Umeå University's logo

This study investigates the physiological and biochemical responses of a newly isolated microalgal strain, Dictyosphaerium sp. AM-2024a, identified through 18S rDNA sequencing, under varying environmental conditions and microplastic (MP) interactions. Optimal growth of strain AM-2024a was achieved at pH 9, with a 3.55% increase in biomass compared to the control. Sodium bicarbonate supplementation at 50 mM significantly enhanced productivity, with biomass increasing by 45.17%, chlorophyll a by 393.56%, and carbohydrates by 146.42%. This is the first report exploring the interaction of this strain with MPs, specifically low-density polyethylene (LDPE), selected for its environmental prevalence and relevance to aquatic pollution. Exposure to LDPE MPs resulted in a concentration-dependent reduction in biomass (up to 13.95% at 50 mg/L), whereas further analysis indicated the strain's ability to utilize LDPE as part of its metabolic processes. Gas chromatography–mass spectrometry (GC–MS) analysis of fatty acid methyl esters (FAMEs) revealed a favorable lipid profile, dominated by C16 and C18 fatty acids, yielding 84.75% FAMEs, underscoring the strain's potential for sustainable biodiesel production. This study highlights Dictyosphaerium sp. AM-2024a as a novel and robust candidate for biofuel applications and pollutant mitigation, providing a foundation for future research into its ecological and industrial applications.

Plant growth-promoting rhizobacteria (PGPR) can influence plant development through hormone signalling, nutrient mobil ization, and activation of defence pathways. While individual bacterial strains can enhance plant performance, microbial consortia may generate complementary or synergistic effects that remain poorly understood, particularly with respect to crop developmental signalling. Potato (Solanum tuberosum), the most important dicot food crop globally, represents a suit able model for investigating how beneficial microbes influence tuber development. In this study, we investigated the effects of two well-characterized PGPR strains, Pseudomonas protegens CHA0 and P. simiae WCS417, applied individually or in combination, on two potato cultivars (‘Mandel’ and ‘Désirée’) under long-day conditions. Confocal microscopy confirmed rapid root colonization by both strains within 24 h of inoculation. Metabolomic profiling of bacterial exudates revealed dis tinct metabolic signatures for the two strains and non-additive metabolite patterns when cultured together, suggesting metabolic interactions within the bacterial consortium. Plant responses were cultivar dependent, with bacterial treatments influencing vegetative growth and selected tuber quality traits, including starch and ascorbic acid levels. Gene expression analyses revealed strong induction of the tuberization regulator StSP6A in roots, with up to 5-fold increased expression fol lowing P. protegens and combined inoculation, accompanied by activation of jasmonic acid-related signalling pathways. Together, these results indicate that interactions between beneficial Pseudomonas strains can influence potato develop ment through coordinated effects on root architecture and signalling pathways associated with tuberization and defence.

Plant-derived proteins have emerged as sustainable and nutritionally valuable alternatives to animal-based proteins, gaining increasing attention for their roles in health, food security, and industrial applications. A growing area of research focuses on the intricate interactions between plant proteins and microorganisms, which significantly influence the structural, functional, and bioactive properties of these proteins. Microbial fermentation, enzymatic processing, and co-culturing techniques can enhance the digestibility, amino acid profile, and nutritional quality of plant proteins while reducing anti-nutritional factors such as phytates and tannins. Various microorganisms, including lactic acid bacteria, Bacillus spp., and fungi like Aspergillus and Rhizopus, play pivotal roles in these transformations. These interactions also lead to the generation of bioactive peptides with antioxidant, antimicrobial, and immunomodulatory properties, adding functional value to plant proteins in food and pharmaceutical formulations. In agriculture, plant-microbe interactions influence protein biosynthesis, stress resistance, and nutrient cycling, contributing to plant health and productivity. Technological innovations, such as synthetic biology and genome-editing tools like CRISPR-Cas9, are being applied to engineer both microbial strains and plant genomes, optimizing protein expression and microbial synergy for targeted outcomes. These advances pave the way for novel applications in the development of high-protein functional foods, plant-based meat alternatives, biostimulants, and therapeutic compounds. This chapter highlights the dynamic interplay between plant proteins and microbes, showcasing the vast potential of their interactions in food technology, agriculture, and biotechnology. Continued interdisciplinary research is essential to fully harness these biological relationships for sustainable development and innovation in protein-based solutions.

Potato is the world's third most important food crop, yet its production relies heavily on pesticides, creating a need for sustainable alternatives. We assessed how straw mulching, a practice known to improve soil fertility, enrich microbial activity, and suppress diseases, affects below-ground bacterial community structure and functional potential across different potato-associated sample types. A field experiment was conducted in northern Sweden using two potato cultivars under mulched and control soil conditions. Samples from the rhizosphere, root, soil, and tuber peel were analyzed using 16S ribosomal RNA (rRNA) gene sequencing (Illumina platform) to assess bacterial diversity and community composition. Straw mulching significantly increased bacterial richness and altered community structure across sample types and cultivars. Copiotrophic genera, which thrive in nutrient-rich environments, included Rhodanobacter, Mucilaginibacter, Flavobacterium, and Pseudomonas, and were enriched in rhizosphere, root, and tuber peel. Oligotrophs such as Bryobacter and Candidatus Solibacter dominated the soil and are known to contribute to organic matter turnover and plant growth. Notably, in the peel of one cultivar (King Edward), the abundance of Pseudomonas increased 5–7-fold, correlating with elevated starch and ascorbic acid contents of the tubers. In conclusion, the effect of straw mulching on soil bacterial communities and tuber quality appears to be diverse and cultivar dependent. Long-term and large-scale studies are needed to evaluate cumulative impacts on soil health, yield, and resilience.

Plants are associated with microbial communities, which are inherited through the seed and acquired from the environment. These microbiomes influence plant physiology, chemistry, and functioning. Yet, we lack insights into how seed origin and the environmental microbiome jointly influence the leaf metabolome. We used untargeted metabolomics (gas chromatography/mass spectrometry) on leaves of pedunculate oak (Quercus robur) seedlings to examine metabolic responses to different seed origins and environmental microbiomes, as well as home and away environments. For this, acorns were collected from three mother trees and grown in a multifactorial design with soil and canopy microbiomes originating from the local mother tree (i.e., the home treatment) and neighbouring trees (i.e., the away treatment). We also measured two plant traits—plant height and leaf chlorophyll content—to examine relationships between plant traits and the metabolome. The leaf metabolome did not differ significantly between plants growing with different soil and canopy microbiomes. However, the leaf metabolome differed among acorn origins and between seedlings growing in home vs. away treatments. We found no clear link between plant traits and the leaf metabolome. This study is one of the first to disentangle the combined effects of seed origin and environmental microbiomes on plant leaf chemistry, and the home vs. away framework provides novel insights into local adaptation effects on plant metabolomes within forest ecosystems. These findings have practical implications for the use of local genotypes and the development of microorganism-based management practices in sustainable forestry and agriculture.

Phytoplankton, the microscopic photosynthetic organisms found in aquatic environments, play a vital role in sustaining life on Earth. Despite their minute size, these diverse assemblages of microalgae, cyanobacteria, and other photosynthetic protists contribute significantly to a wide range of ecosystem services that support human well-being and the health of our planet. As primary producers, phytoplankton form the base of aquatic food webs, converting sunlight, carbon dioxide, and nutrients into organic matter, thereby fuelling marine and freshwater ecosystems. Their productivity supports the growth and survival of numerous organisms, from zooplankton and fish to marine mammals and seabirds. Furthermore, phytoplankton contribute substantially to global biogeochemical cycles, regulating the fluxes of essential elements such as carbon, nitrogen, and phosphorus. Beyond their ecological significance, phytoplankton provide invaluable ecosystem services to humanity. They are responsible for approximately half of the world's oxygen production through photosynthesis, sustaining life on Earth. Additionally, certain phytoplankton species are being explored for their potential in carbon sequestration, mitigating the impacts of climate change through the biological capture and storage of atmospheric carbon dioxide. Phytoplankton also plays a role in water purification, as some species can remove pollutants and contaminants from aquatic environments through bioaccumulation or biotransformation processes. Moreover, their diverse metabolic pathways and bioactive compounds hold promise for various biotechnological applications, ranging from biofuel production to pharmaceutical and nutraceutical development. However, anthropogenic activities and environmental changes pose significant threats to phytoplankton communities, with potential cascading effects on the ecosystem services they provide. Climate change, eutrophication, ocean acidification, and other stressors can disrupt phytoplankton dynamics, leading to shifts in community composition, harmful algal blooms, and disruptions in food webs and biogeochemical cycles. This chapter explores the multifaceted roles of phytoplankton in aquatic ecosystems and their contributions to ecosystem services vital for human well-being. It examines the ecological, biogeochemical, and biotechnological significance of these microscopic organisms, while also addressing the potential impacts of environmental stressors on phytoplankton communities and the consequent implications for ecosystem functioning and the services they provide.

Pesticides play an important role in increasing crop productivity and ensuring food security. However, the extensive and irrational use of pesticides has affected soil health globally. The physicochemical and biological properties of soil determine soil health. Soil microbiota and soil fauna play an important role in the ecological functioning of soils and nutrient cycling in agroecosystems. Pesticides have been shown to negatively affect soil microbiota, structure, composition and fertility. As a consequence, the availability and absorption of nutrients for plants are affected. In this chapter, we address comprehensively the impact of pesticides on soil health and plant nutrition. Also discussed are the probable approaches and challenges faced while addressing the issue of excessive pesticide use in agriculture, including policy and regulatory approaches, biotechnology and technology-based solutions, practising sustainable agriculture based upon principles of agroecology, and integrated pest management (IPM).

Plant growth-promoting rhizobacteria (PGPRs) play a crucial role in enhancing plant development through a variety of direct and indirect mechanisms. These include the production of phytohormones, nitrogen fixation, phosphate solubilization, siderophore-mediated iron acquisition, and biocontrol of plant pathogens. Predominantly inhabiting the rhizosphere, PGPRs interact with plant roots via complex molecular and ecological processes involving signalling molecules, metabolite exchanges, and modulation of plant immune responses. Such interactions enhance nutrient uptake and stress tolerance but also contribute to long-term plant health and productivity across diverse environmental conditions. This review focuses on the genera Pseudomonas and Bacillus, which are extensively studied for their strong colonization abilities, metabolic versability, and demonstrated potential in improving crop resilience. Advances in microbial genomics, metagenomics, and high-throughput phenotyping have greatly enhanced our ability to identify, characterize, and apply beneficial microbes across a range of crop systems. However, key challenges remain, including limited understanding of native soil microbiotas, the functional outcome of microbiome-soil-plant interactions, and the development of agricultural practices that efficiently integrate microbial solutions. With potato (Solanum tuberosum) as a model crop, this review synthesizes current knowledge on PGRP-mediated growth promotion - primarily by Pseudomonas and Bacillus acting alone or in microbial consortia, identifies critical research gaps, and outlines future directions for the application of PGPRs in sustainable crop production.

Anthropogenic emissions, particularly from industrial and agriculture activities, have significantly elevated the concentrations of highly toxic Heavy Metals (HMs), such as lead (Pb), cadmium (Cd), and arsenic (As), in the soil, leading to their accumulation in plants. These HMs, when exceeding toxicity thresholds (e.g., Pb >10 mg/kg, Cd >0.5 mg/kg, As >1 mg/kg), disrupt the plant physiology and metabolism. To mitigate this toxicity, plants employ diverse detoxification and sequestration strategies, including mycorrhizal associations, root exudates, cellular compartmentalization, and the production of organic acids, phytochelatins, metallothioneins, proline, stress proteins, and plant hormones. This review aims to critically examine the molecular mechanisms by which key crop plants, such as rice, wheat, maize, and other higher plants, sequester these primary heavy metal contaminants. Additionally, it highlights the role of nanotechnology in enhancing plant resistance and facilitating nano-bioremediation under HMs stress conditions. This review provides valuable insights into innovative clean-up strategies for agriculturally important crops by exploring nanoparticle -mediated remediation mechanisms.

Industrialization, urbanization, and modern globalization increased the amount of pollutants in aquatic bodies, lowering the water purity. Surface and pollution of groundwater occur due to emerging pollutants, which result in drinking water scarcity. Plants and aquatic life, as well as human health, are significantly impacted by water contaminants, to ensure that natural aquifers provide clean, safe water and to comprehend how water contaminants change over time and space. Therefore, water quality monitoring has grown in significance during the past few years. Traditional methods of measuring water quality parameters are being replaced by new ideas and approaches. In the current era of sensors, biosensors, optical sensors, and microelectronic mechanical systems (MEMS) are significant sensing methods for detecting various water quality parameters. In addition, these sensors have a fast response time, excellent selectivity, sensitivity, affordability, and ease of use. This chapter focuses on the use of nanomaterial-based optical, electronic, and electrochemical sensors for the quick identification of water contaminants, such as microorganisms, anions, heavy metals, etc. There is a need for major development in the identification of pollutants in water due to the limits of present sensing technology. The benefits of sensing technologies based on nanomaterials are emphasized. The latest developments in nanomaterial-based sensors for quick detection of water contaminants have been discussed.