Lipid production and mixotrophic growth features of cyanobacterial strains isolated from various aquatic sites.

The present study was conducted to determine the potential of five cyanobacteria strains isolated from aquatic zones to induce lipid production. The phylogenetic affiliation of the isolates was determined by 16S rRNA gene sequencing. Amongst the isolates, an efficient cyanobacterium, Synechococcus sp. HS01 showing maximal biomass and lipid productivity, was selected for further studies. In order to compare lipid productivity, the HS01 strain was grown in different media to screen potential significant culture ingredients and to evaluate mixotrophic cultivation. Mixotrophic cultivation of the strain using ostrich oil as a carbon source resulted in the best lipid productivity. GC analysis of fatty acid methyl esters of the selected cyanobacterial strain grown in media supplemented with ostrich oil showed a high content of C16 (palmitoleic acid and palmitic acid) and C18 (linoleic acid, oleic acid and linolenic acid) fatty acids of 42.7 and 42.8 %, respectively. Transmission electron micrographs showed that the HS01 cells exhibited an elongated rod-shaped appearance, either isolated, paired, linearly connected or in small clusters. According to initial experiments, ostrich oil, NaNO3 and NaCl were recognized as potential essential nutrients and selected for optimization of media with the goal of maximizing lipid productivity. A culture optimization technique using the response surface method demonstrated a maximum lipid productivity of 56.5 mg l(-1) day(-1). This value was 2.82-fold higher than that for the control, and was achieved in medium containing 1.12 g l(-1) NaNO3, 1 % (v/v) ostrich oil and 0.09 % (w/v) NaCl.

Calcium carbonate precipitation by strain Bacillus licheniformis AK01, newly isolated from loamy soil: a promising alternative for sealing cement-based materials.

The relevant experiments were designed to determine the ability of indigenous bacterial strains isolated from limestone caves, mineral springs, and loamy soils to induce calcium carbonate precipitation. Among all isolates examined in this study, an efficient carbonate-precipitating soil bacterium was selected from among the isolates and identified by 16S rRNA gene sequences as Bacillus licheniformis AK01. The ureolytic isolate was able to grow well on alkaline carbonate-precipitation medium and precipitate calcium carbonate more than 1 g L(-1). Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) analyses, and scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy (EDX) examinations were performed in order to confirm the presence of calcium carbonate in the precipitate and to determine which polymorphs were present. The selected isolate was determined to be an appropriate candidate for application in a surface treatment of cement-based material to improve the properties of the mortar. Biodeposition of a layer of calcite on the surface of cement specimens resulted in filling in pore spaces. This could be an alternative method to improve the durability of the mortar. The kind of bacterial culture and medium composition had a profound impact on the resultant CaCO(3) crystal morphology.

Lactobacillus paracasei BEJ01 prevents immunotoxic effects during chronic zearalenone exposure in Balb/c mice.

BACKGROUND AND AIM: Zearalenone (ZEN) is an estrogenic mycotoxin produced by numerous Fusarium species in pre- or post-harvest cereals. ZEN displays a potent estrogenicity in livestock and also causes severe immunological problems. The aims of this study were to isolate a new ZEN-degrading micro-organism for biological detoxification, to examine its ability to degrade ZEN in liquid medium, and to evaluate its potential for in vivo preventitive effects against ZEN (as would occur with contaminated feed)-induced immunomodulation in mice. MATERIALS AND METHODS: Lactobacillus paracasei BEJ01 (LP) isolated from Tunisian artisanal butter was found to display significant binding ability to ZEN in phosphate-buffered saline (i.e. 96.6%) within 24 h of incubation. The in vivo study was conducted using Balb/c mice that received either vehicle (control), LP only (at 2 × 10(9 )cfu/l, ∼2 mg/kg BW), ZEN alone (at 40 mg/kg BW), or ZEN + LP daily for 15 d. RESULTS: Compared to control mice, ZEN treatment led to significantly decreased body weight gains and decrements in all immune parameters assessed. The addition of LP to ZEN strongly reduced the adverse effects of ZEN on each parameter. In fact, mice receiving ZEN + LP co-treatment displayed no significant differences in the assayed parameters as compared to the control mice. The exposures to the bacteria alone had no adverse effects in the mice. CONCLUSION: From these data, we conclude that LP bacteria could be beneficial in human and animals for protection against immunotoxicity from ZEN at high levels and during chronic exposures.

Response surface optimization of biosurfactant produced by Pseudomonas aeruginosa MA01 isolated from spoiled apples.

A potent biosurfactant-producing bacterial strain isolated from spoiled apples was identified by 16S rRNA as Pseudomonas aeruginosa MA01. Compositional analysis revealed that the extracted biosurfactant was composed of high percentages of lipid (66%, w/w) and carbohydrate (32%, w/w). The surface tension of pure water decreased gradually with increasing biosurfactant concentration to 32.5 mN m(-1) with critical micelle concentration (CMC) value of 10.1 mg L(-1). The Fourier transform infrared spectrum of extracted biosurfactant confirmed the glycolipid nature of this natural product. Response surface methodology (RSM) was employed to optimize the biosynthesis medium for the production of MA01 biosurfactant. Nineteen carbon sources and 11 nitrogen sources were examined, with soybean oil and sodium nitrate being the most effective carbon and nitrogen sources on biosurfactant production, respectively. Among the organic nitrogen sources examined, yeast extract was necessary as a complementary nitrogen source for high production yield. Biosurfactant production at the optimum value of fermentation processing factor (15.68 g/L) was 29.5% higher than the biosurfactant concentration obtained before the RSM optimization (12.1 g/L). A central composite design algorithm was used to optimize the levels of key medium components, and it was concluded that two stages of optimization using RSM could increase biosurfactant production by 1.46 times, as compared to the values obtained before optimization.

Interaction of Lactobacillus plantarum MON03 with Tunisian montmorillonite clay and ability of the composite to immobilize Zearalenone in vitro and counteract immunotoxicity in vivo.

BACKGROUND AND AIM: The present study was conducted to determine the abilities of the living Lactobacillus plantarum MON03 (LP) cells, Tunisian montmorillonite clay and their composites to accumulate Zearalenone (ZEA) from a liquid medium and elucidate the preventive effect of their composite in ZEA-contaminated balb/c mice showing immunotoxicity disorders. MATERIALS AND METHODS: In the in vitro study, LP (2 × 10(9) CFU/mL), TM (0.5 mg) and LP+TM were incubated with 50 µg mL(-1) ZEA for 0, 12 and 24 h. For the in vivo study, the composite MT+LP was evaluated also for possible protection regarding ZEA-immunotoxicity in Balb/c mice as a sensitive model. RESULTS: Results indicated that TM and LP+TM had a high capacity of adsorbing ZEA 87.2 ± 2.1 and 94.2 ± 2.1%, respectively. However, LP alone able to remove only 78% after 24 h of incubation. The quantity of adsorbed ZEA by LP, TM and LP+TM were 39, 43,5 and 47 µg mL(-1) of PBS, respectively. The in vivo results indicated that mice orally exposed to ZEA- (40 mg/kg bw) for 2 weeks showed severe immunotoxicity typical of fusarotoxicosis regarding thymocytes and splenocytes cell viability count, IFN-γ, IL-12, TNF-α production and B-cell activation. Mice treated with LP and TM alone, and LP+MT in combination with ZEA were comparable to the control. CONCLUSION: Both LP and TM are safe by themselves and their composite succeeded to exert a potential prevention by counteracting ZEA-immunotoxicity and can be implicated in the biotechnology of ZEA removal in human food and animal feed.

Lipid Production Capacity of a Newly Characterized Cyanobacterial Strain Synechocystissp. MH01: A Comparative Performance Evaluation of Cyanobacterial Lipid-Based Biodiesel.

BACKGROUND: Cyanobacteria have been the focus of extensive researches because of their high potential for the development of new generations of useful natural compounds with vast applications. For the entire last ten years, a lot of attention has been dedicated to the cyanobacterial lipids as a main source of valuable materials for clean energy production. OBJECTIVES: As there is a direct relationship between biofuel properties and compositional characteristics of fatty acids, a selected lipid-producing cyanobacterial strain was examined and analyzed in terms of fatty acid composition. The biodiesel quality parameters were carefully examined as well. MATERIALS AND METHODS: A cyanobacterial strain was isolated from waterfalls in the northern part of Iran and identified as Synechocystis sp. MH01. The fatty acids profile of the selected strain, as tested in various culture conditions, was analyzed by gas chromatography (GC) and compared with control subjects to further validating the biodiesel quality parameters. RESULTS: The autotrophic cultivation of Synechocystissp. MH01 resulted in biomass and lipid productivity of 109 mg.L-1 day-1 and 22.89 mg.L-1 day-1, respectively. The mixotrophic cultivation of MH01 strain in sucrose-containing medium led to an approximately 1.8 and 1.22 fold increase in biomass and lipid productivity compared with the autotrophic condition. The addition of glycine to BG11 medium caused up to ~1.3 and ~1.18 fold increase in biomass and lipid productivity compared with control subjects. The analysis of qualitative parameters of the biodiesel, as derived from the lipids, indicated that Synechocystis sp. MH01 has a high ability for lipid production under optimal culture conditions. CONCLUSIONS: It seems feasible to evolve the Synechocystissp. MH01 further particularly for more lipid production as a promising primary raw material for biofuel production through fine-tuning of medium composition.

Lactobacillus salivarius NK02: a Potent Probiotic for Clinical Application in Mouthwash.

A specific strain of naturally occurring oral lactobacilli was isolated and identified based on morphological, biochemical, and 16S rRNA gene sequencing. The phylogenetic affiliation of the isolate confirmed that the NK02 strain had close association with the Lactobacillus salivarius. An effective mouthwash was developed for treatment of periodontitis and suppression of the indicator bacterium Aggregatibacter actinomycetemcomitans which is an obvious pathogen of periodontal disease. The mouthwash containing L. salivarius NK02 was tested at a dose level of 108 (colony forming units (CFU) ml-1), monitoring over a period of 4 weeks. The study was a randomized double-blind placebo control trial, and the patients were treated in two groups of control and test by using scaling and root planing (SRP) + placebo and scaling and root planing (SRP) + probiotic, respectively. It appeared that the probiotic mouthwash was able to inhibit the bacterial growth on both saliva and sub-gingival crevice and exhibited antibacterial activity against A. actinomycetemcomitans. The results also showed that SRP+ probiotic treatment led to a significant decrease of gingival index (GI) and bleeding on probing (BOP) compared with that of SRP + placebo for the probiotic group. The rate of decrease in pocket depth was displayed in the group with SRP + probiotic treatment equal to 1/2 mm, and probing pocket depth (PPD) value was decreased in the probiotic bacteria treatment group that can explain the decrease in inflammation in gingiva. Our findings suggest that probiotic mouthwash is healthy for daily use as an alternative for maintaining dental and periodontal health.

Immuno-physiological alterations from AFB1 in rats counteracted by treatments with Lactobacillus paracasei BEJ01 and montmorillonite clay mixture.

High contamination by aflatoxin B1 (AFB1) has been detected in Beja province (Tunisia) in many dairy products and animal feed, which has resulted in many tons of cereals and cereals being removed from the market, causing economic loss. While removal represents a means of reducing risk, exposures still occur. Studies have increasingly focused on means of AFB1 biodegradation/elimination using lactic acid bacteria and clay mineral. In the study here, Lactobacillus paracasei BEJ01 (LP) and montmorilonite clay (MT) were used to reduce the physio-/immunotoxicologic disorders that could develop in rats that underwent AFB1 exposures for a total of 7 consecutive days. The results indicated that rats treated with AFB1 (80 µg/kg BW) alone had significant decreases in lymphocytes in their blood (including B-lymphocytes, CD3(+), CD4(+), and CD8(+) T-lymphocyte subtypes, and NK cells), immunoglobulins (IgA and IgG) and pro-inflammatory cytokines; these rats also had altered oxidative stress status. In contrast, in rats treated with LP + MT (2 × 10(9) cfu/ml [∼ 2 mg/kg] + 0.5 mg MT/kg BW) for a total of 7 days before, concurrent with or after AFB1 treatment, there was a significant blockade/mitigation of each AFB1-impacted parameter. Moreover, treatment with the mixture at any point in relation to AFB1 treatment expectedly caused enhanced TNFα and IL-1ß expression relative to control values; all other parameters were comparable to values noted in control rats. Alone, the mixture had no impact on host parameters. From the results here it may be concluded the the LP + MT mixture was effective in protecting these hosts against AFB1-induced immunologic/physiologic disorders and that LP + MT could prevent and/or mitigate AFB1 toxicities in vivo.

Lactobacillus crustorum KH: novel prospective probiotic strain isolated from Iranian traditional dairy products.

In recent years, exploring novel probiotic strains for therapeutic intervention has been raised due to the significant increase in market demand. This study aimed to investigate the certain probiotic properties of 15 Lactobacillus isolates from Iranian traditional dairy products. Among them, a novel potential probiotic strain was isolated and identified as Lactobacillus crustorum. The characteristics of potential probiotics were examined in terms of resistance to acidity, bile, and salinity as well as antibiotic tolerance and antibacterial activity. L. crustorum KH has shown tolerance property to bile (0.3 % w), acidity (pH 2-9), and salinity (1-5 % NaCl) and strong antibacterial activity against tested enteropathogens by well-diffusion assay. Furthermore, in vivo study and histological assays were performed to study whether live and heat-killed cells of L. crustorum KH are able to protect against the challenge of Escherichia coli O157:H7 in the gastrointestinal tract of mice used as an experimental model. Therefore, heat-killed and live cells of L. crustorum KH were inoculated by gavage to different groups of 4-6-week-old female BALB/c mice in doses of 10(8) colony-forming unit (CFU)/dose. Thereafter, these mice were challenged with E. coli O157:H7 also inoculated in the gastrointestinal tract (GIT) of the animals. The results showed that heat-killed cells of L. crustorum KH exert a protective effect against E. coli O157:H7 colonization at different degrees, being lower than that produced by viable cells.

First report of a lipopeptide biosurfactant from thermophilic bacterium Aneurinibacillus thermoaerophilus MK01 newly isolated from municipal landfill site.

A biosurfactant-producing thermophile was isolated from the Kahrizak landfill of Tehran and identified as a bacterium belonging to the genus Aneurinibacillus. A thermostable lipopeptide-type biosurfactant was purified from the culture medium of this bacterium and showed stability in the temperature range of 20-90 °C and pH range of 5-10. The produced biosurfactant could reduce the surface tension of water from 72 to 43 mN/m with a CMC of 1.21 mg/mL. The strain growing at a temperature of 45 °C produces a substantial amount of 5 g/L of biosurfactant in the medium supplemented with sunflower oil as the sole carbon source. Response surface methodology was employed to optimize the biosurfactant production using sunflower oil, sodium nitrate, and yeast extract as variables. The optimization resulted in 6.75 g/L biosurfactant production, i.e., 35% improved as compared to the unoptimized condition. Thin-layer chromatography, FTIR spectroscopy, 1H-NMR spectroscopy, and biochemical composition analysis confirmed the lipopeptide structure of the biosurfactant.

Distinctive protein expression patterns of the strain Brevundimonas sp. ZF12 isolated from the aqueous zone containing high levels of radiation to cadmium-induced stress.

In the current study, different protein expression profiles in a strain Brevundimonas sp. ZF12, isolated from the aqueous zone containing high levels of radiation, were characterized following exposure to cadmium (II) using a proteomic strategy. In order to gain a deeper understanding of the cellular events that allow this strain to survive and undergo cadmium adaptation and sorption, the strain was tested under three experimental conditions of 5, 10 and 30 ppm cadmium (II) ions stress. Two-dimensional polyacrylamide gel electrophoresis and mass spectrometry were used to identify the differentially expressed proteins under cadmium (II) stress. 20 differentially expressed spots were successfully identified by MS/MS analysis. These proteins are involved in DNA repair and protection, amino acid metabolism, nucleotide metabolism, energy homeostasis, oxidative stress response, redox homeostasis, protein folding and heat-shock response. The results obviously indicate that the ZF12 strain tends to endure the cadmium (II) stress conditions by modification in many aspects of its cellular physiology and metabolism.

Ability of Lactobacillus rhamnosus GAF01 to remove AFM1 in vitro and to counteract AFM1 immunotoxicity in vivo.

Aflatoxin M1 (AFM1) has been detected in many parts of the world both in raw milk and many dairy products, causing great economic losses and human disease. Unfortunately, there are few studies dealing with AFM1 immunotoxicity/interactions with lactic acid bacteria for potential application as a natural preventive agent. The aim of this study was to isolate (from dairy products) food-grade probiotic bacteria able to degrade/bind AFM1 in vitro and evaluate whether the same organism(s) could impart a protective role against AFM1-induced immunotoxicity in exposed Balb/c mice. Bacteria (Lactobacillus plantarum MON03 and L. rhamnosus GAF01) were isolated from Tunisian artisanal butter and then tested for abilities to eliminate AFM1 from phosphate-buffered saline (PBS) and reconstituted milk (containing 0.05, 0.10, and 0.20 µg AFM1/ml) after 0, 6, and 24 h at 37°C. Results showed that the selected bacteria could 'remove' AFM1 both in PBS and skimmed milk. The binding abilities of AFM1 by L. plantarum MON03 and L. rhamnosus GAF01 strains (at 10(8) CFU/ml) in PBS and reconstituted milk ranged, respectively, from 16.1-78.6% and 15.3-95.1%; overall, L. rhamnosus showed a better potential for removal than L. plantarum. 'Removal' appeared to be by simple binding; the bacteria/AFM1 complex was stable and only a very small proportion of mycotoxin was released back into the solution. L. rhamnosus GAF01 had the highest binding capacity and was selected for use in the in vivo study. Those results indicated that use of the organism prevented AFM1-induced effects on total white and red blood cells, and lymphocyte subtypes, after 15 days of host treatment. These studies clearly indicated that L. rhamnosus GAF01 was able to bind AFM1 in vitro and-by mechanisms that might also be related to a binding effect-counteract AFM1-induced immunotoxicity. Moreover, by itself, this bacterium was not toxic and could potentially be used as an additive in dairy products and in biotechnology for mycotoxin detoxification.

Antibacterial activity and probiotic potential of Lactobacillus plantarum HKN01: a new insight into the morphological changes of antibacterial compound-treated Escherichia coli by electron microscopy.

Among several bacteria examined, an antibacterial-producing Lactobacillus strain with probiotic characteristics was selected and identified based on 16S rRNA gene sequencing. Subsequent purification and mode of action of the antibacterial compounds on target cells including E. coli were investigated. Maximum production of the antibacterial compound was recorded at 18 h incubation at 30 degrees C. Interestingly, antibacterial activity remained unchanged after heating at 121 degrees C for 45 min, 24 h storage in temperature range of 70 degrees C to room temperature, and 15 min exposure to UV light, and it was stable in the pH of range 2-10. The active compounds were inactivated by proteolytic enzymes, indicating their proteinaceous nature, and, therefore, referred to as bacteriocin-like inhibitory substances. Isolation and partial purification of the effective agent was done by performing ammonium sulfate precipitation and gel filtration chromatography. The molecular mass of the GFC-purified active compound (~3 kDa) was determined by Tris-Tricine SDS-PAGE. To predict the mechanisms of action, transmission electron microscopy (TEM) analysis of ultrathin sections of E. coli before and after antibacterial treatment was carried out. TEM analysis of antibacterial compounds-treated E. coli demonstrated that the completely altered bacteria appear much darker compared with the less altered bacteria, suggesting a change in the cytoplasmic composition. There were also some membrane-bound convoluted structures visible within the completely altered bacteria, which could be attributed to the response of the E. coli to the treatment with the antibacterial compound. According to the in vivo experiments oral administration of L. plantarum HKN01 resulted in recovery of infected BALB/c mice with Salmonella enterica ser. Typhimurium.

Antibacterial Activity of Probiotic Lactobacillus plantarum HK01: Effect of Divalent Metal Cations and Food Additives on Production Efficiency of Antibacterial Compounds.

One hundred and sixty lactic acid bacteria, isolated from Iranian traditional dairy products, were screened for antibacterial potential. Among them, an isolate showing remarkable antibacterial activity against both Staphylococcus aureus (PTCC 1112) and Escherichia coli (PTCC 1338) was selected based on minimum inhibitory concentration (AU/mL). The morphological and biochemical characteristics of the isolate matched the literature description about genus Lactobacillus. Partial sequencing of 16S rRNA gene and its alignment with other Lactobacillus strains revealed that the isolate was closely related to the Lactobacillus plantarum. The isolate also exhibited the highest similarity (>99 %) to L. plantarum. We thus tentatively classified the bacterial isolate as L. plantarum HK01. The antibacterial active compound from HK01 strain remained stable for 45 min at 121 °C, and it reached a maximum activity at the end of log phase and the early part of stationary phase. The antibacterial activity of the test isolate, its probiotic properties and production efficacy through addition of some divalent metal cations and food additives were studied as well. The study of bile salt hydrolase (BSH) activity as a function of growth revealed that HK01 strain hydrolysing up to 5 % of sodium salt of glycodeoxycholic acid, correlated with the presence of bsh gene in the isolate. HK01 strain showed high resistance to lysozyme, good adaptation to simulated gastric juice and a moderate bile tolerance. Results obtained from simulated gastric juice conditions showed no significant difference occured during the 70 min. HK01 strain was classified as a strain with low hydrophobicity (34.2 %). Addition of trisodium citrate dehydrates as a food-grade chelator of divalent cations restored antibacterial compound production in MRS broth. Antibacterial compounds of L. plantarum HK01 endured treatment with 10 g/L of SDS, Tween 20, Tween 80 and urea. Concerning food additives, the results demonstrated that antibacterial compound production by L. plantarum HK01 was influenced by the presence of surfactants, EDTA, KCl and sodium citrate.

Differential proteome analysis of a selected bacterial strain isolated from a high background radiation area in response to radium stress.

The present study describes the response of a bacterial strain, isolated from a hot spring in an area with the highest levels of natural radiation, under radium ((226)Ra) stress. The bacterium has been characterized as a novel and efficient radium biosorbent and identified as a variant of Serratia marcescens by biochemical tests and molecular recognition. In order to gain insights into key cellular events that allow this strain to survive and undergo (226)Ra adaptation and biosorption, the strain was tested under two experimental conditions of 1000 and 6000 Bq (226)Ra stress. A proteomic approach involving two-dimensional polyacrylamide gel electrophoresis and mass spectrometry was used to identify the differentially expressed proteins under (226)Ra stress. Functional assessment of identified proteins with significantly altered expression levels revealed several mechanisms thought to be involved in (226)Ra adaptation and conferring resistant phenotype to the isolate, including general stress adaptation, anti-oxidative stress, protein and nucleic acid synthesis, energy metabolism, efflux and transport proteins. It suggests that this strain through evolution is particularly well adapted to the high background radiation environment and could represent an alternative source to remove (226)Ra from such areas as well as industrial radionuclide polluted wastewaters.

Biosurfactant-producing bacterium, Pseudomonas aeruginosa MA01 isolated from spoiled apples: physicochemical and structural characteristics of isolated biosurfactant.

An extensive investigation was conducted to isolate indigenous bacterial strains with outstanding performance for biosurfactant production from different types of spoiled fruits, food-related products and food processing industries. An isolate was selected from 800 by the highest biosurfactant yield in soybean oil medium and it was identified by 16S rRNA and the two most relevant hypervariable regions of this gene; V3 and V6 as Pseudomonas aeruginosa MA01. The isolate was able to produce 12 g/l of a glycolipid-type biosurfactant and generally less efficient to emulsify vegetable oils compared to hydrocarbons and could emulsify corn and coconut oils more than 50%. However, emulsification index (E(24)) of different hydrocarbons including hexane, toluene, xylene, brake oil, kerosene and hexadecane was between 55.8% and 100%. The surface tension of pure water decreased gradually with increasing biosurfactant concentration to 32.5 mNm(-1) with critical micelle concentration (CMC) value of 10.1mg/l. Among all carbon substrates examined, vegetable oils were the most effective on biosurfactant production. Two glycolipid fractions were purified from the biosurfactant crude extracts, and FTIR and ES-MS were used to determine the structure of these compounds. The analysis indicated the presence of three major monorhamnolipid species: R(1)C(10)C(10), R(1)C(10)C(12:1), and R(1)C(10)C(12); as well as another three major dirhamnolipid species: R(2)C(10)C(10), R(2)C(10)C(12:1), and R(2)C(10)C(12). The strain sweep experiment for measuring the linear viscoelastic of biosurfactant showed that typical behavior characteristics of a weak viscoelastic gel, with storage modulus greater than loss modulus at all frequencies examined, both showing some frequency dependence.

Biosorption of cadmium by Brevundimonas sp. ZF12 strain, a novel biosorbent isolated from hot-spring waters in high background radiation areas.

The aim of this study is to screen cadmium biosorbing bacterial strains isolated from soils and hot-springs containing high concentrations of radium ((226)Ra) in Ramsar using a batch system. Brevundimonas sp. ZF12 strain isolated from the water with high (226)Ra content caused 50% removal of cadmium at a concentration level of 250 ppm. The biosorption equilibrium data are fitted well by the Langmuir adsorption isotherm and kinetic studies indicated that the biosorption follows pseudo second-order model. The effect of different physico-chemical parameters like biomass concentration, pH, cadmium concentration, temperature and contact time on cadmium sorption was also investigated using FTIR, SEM and XRD analytical techniques. A high desorption efficiency (above 90%) was obtained using a pH range of 2.0-4.0. Reusability of the biomass was examined under consecutive biosorption-desorption cycles repeated thrice. In conclusion, Brevundimonas sp. ZF12 is proposed as an excellent cadmium biosorbent that may have important applications in Cd removal from wastewaters.