Isolation, screening and molecular identification of novel bacterial strain removing methylene blue from water solutions

Abstract

The potentially deleterious effects of methylene blue (MB) on human health drove the interest in its removal promptly. Bioremediation is an effective and eco friendly for removing MB. Soil bacteria were isolated and examined for their potential to remove MB. The most potent bacterial candidate was characterized and identified using 16S rRNA sequence technique. The evolutionary history of the isolate was conducted by maximum likelihood method. Some physiochemical parameters were optimized for maximum decolorization. Decolorization mechanism and microbial toxicity study of MB (100 mg/l) and by-products were investigated. Participation of heat killed bacteria in color adsorption have been investigated too. The bacterial isolate was identified as Stenotrophomonas maltophilia strain Kilany_MB 16S ribosomal RNA gene with 99% sequence similarity. The sequence was submitted to NCBI (Accession number = KU533726). Phylogeny depicted the phylogenetic relationships between 16S ribosomal RNA gene, partial sequence (1442 bp), of the isolated strain and other strains related to Stenotrophomonas maltophilia in the GenBank database. The optimal conditions were investigated to be pH 5 at 30°C, after 24 h using 5 mg/l MB showing optimum decolorization percentage (61.3%). Microbial toxicity study demonstrated relative reduction in the toxicity of MB decolorized products on test bacteria. Mechanism of color removal was proved by both biosorption and biodegradation, where heat-killed and live cells showed 43 and 52% of decolorization, respectively, as a maximum value after 24-h incubation. It was demonstrated that the mechanism of color removal is by adsorption. Therefore, good performance of S maltophilia in MB color removal reinforces the exploitation of these bacteria in environmental clean-up and restoration of the ecosystem.

Silver Nanoparticle Production by Ruta graveolens and Testing Its Safety, Bioactivity, Immune Modulation, Anticancer, and Insecticidal Potentials

“…The positive control (penicillin/streptomycin at 20 units/20 μ g, respectively) solution and the negative control (nutrient broth) solution, 30 μ L each, were included. Different plates were incubated for 24 h at 37°C, and zones (mm diameter) of inhibition around each well were measured in triplicate [ 37 ].…”

Methylene blue decolorizing bacteria isolated from water sewage in Yogyakarta, Indonesia

“…The exact mechanism of methylene blue decolorization by C. aquatica PMB-1 and R. mannitolilytica PMB-2 still needs to be studied. However, previous studies on methylene blue-decolorizing bacteria showed that methylene blue removal from aqueous solution mainly achieved by two primary mechanisms, i.e.,: biosorption and biodegradation (Noraini et al 2012;Eslami et al 2017;Habibi and Mehrabi 2017;Kilany 2017). Biosorption of cationic dyes which was observed not only on bacterial surface but also on other biomass including fungi (Maas et al 2018), algae (Guarin et al 2018) and water plant (Pinontoan et al 2019), occurs through interaction between negatively-charged phosphate groups on the surface of the biomass and positively-charged dyes.…”

“…Biosorption of cationic dyes which was observed not only on bacterial surface but also on other biomass including fungi (Maas et al 2018), algae (Guarin et al 2018) and water plant (Pinontoan et al 2019), occurs through interaction between negatively-charged phosphate groups on the surface of the biomass and positively-charged dyes. Electrostatic attraction keeps the dyes bound to the biomass, which indicated by a noticeable change of the biomass color (Habibi and Mehrabi 2017;Kilany 2017). Biodegradation occurs because of the presence of enzymes produced by the living cell, which can break down directly the toxic dyes.…”

“…The previous study showed that other Proteobacteria, namely Stenotrophomonas maltophilia and Pseudomonas aeruginosa isolated from contaminated soil, were able to decolorize methylene blue effectively through biosorption and biodegradation process (Eslami et al 2017;Kilany 2017). Sphingomonas paucimobilis, isolated from a closed drainage system in Malaysia, can break down methylene blue enzymatically under aerobic conditions (Noraini et al 2012).…”

“…In the biological method, microbes were utilized for the degradation of the toxic textile dyes. Microorganisms that have been studied and demonstrated effective removal of methylene blue include Stenotrophomonas maltophilia and Pseudomonas aeruginosa isolated from contaminated soil, Sphingomonas paucimobilis isolated from the drainage system, and Bacillus thuringiensis (Noraini et al 2012;Chen et al 2015;Eslami et al 2017;Kilany 2017).…”