The effect of Ralstonia pickettii bacterium addition on methylene blue dye biodecolorization by brown-rot fungus Daedalea dickinsii

Simplex-lattice design and decision tree optimization of endophytic Trichoderma-multi-walled carbon nanotube composite for enhanced methylene blue removal

This study investigates a novel approach for enhancing methylene blue (MB) removal from water using a composite of endophytic Trichoderma mate and multi-walled carbon nanotubes (MWCNTs). For the first time, a unique combination of simplex-lattice design and decision tree learning algorithm was employed to optimize MB removal. This innovative approach effectively identified the optimal composite ratio of hyphal mate (0.5354 g/L) and MWCNTs (0.4646 g/L) for maximizing MB removal, which achieved remarkable removal efficiency ranging from 63.50 to 95.78 % depending on the combination used. The DT model further demonstrated promising potential for predicting MB removal efficiency. SEM revealed a unique hybrid material formed by the intertwining or entrapment of MWCNTs within the hyphal network of Trichoderma mate. FT-IR analysis confirmed the presence of novel functional groups on the MWCNTs' surface at 2438.79 and 528.25 cm-1, likely due to interactions with the endophytic fungi's biomolecules. These functional groups presumably act as reducing and stabilizing agents, promoting efficient MB adsorption. This research paves the way for utilizing the combined biological and chemical approach (fungal biomass and MWCNTs) in bioremediation applications. The findings suggest significant potential for practical applications in wastewater treatment, providing an eco-friendly and cost-effective method for dye removal. Furthermore, the proposed method shows promise for scaling up to industrial wastewater treatment and applicability in resource-limited settings, offering a sustainable solution for global water pollution challenges. Further investigations with larger datasets incorporating additional influencing factors are necessary to refine the predictive power of the DT model for practical applications.

Romanowsky staining: history, recent advances and future prospects from a chemistry perspective

Romanowsky staining was an important methodological breakthrough in diagnostic hematology and cytopathology during the late 19th and early 20th centuries; it has facilitated for decades the work of biologists, hematologists and pathologists working with blood cells. Despite more than a century of studying Romanowsky staining, no systematic review has been published that explains the chemical processes that produce the "Romanowsky effect" or "Romanowsky-Giemsa effect" (RGE), i.e., a purple coloration arising from the interaction of an azure dye with eosin and not due merely to their simultaneous presence. Our review is an attempt to build a bridge between chemists and biomedical scientists and to summarize the available data on methylene blue (MB) demethylation as well as the related reduction and decomposition of MB to simpler compounds by both light and enzyme systems and microorganisms. To do this, we analyze modern data on the mechanisms of MB demethylation both in the presence of acids and bases and by disproportionation due to the action of light. We also offer an explanation for why the RGE occurs only when azure B, or to a lesser extent, azure A is present by applying experimental and calculated physicochemical parameters including dye-DNA binding constants and electron density distributions in the molecules of these ligands. Finally, we discuss modern techniques for obtaining new varieties of Romanowsky dyes by modifying previously known ones. We hope that our critical literature study will help scientists understand better the chemical and physicochemical processes and mechanisms of cell staining with such dyes.

Biodecolorization and biotransformation of methylene blue using mixed cultures of brown-rot fungus Daedalea dickinsii and filamentous fungus Aspergillus oryzae: identification of metabolites and degradation pathway

This study aimed to examine biodecolorization and biotransformation of methylene blue (MB) using mixed cultures of brown-rot fungus Daedalea dickinsii and filamentous fungus Aspergillus oryzae. In addition, the ratio of D. dickinsii and A. oryzae in mixed cultures was 1 : 1, and the sample was incubated at 30 °C for 7 days in liquid medium potato dextrose broth (PDB). The results showed that the sample had the ability to remove and transform 95.24 mg L-1 MB. In this study, mixed cultures had the highest removal percentage of 64.77%, while values of 5.94% and 36.82% were obtained for single cultures of D. dickinsii and A. oryzae, respectively. LC-TOF/MS analysis results showed that peak intensity of MB compound (m/z 284) in each treatment chromatogram decreased compared to the control. The metabolites of decolorization by D. dickinsii were C15H16N3S, C16H19N3SO, and C16H21N3SO, while C31H48N3S+ was obtained using A. oryzae. For mixed cultures, the metabolites obtained included C26H37N2O3S, C9H8N2O3S, C28H38NO2S, and C27H27N5S2. Based on the results, mixed cultures of D. dickinsii and A. oryzae had a high MB decolorization and could be used in the textile industry.

The application of biosurfactant-producing bacteria immobilized in PVA/SA/bentonite bio-composite for hydrocarbon-contaminated soil bioremediation

Oil spills that contaminate the environment can harm the surrounding ecosystem. The oil contains petroleum hydrocarbon which is toxic to the environment hence it needs to be removed. The use of bacteria as remediation media was modified by immobilizing into a matrix hence the bacteria can survive in harsh conditions. In this research, the ability of biosurfactant-producing bacteria (Pseudomonas aeruginosa, Bacillus subtilis, and Ralstonia pickettii) immobilized in the PVA/SA/bentonite matrix was tested in remediation on oil-contaminated soil. The immobilized beads filled with bacteria were added to the original soil sample, as well as washed soil. The beads were characterized by using FTIR and SEM. Based on FTIR analysis, the PVA/SA/bentonite@bacteria beads had similar functional groups compared to each other. SEM analysis showed that the beads had non-smooth structure, while the bacteria were spread outside and agglomerated. Furthermore, GC-MS analysis results showed that immobilized B. subtilis and R. pickettii completely degraded tetratriacontane and heneicosane, respectively. Meanwhile, after soil washing pre-treatment, immobilized bacteria could completely degrade octadecane (P. aeruginosa and R. pickettii) and tetratriacontane (P. aeruginosa and B. subtilis). Based on those results, immobilized bacteria could degrade oil compounds. The degradation result was influenced by the enzymes produced, the ability of the bacteria, the suitability of the test media, and the matrix used. Therefore, this study can be a reference for further soil remediation using eco-friendly methods.