The photo-catalytic degradation efficiency of several commercial titania powders (Degussa P-25 and Ishihara Sangyo ST-01) and ofTiO2supported on diatomite were investigated in the degradation of a reactive dye (RED-3BA) under UV-Visible light. The observed rate constant for Degussa P-25 was found to be higher than that achieved by using Ishihara Sangyo ST-01 (kobs=3.3×10−2min−1for Degussa P-25 and4×10−4min−1for Ishihara Sangyo ST-01). This could be related to the amount of basic hydroxyl groups on the surface ofTiO2particles as shown in the IR spectra.TiO2Degussa P-25 supported on diatomite was prepared by dip-coating method. The photo-catalytic activity of supportedTiO2was twice smaller thanTiO2Degussa P-25 (kp-25=3.3×10−2min−1;kp25/diatomite=1.6×10−2min−1). The higher surface areas of ST-01 and theTiO2/diatomite could not lead to a higher degradation rate and to a higher degree of mineralization butTiO2/diatomite could be separated more promptly and more easily from the solution. The effect of pH was investigated in the range 4–9. Acidic (pH = 4)mediumwas found to favor the adsorption and degradation rate with P-25 particles.
In the context of global climate changes, mangroves are not only considered as an important ecological region but also as a source of exploitation of specific biological objects for researches and applications. In this study, mangrove-derived bacteria were isolated and screened for antimicrobial producers. Also, the strains with potential antibacterial activity were identified by 16S rRNA gene analysis. Results showed that 43% of 21 strains possessed antibacterial activity. The strain R10 showed inhibition against all four indicator bacteria and was identified as Bacillus pumilus with the highest sequence similarity of 100% to Bacillus pumilus NCTC10337 (GenBank accession number LT906438.1). The strain R7 inhibited Serratia marcescens causing severe “white spot” disease in reef building coral Acropora palmata and was closely related to Bacillus toyonesis BCT 7112 (GenBank accession number NR121761.1) with 99% sequence similarity. The strain R3 was the strongest strain against Bacillus subtilis compared with other strains which revealed the same antimicrobial activity pattern. The strain R3 was affiliated with Bacillus marisflavi TF-11 (GenBank accession number NR025240.1) with 98% sequence similarity and may be considered to represent new species. Moreover, the strain R9 inhibited only Gram negative tested strain and this strain was considered as a potential candidate for further search of antibiotics with spectrum of Gram negative bacteria.
Abstract:The high demand of Oncidium orchids leads us to find out efficient methods of propagating them. However, the propagation rate of traditional methods are low in nature and a hybrid seed is not genetically stable. Thus, plant cell biotechnology is examined as the most effective way to resolve the barrier of elite clone production. Shoot clusters were cultured on MS medium supplemented with 2,4-D (1 mg/l) for callus induction (76.19%) before induced callus was favoured for PLBs regeneration (98 PLBs/callus cluster) on MS medium supplemented with NAA (0.75 mg/l); the combination of BA (0.5 mg/l) and NAA (0.5 mg/l) was favoured for PLBs regeneration (28.18 PLBs/shoot cluster) from shoots cultivation. The PLBs (79.21 PLBs/PLB cluster) were then proliferated on MS medium supplemented with NAA (1 mg/l) and BA (1 mg/l) for shoot regeneration (12.42 shoots/PLBs cluster). Multiple-shoots were divided to 3-4 shoots/cluster for micropropagation on the MS medium supplemented with the combination of BA (0.25 mg/l) and NAA (0.25 mg/l) to reach 11.66 shoots/cluster. Shoots were finally separated to single-shoot for rooting on the MS medium supplemented with NAA (0.75 mg/l). A scheme for Oncidium micropropagation using PLBs culture techniques was set up.UDC Classification: 57.01; DOI: http://dx
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