Bacterial Immobilization Research Articles

Synergic Effect of Adsorption and Biodegradation by Microsphere Immobilizing Bacillus velezensis for Enhanced Removal Organics in Slaughter Wastewater

Bacterial cell immobilization offers considerable advantages over traditional biotreatment methods using free bacteria. Bacillus velezensis was underwented isolation and genetic identification as COD-degrading bacteria in slaughter wastewaterand immobilized on the surface of polyvinyl alcohol (PVA) microsphere with the adhesion to bio-carrier through direct physical adsorption. The removal CODMn rates of microsphere (PVA) immobilized cells were 16.99%, increased 9.38% from a 50% concentration of slaughter wastewater within 24 h at 37 °C, pH 7.0, and 120 rpm, which was about 2.2 times that of the free bacteria. A significant difference was found in two groups (p < 0.01 p value less than 0.01 means statistical significance), and the COD degradation rate of the microsphere immobilized Bacillus velezensis strain was higher than the control group (PVA: control vs 20.08: 10.81), with the processing time reaching 36 h (p < 0.05). Additionally, similar results were obtained from a 20% concentration of slaughter wastewater within 24 h and 36 h. Moreover, the starch and protein digestibility of the immobilized Bacillus velezensis strain was higher than that of the free bacteria (20.1%: 42.2% vs. 17.5%: 37.2%). These findings revealed that the PVA-bacteria system was a simple, green, and inexpensive process, as well as a promising method. The research goal is aimed to synergize the effects of adsorption and biodegradation, as it can enhance organic removal by immobilized Bacillus velezensis in slaughter wastewater. Moreover, it may be possible that more potential materials can be used as biological carriers for the immobilization of bacterial cells later, which is beneficial for the recycling of resources.

Bacterial Immobilization and Toxicity Induced by a Bean Plant Immune System.

Pseudomonas savastanoi pv. phaseolicola causes halo blight disease in the common bean Phaseolus vulgaris. The bacterium invades the leaf apoplast and uses a type III secretion system to inject effector proteins into a bean cell to interfere with the bean immune system. Beans counter with resistance proteins that can detect effectors and coordinate effector-triggered immunity responses transduced by salicylic acid, the primary defense hormone. Effector-triggered immunity halts bacterial spread, but its direct effect on the bacterium is not known. In this study, mass spectrometry of bacterial infections from immune and susceptible beans revealed that immune beans inhibited the accumulation of bacterial proteins required for virulence, secretion, motility, chemotaxis, quorum sensing, and alginate production. Sets of genes encoding these proteins appeared to function in operons, which implies that immunity altered the coregulated genes in the bacterium. Immunity also reduced amounts of bacterial methylglyoxal detoxification enzymes and their transcripts. Treatment of bacteria with salicylic acid, the plant hormone produced during immunity, reduced bacterial growth, decreased gene expression for methylglyoxal detoxification enzymes, and increased bacterial methylglyoxal concentrations in vitro. Increased methylglyoxal concentrations reduced bacterial reproduction. These findings support the hypothesis that plant immunity involves the chemical induction of adverse changes to the bacterial proteome to reduce pathogenicity and to cause bacterial self-toxicity.

Capability of Immobilized Clostridium beijerinckii TISTR 1461 on Lotus Stalk Pieces to Produce Butanol from Sugarcane Molasses

Immobilized Clostridium beijerinckii TISTR 1461 was used to enhance the butanol production efficiency from sugarcane molasses. Lotus stalk (LS) pieces were used as carriers for cell immobilization. Sugarcane molasses containing 50 g/L of sugar supplemented with 1 g/L of yeast extract was found to be an appropriate medium for bacterial cell immobilization on the LS pieces. Carrier size (4, 12 and 20 mm in length) and carrier loading (1:15, 1:30 and 1:45, w/v) were optimized for high levels of butanol production using response surface methodology (RSM). The batch fermentation was carried out under anaerobic conditions in 1 L screw-capped bottles at 37 °C and an agitation rate of 150 rpm. It was found that the optimum conditions for the butanol production were the carrier size of 4 mm and carrier loading of 1:31 (w/v). Under these conditions, the butanol concentration (PB) was 12.89 g/L, corresponding to the butanol productivity (QB) of 0.36 g/L∙h and butanol yield (YB/S) of 0.36 g/g. These values were higher than those using free cells (PB, 10.20 g/L, QB, 0.28 g/L∙h and YB/S, 0.32 g/g). In addition, it was found that a 24 h incubation time for cell immobilization was appropriate for the immobilization process, which was confirmed by the results of the scanning electron microscope (SEM) and atomic force microscopy (AFM) images and specific surface area measurement. When the fermentation using the immobilized cells was carried out in a stirred-tank reactor (STR), column reactor (CR) and CR coupled with STR, the results showed that all reactors could be used to produce butanol production from the immobilized cells on LS pieces. However, the PB using CR and CR coupled with STR were only 75% and 45% of those using the screw-capped bottle and STR.

Immobilization of Acidithiobacillus ferrooxidans in bacterial cellulose for a more sustainable bioleaching process

This study used bacterial cellulose (BC) as novel support material for Acidithiobacillus ferrooxidans immobilization, with the objective of improving the performance of bioleaching and increasing its sustainability. The BC was synthesized in the laboratory, which allowed selecting the desired size of this highly porous and mechanically resistant material. After bacterial immobilization, the biologically active material (BAM) was used to assess the effect that several operating parameters had on the process (shaking mode and speed, the nutrient medium volume-to-exposed surface area ratio –NMV:ESA-, and Fe2+ concentration). The influence of dissolved copper and BAM storage was also determined. The results showed that the NMV:ESA ratio conditioned Fe2+ bio-oxidation time: after 33 h, 60% and 90% of the initial Fe2+ in the samples was converted, with a 1:0.1 and 1:0.6 ratio, respectively. In addition, Fe3+ productivity increased 16% when raising the initial Fe2+ content from 6 to 9 g L−1. A considerable increase in productivity (from 190 to 223 mg L−1 h−1) was also recorded when the shaking speed was increased from 130 to 170 rpm. BAM successfully adapted to the presence of dissolved copper and oxidized Fe2+ in the presence of up to 30 g Cu2+ L−1. Finally, the integrity of the material was not affected by the demanding operating conditions, and bacterial activity was successfully recovered after storage at 4 °C and 22 °C. In sum, biocellulose has proven to be a suitable candidate for A. ferrooxidans immobilization, which could contribute to improving the efficiency of bioleaching.

Performance and microbial community of a novel PVA/iron-carbon (Fe–C) immobilized bioreactor for nitrate removal from groundwater

Abstract An efficient immobilized denitrification bioreactor functioning under anaerobic conditions was developed by combining bacterial immobilization technology with iron-carbon (Fe–C) particles. The effects of key factors on nitrate (NO3 −–N) removal efficiency were invested, such as the carbon-nitrogen ratio (C/N), pH and hydraulic retention time (HRT). Experimental results show that 100.00% NO3 −–N removal efficiency and a low level of nitrite (NO2 −–N) accumulation less than 0.05 mg L−1 were obtained under the condition of a C/N ratio of 3, pH 7.0 and HRT of 6 h. Meteorological chromatographic analysis showed that the final product of denitrification was mainly nitrogen (N2). The main component of precipitation formed in the bioreactor was characterized as Fe3O4 by X-ray diffraction. High-throughput sequencing analysis indicated that the dominant bacterial class in the Fe–C bioreactor was Gammaproteobacteria, while the dominant genera were Zoogloea and Azospira, the relative abundances of which were as high as 23.25 and 15.43%, respectively.

Evaluation of various waste substrates for biofilm formation and subsequent use in aerobic packed-bed reactor for secondary treatment of domestic wastewater.

Immobilization of bacterial cells on suitable substrates is of utmost importance in the secondary treatment of wastewater using fixed-film reactors. Therefore, screening of efficient and cheaper materials for bacterial surface immobilization was carried out. Eleven waste materials were used as substrates, packed in a column, and bacterial surface immobilization was carried out using cow dung slurry/MLSS mixture. All the chosen substrates were screened for bacterial immobilization/biofilm formation by standard bacterial enumeration technique. The substrate with the highest biofilm-forming ability was used for secondary treatment of raw domestic wastewater. The results showed that high-density polyethylene and aluminium foil sheets have poor immobilizing characteristics with 2.2 × 108 and 2.4 × 108CFU/cm2 respectively, whereas jute fibres were observed to be the most efficient among the substrates with 5.1 × 1023CFU/cm2. The column packed with jute fibres was used for wastewater treatment. Various physico-chemical parameters were analyzed before and after treatment and there was a significant reduction in major parameters after treatment. The bacteria-immobilized jute fibres showed maximum immobilization potential and were highly efficient in wastewater treatment, and therefore these findings offer immense promise in the synthesis of composite polymers for bacterial immobilization and subsequent secondary treatment.

Fe(III)-complex mediated bacterial cell surface immobilization of eGFP and enzymes.

We report a facile and reversible method to immobilize a broad range of His6-tagged proteins on the E. coli cell surface through Fe(iii)-metal complexes. A His6-tagged eGFP and four His6-tagged enzymes were successfully immobilized on the cell surface. Additionally, a hydrogel sheath around E. coli cells was generated by immobilized His6-tagged HRP.

Calculation of fungal and bacterial inorganic nitrogen immobilization rates in soil

Microbial inorganic nitrogen (N) immobilization is an important mechanism in the retention of N in soils. However, as a result of the high diversity and complexity of soil microorganisms, there is still no effective approach to measuring the respective immobilization rates of inorganic N by fungi and bacteria, which are the two dominant microbial communities in soils. We propose a mathematical framework, combining the experimentally measurable gross inorganic N immobilization rate and proxies for fungal and bacterial inorganic N immobilization rates, to quantify the respective immobilization rates of inorganic N by fungal and bacterial communities in soil. Our approach will help to unravel the mechanisms of microbial N retention in soils.

The Fate of Lead (Pb) in Multitrophic Interactions Among Bacteria, Fungi, and Bacterivorous Soil Nematodes

AbstractContamination of potentially toxic metals poses threats to living organisms due to prolonged existence in an ecosystem. The effects of toxic metals on soil microbes have broadly been reported but the study on interactions among soil micro‐ and macro‐organisms under metal stress needs to be elaborated. In current study, the immobilization of lead (Pb) is investigated by using five resistant microbial strains; (2) Bacillus cereus, (1) Bacillus subtilis, (1) Brevundimonas naejangsanensis, and (1) fungal strain Fusarium equiseti isolated from contaminated soil of Hattar, Pakistan. Bacterial and fungal strains and their consortia are tested in the presence/absence of nematodes for Pb immobilization in a medium containing 250 mg L−1 Pb. Single bacterial strains immobilize Pb up to 72%, while in the presence of nematodes, bacterial immobilization potential decreases. An increased Pb immobilization up to 185 mg L−1 is found when bacterial and fungal consortia are inoculated with nematodes. The maximum 80% Pb immobilization is found in bacterial–bacterial combinations with nematodes. This study, reveals that inoculation of bacterial–bacterial consortia in the presence of nematodes enhanced bacterial growth via feeding resulting in higher Pb immobilization. These resistant microbial strains can thus be used to treat contaminated sites for better ecosystem functioning.

Smartphone-Based Whole-Cell Biosensor Platform Utilizing an Immobilization Approach on a Filter Membrane Disk for the Monitoring of Water Toxicants.

Bioluminescent bacteria whole-cell biosensors (WCBs) have been widely used in a range of sensing applications in environmental monitoring and medical diagnostics. However, most of them use planktonic bacteria cells that require complicated signal measurement processes and therefore limit the portability of the biosensor device. In this study, a simple and low-cost immobilization method was examined. The bioluminescent bioreporter bacteria was absorbed on a filter membrane disk. Further optimization of the immobilization process was conducted by comparing different surface materials (polyester and parafilm) or by adding glucose and ampicillin. The filter membrane disks with immobilized bacteria cells were stored at −20 °C for three weeks without a compromise in the stability of its biosensing functionality for water toxicants monitoring. Also, the bacterial immobilized disks were integrated with smartphones-based signal detection. Then, they were exposed to water samples with ethanol, chloroform, and H2O2, as common toxicants. The sensitivity of the smartphone-based WCB for the detection of ethanol, chloroform, and H2O2 was 1% (v/v), 0.02% (v/v), and 0.0006% (v/v), respectively. To conclude, this bacterial immobilization approach demonstrated higher sensitivity, portability, and improved storability than the planktonic counterpart. The developed smartphone-based WCB establishes a model for future applications in the detection of environmental water toxicants.

Immobilization of vaginal Lactobacillus in polymeric nanofibers for its incorporation in vaginal probiotic products

Probiotic products require high number of viable and active microorganisms during storage. In this work, the survival of human vaginal Lactobacillus gasseri CRL1320 and Lactobacillus rhamnosus CRL1332 after nanofiber-immobilization by electrospinning with polyvinyl-alcohol, and during storage was evaluated. The optimization of bacterial immobilization and storage conditions using bioprotectors (skim milk-lactose and glycerol) and oxygen-excluding packaging was carried out, compared with lyophilization. After electrospinning, a higher survival rate of L. rhamnosus (93%) compared to L. gasseri (84%) was obtained in nanofibers, with high viable cells (>107 colony-forming unit/g) of the two probiotics in nanofibers stored at -20°C up to 14 days. The storage in oxygen-excluding packaging was an excellent strategy to extend the shelf-life of L. rhamnosus (up to 1.7 × 108 CFU/g) in nanofibers stored at 4°C during 360 days, with no addition of bioprotectives, resulting similar to freeze-dried-cells. L. rhamnosus was successfully incorporated into polymeric hydrophilic nanofibers with a mean diameter of 95 nm. The composite materials were characterized in terms of morphology, and their physicochemical and thermal properties assessed. Nanofiber-immobilized L. rhamnosus cells maintained the inhibition to urogenital pathogens. Thus, polymeric nanofiber-immobilized L. rhamnosus CRL1332 can be included in vaginal probiotic products to prevent or treat urogenital infections.

Revisiting of the physico-chemical properties of polyelectrolyte multilayers for a fine tuning of the immobilization of bacteria or nanoparticles

Increasingly used in industrial coatings, polyelectrolytes multilayers (PEMs) are self-assembled systems made of the alternate deposition of oppositely charged polymers on substrates, usually built by the traditional layer-by-layer method. Their properties strongly depend on environmental physico-chemical parameters. Due to the variety of conditions used in the literature on the one hand and the diversity of polyelectrolytes systems on the other hand, it remains difficult to bring out general principles, leading now to a lack of a real understanding of the PEM buildup, from the macro- to the nanoscale. Here, combining acoustic and electrochemical methods with atomic force microscopy, in a systematic approach, we uncover the critical role of the deposition protocol in the growth regime of PEMs made of cationic poly (allylamine hydrochloride) and anionic poly(4-styrene sulfonate, sodium). Traditional dipping leads to thick, heterogeneous and relatively isolating PEMs whereas a spin-coating assisted method leads to thinner, homogeneous and more permeable PEMs. We also highlight that the pH and the ionic strength influence not only the electrostatic interactions and polyelectrolyte conformation in solution but also their organization after their adsorption on the substrate. Finally, our easily and rapidly adaptable protocol paves the way for promising potential bio-applications, since PEMs are applied to the bacterial immobilization on substrates or as a coating for nanostructured biosensor transducer.

Cantilever Sensors for Rapid Optical Antimicrobial Sensitivity Testing.

Growing antimicrobial resistance (AMR) is a serious global threat to human health. Current methods to detect resistance include phenotypic antibiotic sensitivity testing (AST), which measures bacterial growth and is therefore hampered by a slow time to obtain results (∼12–24 h). Therefore, new rapid phenotypic methods for AST are urgently needed. Nanomechanical cantilever sensors have recently shown promise for rapid AST but challenges of bacterial immobilization can lead to variable results. Herein, a novel cantilever-based method is described for detecting phenotypic antibiotic resistance within ∼45 min, capable of detecting single bacteria. This method does not require complex, variable bacterial immobilization and instead uses a laser and detector system to detect single bacterial cells in media as they pass through the laser focus. This provides a simple readout of bacterial antibiotic resistance by detecting growth (resistant) or death (sensitive), much faster than the current methods. The potential of this technique is demonstrated by determining the resistance in both laboratory and clinical strains of Escherichia coli (E. coli), a key species responsible for clinically burdensome urinary tract infections. This work provides the basis for a simple and fast diagnostic tool to detect antibiotic resistance in bacteria, reducing the health and economic burdens of AMR.

Biochar-immobilized Sphingomonas sp. and Acinetobacter sp. isolates to enhance nutrient removal: potential application in crab aquaculture

The frequency of water exchange and reducing the risk of eutrophication to surrounding water bodies have always been water-quality control issues in recirculating aquaculture systems. In this study, maize straw biochar prepared through pyrolysis showed great potential for both bacterial immobilization and pollutant adsorption. Heterotrophic bacterial strains of Sphingomonas sp. PDD-57b-25 and Acinetobacter towneri were isolated in situ from wastewater for pollutant remediation through a 16S rDNA-based method, which has been rarely reported to date. The selected strains had higher ammonia nitrogen (NH4+-N, 63%), nitrite nitrogen (NO2--N, 38%), nitrate nitrogen (NO3--N, 25%) and total phosphorus (TP, 35%) assimilation capacities than those of other widely applied bacteria under similar medium conditions. In addition, more NH4+-N (+16%), NO2--N (+14%), NO3--N (+17%) and TP (+19%) was removed by biochar-immobilized isolated strains than dissociated strains, suggesting their use may provide a means of improving water-quality control in recirculating aquaculture. With specific additions (4 g l-1) of biochar-immobilized Sphingomonas sp. PDD-57b-25 and A. towneri, the dissolved inorganic nitrogen (approximately 0.45 mg l-1) and TP (approximately 0.09 mg l-1) levels were maintained below the clean water threshold for recirculating aquaculture of crab Eriocheir sinensis. Furthermore, the added strains exhibited high bio-safety and were capable of improving the yield and quality of crabs. Results indicate the potential applicability of biochar-immobilized Sphingomonas sp. PDD-57b-25 and A. towneri in agricultural sewage treatments. Further, the experimental methodology developed here may be used for the exploration of new strains for practical aquaculture.

Multivalent Bacteria Binding by Flexible Polycationic Microsheets Matching Their Surface Charge Density

AbstractAiming at the overall negative surface charge of bacteria, a new strategy of antibacterial agents based on large polymer‐modified graphene oxide (GO) sheets is assessed. The presented flexible, polycationic sheets match the size and charge density of the Escherichia coli surface charge density (2 × 1014 cm−2). These matching parameters create an unspecific but very strong bacteria adsorber by multivalent, electrostatic attraction. Their interaction with bacteria is visualized via atomic force and confocal microscopy and shows that they effectively bind and wrap around E. coli cells, and thereby immobilize them. The incubation of Gram‐negative and ‐positive bacteria (E. coli and methicillin‐resistant Staphylococcus aureus, MRSA) with these polycationic sheets leads to the inhibition of proliferation and a reduction of the colony forming bacteria over time. This new type of antibacterial agent acts in a different mode of action than classical biocides and could potentially be employed in medicinal, technical, or agriculture applications. The presented microsheets and their unspecific binding of cell interfaces could further be employed as adsorber material for bacterial filtration or immobilization for imaging, analysis, or sensor technologies.

Bacterial compatibility and immobilization with biochar improved tebuconazole degradation, soil microbiome composition and functioning

Tebuconazole is a widely used fungicide that may impair soil health. Presently, limited information is available on the bioremediation of tebuconazole-contaminated soil using biochar as a carrier for bacteria. In this study, we firstly isolated a tebuconazole-degrading strain and identified it as Alcaligenes faecalis WZ-2. Then, we used wheat straw-derived biochar as carrier to capture strain WZ-2 to assemble microorganism-immobilized composite. Finally, we investigated the effects of strain WZ-2 and biochar-immobilized WZ-2 on tebuconazole biodegradation, microbial enzyme activities and community composition in the contaminated soil. Results showed that, as compared to control, the strain WZ-2 and biochar-immobilized WZ-2 accelerated the degradation of tebuconazole, while reducing the half-life of tebuconazole from 40.8 to 18.7 and 13.3 days in soil, respectively. However, biochar alone than control slightly retarded the degradation of tebuconazole in soil. Though tebuconazole (10 mg/kg) negatively affected the soil enzyme activities (urease, dehydrogenase, and invertase) and microbiome community structure, the biochar-immobilized WZ-2 not only accelerated the degradation of tebuconazole but also restored native soil microbial enzyme activities and microbiome community composition. Our results suggest that a compatible combination of bacteria with biochar is an attractive and efficient approach for remediation of pesticide-contaminated soil and improvement of soil biological health.

Disentangling immobilization of nitrate by fungi and bacteria in soil to plant residue amendment

Plant residue incorporation improves soil microbial nitrate immobilization, which in turn alleviates nitrate accumulation, thereby improving N retention capacity and reducing N losses. However, how and why the respective nitrate immobilization by fungi and bacteria, which are dominant microorganisms in soil, responds to residue addition remains unknown. By adopting a novel amino sugar-based stable isotope probing approach, we show that both fungal and bacterial nitrate immobilization increased after Paspalum notatum residue addition. The increased proportion of the former was higher than that of the latter, and their difference became much larger with the increased residue addition rate. Furthermore, 70% and 32% of the variations in fungal and bacterial nitrate immobilization activities were explained by their respective biomass. The relative importance of fungal and bacterial nitrate immobilization shifted in a consistent manner with the relative abundance of fungi and bacteria, and the magnitude of these shifts was related to the residue addition rate. Our work demonstrates strong links between increased residue inputs, alterations in microbial community composition, and enhanced ecosystem functioning of nitrate immobilization and retention in soil.

Immobilization of Acidithiobacillus Ferrooxidans on Two Hydrogels

Bioleaching is considered a sustainable and effective alternative to conventional micromachining and extracting processes for recovering valuable metals from electronic waste. Nevertheless, the industrial scaling-up of these applications is limited by several factors.Among these factors, the use of free cells and low microbial density have been reported to reduce process efficiency. Recent research has therefore focused on bacterial immobilization on different support materials as a solution for increasing microbial density inside the bioreactor and protecting microorganisms from toxic compounds. Furthermore, biomass immobilization facilitates biomass replacement whenever required. The increasing amount of metals in the solution is also a factor to be controlled, as it can inhibit bacterial activity.This study set out to assess the suitability of two hydrogels, polyvinyl alcohol (PVA) and biocellulose (BC) as support materials for Acidithiobacillus ferrooxidans (A. ferrooxidans) immobilisation, and to analyse the effectiveness of the active material generated for use in metal bioleaching processes. In addition, an assessment was conducted of the influence of the amount of dissolved copper (0-20 g Cu2+/L) on the time required for complete Fe2+ oxidation to Fe3+.The two hydrogels tested, PVA and BC, were viable as support materials for A. ferrooxidans immobilisation. Both active materials successfully transformed all the Fe2+ contained in the nutrient medium to Fe3+. Nevertheless, BC was specifically selected for further studies because of its higher efficiency (shorter oxidation time needed for complete iron transformation), longer integrity maintenance, and higher resistance to dissolved copper up to 20 g Cu2+/L.

Evaluation of Surface-modified Superparamagnetic Iron Oxide Nanoparticles to Optimize Bacterial Immobilization for Bio-separation with the Least Inhibitory Effect on Microorganism Activity

Background: Magnetic cell immobilization has been introduced as a novel, facile and highly efficient approach for cell separation. A stable attachment between bacterial cell wall with superparamagnetic iron oxide nanoparticles (SPIONs) would enable the microorganisms to be affected by an outer magnetic field. At high concentrations, SPIONs produce reactive oxygen species in cytoplasm, which induce apoptosis or necrosis in microorganisms. Choosing a proper surface coating could cover the defects and increase the efficiency. Methods: In this study, asparagine, APTES, lipo-amino acid and PEG surface modified SPIONs was synthesized by co-precipitation method and characterized by FTIR, TEM, VSM, XRD, DLS techniques. Then, their protective effects against four Gram-positive and Gram-negative bacterial strains including Enterococcus faecalis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa were examined through microdilution broth and compared to naked SPION. Results: The evaluation of characterization results showed that functionalization of magnetic nanoparticles could change their MS value, size and surface charges. Also, the microbial analysis revealed that lipo-amino acid coated magnetic nanoparticles has the least adverse effect on microbial strain among tested SPIONs. Conclusion: This study showed lipo-amino acid could be considered as the most protective and even promotive surface coating, which is explained by its optimizing effect on cell penetration and negligible reductive effects on magnetic properties of SPIONs. lipo-amino acid coated magnetic nanoparticles could be used in microbial biotechnology and industrial microbiology.

Silica-cellulose material application as the immobilization matrix of Pseudomonas fluorescens

Waste management, including heavy metal removal through bioremediation, requires process optimization. One of the important processes in a modern method is bacterial immobilization intended to improve the performance of bioremediation. In this preliminary study, silica material from rice husk processed via sol-gel was used, and cellulose of Nata de Coco was incorporated in situ during gelling to give balanced surface properties of a porous matrix. The modified could hold bacteria such as Pseudomonas fluorescens to be immobilized for further use. Variation of contact time was done, while temperature and stirring speed were kept constant. Assessment of Pseudomonas fluorescens bioremediation activity was carried out in cadmium standard solution. The result showed that the optimum contact time of Pseudomonas fluorescens and silica matrices was achieved at 30 min contact time as 99.19% was embedded in the matrices. This system decreased 80% of heavy metal in solution. This result indicates the compatibility of silica-cellulose matrix in Pseudomonas fluorescens immobilization, as predicted for other types of bacteria as well.