Articles
Karimi-avargani m., M.,
Biria, D.,
Dehghanifar, S.,
Bazooyar f., F.,
Skrifvars m., M. International Journal of Environmental Science and Technology (17351472)22(4)pp. 2601-2612
The complexity of the vulcanized rubber makes it difficult to be degraded by microorganisms. It is believed that a microbial consortium can improve the efficiency of the biodegradation process. Fertile soil houses a plethora of microorganisms with innate ability to adapt to various chemical substances come into contact with its texture. Consequently, a soil sample which was in direct contact with tire wastes for more than 13 years was employed in this work to enhance the biodegradation of natural rubber (NR) gloves. The active soil microorganisms associated with the NR latex degradation were isolated and identified using 16S rRNA gene sequencing method. The biodegradation of NR gloves in the soil sample containing these bacteria was investigated and the results represented 87% and 79% weight loss in the examination and surgical gloves after 12 months of treatment, respectively. The total biodegradation was achieved after 13 and 15 months which was nearly half of the reported time in the landfill processes. Thermal gravimetric analysis (TGA) showed 15% incremental weight decrease for the treated samples after three months in comparison with the blanks and the FT-IR spectra approved the breaking of the cross-link sulfur bonds as well as the formation of carbonyl groups which indicated oxidative cleavage of double bonds of the polymer chain. A chemical mechanism for the biodegradation was suggested based on the obtained results to explain the higher efficiency of biodegradation in this work. © The Author(s) under exclusive licence to Iranian Society of Environmentalists (IRSEN) and Science and Research Branch, Islamic Azad University 2024.
RSC Advances (20462069)15(30)pp. 24624-24638
The regulation and improvement of mass transfer through the living cell's membrane is of great importance in various industrial, environmental and medical applications. Designing membrane channels based on carbon nanotubes (CNTs) has been considered as a promising approach to this end because of the geometry of CNTs, their physical properties, high chemical stability, and excellent transport features. Despite their advantages, CNTs have a few problems such as their toxicity to living cells, low bioavailability in an aqueous medium and difficulties with managing their orientation within the cell membrane which should be addressed in the first place. Here, we tried to review recent studies on overcoming these challenges and critically evaluate their advances and suggestions for future research. Functionalization of CNTs with biocompatible materials has been recommended as the main solution which decreases the inherent cytotoxicity of the pristine CNTs, enhances their solubility and dispersibility in aqueous solution, and affects their orientation in the cell membrane. Molecular dynamics simulation results for the interactions of the functionalized CNTs and the cell membrane have been reviewed as well to demonstrate the effectiveness of functionalizing CNTs for membrane channel applications. Finally, we highlighted that modified CNTs with appropriate functional groups and favorable physical and geometrical conditions can be considered as an effective tool to make artificial channels in the cell membrane. © 2025 The Royal Society of Chemistry.
Pseudomonas putida is a soil bacterium with multiple uses in fermentation and biotransformation processes. P. putida ATCC 12633 can biotransform benzaldehyde and other aldehydes into valuable α-hydroxyketones, such as (S)-2-hydroxypropiophenone. However, poor tolerance of this strain toward chaotropic aldehydes hampers efficient biotransformation processes. To circumvent this problem, we expressed the gene encoding the global regulator PprI from Deinococcus radiodurans, an inducer of pleiotropic proteins promoting DNA repair, in P. putida. Fine-tuned gene expression was achieved using an expression plasmid under the control of the LacIQ/Ptrc system, and the cross-protective role of PprI was assessed against multiple stress treatments. Moreover, the stress-tolerant P. putida strain was tested for 2-hydroxypropiophenone production using whole resting cells in the presence of relevant aldehyde substrates. P. putida cells harbouring the global transcriptional regulator exhibited high tolerance toward benzaldehyde, acetaldehyde, ethanol, butanol, NaCl, H2O2 and thermal stress, thereby reflecting the multistress protection profile conferred by PprI. Additionally, the engineered cells converted aldehydes to 2-hydroxypropiophenone more efficiently than the parental P. putida strain. 2-Hydroxypropiophenone concentration reached 1.6 g L−1 upon a 3-h incubation under optimized conditions, at a cell concentration of 0.033 g wet cell weight mL−1 in the presence of 20 mM benzaldehyde and 600 mM acetaldehyde. Product yield and productivity were 0.74 g 2-HPP g−1 benzaldehyde and 0.089 g 2-HPP g cell dry weight−1 h−1, respectively, 35% higher than the control experiments. Taken together, these results demonstrate that introducing PprI from D. radiodurans enhances chaotrope tolerance and 2-HPP production in P. putida ATCC 12633. © 2024 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd.
