Aim: To isolate and characterize lactic acid bacteria (LAB) and determine whether they could potentially be used as heavy metal (cadmium and lead) absorbing probiotics. Methods and Results: The study ...used 53 environmental (mud and sludge) samples to isolate cadmium‐ and lead‐resistant LAB, by following spared plate technique. A total of 255 cadmium‐ and lead‐resistant LAB were isolated from these samples. The survival of 26 of the LAB was found after passing through sequential probiotic characterizations. These 26 probiotic LAB exhibited remarkable variations in their metal‐resistant and metal‐removal abilities. Of 26, seven (Cd54‐2, Cd61‐7, Cd69‐12, Cd70‐13, Pb82‐8, Pb96‐19 and Cd109‐16) and four (Pb71‐1, Pb73‐2, Pb85‐9 and Pb96‐19) strains displayed relatively elevated cadmium‐ and lead‐removal efficiencies from water, respectively, compare with that of the remaining strains. Strains Cd70‐13 and Pb71‐1 showed the highest cadmium (25%) and lead (59%) removal capacity from MRS (De Man, Rogosa and Sharpe) culture medium, respectively, amongst the selected strains and showed a good adhesive ability on fish mucus. A phylogenetic analysis of their 16S rDNA sequences revealed that the strains Cd70‐13 and Pb71‐1 belong to Lactobacillus reuteri. Conclusion: Excellent probiotic, metal sorption and adhesive characteristics of newly identified Lact. reuteri strains Cd70‐13 and Pb71‐1 were isolated, which indicated their high potential abilities to survive in the intestinal milieu and to uptake the tested metals from the environment. Significance and Impact of the Study: To our knowledge, this is the first study that has aimed to isolate, characterize and identify metal‐resistant LAB strains that have potential to be a probiotic candidate for food and in vivo challenge studies in the intestinal milieu of fish for the uptake and control of heavy metal bioaccumulation.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
PGR5 has been reported as an important factor for the activity of the ferredoxin-dependent cyclic electron transport around PSI. To elucidate the role of PGR5 in C3 photosynthesis, we characterized ...the photosynthetic electron transport rate (ETR), CO2 assimilation and growth in the Arabidopsis thaliana pgr5 mutant at various irradiances and with CO2 regimes. In low-light-grown pgr5, the CO2 assimilation rate and ETR were similar to the those of the wild type at low irradiance, but decreased at saturating irradiance under photorespiratory conditions as well as non-photorespiratory conditions. Although non-photochemical quenching of chlorophyll fluorescence (NPQ) was not induced in the pgr5 mutant under steady-state photosynthesis, we show that it was induced under dark to light transition at low CO2 concentration. Under low light conditions in air, pgr5 showed the same growth as the wild type, but a significant growth reduction compared with the wild type at >150 μmol photons m−2 s−1. This growth impairment was largely suppressed under high CO2 concentrations. Based on the intercellular CO2 concentration dependency of CO2 assimilation, ETR and P700 oxidation measurements, we conclude that reduction of photosynthesis and growth result from (i) ATP deficiency and (ii) inactivation of PSI. We discuss these data in relation to the role of PGR5-dependent regulatory mechanisms in tuning the ATP/NADPH ratio and preventing inactivation of PSI, especially under conditions of high irradiance or enhanced photorespiration.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The present study attempted to identify the efficient hazardous metal-removing sorbent from specific types of soil, upper and middle layer shirasu, shell fossil, tuff, akadama and kanuma soils of ...Japan by physico-chemical and metal (arsenic, cadmium and lead) removal characterizations. The physico-chemical characteristics of soil were evaluated using X-ray diffraction and scanning electron microscopy with energy dispersive spectroscopy techniques, whereas metal removal properties of soil were characterized by analyzing removal capacity and sorption kinetics of potential metal-removing soils. The chemical characteristics revealed that all soils are prevalently constituted of silicon dioxide (21.83–78.58 %), aluminum oxide (4.13–38 %) and ferrous oxide (0.835–7.7 %), whereas calcium oxide showed the highest percentage (65.36 %) followed by silicon dioxide (21.83 %) in tuff soil. The results demonstrated that arsenic removal efficiency was higher in elevated aluminum oxide-containing akadama (0.00452 mg/L/g/h) and kanuma (0.00225 mg/L/g/h) soils, whereas cadmium (0.00634 mg/L/g/h) and lead (0.00693 mg/L/g/h) removal efficiencies were maximum in elevated calcium oxide-containing tuff soil. Physico-chemical sorption and ion exchange processes are the metal removal mechanisms. The critical appraisal of three metal removal data also clearly revealed cadmium > lead > arsenic order of removal efficiency in different soils, except in tuff and akadama soils followed by lead > cadmium > arsenic. It clearly signified that each type of soil had a specific metal adsorption affinity which was regulated by the specific chemical composition. It may be concluded that akadama would be potential arsenic-removing and tuff would be efficient cadmium and lead-removing soil sorbents.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The contamination of hazardous metal(loid) is one of the serious environmental and human health risks. This study isolated a total of 40 cadmium (Cd)- and arsenic (As)-resistant bacterial isolates ...from coastal sediments by pour plate technique using tryptic soy agar supplemented with Cd or As (50 mg l⁻¹) for use as metal(loid) bioremediation agents. Out of 40, 4 isolates, RCd3, RCd6, RAs7, and RAs10, showed a relatively higher growth rate in Cd- or As-supplemented culture media which were selected for further study. The selected isolates showed a high minimum inhibitory concentration (60–400 mg l⁻¹for Cd and 400–2200 mg l⁻¹for As), which demonstrated their remarkable Cd and As resistance capabilities. The metal(loid) removal efficiencies (0.032–0.268 μg Cd h⁻¹ mg⁻¹and 0.0003–0.0172 μg As h⁻¹ mg⁻¹wet weight cell) of selected isolates indicated their greater magnitude in absorbing Cd compared to As from water. Phylogenetic analysis of the 16S rDNA sequences revealed that isolates RCd3, RCd6, RAs7, and RAs10 were closely related to Acinetobacter brisouii, Pseudomonas abietaniphila, Exiguobacterium aestuarii, and Planococcus rifietoensis, respectively. Because of high Cd and As resistance and removal efficiency, the selected isolates can survive in a high metal(loid)-contaminated environment and could be a potential tool for bioremediation of high metal(loid)-contaminated effluents to protect the aquatic environment.
The purpose of the present study was to isolate and identify the metal-resistant lactic acid bacteria from sediments of coastal aquaculture habitats for removal of cadmium and lead from ambience. ...Collected sediment samples were used to isolate the cadmium- and lead-resistant bacterial colonies by spread plate technique using agar media (De Man, Rogosa and Sharpe) supplemented with cadmium or lead at 50 mg/l. Isolates were identified by bacterial colony polymerase chain reaction and sequencing of 16S ribosomal deoxyribonucleic acid. Metal removing probiotic was determined by characterizing the lactic acid yield in culture media, viability in fish intestine, metal-resistant and metal-removal efficiencies. 16S ribosomal deoxyribonucleic acid sequencing data of five (Cd10, Cd11, Pb9, Pb12 and Pb18) and other all isolates clearly showed 99 % similarities to
Enterococcus faecium
and
Bacillus cereus,
respectively. The Pb12 exhibited higher lactic acid yield (180 mmol) than that of the remaining
E. faecium
strains and excellent viability without pathogenicity; therefore, further study was carried out using Pb12 strain. The selected Pb12 strain showed elevated metal resistant (minimum inhibitory concentrations 120 and 800 mg/l for cadmium and lead, respectively) and removal efficiencies Cadmium 0.0377 mg/h/g and lead 0.0460 mg/h/g of cells (wet weight). From the viability and metal removal points of view, it can be concluded that isolated metal-resistant
E. faecium
Pb12 strains might be used as potential probiotic strains for removing heavy metals from fish intestinal milieu to control the progressive bioaccumulation of heavy metals in the fish.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Shrimp farming is a sufficiently large and mature industry to have an effective range of antimicrobial agents for most bacterial diseases in shrimp culture. However, at present, there exists great ...concern over the widespread use of antibiotics in aquaculture, which may result in residue of antibiotics in water and mud, and subsequently, the development of antibiotic resistance in bacteria in the environment. There is limited understanding about the effect of antibiotic residues on bacteria resistance in shrimp farming environment. Therefore, a study was conducted to investigate bacterial resistance to Norfloxacin (NFXC), Oxolinic Acid (OXLA), Trimethoprim (TMP) and Sulfamethoxazole (SMX), which were found in four shrimp farming locations in mangrove areas in Vietnam. Findings indicate that there is a relatively high incidence of bacteria resistance to these antibiotics observed in most of the studied sites, particularly to antibiotics with concentration of 0.1 μg/ml. Yet the relation between concentration of antibiotic residues and incidence of antibiotic resistance is not clearly defined. Among individual antibiotics, the incidence of resistance to TMP and SMX was higher than the others. Identification of bacteria isolated from mud samples by DNA analyzer shows that
Bacillus and
Vibrio are predominant among bacteria resistant to the antibiotics. The result of the study also indicates that these antibiotics in media degraded more rapidly due to the presence of resistant bacteria.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
An experiment was conducted using 15 glass aquariums to ascertain the pathways of removal of cadmium through numerical and compositional manipulation of ecosystem components and their role in Cd ...removal in different aquatic ecosystems. Each aquarium was provided with surface sediment @ 2
kg, filled with 15
L tap water and randomly distributed into five treatments having three replicates in each. Cadmium chloride (CdCl
2) of analytical grade was added @ 2
mg/L to the water of each aquarium and mixed gently. Except for the first one, the other four systems received unio (
Lamellidens marginalis, 55
±
2.5
g) @ 6
pieces/aquarium. Tilapia (
Oreochromis mossambicus, 35
±
3
g) was introduced @ 6
fish/aquarium in the third and fifth systems, whereas pistia
(Pistia stratiotes) was introduced @ 50
g/aquarium in the fourth and fifth systems for a 28-day observation period. The samples of water, sediment, unio, fish and pistia were collected from different systems at 7-day intervals and analyzed. Results revealed that mean substantial reduction of Cd in water varied between 1.820 and 1.994
mg/L in different simulated ecosystems. Ecosystem efficiency of Cd removal varied in the different ecosystems and showed highest (11%) value in the ecosystem carrying five components, which suggested a cumulative effect of increasing number of components employed in different simulated aquatic ecosystems significantly facilitated the reduction of the level of Cd concentration in water column. Pistia exerted (12.88–547.5 times) higher rate of Cd accumulation over the other components employed in five simulated ecosystems of various component structures. Therefore, in the present study, it may be concluded that ecosystems carrying five components exhibited the best performance for optimum minimization of Cd removal from water column. It can also be concluded that ecosystem components showed a variable performance and pistia was the efficient component from the perspective of Cd removal.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The removal of As(III) ions from aqueous solutions has been investigated using silica ceramic under different experimental conditions of initial arsenite concentration, adsorbent dose, temperature ...and pH. Better removal was obtained at temperature 25 degree C and pH 7.5. The adsorption data have been explained in terms of Langmuir and Freundlich equations. The sorption kinetics was tested for the pseudo-first order, pseudo-second order reaction and intra-particle diffusion, at different experimental conditions. The results revealed that the adsorptions of As(III) onto silica ceramic, which were found to well, fit by the Freundlich isotherm. The rate constants of sorption for kinetic models were calculated and good correlation coefficients (R super(2)> 0.9974) obtained for the pseudo-second order kinetic model. The result indicates that under the optimum conditions, the maximum adsorption value (1.7886 mg/g) comply that the silica ceramic is an effective adsorbent for arsenite.
The present investigation attempted to develop the ceramic adsorbent media in order to remove the mercury from aqueous phase. Two ceramics, akadama volcanic ash soil-ceramic (A-ceramic) and improved ...magnesium oxide impregnated akadama volcanic ash soil-ceramic (MA-ceramic) were produced from raw akadama volcanic ash soil by heating process to determine the Hg (II) adsorption capacity. Adsorption experiments of ceramics were performed as a function of contact time, solution pH, adsorbent dosage and adsorbate concentration following the batch mode operation. Results clearly revealed the adsorption capacity (265 plus or minus 8.5 mu g/g) of MA-ceramic is significantly higher ( similar to 12 times) than that of the A-ceramic material. The adsorption was largely pH dependent and neutral pH was associated with higher mercury adsorption capacity in both ceramics. MA-ceramic showed 94% and 86% desorption and resorption capacities, respectively.
Photosynthesis provides at least two routes through which light energy can be used to generate a proton gradient across the thylakoid membrane of chloroplasts, which is subsequently used to ...synthesize ATP. In the first route, electrons released from water in photosystem II (PSII) are eventually transferred to NADP+ by way of photosystem I (PSI). This linear electron flow is driven by two photochemical reactions that function in series. The cytochrome b6f complex mediates electron transport between the two photosystems and generates the proton gradient (deltapH). In the second route, driven solely by PSI, electrons can be recycled from either reduced ferredoxin or NADPH to plastoquinone, and subsequently to the cytochrome b6f complex. Such cyclic flow generates deltapH and thus ATP without the accumulation of reduced species. Whereas linear flow from water to NADP+ is commonly used to explain the function of the light-dependent reactions of photosynthesis, the role of cyclic flow is less clear. In higher plants cyclic flow consists of two partially redundant pathways. Here we have constructed mutants in Arabidopsis thaliana in which both PSI cyclic pathways are impaired, and present evidence that cyclic flow is essential for efficient photosynthesis.
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DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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