“Nature-like” Cryoimmobilization of Phototrophic Microorganisms: New Opportunities for Their Long-Term Storage and Sustainable Use

It was found that immobilization of cells in poly(vinyl alcohol) (PVA) cryogel can be successfully applied for concurrent cryoimmobilization, cryoconservation and long-term storage of the cells of various phototrophic microorganisms (green and red microalgae, diatoms and cyanobacteria). For the first time, it was shown for 12 different immobilized microalgal cells that they can be stored frozen for at least 18 months while retaining a high level of viability (90%), and can further be used as an inoculum upon defrosting for cell-free biomass accumulation. Application of cryoimmobilized Chlorella vulgaris cells as inocula allowed the loading of a high concentration of the microalgal cells into the media for free biomass accumulation, thus increasing the rate of the process. It was shown that as minimum of 5 cycles of reuse of the same immobilized cells as inocula for cell accumulation could be realized when various real wastewater samples were applied as media for simultaneous microalgae cultivation and water purification.

USE OF ANALYSIS TECHNIQUE FOR IMMOBILIZED YEAST SACCHAROMYCES CEREVISIAE IN THE BIOTECHNOLOGICAL INDUSTRY

Article is devoted to the current state and problems of microbial cells immobilization and also prolonged storage of immobilized cells systems for the aims of biotechnological industry. In the experimental part immobilization conditions for the cells S. cerevisiae in alginate gel and vitality test, which had given high reproducibility of experimental results, were developed. Experimental results showed that viability of immobilized cells was higher than that of free yeast cells. It is possible that gel matrix has a protective effect on yeast cells during freezing. Comprehensive effect of cooling modes and preservation protective mediums, which contain sodium alginate, on viability of yeasts has been investigated. Advantage of yeast cells storage in immobilized state was shown experimentally. It was found that cooling mode and composition of preservation medium affect on the viability of S. cerevisiae cells during cryopreservation. In all freezing medium, both without protective components and with addition of a cryoprotective agent, the best results were obtained with cooling at a rate of 1°C/min. Viability indices in the samples were: 73.1 % – in distilled water; 90.8 % – in 1 % sodium alginate solution; 87.1 % – in 5 % DMSO solution and 86.1 % – in 1 % sodium alginate solution with the addition of 5 % DMSO. When cells were frozen in a 5 % DMSO solution and in a 1 % sodium alginate solution with the addition of 5 % DMSO, number of viable cells also decreased as cooling rate increased, but, probably, did not differ from the cell viability index in those samples that were frozen in 1 % sodium alginate solution. The highest results of viability for S. cerevisiae yeast cells were obtained during slow cooling for all cryoprotective mediums. For the first time, high cryoprotective properties of sodium alginate solution, were shown. Obtained results are enable to recommend the sodium alginate as a carrier for cryopreserved immobilized cells when using it in biotechnological processing for biologically active substances production.

Relationship Between Immobilization of Cells and Characterization of Binding Sites and of Cell-Free Bacteria and Immobilized Metal Biosorbents

Cell immobilization is preferred. Immobilized cells have been traditionally used for the treatment of sewage. The techniques employed for immobilization of cells are almost the same as those used for immobilization of enzymes with appropriate modifications. Entrapment and surface attachment techniques are commonly used. Gels, and to some extent membranes, are employed. Certain microorganisms were found to amass metallic components at a high limit Was Known as Bacterial Biosorption, Potent metal biosorbents among microorganisms, at low pH esteems, cell divider ligands are protonated and contend essentially with metals for official. With expanding pH, more ligands, such as amino and carboxyl groups, could be exposed, leading to attraction between these negative charges and the metals and consequently incremental biosorption onto the cell surface. Starting with isolation and identification of heavy metal-resistant bacteria from rock ore. Studying Factors Affecting Uranium Biosorption, Optimization of bacterial growth conditions and optimum for metal uptake by free and immobilized bacterial cells. All this evidence suggest that functions groups Represented in our study are responsible for metal uptake in our bacterial biomass beside change in peaks position which assigned for its groups confirm biosorption of metal ions from waste due to ions charge interaction comparing with immobilized we found increase in no of binding sites indicate that immobilized bacterial have high efficiency for metal up take which also change in peaks position which assigned for its groups confirm biosorption of metal ions from waste due to ions charge interaction, Where the high biosorption yield obtained by bacteria.

Enhanced L-glutamic acid production by immobilized Corynebacterium glutamicum X680 using Response Surface Methodology

L-glutamic acid is a non-essential amino acid largely used as flavor enhancer and food additive. It also has several therapeutic applications. Fermentation has gained superiority over its chemical synthesis as it produced stereo-specific isomer. Corynebacterium glutamicum is mostly used microorganism for Lglutamic acid fermentation. The study was dealing with optimization of L-glutamic acid production by immobilized mutant Corynebacterium glutamicum X680 in calcium alginate beads using response surface methodology as effective statistical tool. Among several parameters studied, pH, inoculums size, incubation time, concentration of sodium alginate, agitation and cell:alginate ration showed the most significant effect. Immobilized cells produced significantly (p<0.01) lower amount of L-glutamic acid (24.3mg/ml) compared to the production by free cells (27.6mg/ml). However, reusability of the beads minimized production cost and hence conferred benefit as far as the market economy is concerned.

Immobilization of Providencia stuartii Cells in Pumice Stone and Its Application for N-Acetylglucosamine Production

Research background. Shrimp shells contain chitin that can further be processed into N-acetylglucosamine which has been extensively used to treat joint damage. Providencia stuartii isolated form previous research has strong chitinolytic activity and may be utilized in the form of immobilized cells to be used in repeated fermentation. Pumice is a porous and rigid stone that offers superior mechanical strength, making it suitable to be used for immobilization process. Experimental approach. The research used experimental method to conduct the submerged fermentation process with different pumice stone size and pumice stone:growth medium ratio (m/V). The fermentation was carried out for 4 days at 37 C and pH of 7.0. The optimum pumice stone size and pumice stone:growth medium ratio (m/V) were used to determine the optimum fermentation cycle to produce N-acetylglucosamine. Results and conclusions. Pumice stones of 1.0×1.0×1.0 cm and pumice stone:growth medium ratio (m/V) of 1:5 were found to be the optimum conditions which successfully immobilized (89.99±1.65) % cells and produced (331.37±7.34) g/L N-acetylglucosamine. The highest N-acetylglucosamine concentration of (322.97±2.46) g/L was obtained in the first fermentation cycle which then decreased and remained stable throughout the last three cycles of fermentation. Novelty and scientific contribution. P. stuartii was a strong chitinolytic bacteria previously isolated from rotten shrimp shells and was used for the first time in immobilized form to produce N-acetylglucosamine. The findings in this research showed potential use of P. stuartii cells immobilized in pumice stone for continuous production of N-acetylglucosamine using fermentation method.

Effects of Constant Electric Field on Biodegradation of Phenol by Free and Immobilized Cells of Bradyrhizobium japonicum 273

It is shown that bacteria Bradyrhizobium japonicum 273 were capable of degrading phenol at moderate concentrations either in a free cell culture or by immobilized cells on granulated activated carbon particles. The amount of degraded phenol was greater in an immobilized cell preparation than in a free culture. The application of a constant electric field during cultivation led to enhanced phenol biodegradation in a free culture and in immobilized cells on granulated activated carbon. The highest phenol removal efficiency was observed for an anode potential of 1.0 V/S.H.E. The effect was better pronounced in a free culture. The enzyme activities of free cells for phenol oxidation and benzene ring cleavage were very sensitive to the anode potential in the first two steps of the metabolic pathway of phenol biodegradation catalyzed by phenol hydroxylase—catechol-1,2-dioxygenase and catechol-2,3-dioxygenase. It was observed that at an anode potential of 0.8 V/S.H.E., the meta-pathway of cleavage of the benzene ring catalyzed by catechol-2,3-dioxygenase became competitive with the ortho-pathway, catalyzed by catechol-1,2-dioxygenase. The obtained results showed that the positive effect of constant electric field on phenol biodegradation was rather due to electric stimulation of enzyme activity than electrochemical anode oxidation.

Study on the effect of headspace on biohydrogen production using palm oil mill effluent (POME) via immobilized and suspended growth

The world has been using fossil fuels to generate energy for centuries and has had adverse effects on the environment; hence renewable energy needs to be discovered and developed. Biohydrogen production is renewable energy since it emits no greenhouse gases and may provide clean energy. Therefore, this study aimed to investigate the optimum headspace ratio and biohydrogen production for suspended and immobilized cells using Palm Oil Mill Effluent (POME) as the fermentation substrate, while its anaerobic sludge acted as the inoculum. Five different ratios were investigated, which are 0.2, 0.3, 0.4, 0.5, and 0.6. These are equivalent to working volume (WV) of 80 mL, 70 mL, 60 mL, 50 mL, and 40 mL, respectively. The solution contained 10 % of inoculum and 90 % (v/v) of the feedstock. For immobilized cells, additional of glass beads as carrier material was added into the solution, using the ratio of 1:1 for anaerobic sludge (mL) to support carrier (g). The kinetic study was investigated using a modified Gompertz equation whereby for suspended cells, the best ratio was 0.3, with the highest biohydrogen concentration of 357.6 ppm. Meanwhile, the optimum ratio for the immobilized cell was 0.2, with the highest biohydrogen concentration of 479.3 ppm. Based on the kinetic studies, the kinetic parameters for suspended cells were: Hm = 89.8 mL, Rm = 6.8 mL/h, and λ = 0.1 hr. Meanwhile for immobilized cell, the kinetic parameters were: Hm = 73.6 mL, Rm = 6.9 mL/h and X λ 0 hr. In conclusion, selecting the suitable headspace ratio could affect the biohydrogen quality and improve the effectiveness of the production rate.

Ene-reductase transformation of massoia lactone to δ-decalactone in a continuous-flow reactor

The demand for natural food flavorings increases every year. Biotransformation has become an attractive approach to obtain natural products. In this work, enantiomerically pure (R)-(+)-δ-decalactone was obtained by reduction of the C=C double bond of natural massoia lactone in a continuous-flow reactor. Of 13 different ene-reductases isolated, purified and tested, OYE3 was found to be the most efficient biocatalyst. The selected biocatalyst, either in the form of purified enzyme, cell lysate, whole cells or immobilized cells, was tested in the batch system as well as in the packed-bed flow bioreactor. The biotransformation performed in batch mode, using Ca2+-alginate immobilized cells of Escherichia coli BL21(DE3)/pET30a-OYE3, furnished the desired product with complete conversion in 30 min. The process was intensified using a continuous-flow reactor-membrane filtration system (flow 0.1 mL/min, substrate concentration 10 mM, pH 7, 24 °C) with cell lysate as biocatalyst combined with a cofactor regeneration system, which allowed obtaining > 99% bioconversion of massoia lactone.

Anaerobic Acidogenic Fermentation of Cellobiose by Immobilized Cells: Prediction of Organic Acids Production by Response Surface Methodology

Response surface methodology was used to derive a prediction model for organic acids production by anaerobic acidogenic fermentation of cellobiose, using a mixed culture immobilized on γ-alumina. Three parameters (substrate concentration, temperature, and initial pH) were evaluated. In order to determine the limits of the parameters, preliminary experiments at 37 °C were conducted using substrates of various cellobiose concentrations and pH values. Cellobiose was used as a model sugar for subsequent experiments with lignocellulosic biomass. The culture was well adapted to cellobiose by successive subculturing at 37 °C in synthetic media (with 100:5:1 COD:N:P ratio). The experimental data of successive batch fermentations were fitted into a polynomial model for the total organic acids concentration in order to derive a predictive model that could be utilized as a tool to predict fermentation results when lignocellulosic biomass is used as a substrate. The quadratic effect of temperature was the most significant, followed by the quadratic effect of initial pH and the linear effect of cellobiose concentration. The results corroborated the validity and effectiveness of the model.