Removal of lead (Pb(2+)) by the cyanobacterium Gloeocapsa sp

Pb²⁺ removal ability of the viable-freshwater cyanobacterium Gloeocapsa sp. was studied in batch experiments. Gloeocapsa sp. was cultured in the Medium 18 with pH adjusted to 3, 4, 5, 6 and 7. Growth was subsequently determined based on the increase of chlorophyll-a content. Gloeocapsa sp. was able to grow at all pH levels tested, except at pH 3. Removal of Pb²⁺ was then further studied under pH 4. The results showed that Pb²⁺ concentration in the range of 0–20 mg L⁻¹ was not inhibitory to Gloeocapsa sp. growth but reduced its Pb²⁺ removal efficiency (by 4.5% when Pb²⁺ concentration increased from 2.5 to 20 mg L⁻¹). Pb²⁺ removal characteristics followed the Langmuir adsorption isotherm with the maximum removal capacity (q_max) of 232.56 mg g⁻¹. Adsorption of Pb²⁺ by this cyanobacterium followed the second order rate reaction and intraparticle diffusion was likely the rate-determining step. The initial rate of Pb²⁺adsorption during intraparticle diffusion was slower under light than under dark conditions, indicating that light probably slowed down the initial rate of intraparticle diffusion through the repulsion effects on cell membrane.     

Serotypes of Cryptococcus neoformans isolated from patients prior to and during the AIDS era in Thailand

One hundred and eighty-seven strains of Cryptococcus neoformans isolated from patients in Thailand were charcterized by biochemical varieties relating to serogroups. Canavanine-glycine-bromothymol blue (CGB) agar was used for differentiating the varieties of C. neoformans. Slide agglutination tests were performed with Crypto Check (Iatron, Inc., Tokyo) to determine their serotypes. Fifty-five percent (10 out of 18) of the pre-AIDS isolates were serotype B, 28% were serotype A, 5% were serotype D, and an unexpected 11% (2 out of 18) were serotype C. These are the first to be recorded in Asia. In contrast, among the 169 clinical isolates obtained between January 1993 and March 1995 (AIDS epidemic), serotype A was outstandingly predominant-93% (157 out of 169), serotype B was relatively low (3.6%) and both serotypes D and AD were 1.8%. The pattern of serotypes of the 59 isolates from known HIV-positive patients was closely similar to the total isolates during the AIDS epidemic. In determining the varieties of C. neoformans by CGB, only 1 of the 187 isolates gave a false reaction. On the basis of our findings, we believe that in the pre-AIDS era either C. neoformans var. gattii serorype B or serotype C were the common causative agents of cryptococcosis in Thailand. The advent of AIDS changed the pattern of serotypes with serotype A becoming predominant as has been reported world wide.     

Role of curcuminoids in ameliorating oxidative modification in β-thalassemia/Hb E plasma proteome

Thalassemic patients often exhibit high levels of oxidative stress and iron overload, which can lead to hazardous complications. Curcuminoids, extracted from the spice turmeric, are known to have antioxidant and iron-chelating properties and have been proposed as a potential upstream therapy of thalassemia. Here we have applied proteomic techniques to study the protein profile and oxidative damage in the plasma of β-thalassemia/Hb E patients before and after treatment with curcuminoids. In this study, 10 β-thalassemia/Hb E patients were treated with 500 mg curcuminoids daily for 12 months. The plasma protein profile and protein carbonyl content were determined at baseline, 6 and 12 months using two-dimensional fluorescence difference gel electrophoresis and carbonyl immunoblotting, respectively. Other hematological, clinical, and biochemical parameters were also analyzed. Twenty-six spots, identified as coagulation factors and proteins involved in iron homeostasis, showed significantly decreased intensity in thalassemic plasma, compared to those of normal subjects. Treatment with curcuminoids up-regulated the plasma levels of these proteins and reduced their oxidative damage. Serum non-transferrin bound iron, platelet factor-3 like activity, oxidative stress parameters and antioxidant enzymes were also improved after curcuminoids treatment. This study is the first proteomic study of plasma in the thalassemic state and also shows the ameliorating role of curcuminoids towards oxidative stress and iron overload in the plasma proteome.     

Plant regeneration by somatic embryogenesis and organogenesis in commercial pineapple (<Emphasis Type="Italic">Ananas comosus</Emphasis> L.)

Summary Axillary and terminal buds from suckers of Ananas comosus cv. Phuket were established on Murashige and Tucker-based (MT) medium with 2.0 mgl⁻¹ (9.8 μM) indolebutyric acid, 2.0 mgl⁻¹ (10.74 μM) naphthaleneacetic acid, and 2.0 mgl⁻¹ (9.29 μM) kinetin, followed by multiplication on Murashige and Skoog-based (MS) medium containing 2.0 mgl⁻¹ (8.87 μM) benzyladenine (BA) to provide a continuous supply of axenic shoots. Leaves, excised from such cultured shoots, produced adventitious shoots from their bases when these explants were cultured on MS medium containing 0.5 mgl⁻¹ (2.26 μM) 2,4-dichlorophenoxyacetic acid (2,4-D) and 2.0 mgl⁻¹ (8.87 μM) BA. Embryogenic callus was produced when leaf explants were cultured on MS medium with 3.0 mgl⁻¹ (12.42 μM) 4-amino-3,5,6-trichloropicolinic acid (picloram). Somatic embryos developed into shoots following transfer of embryogenic tissues to MS medium with 1.0 mgl⁻¹ (4.44 μM) BA. Cell suspensions, initiated by transfer of embryogenic callus to liquid MS medium with 1.0 mgl⁻¹ (4.14 μM) picloram or 1.0 mgl⁻¹ (4.52 μM) 2,4-D, also regenerated shoots by somatic embryogenesis, on transfer of cells to semisolid MS medium with 1.0 mgl⁻¹ (4.44 μM) BA. All regenerated shoots rooted on growth regulator-free MS medium, prior to ex vitro acclimation and transfer to the glasshouse. These studies provide a baseline for propagation, conservation, and genetic manipulation of elite pineapple germplasms.     

Effects of different nitrogen, phosphorus, and iron concentrations and salinity on lipid production in newly isolated strain of the tropical green microalga, Scenedesmus dimorphus KMITL

The fatty acid composition, the effect of different concentrations of nitrogen (16.5-344 mg ?L^?1), phosphorus (9–45 mg? L^?1), iron (9–45 mg? L^?1) and salinity levels (0–20 psu) on lipid production in the green microalga Scenedesmus dimorphus KMITL, a new strain isolated from a tropical country, Thailand, were studied. The alga was isolated from a freshwater fish pond, and cultured in Chlorella medium by varying one parameter at a time. The main fatty acid composition of this strain was C16–C18 (97.52 %) fatty acids. A high lipid content was observed in conditions of 16.5 mg? L^?1-N, or 22 mg ?L^?1-P, or 45 mg ?L^?1-Fe, or 5 psu salinity, which accumulated lipids to 20.3?±?0.4, 19.4?±?0.2, 24.7?±?0.5, and 14.3?±?0.2 % of algal biomass, respectively. Increasing lipid content and lipid productivity was noted when the alga was cultured under high iron concentration and high salinity, as well as under reduced phosphorus conditions, whereas nitrogen limitation only resulted in an increased lipid content.     

Effects of low pH and Pb2+ stress on living cyanobacterium, Phormidium angustissimum West & G.S.West : A test of its feasibility as a living biosorbent

Pb²⁺ adsorption by the living cyanobacterium, Phormidium angustissimum followed the Langmuir adsorption model, with the maximum adsorption capacity (q _max ) of 295.4?±?13.8 mg g^?1. This result suggests that P. angustissimum is a promising living biosorbent to remove Pb²⁺ from wastewaters. Living biosorbents are better able to remove Pb²⁺ from wastewater than dead biosorbents, however there are practical limitations for their use are encountered in extreme conditions such as low pH and high Pb²⁺ concentration. The feasibility of using cyanobacterium, P. angustissimum, as a living biosorbent for the extraction of Pb²⁺ from wastewater was studied by investigating its photosynthestic performance and tolerance under Pb²⁺ (0–5 mg ?L^?1) contamination and low pH (pH?3–7). Decreased photosynthetic performance caused by Pb²⁺ contamination and low pH stress was detected in this study by means of a reduction of the maximum photochemical efficiency of PSII (F_v/F_m). Detoxification mechanisms of P. angustissimum on Pb²⁺ appeared to increase its intracellular polysaccharides (IPS), exocellular polysaccharides (EPS), and protein. Living P. angustissimum could increase the pH of the solution which resulted in Pb²⁺ precipitation. The unique ability of P. angustissimum to remove Pb²⁺ and to grow under toxic conditions, demonstrated herein, indicates that it is a promising living biosorbent for mildly acidic water contaminated with Pb²⁺ in bioremoval systems in the which pH is not lower than 5 and Pb²⁺ is not higher than 5 mg L^?1.