Immobilized Cell Systems Research Articles

Bioremediation of textile wastewater using Bacillus cereus isolated from refinery site: Comparative analysis of free and immobilized cells systems

The textile industries consume a considerable amount of freshwater and discharge untreated or semi-treated pollutants to the environment. Azo dyes, generally employed in textile manufacturing industries, have a hazardous impact on the ecosystem. Incomplete treatment of wastewater containing azo dyes discharges into the aquatic system, which has recalcitrant and toxic properties. Hence, the need for cost-effective and high-performing technologies is essential. In this direction, bacterial degradation is considered an economically viable and efficient technique for the treatment of Active blue (AB) dye. Polyurethane foam (PUF) is a low-cost and hydrophilic material with a microporous structure, which offers an excellent surface-to-volume ratio. Hence, PUF was preferred for the immobilization of isolated bacterial species. For this, a dye-degrading gram-positive bacteria namely Bacillus cereus GS2 IIT (BHU) was isolated from the petroleum sludge. A comparative analysis between free and immobilized cell systems was carried out by varying the process parameters, i.e., batch time, pH, temperature, glucose concentration, and initial AB dye concentration. The corresponding optimum conditions were found to be 6.0 days, 6.5, 30 °C, 1.0 g/L, and 50 mg/L, respectively. The immobilized cell system exceeds the dye removal efficiency (RE) by 10. 7 % compared to the free cell system. The packed bed bioreactor could be able to deliver 98.56 % of dye removal at an inlet loading rate of 30 mg/L d and 50 mg/L of initial dye concentration.

Generation of biosurfactants by P. aeruginosa gi |KP163922| on waste engine oil in a free and immobilized cells system

AbstractThis study investigated biosurfactant production by the bacterial strain of P. aeruginosa gi |KP 163922| for a free and immobilized cells system using waste engine oil (WEO) as a substrate. The polyurethane foam (PUF) cubes (1 cm × 1 cm × 1 cm) were used as carriers for the immobilization. The batch experiments were performed in Erlenmeyer flasks and monitored at every 24‐h interval for both cell systems. The microbial population was counted using the plate count method, and the hydrocarbon degradation percentage was calculated to evaluate the bacterial activity. Surface tension was measured at regular intervals to ensure the presence of biosurfactants. The maximum reduction was 37 and 35 mN/m in a free and immobilized cells system. Immobilization of cells using PUF was found to be efficient in supporting bacterial growth, and after 48 h of incubation, the growth was 2.5 (±0.58) × 1011 CFU/mL. The chemical characterization using Fourier transform infrared (FTIR) spectroscopy confirmed the obtained product as rhamnolipid. Crude biosurfactant yield was found to be maximum in the case of the immobilized system, which was approximately 18 g/L. Scanning electron micrographs (SEM) of the used PUF cubes showed the strong adherence of biofilm to the cube surface and the potential of its reuse in multiple cycles. Gas chromatography–mass spectrometry (GC–MS) analysis confirms that the immobilized strain of P. aeruginosa exhibited superior biodegradation capabilities compared to free cells. Specifically, it was capable of reducing the concentration of polyaromatic hydrocarbons and converting more significant aliphatic compounds into metabolic byproducts such as alkanes, alkenes, cycloalkanes, and carbonyl groups.

Fermentative processes for the upcycling of xylose to xylitol by immobilized cells of Pichia fermentans WC1507.

Xylitol is a pentose-polyol widely applied in the food and pharmaceutical industry. It can be produced from lignocellulosic biomass, valorizing second-generation feedstocks. Biotechnological production of xylitol requires scalable solutions suitable for industrial scale processes. Immobilized-cells systems offer numerous advantages. Although fungal pellet carriers have gained attention, their application in xylitol production remains unexplored. In this study, the yeast strain P. fermentans WC 1507 was employed for xylitol production. The optimal conditions were observed with free-cell cultures at pH above 3.5, low oxygenation, and medium containing (NH4)2SO4 and yeast extract as nitrogen sources (xylitol titer 79.4g/L, YP/S 66.3%, and volumetric productivity 1.3g/L/h). Yeast cells were immobilized using inactive Aspergillus oryzae pellet mycelial carrier (MC) and alginate beads (AB) and were tested in flasks over three consecutive production runs. Additionally, the effect of a 0.2% w/v alginate layer, coating the outer surface of the carriers (cMC and cAB, respectively), was examined. While YP/S values observed with both immobilized and free cells were similar, the immobilized cells exhibited lower final xylitol titer and volumetric productivity, likely due to mass transfer limitations. AB and cAB outperformed MC and cMC. The uncoated AB carriers were tested in a laboratory-scale airlift bioreactor, which demonstrated a progressive increase in xylitol production in a repeated batch process: in the third run, a xylitol titer of 63.0g/L, YP/S of 61.5%, and volumetric productivity of 0.52g/L/h were achieved. This study confirmed P. fermentans WC 1507 as a promising strain for xylitol production in both free- and entrapped-cells systems. Considering the performance of the wild strain, a metabolic engineering intervention aiming at further improving the efficiency of xylitol production could be justified. MC and AB proved to be viable supports for cell immobilization, but additional process development is necessary to identify the optimal bioreactor configuration and fermentation conditions.

Effect of the Mode of Fermentation on the Behavior of Penicillium bilaiae in Conditions of Abiotic Stress.

The ability of a Penicillium bilaiae strain to support acid production and simultaneously solubilize inorganic sources of phosphate in conditions of submerged, solid-state fermentation (SSF) and immobilized cell system was examined in this study. Abiotic stress factors such as NaCl and different values of pH were introduced into the different fermentation process schemes to measure the fungal response. The results showed a higher tolerance of P. bilaiae when the fermentation process was carried out in solid-state and immobilized-cell conditions, which mimics the natural state of the soil microorganisms. The acidic culture conditions were not found to be suitable for fungal growth, which increased at a higher pH, with values of 4.0 and 6.0 being optimal for all types of fermentation. The presence of increasing amounts of NaCl provoked low biomass growth, titratable acidity, and simultaneous phosphate (P) solubilization. These results were, however, less pronounced at pH 4.0 and 6.0, particularly in conditions of SSF. Studying stress-tolerant microbial characteristics, particularly in different conditions and combinations of stress factors, is of great importance for further managing the overall microbial inoculants' production and formulation process as well as their applications in specific soil-plant systems.

Enhanced excretion of recombinant cyclodextrin glucanotransferase and cell stability of immobilized recombinant Escherichia coli by reducing tryptone concentration

AbstractBACKGROUNDRecombinant protein excretion has become a mainstream strategy in reducing downstream processing costs. However, recombinant protein excretion is often bottlenecked by cell lysis and plasmid stability. In the present study, recombinant Escherichia coli cell immobilization was performed on a hollow fiber membrane. Tryptone concentration in the expression medium (Super Optimal Broth), which was used as a nitrogen source, was varied between 5 and 20 g L−1 to enhance the excretion of recombinant cyclodextrin glucanotransferase (CGTase), plasmid stability, and resistance of cell lysis.RESULTSThe immobilized cells with 5 g L−1 concentration of tryptone improved the plasmid stability with 119% improvement and 69% reduction of cell lysis without remarkably altering the excretion of CGTase compared with the tryptone concentration of 20 g L−1. The immobilized cells showed a 2‐fold increase in excretion of CGTase, a 45% reduction in cell lysis, and a 172% gain in plasmid stability in comparison with the free cells. Moreover, the doubling time increased to 58 and 5 h for the immobilized and free cells, respectively. The immobilized cells recorded 2301.62 U mL−1 of cumulative CGTase activity through seven fermentation cycles using the untreated membrane, marking their excellent reusability.CONCLUSIONThis new technique of recombinant protein expression utilizing an immobilized cell system under low tryptone concentration is an outstanding approach to improve recombinant CGTase excretion and plasmid stability with low cell lysis. © 2023 Society of Chemical Industry (SCI).

Investigating the effect of electrosprayed alginate/PVA beads size on the microbial growth kinetics: Phenol biodegradation through immobilized activated sludge

The presence of cyclic organic compounds, including phenol, in the wastewater of many industries has made phenol removal an important issue. Meanwhile, the biological methods of removing phenol have attracted the attention of researchers in recent years. Recently, the use of immobilized microbial cells is proposed as a new approach in industrial wastewater treatment. In this research, the aim is to study the effect of immobilized beads size on the phenol biodegradation efficiency and specific microbial growth rate. For this purpose, electrospray technique was used to immobilize activated sludge in hybrid matrix of alginate and polyvinyl alcohol (PVA). The fabricated alginate/PVA beads were characterized using Fourier transform infrared spectroscopy (FTIR). Evaluation of the results related to the free and immobilized cell systems in the shake flask experiments showed that at low phenol concentrations the immobilized cell system had the same performance as the free cell system, while the immobilized cell system at higher concentrations had a better performance in removing phenol so that at a concentration of 2000 mg/L, removal percentage has increased from 15% to 25–34%. On the other hand, in this survey, the kinetic behavior of activated sludge was in good agreement with Haldane's equation. Moreover, the maximum specific growth rate was measured 0.033 and 0.041 (h−1) beside 544 and 636 mg/L substrate inhibition constant, for free and immobilized cell systems, respectively. This result shows that the phenol biodegradation has been improved by using the cell immobilization technique especially with applying the smaller beads, which is due to improved mass transfer and microbial cell protection from harsh environments.

Preliminary Evaluation of the Use of Thermally-Dried Immobilized Kefir Cells in Low Alcohol Winemaking

Low alcohol wines (≤10.5% vol) are novel products that have gradually been gaining the consumers’ and market’s interest over the last decade. Taking into account the technological properties of immobilized cell systems alongside with the commercial need for dry cultures, the aim of the present study was to assess the suitability of thermally-dried immobilized kefir cells on DCM, apples pieces, and grape skins in low alcohol wine production. Storage of thermally-dried kefir culture in various temperatures (−18, 5, and 20 °C) resulted in high viability rates for immobilized cells (up to 93% for yeasts/molds immobilized on grape skins and stored at −18 °C for 6 months). Fermentation activity was maintained after storage in all cases, while high operational stability was confirmed in repeated batch fermentations for a period of 6 months. Principal Component Analysis (PCA) revealed that the fermentation temperature rather than the state of kefir culture affected significantly volatiles detected by Head Space Solid-Phase Microextraction Gas Chromatography–Mass Spectrometry analysis. Notably, all new products were of high quality and approved by the sensory panel.

Continuous Bioethanol Production by Fungi and Yeast Working in Tandem

Biofuel is considered one of the most viable alternatives to fossil fuels derived from the dwindling petroleum resources that damage the environment. Bioethanol could be manufactured from agricultural wastes, thus providing inexpensive natural resources. Several strategies have been utilized to convert lignocellulosic hydrolysate to bioethanol with various suspended microorganisms. In this study, we alternatively propose to encapsulate these microorganisms in bioreactor setups. An immobilized cell system can provide resistance to the inhibitors present in hydrolysates, enhance productivity, facilitate the separation process, and improve microorganism recycling. Herein, we developed a continuous bioethanol production process by encapsulating three types of micro-organisms: T. reesei, S. cerevisiae, and P. stipitis. These microorganisms were encapsulated in SBP (“Small Bioreactor Platform”) capsules and tested for their viability post encapsulation, biological activity, and bioethanol production. Encapsulating microorganisms in SBP capsules provided a confined protective environment for the microorganisms, facilitated their acclimation, and ensured their long-term prosperity and activity. An additional significant benefit of utilizing SBP capsules was the simultaneous availability of saccharification and fermentation over a very long time—about 2.5–3 months—with no need to renew the cells or encapsulating matrices. Two different configurations were tested. The first one consisted of columns packed with fungal cells and specific yeast cells together. In the second configuration, the fungal cells were separated from the yeast cells into two columns in series. The presented systems achieved an efficiency of 60–70%, suggesting the long-term prosperity and uninterrupted metabolic activity of the microorganisms.

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.

A GLP-1/GLP-2 receptor dual agonist to treat NASH: Targeting the gut-liver axis and microbiome.

Currently there is no Food and Drug Administration-approved drug to treat NAFLD and NASH, the rates of which are increasing worldwide. Although NAFLD/NASH are highly complex and heterogeneous conditions, most pharmacotherapy pipelines focus on a single mechanistic target. Considering the importance of the gut-liver axis in their pathogenesis, we investigated the therapeutic effect of a long-acting dual agonist of glucagon-like peptide (GLP)-1 and GLP-2 receptors in mice with NAFLD/NASH. C57BL/6J mice were fed a choline-deficient high-fat diet/high fructose and sucrose solution. After 16 weeks, mice were randomly allocated to receive vehicle, GLP1-Fc, GLP2-Fc, or GLP1/2-Fc fusion (GLP1/2-Fc) subcutaneously every 2 days for 4 weeks. Body weight was monitored, insulin/glucose tolerance tests were performed, feces were collected, and microbiome profiles were analyzed. Immobilized cell systems were used to evaluate direct peptide effect. Immunohistochemistry, quantitative PCR, immunoblot analysis, tunnel assay, and biochemical assays were performed to assess drug effects on inflammation, hepatic fibrosis, cell death, and intestinal structures. The mice had well-developed NASH phenotypes. GLP1/2-Fc reduced body weight, glucose levels, hepatic triglyceride levels, and cellular apoptosis. It improved liver fibrosis, insulin sensitivity, and intestinal tight junctions, and increased microvillus height, crypt depth, and goblet cells of intestine compared with a vehicle group. Similar effects of GLP1/2-Fc were found in in vitro cell systems. GLP1/2-Fc also changed microbiome profiles. We applied fecal microbiota transplantation (FMT) gain further insight into the mechanism of GLP1/2-Fc-mediated protection. We confirmed that FMT exerted an additive effect on GLP1-Fc group, including the body weight change, liver weight, hepatic fat accumulation, inflammation, and hepatic fibrosis. A long-acting dual agonist of GLP-1 and GLP-2 receptors is a promising therapeutic strategy to treat NAFLD/NASH.

Performance of xylose-fermenting yeasts in oat and soybean hulls hydrolysate and improvement of ethanol production using immobilized cell systems.

We investigated the fermentation of a mixture of oat and soybean hulls (1:1) subjected to acid (AH) or enzymatic (EH) hydrolyses, with both showing high osmotic pressures (> 1200Osmkg-1) for the production of ethanol. Yeasts of genera Spathaspora, Scheffersomyces, Sugiymaella, and Candida, most of them biodiverse Brazilian isolates and previously untested in bioprocesses, were cultivated in these hydrolysates. Spathaspora passalidarum UFMG-CM-469 showed the best ethanol production kinetics in suspended cells cultures in acid hydrolysate, under microaerobic and anaerobic conditions. This strain was immobilized in LentiKats® (polyvinyl alcohol) and cultured in AH and EH. Supplementation of hydrolysates with crude yeast extract and peptone was also performed. The highest ethanol production was obtained using hydrolysates supplemented with crude yeast extract (AH-CYE and EH-CYE) showing yields of 0.40 and 0.44gg-1, and productivities of 0.39 and 0.29g(Lh)-1, respectively. The reuse of the immobilized cells was tested in sequential fermentations of AH-CYE, EH-CYE, and a mixture of acid and enzymatic hydrolysates (AEH-CYE) operated under batch fluidized bed, with ethanol yields ranging from 0.31 to 0.40gg-1 and productivities from 0.14 to 0.23g(Lh)-1. These results warrant further research using Spathaspora yeasts for second-generation ethanol production.

Bioethanol Production from Oil Palm Empty Fruit Bunches Using Saccharomyces cerevisiae Immobilized on Sodium Alginate Beads

Bioethanol is an environmentally benign renewable energy commonly obtained from glucose fermentation using Saccharomyces cerevisiae. The purposes of this study are to investigate the effects of time, temperature, pH, immobilized yeast cell loading, beads reuse during ethanol production through batch fermentation of glucose derived from oil palm empty fruit bunches by S. cerevisiae immobilized on Na-alginate beads and to compare the performance of fermentation using immobilized yeast cells and that of using a free cell system. The results revealed that time, temperature, pH, yeast mass and beads reuse significantly affected the ethanol and final glucose concentrations. As expected, a maximum ethanol concentration was obtained from fermentation using immobilized yeast cells at 30 °C, pH 5, and immobilized yeast cell loading of 0.75 g for 48 hours. However, fermentation with a free cell system at the same conditions resulted in lower ethanol yield. The highest ethanol concentration of 88.125 g/L with a productivity of 1.84 g/L·h was achieved from the second cycle fermentation using of immobilized cells beads. The results suggest that an immobilized cell system exhibits great potential applications for improved ethanol production due to its ability to sustain the stability of cell activity, reduce contamination tendency, and protect yeast cells from any possible inhibitions.

A Composite Membrane System with Gold Nanoparticles, Hydroxyapatite, and Fullerenol for Dual Interaction for Biomedical Purposes.

Background: Wound dressing plays a vital role in post-operative aftercare. There is the necessity to develop dressings for application on the border of soft and hard tissue. This study aimed to develop multifunctional polyelectrolyte layers enhanced by hydroxyapatite nanoparticles, gold nanoparticles (AuNPs), and/or fullerenol nanocomposites to achieve a wound dressing that could be applied on the bone-skin interface. Methods: Constructed shells were examined using TEM, STEM, and EDX techniques. The human osteoblasts or fibroblasts were immobilized within the shells. The systems morphology was assessed using SEM. The functioning of cells was determined by flow cytomery. Moreover, the internalization of AuNPs was assessed. Results: Involvement of fullerenol and/or hydroxyapatite nanoparticles influenced the immobilized cell systems morphology. Membranes with fullerenol and hydroxyapatite nanoparticles were observed to block the internalization of AuNPs by immobilized hFOB cells. Conclusions: The designed bilayer membranes incorporating fullerenol, and bacteriostatic elements, prevented the internalization of AuNPs by hFOB cells and ensured the proper counts and morphology of eukaryotic cells. The developed material can be recommended for dressings at the bone-skin interface.

Fermentation Strategies to Improve Soil Bio-Inoculant Production and Quality.

The application of plant beneficial microorganisms has been widely accepted as an efficient alternative to chemical fertilizers and pesticides. Isolation and selection of efficient microorganisms, their characterization and testing in soil-plant systems are well studied. However, the production stage and formulation of the final products are not in the focus of the research, which affects the achievement of stable and consistent results in the field. Recent analysis of the field of plant beneficial microorganisms suggests a more integrated view on soil inoculants with a special emphasis on the inoculant production process, including fermentation, formulation, processes, and additives. This mini-review describes the different groups of fermentation processes and their characteristics, bearing in mind different factors, both nutritional and operational, which affect the biomass/spores yield and microbial metabolite activity. The characteristics of the final products of fermentation process optimization strategies determine further steps of development of the microbial inoculants. Submerged liquid and solid-state fermentation processes, fed-batch operations, immobilized cell systems, and production of arbuscular mycorrhiza are presented and their advantages and disadvantages are discussed. Recommendations for further development of the fermentation strategies for biofertilizer production are also considered.

Enhanced biodegradation of light crude oil by immobilized Bacillus licheniformis in fabricated alginate beads through electrospray technique.

Petroleum contamination of marine environments due to exploitation and accidental spills causes serious harm to ecosystems. Bioremediation with immobilized microorganisms is an environmentally friendly and cost-effective emerging technology for treating oil-polluted environments. In this study, Bacillus licheniformis was entrapped in Ca alginate beads using the electrospray technique for light crude oil biodegradation. Three important process variables, including inoculum size (5-15% v/v), initial oil concentration (1500-3500ppm), and NaCl concentration (0-30g/L), were optimized to obtain the best response of crude oil removal using response surface methodology (RSM) and Box-Behnken design (BBD). The highest crude oil removal of 79.58% was obtained for 1500ppm of crude oil after 14days using immobilized cells, and it was lower for freely suspended cells (64.77%). Our result showed similar trends in the effect of variables on the oil biodegradation rate in both free cell (FC) and immobilized cell (IC) systems. However, according to the analysis of variance (ANOVA) results, the extent of the variables' effectiveness was different in FC and IC systems. In the immobilized cell system, all variables had a greater effect on the rate of light crude oil degradation. Moreover, to evaluate the effectiveness of free and immobilized B. licheniformis in bioremediation of an actual polluted site, the crude oil spill in natural seawater was investigated. The results suggested the stability of beads in the seawater, as well as high degradation of petroleum hydrocarbons by free and immobilized cells in the presence of indigenous microorganisms.

ANALYSIS OF THE EFFICIENCY OF WASTEWATER REMEDIATION TECHNOLOGIES USING MICROALGAE

The object of research: the technology of wastewater remediation. Investigated problem: improving the efficiency of biogenic and toxic elements removal from different types of wastewater and reducing the amount of waste in the removal process. The main scientific results: Possible strains of microalgae, which have ability to absorb biogenic and toxic elements during their metabolism, are identified. It is shown that the use of microalgae is a promising method of wastewater remediation due to their wide availability, the ability to reduce pollution to the established maximum allowable discharge into reservoirs and the ability to accumulate high biomass, which can serve as raw material for industrial products. In particular, Oscillatoria spp. effectively removes chromium, Chlorella vulgaris effectively removes cadmium, copper and zinc, Chlamydomonas spp. effectively removes lead, Euglena gracilis effectively removes nitrogen and phosphorus compounds. It is also shown that the most effective way to solve the problem of restoring the biomass of algae obtained in wastewater is to use immobilized cell systems. The use of immobilized systems can also increase the resistance of cells and the rate of their removal of various pollutants and xenobiotics from wastewater. The area of practical use of the research results: Municipal enterprises for domestic and surface wastewater treatment. Enterprises for the treatment of industrial effluents. Enterprises for biomass processing, production of motor fuels, biogas, organic fertilizers. Innovative technological product: The technology of remediation of domestic, surface and industrial wastewater, which allows to effectively purify these waters from toxic and biogenic elements and reduce pollution of surface water bodies. The technology assumes the absence of waste, as the resulting biomass of microalgae is considered as a raw material for the production of various products. Scope of the innovative technological product: Technological schemes of domestic, rain and industrial wastewater remediation, protection water bodies from pollution, improvement of surface water quality.

Investigating the biodegradation of sulfadiazine in soil using Enterobacter cloacae T2 immobilized on bagasse

The application of the antibiotic sulfadiazine (SD) in veterinary medicine has created serious environmental issues due to its high mobility and non-degradability. A novel immobilized cell system has been developed and showed significant SD biodegradation potential in soil.

A novel immobilized cell system involving Taiwanese kefir microorganisms and sugar cane pieces for fermented milk production

The objective of this study was to develop a novel immobilized system using kefir lactic acid bacteria and sugar cane pieces for the production of fermented milk. Lactobacillus kefiranofaciens HL1, Lactobacillus kefiri HL2, Leuconostoc mesenteroides HL3, and Lactococcus lactis HL4 were isolated from Taiwanese kefir grains and immobilized on pieces of sugar cane using adsorption. Scanning electron micrographs of the cell-immobilized sugar cane pieces (CISCP) showed that the microorganisms were embedded within the porous structures of the sugar cane pieces. During 28 cycles of repeated batch fermentation, viable cells on both sugar cane pieces and fermented products were maintained at 10 log cfu/g (cfu/mL). Random amplified polymorphic DNA PCR analysis revealed that Leu. mesenteroides HL3 (29-43%) and Lc. lactis HL4 (31-49%) were predominant on the CISCP, and the fermented samples had 79% Lc. lactis HL4. When tracking fermentation parameters, the data on the microbial, chemical, and physical properties of the fermented milk suggested that the CISCP had stable fermentative ability over the course of successive fermentations. We found an enhancement of the acid-producing ability of CISCP as the number of fermentations increased, with a significant growth in titratable acidity from 0.65 to 0.81% by the end.

Effect of Liquid Media Height on the Pressure Drop during Production of Antibiotics in Bioreactor

Three phase gas-liquid-solid systems are widely used by the pharmaceutical industries for the production of antibiotics such as patulin, penicillin, bacitracin etc. for which immobilized cell system or biofilms are used. During the process immobilized cells are fluidized in the liquid media using air. The present paper investigates regarding the dependency of the pressure drop on the height of liquid media present in the fluidizer.

Fermentative Hydrogen Production and Bacterial Community Analysis of Immobilized Sewage Sludge

A novel anaerobic batch fermentation seeded with immobilized sludge was developed for enhanced fermentative hydrogen production using pretreated sweet sorghum substrate as carbon source. Municipal sewage sludge was immobilized to produce hydrogen gas under anaerobic conditions. Cell immobilization was essentially achieved by gel entrapment approach. Hydrogen production was more efficient with the immobilized-cell system than with the free sludge. When the heat treated and acclimatized sludge's were immobilized, the cumulative hydrogen production enhanced. The batch fermentation was operated at a hydraulic retention time (HRT) of 24 h and an influent substrate concentration of 10–40 g/L. With highest concentration of substrate, the acclimatized sludge produced 15.98 mL of H2/g of substrate. In all the treatments, maximum hydrogen yield was obtained at the substrate concentration of 40 g/L, inoculum volume of 10 g/L, at room temperature and HRT of 24 h. The immobilized beads retained 60% of their activity up to three cycles. The best fermentative hydrogen production performance was eventually dominated by presumably enhanced hydrogen-producing bacterial species identified as Escherichia coli.