Search

Recently, plastic wastes are considered a main environmental problem, and many bacterial isolates were tested to biodegrade them. The low-density polyethylene (LDPE) plastic sheets were tested to be degraded by a marine bacterial consortium. The potent marine plastic degrading isolates were biochemically identified as Bacillus licheniformis, Bacillus subtilis, and Paenibacillus xylanilyticus using the BIOLOG identification system. The identification of the most potent plastic-degrading bacterium was confirmed as Bacillus licheniformis FMMA using the 16S rRNA gene sequence. This bacterial consortium was physiologically adjusted as follows: pH 7, temperature 35°C, inoculum size 4ml/ 100ml (1.0X107CFU/ ml), and an incubation period of 30 days. It led to 34.1% plastic loss of weight. The mechanical properties (maximum force and the elongation% at break) of these treated LDPE plastic sheets showed 7.49N and 112.2%, respectively, compared to that of B. licheniformis FMMA, which showed a 25.5% plastic weight loss, with maximum force and elongation% at a breakpoint of 8.9N and 114.2%, respectively. In addition, the plastic biodegradation was also estimated through a scanning electron microscopy and Fourier transform-infrared (FTIR) spectroscopy, were a great reduction in the intensity of the -CH2 peak appeared at 2900cm-1, and the disappearance of the -OH peak at 3500cm-1 was observed. [ABSTRACT FROM AUTHOR]

In biological engineering, cell immobilization is a modern technique for immobilizing free cells in a small space. Disintegration and elimination of azo dyes [Reactive Orange 122 (orange 2RL) and Reactive Red 194 (Reactive Red M-2BF)] were investigated by using Chlorococcum sp. and Chlorococcum sp. mixed with Scenedesmus obliquus, respectively. After 7 days of incubation, the maximum decolorization was spotted at 40 ppm for Reactive Orange 122 and 20 ppm for Reactive Red 194 by Chlorococcum sp. and Chlorococcum sp. mixed with S. obliquus, respectively. The findings revealed that the best decolorization activity was found at pH 11 and 25 °C under aeration conditions. BG11 was considered the best medium for azo dye decolorization with a high decolorization percentage. Additionally, different concentrations of nitrogen and phosphorus show the high activity of decolorization of both dyes. Referring to vitamins (thiamin and Ascorbic acid), all studied concentrations showed high decolorization activity with immobilized Chlorococcum sp. mixed with S. obliquus; however, different concentrations (20, 40, and 60 mg/l) of thiamin showed completely decolorization of Reactive Red 194 after 3 days, and 60 mg/l of ascorbic acid showed completely decolorization of Reactive Orange 122 after 5 days of inoculation. FT-IR and GC-Ms analysis for azo dyes after and before treatment with Immobilization of Chlorococcum sp. and Chlorococcum sp. mixed with Scenedesmus obliquus were detected. Novelty statement: The natural carrier algae and its consortium combined with a suitable immobilization technique were considered in this study, which is non-toxic, enhanced their bioremediation potential for dyes, and allowed multiple uses of biocatalysts. The novel use of the immobilization and its consortium of algae on the degradation efficiency of azo dyes and studying the effect of physicochemical conditions on decolorization and degradation of azo dyes. Application of immobilization techniques using microalgae could be excellent bioremediation of wastewaters. [ABSTRACT FROM AUTHOR]

Copyright of Egyptian Journal of Experimental Biology (Botany) is the property of Egyptian Society of Experimental Biology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Environmental pollution with toxic heavy metals is increasing throughout the world alongside industrial development. Microorganisms and microbial products can be highly efficient bioaccumulators of soluble and particulate forms of metals, especially dilute external solutions. Microbe related technologies (Biotechnology) may provide an alternative or additive conventional method for metal removal or metal recovery. This study dealt with isolation, identification and characterization of heavy metal-resistant (Pb2+, Cd2+, Al3+, Cu2+, Ag2+ and Sn2+) bacteria from sewage wastewater at Taif Province, Saudi Arabia. Nine bacterial isolates were selected by using an enrichment isolation procedure based on high level of heavy metal resistance. All the isolates showed high resistance to heavy metals with Minimum Inhibitor Concentration (MIC) ranging from 800 μg/ml to 1400 μg/ml. All nine resistant isolates showed multiple tolerances to heavy metals. On the basis of morphological, biochemical and 16S rRNA characterization, the most potent isolates (Cd1-1, Ag1-1, Ag1-3 and Sn1-1) were identified as Alcaligenes faecalis. Scanning electron microscope analysis showed that the morphology of Alcaligenes faecalis Ag1-1 was unchanged after growth in medium without and with addition of Ag2+ indicative Ag2+ is not toxic to the isolate under the conditions tested. The ability of Alcaligenes faecalis Ag1-1 to synthesize sliver nanoparticles was examined. The heavy metal-resistant bacteria obtained could be useful for the bioremediation of heavy metal-contaminated environment. [ABSTRACT FROM AUTHOR]