Taniya Roy

The growing demand for efficient biosurfactants in various industrial sectors has driven the search for sustainable alternatives, enhanced production methods, and low-cost substrates. This study aimed to optimize the production, characterize, and assess the bioactivities of biosurfactants produced by an oligotrophic PET plastic-associated Bacillus sp. EIKU23. The bacterium yielded the highest amount of biosurfactant after 6 days of incubation in Luria broth medium (pH 7.0) at 30 °C without any additives. FTIR and NMR analyses confirmed the lipopeptide nature of the biosurfactant, which exhibited a negative charge. The biosurfactant remained stable at 4 °C–80 °C and pH 7.0–8.0 for at least 7 days. It exhibited antioxidant properties comparable to the ascorbic acid standard, with efficacy ranging from 23.61% to 89.96% in different antioxidant assays. It showed antibacterial activity against both Gram-positive and Gram-negative potential pathogens. The biosurfactant induced substantial DNA leakage at a concentration of 10 mg/mL and eradicated approximately 48.4% of pre-formed Staphylococcus aureus biofilm and showed anti-attachment behaviour to a polystyrene surface. Additionally, the biosurfactant precipitated up to 98.7% uranium from an aqueous solution, demonstrating its potential for bioremediation. These findings suggest that the biosurfactant produced by Bacillus sp. EIKU23 is multifunctional with promising applications in bioremediation, antibacterial activity, antibiofilm formation, and antioxidant defense, offering a novel solution for sustainable industrial practices and plastic waste management.

The current study employed a rice root plaque-associated bacterium, Burkholderia sp. EIKU24, with the competency to synthesize spherical and crystalline biogenic selenium nanoparticles (BioSeNPs) that have size variability between 230 and 330 nm, as confirmed by SEM and TEM analysis. FT-IR and electron microscopy further revealed a biomolecular coating around the NPs that might have contributed significantly to their antibacterial activity against potential pathogenic Gram-positive and Gram-negative bacteria. The BioSeNPs suspension (10 mg mL−1) inhibited 78 % and 67 % of Staphylococcus aureus and Pseudomonas aeruginosa biofilms, respectively. Furthermore, BioSeNPs showed very high antioxidant capability, reflected by 90 % relative DPPH scavenging activity and photocatalytic capability by the degradation of 86 % methylene blue (10 mg L−1) solution within a contact time of 30 min. Compared to hydro or Na2SeO3 priming, rice seeds from BioSeNPs-priming outperformed in all tested seed germination parameters. Hydroponic cultivation showed better health and growth of the rice plants by an increase in root and shoot lengths, wet and dry biomass, and chlorophyll content, both in arsenic (As)-exposed and unexposed seedlings emerging from BioSeNPs-primed seeds. Notably, in such seedlings, exposure to As did not alter the growth much, indicating increased resilience to As through BioSeNPs priming. Besides, the priming of BioSeNPs decreased the translocation of As to shoot and root by about 50 % compared with hydro priming. The bioactivities, dye degradation, and growth promotion coupled with As resilience in rice seedlings consolidate the sustainable agricultural potential of BioSeNPs. However, their impact on soil ecology and interaction with other contaminants requires further study.

The search for eco-friendly, biodegradable natural dyes has been initiated worldwide to meet sustainable developmental goals. Traditional natural dyes from various plant parts (flowers, roots, barks, leaves, fruits, and seeds), minerals, and animal sources are familiar. The latest addition to the natural sources for dyes is microorganisms including bacteria, fungi, algae, etc. Microbial pigments are secondary metabolites that often help the microorganisms to withstand the stress condition including oxidative stress, ultra-violate damage, pathogenic attack, and many more. These colorful pigments have been shown to possess antimicrobial, antioxidant, anticarcinogenic, and other beneficial properties. Synthesis of pigments involves expression of genes, metabolic pathway, and many more. Many amino acids like tryptophan, proline, l-glutamine, tyrosine act as precursor molecule for the biosynthesis of these microbial pigments including violacein, prodigiosin, indigoidine, melanin, betalains. Violacein is formed by the oxidation and condensation of two tryptophan, whereas, in melanin biosynthesis, precursor molecule tyrosine can be converted to DOPA-type melanin by tyrosinase and laccase. Moreover, tyrosine hydroxylase converts tyrosine to L-DOPA, and subsequently forms betaxanthin and betacyanin in case betalains biosynthesis. Due to their attractive colors, these pigments find their application in textile industry, food industry and cosmetic industry. The chemicals dyes used in textile industries are toxic and harmful for the ecosystem and various life forms. The microbial pigments are emerging as a potential ecofriendly replacement for these chemical dyes. The purple color of violacein, red color of prodigiosin, and other colorful microbial pigments can not only dye textile but also found its role in as food colorants and in cosmetics. These amino-acid–derived pigments displaying UV protection, antiaging activity are being utilized as clean ingredients in these industries. Moreover, these bioactive pigments possess potential role in biotechnological innovations. Violacein, prodigiosin, melanin like pigments exhibit antimicrobial effect against Gram-negative and Gram-positive bacteria, and other pathogenic microbes. These pigments also have significant effect against cancer cell-line, making them promising anti- cancerous agents. Additionally, they also possess antioxidant, antiparasitic, antitumor, and other effects. Thus, these pigments are not only eco-friendly option, but also, they can protect the consumers. In this chapter, we have briefly illustrated the importance of microbial pigments, amino acid–derived microbial pigments, their biosynthetic pathway and their applications. We have also aimed to discuss the limitation and possible resolution for these pigments’ application.

Textile industries are the second most polluting industry in the world in terms of producing solid and liquid wastes. The preparatory processes as well as the dying, printing, and finishing processes of fabric produce a huge amount of liquid waste. The waste generated from these processes contains synthetic dyes, strong acids, alkalis, peroxides, formaldehyde, chlorinated compounds, and their derivatives. These adversely affect the environment due to their carcinogenic and mutagenic nature, which also causes bioaccumulation and biomagnification. Due to the fast fashion trend, the life span of clothing is being reduced. The solid wastes in terms of fabric cut pieces and discarded cloth end up in landfills, which contributes to non-biodegradable solid waste because of the presence of synthetic fibres like polyester, nylon, polypropylene, etc. These solid wastes can be managed through the recovery, recycling, and reuse methods; in some cases, can replace the primary resources with secondary resources. Considering the ecological harm, the implementation of technologies like electrocoagulation, flocculation, floating treatment wetlands system (FTWs), advanced oxidation process (AOP), membrane filtration technology, nanotechnology, ozonation, biological methods for wastewater treatments have shown significant results. Biological methods such as sequential degradation, and aerobic, anaerobic, and anoxic treatment are taken into account for sustainable development. However, it is difficult to choose particular processes since the textile sector might utilize a variety of chemicals and raw materials. This chapter summarises the risk factors associated with the textile industry and the recent development of their mitigation strategies for the probable reuse of solid and wet wastes. Future scopes, integrating multiple methods including green technologies for mitigation of hazards have also been elucidated.

In this study, a rice root plaque associated bacterium was identified as Burkholderia sp. EIKU24 and evaluated its potentials in the management of heavy metal(loid)s (HMs) contamination in agricultural soil though rice-based pot experiment. The mesophilic, drought and HMs tolerant strain thrived in wide range of pH. The isolated strain removed more than 96% arsenic (As), 98.7% copper (Cu) and 83.4% nickel (Ni) from aqueous solution following different sorption kinetics, while it reduced up to 49.7% hexavalent chromium (Cr(VI)). The bacterium exhibited multiple plant growth promoting (PGP) traits including solubilization of phosphate, potassium, ZnO, ZnCO3 and Zn3(PO4)2. Enhance solubilization of ZnCO3 and Zn3(PO4)2 in As amended liquid culture of the bacterium was noticed, while, ZnO solubilization declined in 15 days of incubation. The solubilization of Zn was found to be related to the drop in pH of the culture medium during growth. Soil augmentation of EIKU24 in pot experiments showed a significant reduction of As translocation to the rice plant which was evident from the As content in the root and shoot of rice seedlings grown under different treatments. Additionally, the root and shoot length and their biomass enhanced in EIKU24 amended soil, even in As spiked pots, suggests the beneficial role of EIKU24 in rice seedling health growing in the As contaminated soil. Burkholderia sp. EIKU24, a root plaque-associated bacterium, emerged as a promising candidate for bioremediation, expression of PGP, and micronutrient solubilization, and thus, might be augmented for sustainable rice cultivation in As affected areas.

Microbial pigments and biogenic nanoparticles have gained increasing attention as sustainable alternatives to their synthetic counterpart due to their eco-friendly nature and diverse applications. This study focuses on harnessing the potential of an isolated bacterium, identified as Burkholderia sp. EIKU21 for pigment production coupled with biogenic ZnO-NP synthesis while solubilizing bulk ZnO (bZnO), and subsequent application in textile dyeing and coating with enhanced antimicrobial properties. EIKU21 started production of pigment in culture medium in 8 days during batch growth when maximum bZnO solubilization (~ 800 mg Zn/L) was observed. Atomic absorption spectrophotometer (AAS), DLS, zeta potential, energy-dispersive X-ray (EDAX), TEM, and XRD analyses of 0.22 μm membrane filtered cell-free supernatant (CFS) affirmed the synthesis of stable biogenic ZnO-NPs of average size 55.08 ± 2.28 nm (hydrodynamic size ~ 78.89 nm) with negative surface charge (~ − 3.86 mV). Pigment in cell-free supernatant was successfully applied to dye cotton fabrics under different condition and optimization through CIElab and K/S measurement indicated excellent color retention at 100 °C for 60 min (K/S-0.5244) even after rinsing with water and detergent. Furthermore, SEM and EDAX analyses, supported by FTIR spectral analysis, confirmed the coating of dyed fabric with stable biogenic ZnO-NP. The dyed fabric exhibited varying degrees of antibacterial activity against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Enterobacter aerogenes, Pseudomonas aeruginosa emphasizing their potential for use in fabric with enhanced hygiene and longevity. Our findings highlight the dual benefits of utilizing Burkholderia sp. EIKU21 derived pigments conjugated with biogenic ZnO-NPs for sustainable textile dyeing and antibacterial coating on the fabric that foster eco-friendly and effective solutions for the textile industry.