Bacterial Polysaccharide-Stabilized Silver Nanoparticles Photocatalytically Decolorize Azo Dyes

Area of Science:

• Biotechnology and Materials Science
• Microbial Polysaccharide Characterization
• Nanoparticle Synthesis and Application

Background:

• Bacterial polysaccharides offer advantages in stability, non-toxicity, and biodegradability over other polysaccharide sources.
• Bacterial cell wall polysaccharides (CPs) are less explored than exopolysaccharides, presenting an opportunity for novel applications.
• Textile industry dye effluent is a source of thermotolerant bacteria with potential for producing valuable biomaterials.

Purpose of the Study:

• To isolate and structurally characterize cell wall polysaccharides (CPs) from the thermotolerant bacterium Chryseobacterium geocarposphaerae DD3.
• To evaluate the industrial applicability of the isolated CPs (CPs3) as additives, focusing on antibacterial, emulsification, and flocculation properties.
• To synthesize and characterize silver nanoparticles (AgNPs) using CPs3 as a stabilizing agent and assess their photocatalytic activity for dye degradation.

Main Methods:

• Isolation of CPs from Chryseobacterium geocarposphaerae DD3.
• Structural and thermal characterization using SEM-EDX, AFM, FTIR, NMR, and TGA.
• Green synthesis of AgNPs using CPs3, followed by characterization (UV-Vis, TEM, AFM, particle size analysis) and photocatalytic activity testing against azo dyes.

Main Results:

• CPs3 exhibited a compact, non-porous amorphous structure with high thermal stability (up to ~350 °C).
• FTIR and NMR confirmed the polysaccharidic nature with specific glycosidic linkages (β-(1→3) and β-(1→4)).
• CPs3 demonstrated antibacterial, emulsification, and flocculation capacities. The CPs3-stabilized AgNPs showed significant photocatalytic degradation of congo red (88.33%), methyl red (76.81%), and malachite green (47.34%) within 3 hours.

Conclusions:

• This study reports for the first time the isolation and characterization of CPs from Chryseobacterium geocarposphaerae.
• CPs3 exhibits multifunctionality, serving as a valuable additive in the biotechnology industry and as a stabilizing agent for AgNPs.
• CPs3-stabilized AgNPs show promise for the bioremediation of azo dyes, highlighting a sustainable approach for wastewater treatment.