Biosynthesis of nanoparticles using microorganisms: A focus on endophytic fungi

Abstract

The concept of this review underscores a significant shift towards sustainable agricultural practices, particularly from the view point of microbial biotechnology and nanotechnology. The global food insecurity that causes increasing ecological imbalances is exacerbating food insecurity, and this has necessitated eco-friendly agricultural innovations. The chemical fertilizers usage aims at boosting crop yields, but with negative environmental impact, thus pushing for alternatives. Microbial biotechnology and nanotechnology fields are gaining traction for their potential in sustainable agriculture. Endophytic fungi promise to synthesize nanoparticles (NPs) that can enhance crop productivity and contribute to ecosystem stability. Leveraging on endophytic fungi could be key to achieving food security goals. Endophytic fungi explore diverse mechanisms in enhancing plant growth and resilience to environmental stresses. The application of endophytic fungi in agricultural settings is profound with notable successes. Hence, adopting interdisciplinary research approaches by combining mycology, nanotechnology, agronomy, and environmental science can meaningfully serve as potential pathways and hurdles for the commercialization of these biotechnologies. Therefore, setting regulatory frameworks for endophytic nanomaterials use in agriculture, by considering their safety and environmental impact assessments will potentially provide future research directions in addressing the current constraints and unlock the potential of endophytic fungi in agriculture.

Keywords: Antifungal; Biogenesis; Nano-biotechnology; Nano-enabled agriculture; Nano-structure; Plant yield component.

Fig. 1

Illustration on the sources of microbial flora representing the plant communities. Adapted from Gupta et al. [35].

Fig. 2

Illustration of the isolation procedure of endophytic fungi.

Fig. 3

Synthesis of NPs from endophytic fungi.

Fig. 4

Biogenic synthesis of metal NPs using endophytic fungi.

Fig. 5

Life cycle assessment (LCA) of fungal-based nanoparticle.

Fig. 6

The challenges, potential risks, nanotechnology's role, safety considerations, and regulations. a. Environmental concerns: Bioaccumulation in organisms, water, soil, and the food chain; ecosystem disruption; contamination of soil and water bodies; degradation of soil health; reduced plant growth rates; destabilization of ecosystems and loss of biodiversity; unintended consequences on plant-microbe interactions. Toxicity to non-target organisms: Health risks to humans and animals through inhalation or ingestion. Harmful effects may include organ damage, carcinogenicity, cytotoxic and genotoxic effects, oxidative stress, inflammation, and disruption of normal cellular functions. Regulatory and ethical challenges: Ethical concerns, lack of standardized guidelines, and risks of accidental contamination. Uncontrolled release and disposal: Waste accumulation and unintended disposal of waste into water, soil, and the environment. Resistance development in pathogens: The development of resistance in microbes, leads to reduced microbial efficacy and diminished antimicrobial effects. Economic and social concerns: High costs and accessibility challenges, along with potential social resistance. Unintended genetic effects: Alterations and mutations in plant and microbial gene expression. b. Contamination control: Developing stabilization techniques to maintain functional traits, optimizing standard procedures for growth conditions, and implementing safety protocols for adopting NPs from endophytic fungi. c. Regulation of environmental and health safety standards: Risk and ecotoxicological assessments by regulatory agencies such as the World Health Organization (WHO), Food and Agriculture Organization (FAO), Environmental Protection Agency (EPA), and European Chemicals Agency (ECHA). Regulations on production and use should follow Good Manufacturing Practice (GMP), with proper registration and approval. Compliance with agricultural and food safety regulations, including nanoparticle use in agriculture and food additives, should be ensured. International standards and conventions: Adequate measures should be taken by the Organisation for Economic Co-operation and Development (OECD), compliance with World Trade Organization (WTO) trade agreements, and adherence to sanitary and phytosanitary (SPS) measures. Ethical use and sustainability considerations should emphasize research transparency and clear labeling for consumer awareness. d. Toxicity to humans and animals: Monitoring cytotoxic levels, allergic reactions, dosage, and exposure limits is crucial. The environmental impact should be assessed for ecotoxicity, persistence, biodegradability, and interactions with soil microbiomes. Handling and manufacturing risks: Careful monitoring of inhalation hazards, skin and eye irritation, and nanoparticle stability is essential. Regulatory and ethical concerns must also be addressed. e. Nanotechnology in agriculture: Multi-purpose applications of endophytic NPs, including their use as nanofertilizers, nanonutrients, nanoinsecticides, nanopesticides, and nanosensors, as well as in medicine, pharmaceuticals, and environmental applications.