Pseudomonas Luteola Research Articles

Mucoid Pseudomonads in Patients With Noncystic Fibrosis Bronchiectasis

To the Editor: Mucoid Pseudomonas aeruginosa is isolated in up to 40% of noncystic fibrosis patients with chronic bronchitis and other obstructive lung diseases.1 Apart from P. aeruginosa, mucoid strains of other species of pseudomonads are infrequently discussed; and in most of the laboratories that lack automated systems, their identification is not attempted and is reported as "Pseudomonas species not aeruginosa." Mucoid pseudomonads are lung colonizers in patients with bronchiectasis and frequently cause secondary infections leading to increased mortality and morbidity.2 In this study, we have characterized and determined the antimicrobial susceptibility of mucoid pseudomonads strains, isolated from sputum of adult patients with noncystic fibrosis bronchiectasis using simple biochemical tests, which are routinely available in a microbiology laboratory. Antimicrobial susceptibility testing and metallo-β-lactamase production were done using standard methods.3 A total of 97 strains were isolated from 871 sputum samples during the study period. Among them, P. aeruginosa (n = 49, 50.5%) was the commonest isolate, followed by Pseudomonas fluorescens (n = 15), Pseudomonas putida (n = 8), Pseudomonas pseudoalcaligenes (n = 5), Brevundimonas vesicularis (n = 5), CDC group Vb-3 (n = 4), Pseudomonas spp group 1(n = 3), Pseudomonas mendocina (n = 2), Burkholderia cepacia complex (n = 2), Ralstonia pickettii (n = 2), Pseudomonas luteola (n = 1), and Brevundimonas diminuta (n = 1). Antimicrobial susceptibility pattern showed that majority of isolates were multidrug resistant, and polymyxin B was found to be most effective antibiotic. Metallo-β-lactamase production was determined in 19 meropenem resistant strains, and 12 (63%) of 19 isolates were metallo-β-lactamase positive (Table 1).TABLE 1: Antimicrobial Susceptibility Pattern of the Common Mucoid Pseudomonads IsolatesAmong pseudomonads, P. aeruginosa is the most common human pathogen. The first report of mucoid P. aeruginosa isolation came in 1927 from a patient with a fistulating abscess of the gallbladder.2 In the first detailed study, Elston and Hoffman4 reported an incidence of mucoid forms as 1.7%, and Fujita et al5 were the first worker to report mucoid P. putida causing pulmonary infection in an immunocompetent host. Generally, "Pseudomonas non-aeruginosa" species are considered as environment contaminant; however, results of this study indicate that Pseudomonas non-aeruginosa constituted 49.5% of mucoid pseudomonal isolates in patients with bronchiectasis and are an emerging cause of respiratory infections in patients with bronchiectasis. Antimicrobial resistance among them is of increasing concern as not only P. aeruginosa but also other pseudomonads were also found to be multidrug resistant, and these probably demonstrate the changing pattern of antimicrobial resistance in pseudomonads. Further large-scale studies are required to look for epidemiological distribution of mucoid strains and study their antimicrobial susceptibility pattern. Atul Garg, MD, DNB S. Sujatha, MD Jaya Garg, MD, DNB Nasreen H., MSc S. C. Parija, MD, FRCPath Department of Microbiology Jawaharlal Institute of Postgraduate Medical Education and Research Pondicherry, India [email protected]

Deciphering azo dye decolorization characteristics by indigenous Proteus hauseri: Chemical structure

This study selected indigenous Proteus hauseri ZMd44 as a model bacterium to explore how chemical structure affected dye decolorization characteristics in comparison with other biodecolorizers. No matter what naturally-existing decolorizer strain was used ( e.g., Pseudomonas luteola, Aeromonas hydrophila and P. hauseri), chemical structures of azo dyes ( e.g., molecular isomers or the presence of different functional groups) apparently affected the performance of dye biodecolorization ( e.g., biodegradability). That is, complete deciphering on azo dye decolorization characteristics of naturally-existing biodecolorizers disclosed which “biodegradable” dye(s) are environmentally-friendly to be used in industry for sustainable development.

The Evaluation of Dihydrorhodamine 123 Assay in Chronic Granulomatous Disease

Reply: The letter by Köker is correct in pointing out that not all patients with autosomal recessive Chronic Granulomatous Disease (CGD) have a broad intermediated Dihydrorhodamine (DHR) stimulated pattern like that depicted in Figure 1 in the article by Bender et al (Pediat Inf Dis J. 2000;28:529–533). We did not mean to infer that all of the AR forms of CGD were associated with this broad pattern. In our experience, however, when autosomal cases present later in life, with less severe infections, and especially those with the p47-phox form of the disorder, there is often a broad intermediate pattern such as that depicted, which is easily confused with variant X-linked CGD. In fact, the broad intermediate DHR pattern shown came from a previously healthy 8-year-old female admitted with pneumonia due to Chryseomonas luteola. Her older sister, at 12 years of age, had a similar DHR pattern but had never suffered a serious infection. One of the main points of our paper was to suggest that determining the mother's DHR pattern is often useful in distinguishing between X-linked and AR disease. As pointed out by Köker, nonrandom inactivation of the good X chromosome in a female X-linked carrier can occur resulting in very little to no respiratory burst in the female, which can even lead to clinical disease. The author is correct in stating that some AR cases including those with p47, p67 and p22 abnormalities may show patterns like that of classic X-linked disease. We have personally observed complete absence of respiratory burst activity in females with p67 phox and p22 light chain of cytochrome b558 associated mutations. Lastly, CYBB mutation nomenclature can be difficult because the CYBB database (starting at the beginning of exon 1) is numbered differently than HUGO nomenclature (starting at the ATG initiation site). Patient 2 is listed as c.266G>A in the manuscript and CYBB database (http://bioinf.uta.fi/CYBBbas), but the HUGO nomenclature is c.252G>A. It is a point mutation at the end of exon 3 (A84A) leading to a splice donor defect. The same 14 base difference explains the difference between c.744T>A (manuscript and database) versus c.730T>A (HUGO). Harry R. Hill, MD Carl T. Wittwer, MD, PhD Departments of Pathology, Pediatrics, and Medicine University of Utah School of Medicine Salt Lake City, UT

Chryseomonas luteola bacteremia in a patient with left pyocele testis with Fournier′s scrotal gangrene

phenotypic characters, including the presence of multi-trichous flagella and single polar flagellum in bio groups Ve-1 and Ve-2, respectively. The CDC groups Ve-1 and Ve-2 are named as Chryseomonas luteola and Flavimonas orrhyzihabitans, respectively. The CDC group Ve-1 is placed under the Pseudomonas stutzeri group in compliance with the colony characters as they form dry and wrinkled colonies. Based on the phylogenetic relationship studies, it was found that Chryseomonas luteola and Flavimonas orrhyzihabitans are junior subjective synonyms of Pseudomonas species. [2] Chryseomonas luteola is an aerobic, Gram-negative, motile rod found in the environment as saprophytes. It was previously named as Pseudomonas luteola and CDC group Ve-1 and was placed under the Pseudomonas stutzeri group based on 16S rRNA analysis. The infections caused by Chryseomonas luteola include bacteremia, pneumonia, biliary tract infections, surgical wound infections, abscesses, peritonitis, subdural empyema and infections associated with the presence of prosthetic devices. We report a case of bacteremia caused by Chryseomonas luteola in a patient with pyocoele testis with Fournier’s scrotal gangrene. CASE REPORT

Chryseomonas luteola from Bile Culture in an Adult Male with Severe Jaundice

A 60-year-old male was admitted in this hospital with severe jaundice, who had open cholecystectomy done 2 months ago. ERCP was performed and bile was sent for culture. It grew Chryseomonas luteola in pure culture. He underwent hepaticojejunostomy after 1 month. Total bilirubin improved gradually. His condition was stable on discharge. Prompt diagnosis of non-fermenters is required, as some of them are resistant to multiple antibiotics. Clinicians have to be made aware of the pathogenic role of C. luteola and its resistance to ampicillin and cephalosporins.

Multiple Brain Abscesses Caused by Pseudomonas luteola

Multiple Brain Abscesses Caused by Pseudomonas luteola

Biosorption of Chromium, Cadmium, and Cobalt from Aqueous Solution by Immobilized Living Cells of Chryseomonas luteola TEM 05

In this work, the potential use of the immobilized cells of Chryseomonas luteola TEM 05 for the removal of Cr+6, Cd+2 and Co+2 ions from aqueous solutions was investigated. The living cells of C. luteola TEM 05 were firstly entrapped both in carrageenan and chitosan coated carrageenan gels and then used in biosoption of the metal ions in batch reactors at pH 6.0, 25°C, in 100 mg L−1 of each metal solution. Besides this, a process of competitive biosorption of these metal ions was also described and compared to single metal ion adsorption in solution. According to the immobilization results, the replacement of KCl by KCl-chitosan as gelling agent improved the mechanical strength and thermal stability of the gel. In addition, the C. luteola TEM 05 immobilized carrageenan-chitosan gel system was quite more efficient for the fast adsorption of metal ions from aqueous solution than the carrageenan gels without biomass.

면역리포좀을 이용한 계란에서의 살모넬라 분석과 시판 간이키트와의 비교

보다 우수한 살모넬라 진단법을 개발하고자, 면역리포좀을 이용하여 계란에서의 살모넬라를 분석하는 새로운 진단법과 시판 간이키트를 사용한 살모넬라 분석과의 결과를 비교하였다. 면역리포좀을 이용하여 난각을 분석한 결과, 36개의 계란 시료 중 1건에서 살모넬라 양성 결과가 나타났으며 시판 간이키트를 이용하여 분석한 결과, 36개의 계란 시료 중 6건에서 살모넬라 양성 결과가 나타났다. 총 7건의 양성 결과는 생화학적 동정에 의해서 살모넬라균이 아닌 것으로 확인되었다. 난황과 난백으로 이루어진 내용물의 경우, 두 분석법에 의하여 살모넬라 균이 전혀 검출되지 않았으며 이는 배지 배양법과 일치하는 결과였다. 면역리포좀을 이용한 진단법은 시판 간이키트에 비해 민감도가 높고 분석에 소요되는 총 시간이 24시간 단축되는 우수성을 보였다. 난각에서는 Acinetobacter baumanni, Chryseomonas luteola, Enterobacter cloacae, Escherichia coli, Escherichia hermannii, Klebsiella pneumonia, Pantoea spp., Pasteurella pneumotropica와 같은 세균이 분리되었는데, A. baumanni와 P. pneumotropica를 제외한 대부분의 세균들은 계란의 전처리 공정 중에 빈번하게 분리되는 균들로 확인되었다. To suggest an improved diagnostic method for Salmonella spp., analyses were conducted with immunoliposomes and compared with the results from a commercial test kit. One sample out of 36 samples of eggshell was Salmonella-positive via immunoliposomes. In the case of the use of the commercial test kit, six samples out of 36 samples were Salmonellapositive. These Salmonella-positive samples were subjected to biochemical identification tests that confirmed that they were Salmonella-negative. As for the egg content samples, they were Salmonella-negative in both analyses with immunoliposomes and the commercial test kit. The Salmonella analysis with immunoliposomes reduced detection time, by 24 h compared to the commercial test kit. Bacteria, including Acinetobacter baumanni, Chryseomonas luteola, Enterobacter cloacae, Escherichia coli, Escherichia hermannii, Klebsiella pneumonia, Pantoea spp., and Pasteurella pneumotropica, were isolated from the eggshells. Other than Acinetobacter baumanni and Pasteurella pneumotropica most of the isolates were known to frequently appear during egg production processing.

Factors Affecting Preference Responses of the Freshwater Ciliate Uronema nigricans to Bacterial Prey

To enhance our understanding of the factors affecting feeding selectivity of bacterivorous protists in aquatic systems, we examined the preference responses of the freshwater ciliate Uronema nigricans towards three bacterial prey taxa, Pseudomonas luteola, Serratia rubidaea, and Aeromonas hydrophila. Potential factors influencing the predator-prey contact rate included the previous feeding history of the ciliate and physiological state of bacteria. Preference indexes were obtained from multiple-choice mazes in which ciliates moved preferentially towards alternative bacteria or the prey species on which they had been feeding. Uronema nigricans showed differential attraction towards the offered prey types, and these preferences varied as a function of the ciliate feeding history: U. nigricans growing on P. luteola showed lower preference responses towards the offered bacteria than U. nigricans growing on S. rubidaea. The bacteria in stationary phase elicited a higher degree of attraction than bacteria in exponential phase, probably due to a higher concentration of carbohydrates in the former. Therefore, this protist will preferentially swim towards bacteria in stationary growth phase, although the degree of this response will be affected by the recent feeding history of the ciliate.

Incidence Of Bacteria Of Public Health Importance In Drinking Water From Water Dispenser Systems In Homes And Offices In Lagos And Ibadan, Nigeria

The isolation and characterization of bacteria in drinking water samples from 11 water dispenser machines was carried out. The water samples were obtained from five homes in Ibadan, Oyo state and eight offices in Victoria Island, Lagos state.Twenty-five bacteria were isolated. They include Pseudomonas aeruginosa (16%), Pseudomonas fluorescens (4%), Chryseomonas luteola (8%), Citrobacter freundii (4%), Enterobacter sp.(8%), Cedecea sp. (4%), Citrobacter sp.(12%), Salmonella sp.(12%), Chromobacter violaceum (4%), Providencia rettgeri (8%), and Escherichia coli (16%). However, the water samples collected from the bottled water before being fixed on the dispenser machines showed no growth of any bacteria on the culture media.The mean values of the heterotrophic counts range between 63 x 10 cfu/ml and 272 x 10 cfu/ml. The mean values of the coliform counts range between 26 x 10 cfu/ml and 162 x 10 cfu/ml.The result of this work of has confirmed the presence of bacteria of public health importance in drinking water from water dispenser machines. Also, the result of the analysis of the water from the bottle before being fixed on the dispenser shows that the contamination of the water is from the dispenser machines.

Decolorization of azo dye with Pseudomonas luteola in a membrane bioreactor

Decolorization of azo dye with Pseudomonas luteola in a membrane bioreactor

Antimicrobial Activities of the Essential Oils ofOriganum onitesL.,Origanum vulgareL. Subspecieshirtum(Link) Ietswaart,Satureja thymbraL., andThymus cilicicusBoiss. & Bal. Growing Wild in Turkey

In the present study, four separate samples of Origanum onites L., three separate samples of Satureja thymbra L., Origanum vulgare L. ssp. hirtum (Link) Ietswaart, and Thymus cilicicus Boiss. & Bal. were collected from various regions of Mugla, Turkey. The essential oils of these plants were obtained by the hydrodistillation method. Antimicrobial activities of the essential oils against microorganisms, including multiple antibiotic-resistant bacteria, were investigated using the disc diffusion method. Different antibiotic discs were used for comparison to the inhibition zones. All the essential oils used in this study were very effective against Gram-positive and Gram-negative bacteria, which included multiple resistant strains, except Pseudomonas aeruginosa ATCC 27853 and Pseudomonas fluorescens MU 87. The essential oils of the O. onites, O. vulgare ssp. hirtum, and S. thymbra were especially very effective against the resistant strains such as Stenotrophomonas maltophilia MU 64, S. maltophilia MU 99, and Chryseomonas luteola MU 65. The maximum antimicrobial activity was observed with the essential oils of O. onites. The antimicrobial activities of the essential oils varied depending on the species, subspecies, or variety. In fact, the essential oils of some plants belonging to the same species that were collected from different locations showed different levels of antimicrobial activities.

Revealing azo-dye decolorization of indigenous Aeromonas hydrophila from fountain spring in Northeast Taiwan

This study provides a first attempt to seek for indigenous strains with excellent decolorization capability for dye-laden wastewater treatment from an unpolluted and likely the most biodiverse region (Lanyang Plain) in Northeast Taiwan. For isolation, serial selections were conducted by using of the fungicide nystatin and model diazo-dye C.I. reactive red 141 (RR141). Thirteen bacterial strains (NIU 01–13) with the excellent capability of azo-dye decolorization were predominantly isolated from samples of a fountain spring near Chiao-Hsi in Lanyang Plain. According to profiles of protein expression and PCR-augmented 16S rRNA gene analyses for strain identification, >98% of gene sequences in isolated strains NIU 01 and NIU 12 were similar to Aeromonas hydrophila compared to available gene sequences in the NCBI BLAST gene bank. Phase-curve profiles indicated that azo-dye decolorization was found to be non-growth associated for isolated strains. Color removal efficiency of the culture was ca. 16-fold to that of Pseudomonas luteola, indicating a promising feasibility of isolated cultures to be used for practical treatments. This point apparently suggested that exploring a biodiverse indigenous microbiota with high performance of specific characteristics (e.g., color removal) from a unpolluted region (e.g., Northeast Taiwan) for practical applications should still be possible.

Comparative assessment upon dye removal capability of indigenous bacterial strains from Lanyang Plain in northeast Taiwan

This study provides a first attempt from a geological and ecological perspective to look forward isolations of indigenous strains with the decolorization capability from the most biodiverse region in Taiwan for dye-laden wastewater treatment. Serial selections were conducted by a specific use of the fungicide nystatin and model azo dye C.I. reactive red 141 (RR141) during isolation. Several bacterial strains with the excellent capability of azo dye decolorization were predominantly isolated from river water and mud samples of Lanyang River Basin. Phase-curve profiles indicated that azo dye decolorization was found to be non-growth associated for both mixed cultures and isolated pure strains. The color removal efficiency of the mixed culture was nearly 10-fold to that of Pseudomonas luteola at ca. 600 mg L −1 RR141, indicating a promising feasibility of isolated cultures to be applicable for practical treatments. The decolorization performance of unacclimated and acclimated pure cultures was at most 20% and 70–80% to that of the mixed cultures, respectively. It might suggest that combined interactions among decolorizers were crucial for the optimal color removal. According to the results of physiological and 16S rRNA gene sequence examinations, the isolated strains should belong to Aeromonas species (very likely A. hydrophila).

Kinetics of reactive azo-dye decolorization by Pseudomonas luteola in a biological activated carbon process

A laboratory-scale biological activated carbon (BAC) process was conducted to treat a reactive azo-dye (reactive red 22) by Pseudomonas luteola and the kinetics of azo-dye decolorization was investigated. The BAC-reactor removed 89% of reactive red 22 while P. luteola biofilm and suspended P. luteola reached a maximum growth rate at a steady-state condition. The azo-dye effluent from BAC-reactor met a discharge standard required by Taiwan government. The kinetic BAC-model, based on fundamental mechanisms, including surface diffusion, liquid-film mass transfer, Monod kinetics, growth of biofilm and suspended cells as well as shear loss of biofilm, was developed to describe the performance of biofilm attached on activated carbon in the azo-dye treatment process. The kinetic BAC-model predictions and experimental results for simultaneous adsorption and biodegradation of azo-dye contaminants were compared. It is shown that the fundamental mechanisms of BAC-process for azo-dye decolorization are not the simple addition but the synergetic combination of carbon adsorption and biodegradation of P. luteola strain. The major aspects of such synergism are the bioregeneration of the adsorbent and the reduction of the toxic effect of azo-dye contaminants in textile wastewater on P. luteola strain. The kinetic BAC-model not only provides insights into underlying mechanisms of adsorption and biodegradation but also can be used as a powerful tool to assist the design of a pilot-scale or full-scale BAC-process to treat azo-dye contaminants by P. luteola cells in textile wastewater.

Exploring effects of chemical structure on azo dye decolorization characteristics by Pseudomonas luteola

This follow-up study tended to provide a systematic comparison for how the variation of functional groups and molecular structures present in model azo dyes affects color removal capability of Pseudomonas luteola. As sulfo group at methyl orange (p-MO) or carboxyl group at 4-(4′-dimethylaminophenylazobenzoic acid) sodium salt (denoted p-MR) were both para to azo bond, the ranking of decolorization rate was p-MO > p-MR due to the stronger electron-withdrawing effect of the sulfo group. For isomers, when the functional groups (sulfo group at 2-(4′-dimethylamino-phenylazo) benzenesulfonic acid sodium salt (o-MO) or carboxyl group at methyl red (o-MR)) were ortho to azo bond, the decolorization rate significantly decreased (e.g., p-MO > o-MO or p-MR≫ o-MR) likely due to steric hindrance near azo linkage(s). Similarly, for phenolic azo dyes the series of decolorization rate was 3-(4′-dimethylaminophenylazo) phenol (m-OH) > 2-(4′-dimethylaminophenylazo) phenol (o-OH). Apparently, azo dyes with different properties of substituent on aromatic ring could affect the efficiency of biodecolorization of P. luteola. Moreover, the relative position (e.g., ortho, meta, para) of the substituent to azo bond could also influence the capability of biodecolorization of P. luteola. Regarding the electronic effect, azo dyes with stronger electron-withdrawing group (e.g., sulfo group) at specific positions (e.g., at para) could be more easily biodecolored than those with a carboxyl group.

Disease of rainbow trout caused by Pseudomonas luteola

Bacteria isolated from rainbow trout, Oncorhynchus mykiss, kept in a farm, in Turkey. During the outbreak, 40% of the rainbow trout (10–40 g) died. Typical clinical signs were exophthalmia, dark pigmentation, hemorrhage at the base of the pectoral, pelvic, anal fins and around the vent. Internal signs were enlarged spleen, pale liver and intestine filled with yellowish fluid. Liver, kidney and spleen of diseased fish, were aseptically streaked on Tryptic Soy Agar. After incubation, pure cultured colonies were observed and biochemically characterized with API 20 NE and other biochemical tests. Cultured bacterial 16 S rDNA gene was sequenced. Based on biochemical characteristics and sequence of 16 S rRNA, the causative bacteria were identified as Pseudomonas luteola. This study reports the first P. luteola infection in fish.

Assessment upon species evolution of mixed consortia for azo dye decolorization

This study provides a novel attempt to put forward, in De Wit's replacement experiments and game theory, interspecific competition in bioaugmentation using constructed mixed-consortia for species growth and biodecolorization. Previous studies stated that species interactions towards mutualism in mixed cultures were vital to determine optimal decolorization in bioaugmentation. In this study, using De Wit's indices trajectories of relative yields over time disclosed interspecific competition of the model binary-biosystems in various dye-free and dye-bearing cultures. In aerobic growth conditions, Escherichia coli DH5α owned a growth advantage to out-compete Pseudomonas luteola due to preferential growth rate of DH5α. However, in static-decolorization conditions DH5α surrendered proportion of its advantage to enhance color removal of P. luteola for total coexistence. Game theory also indicated that there were two Nash equilibria (i.e., total conflict and total cooperation situations) present in the model biosystems. In aerobic growth, DH5α had its growth advantage to exclude P. luteola for dominance (i.e., conflict strategy) according to competitive exclusion principle. In static-decolorization conditions, as the removal of a common dye threat was crucial to both species for survival, both species selected cooperation strategy through metabolite stimulation of DH5α to enhance effective decolorization of P. luteola for long-term sustainable management.

Revealing characteristics of mixed consortia for azo dye decolorization: Lotka–Volterra model and game theory

This study provides a novel explanation to put forward, in Lotka–Volterra competition model and game theory, interspecific competition in bioaugmentation using constructed mixed consortia for azo dye decolorization. As mixed cultures are regularly used in industrial dye-laden wastewater treatment, understanding species competition of mixed consortia is apparently of great importance to azo dye decolorization. In aerobic growth conditions, Escherichia coli DH5α owned a growth advantage to out-compete Pseudomonas luteola due to preferential growth rate of DH5α. However, in static decolorization conditions DH5α surrendered some proportion of its advantage (i.e., a decrease in its competitive power for metabolite stimulation) to enhance color removal of P. luteola for total coexistence. In aerobic growth, DH5α had its growth advantage to exclude P. luteola for dominance (i.e, conflict strategy) according to competitive exclusion principle. In static decolorization conditions, as the removal of a common dye threat was crucial to both species for survival, both species selected cooperation strategy through metabolite stimulation of DH5α to enhance effective decolorization of P. luteola for long-term sustainable management. This analysis of game theory clearly unlocked unsolved mysteries in previous studies.

Decolorization of azo dye by immobilized Pseudomonas luteola entrapped in alginate–silicate sol–gel beads

Pseudomonas luteola was immobilized by entrapment in alginate–silicate sol–gel beads for decolorization of the azo dye, Reactive Red 22. The influences of biomass loading and operating conditions on specific decolorization rate and dye removal efficiency were studied in details. The immobilized cells were found to be less sensitive to changes in agitation rates (dissolved oxygen levels) and pH values. Michaelis–Menten kinetics could be used to describe the decolorization kinetics with the kinetic parameters being 36.5 mg g −1 h −1, 300.1 mg l −1 and 18.2 mg g −1 h −1, 449.8 mg l −1 for free and immobilized cells, respectively. After five repeated batch cycles, the decolorization rate of the free cells decreased by nearly 54%, while immobilized cells still retained 82% of their original activity. The immobilized cells exhibited better thermal stability during storage and reaction when compared with free cells. From SEM observation, a dense silicate gel layer was found to surround the macroporous alginate–silicate core, which resulted in much improved mechanical stability over that of alginate beads when tested under shaking conditions. Alginate–silicate matrices appeared to be the best matrix for immobilization of P. luteola in decolorization of Reactive Red 22 when compared with previous results using synthetic or natural polymer matrices.