium alginate, agar, agarose, carrageenan and chitosan were investigated. Polysaccharide production by cells entrapped in polyurethane foam, polyvinyl alcohol or calcium alginate was highest and the immobilized cells could be reutilized for several cycles. It was shown that the pullulan content of the polysaccharide synthesized by cells entrapped in calcium alginate beads was low, which limits the method’s usefulness for pullulan production. Further, many of the entrapped fungal cells synthesized polysaccharide with a low pullulan content. It was concluded that carrier-binding techniques may be more effective than entrapment techniques for A. pullulans cell immobilization, since carrier-binding is less likely to affect the pullulan content of the polysaccharide being synthesized.

Improvement in desulfurization of dibenzothiophene and dibenzothiophene sulfone by Paenibacillus strains using immobilization or nanoparticle coating.

Biodesulfurization of fossil fuels is a promising technology for deep desulfurization. Previously, we have shown that Paenibacillus strains 32O-W and 32O-Y can desulfurize dibenzothiophene (DBT) and DBT sulfone (DBTS) effectively. In this work, improvements in DBT and DBTS desulfurization by these strains were investigated through immobilization and nanoparticle coating of cells. Paenibacillus strains 32O-W and 32O-Y immobilized in alginate gel beads or coated with Fe3 O4 magnetite nanoparticles were grown at various concentrations (0.1-2 mmol l-1 ) of DBT or DBTS for 96 h. The production of 2-hydroxybiphenyl (2-HBP) from the 4S pathway biotransformation of DBT or DBTS was measured. The highest amounts of 2-HBP production occurred at concentrations of 0.1 and 0.5 mmol l-1 . Compared to planktonic cultures maximum 2-HBP production increased by 54% for DBT and 90% for DBTS desulfurization with immobilized strains, and 44% for DBT and 66% for DBTS desulfurization by nanoparticle-coated strains. Nanoparticle-coated and immobilized cells may be of use in efforts to increase the efficiency of biodesulfurization. Alginate immobilization or nanoparticle coating of bacterial cells may be useful approaches for the enhancement of biodesulfurization for eventual use on an industrial scale.

Lindane bioremediation by Paenibacillus dendritiformis SJPS-4, its metabolic pathway analysis and functional gene annotation

Lindane, hexachlorohexane is an organic persistent pesticide reaches the water bodies via agricultural waste water runoff or rainfall. The present study shows the lindane bioremediation potential of Paenibacillus dendritiformis SJPS-4 and its degradation potential which was evaluated using gas chromatography 7890A equipped with HP-5 column and electron capture detector (μECD). Further, the effect of whole cell immobilization resulted the lindane degradation of 80.72% in mineral salt medium (MSM-L) with significant degradation after immobilization of bacterial cells in alginate beads and agar cubes. The functional gene annotation using KEGG-KASS tools revealed the metabolic pathway for lindane degradation involving lin genes (lin A, lin E, lin B, lin X, lin C, lin D) acting on subsequent compound at each step including the subsequent metabolites in the pathway were utilized. This study gives the new insights on the potential of naturally occurring bacteria Paenibacillus dendritiformis SJPS-4 towards its role in decontaminating such environments.

Synthesis and application of a magnetically recoverable biological nanocomposite material for waste cooking oil removal and commercial product recovery in wastewater treatment

This study proposes magnetically recoverable biological-nanocomposite comprising photosynthetic bacteria , husk biochar, and Fe 3 O 4 nanoparticles to facilitate biomass and commercial product recovery after waste cooking oil removal from water bodies. The photosynthetic bacterium Rhodopseudomonas faecalis PA2 removes oil and produces commercially valuable products such as carotenoids , lipase , and microbial lipids. Biochar serves as a carrier for bacterial adsorption, while synthesized Fe 3 O 4 imparts superparamagnetism to the nanocomposite. Different types of biochars—rice straw, husk, and coconut coir dust—were tested; husk biochar (HB) nanocomposite was preferred owing to its high cell immobilization efficiency. Brunauer–Emmett–Teller analysis indicated that Fe 3 O 4 increased specific surface area of the Fe 3 O 4 /biochar nanocomposite compared with that of biochar alone. The results of X-ray diffractometry and Fourier transform infrared spectroscopy confirmed the presence of Fe 3 O 4 and biochar in the biological nanocomposite, whereas field emission scanning electron microscopy and transmission electron microscopy demonstrated the three components were combined as a composite . After the treatment, the biological nanocomposites could be easily recovered from an aqueous environment using an external magnetic field . Oil removal and recovery of beneficial products were higher in the biological nanocomposite (photosynthetic bacteria/Fe 3 O 4 /HB nanocomposite) than in the Fe 3 O 4 /HB nanocomposite and free cell treatments. Moreover, compared to the free cell experiments, the biological nanocomposite showed an increase in biomass, carotenoid production, and lipase activity by 65.0%, 84.9%, and 31.5%, respectively, with 70.31% oil reduction. This study presents a sustainable treatment for the removal of waste cooking oil and synthesis and recovery of microbial products. • Biological nanocomposites degrade waste oil. • Biological nanocomposites enhance biomass and microbial product recovery. • Rhodopseudomonas faecalis PA2 degrades oil and synthesizes microbial products. • Biochar made from lignocellulosic biomass is used as a microbial cell carrier. • Fe 3 O 4 serves as an inexpensive process for biomass and microbial product recovery.

Continuous Fermentation by Lactobacillus bulgaricus T15 Cells Immobilized in Cross-Linked F127 Hydrogels to Produce ᴅ-Lactic Acid

Lignocellulose biorefinery via continuous cell-recycle fermentation has long been recognized as a promising alternative technique for producing chemicals. ᴅ-lactic acid (D-LA) production by fermentation of corn stover by Lactobacillus bulgaricus was proven to be feasible by a previous study. However, the phenolic compounds and the high glucose content in this substrate may inhibit cell growth. The immobilization of cells in polymer hydrogels can protect them from toxic compounds in the medium and improve fermentation efficiency. Here, we studied the production of D-LA by L. bulgaricus cells immobilized in cross-linkable F127 bis-polyurethane methacrylate (F127-BUM/T15). The Hencky stress and Hencky strain of F127-BUM/T15 was 159.11 KPa and 0.646 respectively. When immobilized and free-living cells were cultured in media containing 5-hydroxymethylfurfural, vanillin, or high glucose concentrations, the immobilized cells were more tolerant, produced higher D-LA yields, and had higher sugar-to-acid conversion ratios. After 100 days of fermentation, the total D-LA production via immobilized cells was 1982.97 ± 1.81 g with a yield of 2.68 ± 0.48 g/L h, which was higher than that of free cells (0.625 ± 0.28 g/L h). This study demonstrated that F127-BUM/T15 has excellent potential for application in the biorefinery industry.

Role of catalyst supports in biocatalysis

AbstractBiocatalysis utilizes enzymes and microbial cells as catalysts for a wide range of applications in biotechnology. Immobilization of biocatalysts on various materials has several advantages, including the capacity for reuse, quick reaction termination, easy biocatalyst recovery and operational stability. The present article focuses on the use of material supports for developing immobilized biocatalysts in applications related to energy, environment and chemical synthesis. The work provides a comprehensive overview of a broad class of materials, including organic, inorganic and composites, that have been shown to be prosperous candidates to support the immobilization of enzymes and microbial cells. It also highlights the properties of nanomaterial support such as large surface area and comfort compartment for immobilization. The availability of different types of materials as catalyst support provides an opportunity to understand and develop efficient biocatalytic systems. The choice of selecting a catalyst support will mostly depend on the interaction of the material with the enzyme or microbial cell. Finally, potential challenges, future approaches in developing immobilized biocatalytic systems for various applications and novel material supports are suggested. © 2022 Society of Chemical Industry (SCI).

Impact of immobilized algae and its consortium in biodegradation of the textile dyes

In biological engineering, cell immobilization is a modern technique for immobilizing free cells in a small space. Disintegration and elimination of azo dyes [Reactive Orange 122 (orange 2RL) and Reactive Red 194 (Reactive Red M-2BF)] were investigated by using Chlorococcum sp. and Chlorococcum sp. mixed with Scenedesmus obliquus, respectively. After 7 days of incubation, the maximum decolorization was spotted at 40 ppm for Reactive Orange 122 and 20 ppm for Reactive Red 194 by Chlorococcum sp. and Chlorococcum sp. mixed with S. obliquus, respectively. The findings revealed that the best decolorization activity was found at pH 11 and 25 °C under aeration conditions. BG11 was considered the best medium for azo dye decolorization with a high decolorization percentage. Additionally, different concentrations of nitrogen and phosphorus show the high activity of decolorization of both dyes. Referring to vitamins (thiamin and Ascorbic acid), all studied concentrations showed high decolorization activity with immobilized Chlorococcum sp. mixed with S. obliquus; however, different concentrations (20, 40, and 60 mg/l) of thiamin showed completely decolorization of Reactive Red 194 after 3 days, and 60 mg/l of ascorbic acid showed completely decolorization of Reactive Orange 122 after 5 days of inoculation. FT-IR and GC-Ms analysis for azo dyes after and before treatment with Immobilization of Chlorococcum sp. and Chlorococcum sp. mixed with Scenedesmus obliquus were detected. Novelty statement: The natural carrier algae and its consortium combined with a suitable immobilization technique were considered in this study, which is non-toxic, enhanced their bioremediation potential for dyes, and allowed multiple uses of biocatalysts. The novel use of the immobilization and its consortium of algae on the degradation efficiency of azo dyes and studying the effect of physicochemical conditions on decolorization and degradation of azo dyes. Application of immobilization techniques using microalgae could be excellent bioremediation of wastewaters.

Comparison of hydrodynamic characteristics of Tulsion and Siran immobilised beads in a fluidised bed bioreactor

The fluidised bed reactors are successfully utilised in various bioprocesses to produce high value products using immobilised cells and enzymes. The present work aims at evaluating hydrodynamic characteristics of a three phase fluidised bed bioreactor using Tulsion® A-1X MP, Tulsion® ADS-400 and Tulsion® ADS-800, polystyrene and polyacrylic based three types of free and immobilised cells solid carriers viz. and comparing their performance with Siran® SIKUG41 glass beads. The hydrodynamic parameters such as particle density (cells and beads), drag coefficient, minimum and maximum fluidisation velocity, particle settling velocity were estimated and compared in water and biological media (E2 and MSM) having varying rheological properties. The relationships between drag coefficient (CD)–Reynolds numbers (NRe), superficial liquid velocity (Uf)–void fraction(ε), expansion index(n)–NRe were obtained.The scanning electron microscopy studies revealed that the pore sizes of Tulsion beads (20–300 nm) were significantly smaller compared to Siran carriers (7–120 μm) leading to cells growth only on the surface of the beads. The biomass grown was estimated to be 0.75–1.2 mgCDW/g for Tulsion beads and 1.27–1.3 mgCDW/g for Siran beads with immobilised cells of P. putida and R. erythropolis, respectively. As per the results obtained, the reactor could be operated as a fluidised bed reactor with Tulsion and Siran beads at ε>0.4 and ε>0.6. The cell immobilised Tulsion and Siran beads have shown higher drag co-efficient in E2 and MSM media compared to water. The empirical correlations describing beads properties in falling (NRe) and fluidisation conditions in the form of Archimedes Number (NAr) were developed for ε in the range of 0.3–0.8 at 0.3<NRe<100 and 10<NAr<1000. The experimental data was statistically analysed using percentage mean relative error ± standard deviation and values were found to be at 95% confidence level.The evaluation of hydrodynamic characteristics of Tulsion and Siran carriers could be used to set up an operating window for three phase fluidised bed reactor for a bioprocess.