Extensive use of carbofuran insecticide harms the environment and human health. Carbofuran is an endocrine disruptor and has the highest acute toxicity to humans than all groups of carbamate pesticides used. Carbofuran is highly mobile in soil and soluble in water with a lengthy half-life (50 days). Therefore, it has the potential to contaminate groundwater and nearby water bodies after rainfall events. A bacterial strain BRC05 was isolated from agricultural soil characterized and presumptively identified as Enterobacter sp. The strain was immobilized using gellan gum as an entrapment material. The effect of different heavy metals and the ability of the immobilized cells to degrade carbofuran were compared with their free cell counterparts. The results showed a significant increase in the degradation of carbofuran by immobilized cells compared with freely suspended cells. Carbofuran was completely degraded within 9 h by immobilized cells at 50 mg/L, while it took 12 h for free cells to degrade carbofuran at the same concentration. Besides, the immobilized cells completely degraded carbofuran within 38 h at 100 mg/L. On the other hand, free cells degraded the compound in 68 h. The viability of the freely suspended cell and degradation efficiency was inhibited at a concentration greater than 100 mg/L. Whereas, the immobilized cells almost completely degraded carbofuran at 100 mg/L. At 250 mg/L concentration, the rate of degradation decreased significantly in free cells. The immobilized cells could also be reused for about nine cycles without losing their degradation activity. Hence, the gellan gum-immobilized cells of Enterobacter sp. could be potentially used in the bioremediation of carbofuran in contaminated soil.
Bioethanol production using yeast has become a popular topic due to worrying depleting worldwide fuel reserve. The aim of the study was to investigate the capability of Malaysia yeast strains isolated from starter culture used in traditional fermented food and alcoholic beverages in producing Bioethanol using alginate beads entrapment method. The starter yeast consists of groups of microbes, thus the yeasts were grown in Sabouraud agar to obtain single colony called ST1 (tuak) and ST3 (tapai). The growth in Yeast Potatoes Dextrose (YPD) resulted in specific growth of ST1 at micro = 0.396 h-1 and ST3 at micro = 0.38 h-1, with maximum ethanol production of 7.36 g L-1 observed using ST1 strain. The two strains were then immobilized using calcium alginate entrapment method producing average alginate beads size of 0.51 cm and were grown in different substrates; YPD medium and Local Brown Sugar (LBS) for 8 h in flask. The maximum ethanol concentration measured after 7 h were at 6.63 and 6.59 g L-1 in YPD media and 1.54 and 1.39 g L-1in LBS media for ST1 and ST3, respectively. The use of LBS as carbon source showed higher yield of product (Yp/s), 0.59 g g-1 compared to YPD, 0.25 g g-1 in ST1 and (Yp/s), 0.54 g g-1 compared to YPD, 0.24 g g-1 in ST3 . This study indicated the possibility of using local strains (STI and ST3) to produce bioethanol via immobilization technique with local materials as substrate.
This study examined the capacity of immobilized bacteria to degrade petroleum hydrocarbons. A mixture of hydrocarbon-degrading bacterial strains was immobilized in alginate and incubated in crude oil-contaminated artificial seawater (ASW). Analysis of hydrocarbon residues following a 30-day incubation period demonstrated that the biodegradation capacity of the microorganisms was not compromised by the immobilization. Removal of n-alkanes was similar in immobilized cells and control cells. To test reusability, the immobilized bacteria were incubated for sequential increments of 30 days. No decline in biodegradation capacity of the immobilized consortium of bacterial cells was noted over its repeated use. We conclude that immobilized hydrocarbon-degrading bacteria represent a promising application in the bioremediation of hydrocarbon-contaminated areas.
The ability of white-rot fungus, Pycnoporus sanguineus to adsorb copper (II) ions from aqueous solution is investigated in a batch system. The live fungus cells were immobilized into Ca-alginate gel to study the influence of pH, initial metal ions concentration, biomass loading and temperature on the biosorption capacity. The optimum uptake of Cu (II) ions was observed at pH 5 with a value of 2.76mg/g. Biosorption equilibrium data were best described by Langmuir isotherm model followed by Redlich-Peterson and Freundlich models, respectively. The biosorption kinetics followed the pseudo-second order and intraparticle diffusion equations. The thermodynamic parameters enthalpy change (10.16kJ/mol) and entropy change (33.78J/molK) were determined from the biosorption equilibrium data. The FTIR analysis showed that OH, NH, CH, CO, COOH and CN groups were involved in the biosorption of Cu (II) ions onto immobilized cells of P. sanguineus. The immobilized cells of P. sanguineus were capable of removing Cu (II) ions from aqueous solution.
A central composite design (CCD) was employed to optimize the biosorption of Pb(II) ions onto immobilized cells of Pycnoporus sanguineus. The independent variables were initial Pb(II) concentration, pH and biomass loading. The combined effects of these variables were analyzed by response surface methodology (RSM) using quadratic model for predicting the optimum point. Under these conditions the model predicted a maximum of 97.7% of Pb(II) ions removal at pH 4, 200mg/L of initial Pb(II) concentration with 10g/L of biosorbent. The experimental values are in good agreement with predicted values within +0.10 to +0.81% error.
Biosorption of cadmium (II) ions from aqueous solution onto immobilized cells of Pycnoporus sanguineus (P. sanguineus) was investigated in a batch system. Equilibrium and kinetic studies were conducted by considering the effect of pH, initial cadmium (II) concentration, biomass loading and temperature. Results showed that the uptake of cadmium (II) ions increased with the increase of initial cadmium (II) concentration, pH and temperature. Langmuir, Freundlich and Redlich-Peterson isotherm models were used to analyze the equilibrium data at different temperatures. Langmuir isotherm model described the experimental data well followed by Redlich-Peterson and Freundlich isotherm models. Biosorption kinetics data were fitted using pseudo-first, pseudo-second-order and intraparticle diffusion. It was found that the kinetics data fitted well the pseudo-second-order followed by intraparticle diffusion. Thermodynamic parameters such as standard Gibbs free energy (Delta G0), standard enthalpy (Delta H0) and standard entropy (Delta S0) were evaluated. The result showed that biosorption of cadmium (II) ions onto immobilized cells of P. sanguineus was spontaneous and endothermic nature.
The removal of heavy metals like lead, copper and cadmium from wastewater streams is an important environmental issue. The capability of immobilized Pycnoporus sanguineus (P. sanguineus), a white-rot macrofungi to remove heavy metals from aqueous solution in a packed bed column was investigated. Lead (Pb (II)) biosorption by immobilized cells of P. sanguineus was investigated in a packed bed column. The experiments were carried out by considering the effect of bed height (5-13 cm), flow rate (4-12 ml min-1) and initial lead (II) concentration (50-300 mg L-1). The breakthrough profiles showed that the saturation of metal ions was achieved faster for 5 cm bed height and 12 ml min-1 influent flow rate. However, the breakthrough time decreased as the initial metal concentration increased from 50 to 300 mg L-1. The column was regenerated using 0.1M HCl solution and biosorptiondesorption studies were carried out for 2 cycles. The results showed that the breakthrough time decreased as the number of cycle was proceeded.
A comparative study on the stability and potential of alginate and pectin based beads for production of poultry probiotic cells using MRS medium in repeated batch fermentation was conducted. The bead cores, made of three types of materials, i.e., ca-alginate, ca-pectinate and ca-alginate/pectinate, were compared. The effect of single and double layer coatings using chitosan and core material, respectively, on the bead stability and cell production were also studied. The pectin based beads were found to be more stable than that of the alginate beads and their stability was further improved by coating with chitosan. The cell concentration in pectin based beads was comparable to that in the alginate beads. On the other hand, pectin based beads gave significantly lower cell concentration in the growth medium for the initial fermentation cycles when compared to the alginate beads. In conclusion, pectin was found to be potential encapsulation material for probiotic cell production owing to its stability and favourable microenvironment for cell growth.
The full-thickness skin wound is a common skin complication affecting millions of people worldwide. Delayed treatment of this condition causes the loss of skin function and integrity that could lead to the development of chronic wounds or even death. This study was aimed to develop a rapid wound treatment modality using ovine tendon collagen type I (OTC-I) bio-scaffold with or without noncultured skin cells. Genipin (GNP) and carbodiimide (EDC) were used to cross-link OTC-I scaffold to improve the mechanical strength of the bio-scaffold. The physicochemical, biomechanical, biodegradation, biocompatibility, and immunogenicity properties of OTC-I scaffolds were investigated. The efficacy of this treatment approach was evaluated in an in vivo skin wound model. The results demonstrated that GNP cross-linked OTC-I scaffold (OTC-I_GNP) had better physicochemical and mechanical properties compared with EDC cross-linked OTC-I scaffold (OTC-I_EDC) and noncross-link OTC-I scaffold (OTC-I_NC). OTC-I_GNP and OTC-I_NC demonstrated no toxic effect on cells as it promoted higher cell attachment and proliferation of both primary human epidermal keratinocytes and human dermal fibroblasts compared with OTC-I_EDC. Both OTC-I_GNP and OTC-I_NC exhibited spontaneous formation of bilayer structure in vitro. Immunogenic evaluation of OTC-I scaffolds, in vitro and in vivo, revealed no sign of immune response. Finally, implantation of OTC-I_NC and OTC-I_GNP scaffolds with noncultured skin cells demonstrated enhanced healing with superior skin maturity and microstructure features, resembling native skin in contrast to other treatment (without noncultured skin cells) and control group. The findings of this study, therefore, suggested that both OTC-I scaffolds with noncultured skin cells could be promising for the rapid treatment of full-thickness skin wound.
In attached microalgae cultivation systems, cell detachment due to fluid hydrodynamic flow is not a subject matter that is commonly looked into. However, this phenomenon is of great relevance to optimizing the operating parameters of algae cultivation and feasible reactor design. Hence, this current work miniaturizes traditional benchtop assays into a microfluidic platform to study the cell detachment of green microalgae, Chlorella vulgaris, from porous substrates during its early cultivation stage under precisely controlled conditions. As revealed by time lapse microscopy, an increase in bulk flow velocity facilitated nutrient transport but also triggered cell detachment events. At a flow rate of 1000 μL min-1 of growth medium for 120 min, the algal cell coverage was up to 5% lower than those at 5 μL min-1 and 50 μL min-1. In static seeding, the evolution of attached cell resistance toward liquid flows was dependent on hydrodynamic zones. The center zone of the microchannel was shown to be a "comfortable zone" of the attached cells to sequester nutrients effectively at lower medium flow rates but there was a profile transition where outlet zones favored cell attachment the most at higher flow rates (1.13 times higher than the center zone for 1000 μL min-1). Besides, computational fluid dynamics (CFD) simulations illustrated that the focusing band varied between cross-sections and depths, while the streamline was the least concentrated along the side walls and bottom plane of the microfluidic devices. It was intriguing to learn that cell detachment was not primarily happening along the symmetry streamline. Insight gained from this study could be further applied in the optimization of operating conditions of attached cultivation systems whilst preserving laminar flow conditions.
Cell immobilization on the magnetic nanoparticles (MNPs) and magnetic harvesting is a novel approach for microalgal cells separation. To date, the effect of these nanoparticles on microalgal cells was only studied over a short period of time. More studies are hence needed for a better understanding of the magnetic harvesting proposes or environmental concerns relating to long-term exposure to nanoparticles. In this study, the impact of various concentrations of MNPs on the microalgal cells growth and their metabolic status was investigated over 12 days. More than 60% reduction in mitochondrial activity and pigments (chlorophyll a, chlorophyll b, and carotenoids) content occurred during the first 6 days of exposure to ≥50 µg/mL nanoparticles. However, more than 50% growth inhibitory effect was seen at concentrations higher than 400 µg/mL. Exposure to MNPs gradually induced cellular adaptation and after about 6 days of exposure to stress generating concentrations (˂400 µg/mL) of IONs, microalgae could overcome the imposed damages. This work provides a better understanding regarding the environmental impact of MNPs and appropriate concentrations of these particles for future algal cells magnetic immobilization and harvesting.
This study aimed to enhance the crystallizability of bio-based succinic acid for its efficient recovery while maintaining the end product at the highest purity. Immobilization of Actinobacillus succinogenes was initially evaluated based on three different carriers: volcanic glass, clay pebbles, and silica particles. The adsorption capacity of metabolites with a low concentration (10 g/L) and a high concentration (40 g/L) was investigated. It was demonstrated that clay pebbles adsorbed the least succinic acid (
The ability of immobilized cell cultures of Aspergillus niger FETL FT3 to produce extracellular tannase was investigated. The production of enzyme was increased by entrapping the fungus in scouring mesh cubes compared to free cells. Using optimized parameters of six scouring mesh cubes and inoculum size of 1 × 10(6) spores/mL, the tannase production of 3.98 U/mL was obtained from the immobilized cells compared to free cells (2.81 U/mL). It was about 41.64% increment. The immobilized cultures exhibited significant tannase production stability of two repeated runs.
Cell immobilization is an alternative to microencapsulation for the maintenance of cells in a liquid medium. The objective of this study was to evaluate the effects of agrowastes from durian (Durio zibethinus), cempedak (Artocarpus champeden), and mangosteen (Garcinia mangostana) as immobilizers for lactobacilli grown in soymilk. Rinds from the agrowastes were separated from the skin, dried, and ground (150 microm) to form powders and used as immobilizers. Scanning electron microscopy revealed that lactobacilli cells were attached and bound to the surface of the immobilizers. Immobilized cells of Lactobacillus acidophilus FTDC 1331, L. acidophilus FTDC 2631, L. acidophilus FTDC 2333, L. acidophilus FTDC 1733, and L. bulgaricus FTCC 0411 were inoculated into soymilk, stored at room temperature (25 degrees C) and growth properties were evaluated over 168 h. Soymilk inoculated with nonimmobilized cells was used as the control. Utilization of substrates, concentrations of lactic and acetic acids, and changes in pH were evaluated in soymilk over 186 h. Immobilized lactobacilli showed significantly better growth (P < 0.05) compared to the control, accompanied by higher production of lactic and acetic acids in soymilk. Soymilk containing immobilized cells showed greater reduction of soy sugars such as stachyose, raffinose, sucrose, fructose, and glucose compared to the control (P < 0.05).
The objective of this study was to evaluate agricultural wastes as immobilizers for probiotics in liquid foods, such as soy milk. Probiotic strains were initially evaluated for acid and bile tolerance and the ability to produce alpha-galactosidase. Rinds of durian, mangosteen, and jackfruit were dried, ground, and sterilized prior to immobilization of selected strains ( Lactobacillus acidophilus FTDC 1331, L. acidophilus FTDC 2631, L. acidophilus FTDC 2333, L. acidophilus FTDC 1733, and Lactobacillus bulgaricus FTCC 0411). Immobilized cells were inoculated into soy milk, and growth properties were evaluated over 168 h at 37 degrees C. Soy milk containing free cells without agrowastes was used as the control. Immobilized probiotics showed increased growth, greater reduction of stachyose, sucrose, and glucose, higher production of lactic and acetic acids, and lower pH in soy milk compared to the control. The results illustrated that agrowastes could be used for the immobilization of probiotics with enhanced growth, utilization of substrates, and production of organic acids.
The main aim of this study was to investigate the effect of different coating materials (i.e. Na-alginate and chitosan) on the viability and release behavior of Bifidobacterium pseudocatenulatum G4 in the simulated gastric fluid (SGF) and simulated intestinal fluid (SIF). This study reports the viability of encapsulated B. pseudocatenulatum G4 coated using different alginate (2-4 g/100mL) and chitosan (0.2-0.8 g/100mL) concentrations. The results indicated that the highest concentration of alginate (4.4142 g/100mL) along with 0.5578 g/100mL chitosan resulted in the highest viability of B. pseudocatenulatum G4. The release behavior of the encapsulated probiotics in SGF (pH 1.5) in 2h followed by 4h in SIF (pH 7.4) was also assessed. The resistance rate of alginate-chitosan capsule in SGF was higher than SIF. The alginate-chitosan encapsulated cells had also more resistance than alginate capsules. The current study revealed that alginate encapsulated B. Pseudocatenulatum G4 exhibited longer survival than its free cells (control).
E. coli has been engineered to produce xylitol, but the production faces bottlenecks in terms of production yield and cell viability. In this study, recombinant E. coli (rE. coli) was immobilized on untreated and treated multiwalled carbon nanotubes (MWCNTs) for xylitol production. The immobilized rE. coli on untreated MWCNTs gave the highest xylitol production (5.47 g L-1) and a productivity of 0.22 g L-1 h-1. The doubling time for the immobilized cells increased up to 20.40 h and was higher than that of free cells (3.67 h). Cell lysis of the immobilized cells was reduced by up to 73 %, and plasmid stability improved by up to 17 % compared to those of free cells. Xylitol production using the optimum parameters (pH 7.4, 0.005 mM and 29 °C) achieved a xylitol production and productivity of 6.33 g L-1 and 0.26 g L-1 h-1, respectively. A seven-cycle repeated batch fermentation was carried out for up to 168 h, which showed maximum xylitol production of 7.36 g L-1 during the third cycle. Hence, this new adsorption immobilization system using MWCNTs is an alternative to improve the production of xylitol.
The increase in the price of commercial succinic acid has necessitated the need for its
synthesis from waste materials such as glycerol. Glycerol residue is a waste product of
Oleochemical production which is cheaply available and a very good source of carbon.
The use of immobilized cells can further reduce the overall cost of the production process.
This study primarily aims to produce succinic acid from glycerol residue through the use
of immobilized Escherichia coli in a batch fermentation process. The parameters which
affect bacterial fermentation process such as the mass substrate, temperature, inoculum
size and duration of fermentation were screened using One-Factor-At-a-Time (OFAT)
method. The result of the screening process shows that a substrate (glycerol) concentration
of 30 g, inoculum size 20% v/v, and time 4 h produced the maximum succinic acid
concentration of 117.99 g/L. The immobilized cells were found to be stable as well as
retain their fermentative ability up to the 6th cycle of recycling, thereby presenting as an
advantage over the free cell system. Therefore, conclude that using immobilized cells can
contribute immensely to the cost-effective production of succinic acid from glycerol
residue.
The aim of this research was to enhance the survivability of Lactobacillus rhamnosus NRRL 442 against heat exposure via a combination of immobilization and microencapsulation processes using sugarcane bagasse (SB) and sodium alginate (NaA), respectively. The microcapsules were synthesized using different alginate concentration of 1, 2 and 3% and NaA:SB ratio of 1:0, 1:1 and 1:1.5. This beneficial step of probiotic immobilization before microencapsulation significantly enhanced microencapsulation efficiency and cell survivability after heat exposure of 90°C for 30s. Interestingly, the microcapsule of SB-immobilized probiotic could obtain protection from heat using microencapsulation of NaA concentration as low as 1%. SEM images illustrated the incorporation of immobilized L. rhamnosus within alginate matrices and its changes after heat exposure. FTIR spectra confirmed the change in functional bonding in the presence of sugarcane bagasse, probiotic and alginate. The results demonstrated a great potential in the synthesis of heat resistant microcapsules for probiotic.
The vulnerability of probiotics at low pH and high temperature has limited their optimal use as nutraceuticals. This study addressed these issues by adopting a physicochemical driven approach of incorporating Lactobacillus plantarum LAB12 into chitosan (Ch) coated alginate-xanthan gum (Alg-XG) beads. Characterisation of Alg-XG-Ch, which elicited little effect on bead size and polydispersity, demonstrated good miscibility with improved bead surface smoothness and L. plantarum LAB12 entrapment when compared to Alg, Alg-Ch and Alg-XG. Sequential incubation of Alg-XG-Ch in simulated gastric juice and intestinal fluid yielded high survival rate of L. plantarum LAB12 (95%) at pH 1.8 which in turn facilitated sufficient release of probiotics (>7 log CFU/g) at pH 6.8 in both time- and pH-dependent manner. Whilst minimising viability loss at 75 and 90 °C, Alg-XG-Ch improved storage durability of L. plantarum LAB12 at 4 °C. The present results implied the possible use of L. plantarum LAB12 incorporated in Alg-XG-Ch as new functional food ingredient with health claims.