Waste to wealth: circular approaches for microbial pigment production

Microorganisms of Technological Interest: A Critical Review of Diversity, Metabolites and Biotechnological Uses

Microorganisms underpin a large fraction of modern food processing, industrial biotechnology, biopharmaceutical production, environmental remediation and agricultural biostimulation, yet the expression 'microorganisms of technological interest' often groups together biologically dissimilar organisms on the basis of use rather than shared taxonomy. This critical narrative review examines how microbial diversity, metabolic repertoire and process phenotype jointly determine technological value. The literature was selected through live searches of multidisciplinary and field-specific scholarly sources, with emphasis on peer-reviewed work concerning industrial bacteria, yeasts, filamentous fungi, archaea, cyanobacteria and eukaryotic microalgae. The synthesis shows that no universal microbial chassis is optimal across products. Fast-growing model organisms offer mature genetic tools, whereas non-conventional hosts can provide superior secretion, redox balance, precursor supply, substrate range or stress tolerance. Primary metabolites such as organic and amino acids illustrate mature fermentation logic, while enzymes, recombinant proteins, natural products, pigments, vitamins, biosurfactants and polyhydroxyalkanoates reveal stronger dependence on host-specific physiology and downstream recovery. Food fermentations and microbiome-based processes further demonstrate that technological function may emerge from stable communities rather than single strains. Across sectors, laboratory titre or yield is an incomplete predictor of industrial success because large-scale gradients, genetic stability, morphology, contamination control, feedstock variability, product toxicity and purification costs frequently dominate process performance. The most defensible direction for the field is therefore phenotype-to-process matching: selecting or engineering microorganisms in relation to the complete manufacturing chain rather than treating strain optimisation as an isolated metabolic problem. Future progress will depend on better non-model genetic toolkits, function-resolved community design, scale-down experimentation, dynamic control, rigorous safety assessment and integrated techno-economic and environmental evaluation. The review concludes that microbial diversity is technologically valuable when converted into predictable, robust and recoverable function at relevant scale.

Poly(3-hydroxybutyrate) Production from Wastewater: Microbial Pathways, Production Strategies, and Sustainability Perspectives

The increasing accumulation of petroleum-based plastic waste and wastewater has intensified the need for sustainable waste management and biodegradable alternatives. Poly(3-hydroxybutyrate) (P3HB), a microbial biopolymer, has emerged as a promising substitute for conventional plastics. This article reviews the potential of wastewater as a renewable substrate for P3HB production, with emphasis on microbial pathways, production strategies, and sustainability aspects. It discusses different wastewater sources, P3HB-producing microorganisms, metabolic engineering approaches, production processes, and polymer recovery techniques, highlighting the factors that influence productivity and product quality. The integration of P3HB production into biorefinery systems and its contribution to resource recovery, greenhouse gas mitigation, and the circular bioeconomy are also addressed. Overall, wastewater-based P3HB production represents a sustainable and economically attractive approach for biodegradable polymer production, although further technological advances are required to support large-scale industrial implementation.

Cost-Effective and Sustainable Microbial Strategies for the Bioremediation of Textile Dyes: A Review

Preliminary Studies on Microbial Bio-colors as Sustainable Alternative to Synthetic Pigments

Present investigation explores the potential of microbial pigments as ecofriendly colorants for application in food industries. Six pigment-producing bacterial strains—Serratia marcescens, Chromobacterium violaceum, Kocuria rosea, Pseudomonas fluorescens, Pantoea agglomerans, and Pseudomonas aeruginosa—were used Extraction and purification of pigments were carried out using solvent-based methods followed by chromatographic (HPLC, GC-MS) and spectroscopic (FTIR, ¹H and ¹³C NMR) characterization. The isolates produced diverse pigments such as prodigiosin, violacein, carotenoids, pyoverdine, and pyocyanin, each showing unique chemical composition for pigment production.. The findings highlighted microbial bio-colors as viable, safe, and sustainable alternatives to synthetic dyes for food applications.

Biotechnological Advances in Microbial Kojic Acid Production and Sustainable Industrial Applications

Kojic acid is an industrially important fungal secondary metabolite widely utilised in the cosmetic, pharmaceutical, and food industries due to its tyrosinase inhibitory, antioxidant, and metal-chelating properties. The increasing commercial demand for naturally derived kojic acid is constrained by limitations associated with substrate costs, fermentation efficiency, and downstream processing. Microbial fermentation using Aspergillus species continues to represent the most practical production route due to its environmental compatibility and scalability. This review critically evaluates recent advances in microbial kojic acid production with an emphasis on biosynthetic regulation, fermentation technologies, strain engineering, downstream processing, and sustainable bioprocessing strategies. Particular attention is given to submerged and solid-state fermentation systems, optimisation of physicochemical parameters, and the utilisation of agro-industrial residues as low-cost substrates. Recent advances in metabolic engineering, including CRISPR-assisted genome modification and pathway optimisation in engineered Aspergillus strains, are also discussed in relation to productivity enhancement and metabolic regulation. In addition, the review highlights emerging industrial applications of kojic acid and its derivatives in nanotechnology-based delivery systems, antimicrobial biomaterials, food preservation, and biomedical formulations. Recent developments in green cosmetic formulations, hydrogel-based delivery systems, niosomal encapsulation, and biorefinery-integrated fermentation have further expanded the industrial significance of kojic acid. Advanced formulation technologies improve compound stability, bioavailability, and skin permeability while supporting environmentally sustainable production systems. Despite substantial progress, industrial production continues to face limitations associated with oxygen transfer, substrate inconsistency, purification costs, and process scalability.  Future research should therefore focus on integrating systems biology, smart bioprocess control, sustainable feedstock utilisation, and circular bioeconomy principles to establish economically viable and environmentally sustainable production platforms for kojic acid.

Exploring the environmental and industrial applications of microbial lipases

Microbial lipases are indispensable in modern environmental management and industry, offering eco-friendly, efficient, and costeffective solutions across diverse sectors. Their broad specificity, high stability, and ability to catalyse reactions under mild conditions underscore their significance in promoting sustainable development and innovative industrial processes. As biotechnological advancements continue to garner momentum, the potential applications of lipases are expected to expand, further enhancing their role in shaping a more sustainable and environmentally conscious future. Lipases are universal enzymes of extensive physiological importance. They have a wide range of applications across industries, including food (dairy, fats and oils, beverages, and bakery), detergents, paper and pulp, biodiesel production, pesticides, pharmaceuticals, and bioremediation of various effluents. Microorganisms producing lipase are derived primarily from bacterial genera such as Bacillus, Pseudomonas, and Burkholderia, as well as fungal species such as Rhizopus, Aspergillus, and yeast-like Candida, enabling efficient production from diverse substrates, including agro-industrial wastes. Their broad substrate specificity, stability under extreme conditions, and ability to catalyze reactions such as hydrolysis, esterification, and transesterification underpin transformative applications across sectors. As global industries increasingly shift toward green technologies and sustainable processes, microbial lipases are expected to play an even more crucial role in addressing environmental challenges while supporting innovation and industrial development.