Biofilms formation in plant growth-promoting bacteria for alleviating agro-environmental stress

Unraveling the synergistic effect of biochar and potassium solubilizing bacteria on potassium availability and rapeseed growth in acidic soil

Potassium (K) is an essential macronutrient for plant growth. However, its bioavailability is low in acidic soils. Excessive K fertilization deteriorates the soil health, thus highlighting the need for sustainable alternatives. In previous studies, biochar application has been proven to be an effective amendment. Meanwhile, various potassium solubilizing bacteria (KSB) have been identified in soil that contributes to K bioavailability. However, their interaction under combine (co) application in acidic soil and its effects on K availability remain poorly understood. Therefore, a pot experiment was conducted to investigate the synergistic effect of co-application of rice straw biochar (BC) and KSB consortium on K availability to promote rapeseed growth. The treatment plan consisted of CK (control), recommended K fertilizer, 2 % BC (2 % w/w), KSB consortium, KSB consortium + 2 % BC (2 % w/w). Results of soil analysis conducted after crop maturity showed that co-application of 2 % BC and KSB consortium significantly improved the soil pH and organic matter contents by 0.62 and 12.52 units respectively, relative to CK. Meanwhile, soil available nutrients were greatly enhanced, as available K content increased by 52.1 %, which indicated that co-application of 2 % BC and KSB consortium could facilitate the better conversion of different forms of soil K and make it available for plant uptake. Furthermore, it also improved extracellular enzymatic activities (26.7-71.6 %) and soil bacterial community (Actinobacteriota and Firmicutes). These improvements greatly enhanced plant biomass (46 %) and yield (31 %). Overall results proved that co-application of 2 % BC and KSB effectively enhanced K availability for sustainable plant growth. Still, there is a need to identify the most efficient KSB strains that, in conjugation with BC, reduce the K fertilizer usage.

Utilizing Microbial Inoculants to Alleviate Continuous Cropping Obstacles: Insights into the Metabolites and Transcriptomic Responses of Pinellia ternata

Pinellia ternata (Thunb.) Breit is a widely used medicinal herb in Traditional Chinese Medicine (TCM). Still, its sustainable cultivation is threatened by continuous cropping obstacles, which disrupt soil ecosystems, reduce yield, and degrade quality. Objectives: This study explores the potential of microbial inoculants to mitigate these challenges through integrated metabolomic and transcriptomic analyses. Methods: Soil samples from fields with and without continuous cropping issues were used to compare the effects of microbial inoculants on the secondary metabolism and gene expression of P. ternata. Results and Discussion: Metabolomic profiling identified 20,969 metabolites, with significant changes in lipid-like molecules (22.2%), organic acids (9.1%), and phenylpropanoids (7.0%) under microbial treatment. Notable increases in phenylalanine and caffeic acid levels were observed in microbial-inoculated plants. Correspondingly, transcriptomic analysis revealed the upregulation of phenylalanine ammonia-lyase (PAL) and other stress-related genes, confirming the metabolic shifts. Clustering and machine learning analyses highlighted the critical roles of metabolites and genes in enhancing plant resilience. Microbial inoculants improved secondary metabolite production. Implications: These findings provide valuable insights into the mechanisms of microbial-plant interactions and establish a sustainable approach for cultivating P. ternata, addressing the challenges of continuous cropping while improving crop productivity and quality.

Bacillus velezensis CNPMS-22 as biocontrol agent of pathogenic fungi and plant growth promoter

Introduction

Bacillus velezensis is a ubiquitous bacterium with potent antifungal activity and a plant growth promoter. This study investigated the potential of B. velezensis CNPMS-22 as a biocontrol agent against phytopathogenic fungi under diverse experimental conditions and its potential as a plant growth promoter. Genome sequencing and analysis revealed putative genes involved in these traits.

Methods

This research performed in vitro experiments to evaluate the CNPMS-22 antagonistic activity against 10 phytopathogenic fungi using dual culture in plate (DCP) and inverted sealed plate assay (ISP). Greenhouse and field tests evaluated the ability of CNPMS-22 to control Fusarium verticillioides in maize plants in vivo. The CNPMS-22 genome was sequenced using the Illumina HiSeq 4,000 platform, and genomic analysis also included manual procedures to identify genes of interest accurately.

Results

CNPMS-22 showed antifungal activity in vitro against all fungi tested, with notable reductions in mycelial growth in both DCP and ISP experiments. In the ISP, volatile organic compounds (VOCs) produced by CNPMS-22 also altered the mycelium coloration of some fungi. Scanning electron microscopy revealed morphological alterations in the hyphae of F. verticillioides in contact with CNPMS-22, including twisted, wrinkled, and ruptured hyphae. Eight cluster candidates for synthesizing non-ribosomal lipopeptides and ribosomal genes for extracellular lytic enzymes, biofilm, VOCs, and other secondary metabolites with antifungal activity and plant growth promoters were identified by genomic analysis. The greenhouse and field experiments showed that seed treatment with CNPMS-22 reduced Fusarium symptoms in plants and increased maize productivity.

Conclusion

Our findings highlight the CNPMS-22's potential as bioinoculant for fungal disease control and plant growth with valuable implications for a sustainable crop productivity.

Beneficial microorganisms: Regulating growth and defense for plant welfare

Beneficial microorganisms (BMs) promote plant growth and enhance stress resistance. This review summarizes how BMs induce growth promotion by improving nutrient uptake, producing growth-promoting hormones and stimulating root development. How BMs enhance disease resistance and help protect plants from abiotic stresses has also been explored. Growth-defense trade-offs are known to affect the ability of plants to survive under unfavourable conditions. This review discusses studies demonstrating that BMs regulate growth-defense trade-offs through microbe-associated molecular patterns and multiple pathways, including the leucine-rich repeat receptor-like kinase pathway, abscisic acid signalling pathway and specific transcriptional factor regulation. This multifaceted relationship underscores the significance of BMs in sustainable agriculture. Finally, the need for integration of artificial intelligence to revolutionize biofertilizer research has been highlighted. This review also elucidates the cutting-edge advancements and potential of plant-microbe synergistic microbial agents.

Enhancing Bacillus thuringiensis Performance: Fertilizer-Driven Improvements in Biofilm Formation, UV Protection, and Pest Control Efficacy

This study investigated the effects of fertilizers on the biofilm formation, ultraviolet (UV) resistance, and insecticidal activity of Bacillus thuringiensis (Bt). Bacillus thuringiensis, a widely used microbial pesticide, has a minimal environmental impact and is highly effective against specific pests but is susceptible to environmental factors in field applications. Bacterial biofilms provide protection for Bt, enhancing its survival and functionality in the environment. However, the mechanisms by which fertilizers regulate the characteristics of microbial pesticides and enhance biofilm formation are not well understood. This study evaluated the effects of six fertilizers on the bacterial biofilm formation, the UV resistance, and the insecticidal activities of Bt wettable powders. The results demonstrated that fertilizers significantly enhanced the performance of three Bt preparations (Lv'an, Kang'xin, and Lu'kang). A compound fertilizer with 8.346 g/L of KCl, 2.751 g/L of ZnSO4·7H2O, and 25.681 μL/mL of humic acid was identified by response surface optimization, achieving the maximum BBF formation with OD595 value of 2.738. Furthermore, KH2PO4, HA, and ZnSO4·7H2O notably improved the survivability of Bt preparations under prolonged UV exposure, with the compound fertilizer providing the greatest protection. What's more, fertilizers reduced the LC50 values of all Bt preparations, with the compound fertilizer decreasing the LC50 of the Lv'an Bt wettable powder to 0.139 g/L, a 3.12-fold increase in efficacy. This study demonstrated that fertilizers significantly enhance the UV resistance and insecticidal activity of Bt wettable powders by promoting bacterial biofilm formation. Herein, this study provides new strategies and theoretical support for Bt applications in modern sustainable agriculture.

A novel scaffold for biofilm formation by soil microbes using iron-cross-linked alginate gels

This study aimed to evaluate the suitability of alginate gels, specifically ferric-ion-cross-linked alginate (Fe-alginate) and calcium-ion-cross-linked alginate (Ca-alginate), as scaffolds for soil microbial attachment and biofilm formation in soil. Staining with crystal violet and observations with scanning electron microscopy showed that microorganisms formed biofilms on Fe-alginate surfaces in the soil. When the soil was incubated with Fe-alginate, microbial biomass, estimated by adenosine triphosphate content, increased not only in the Fe-alginate but also in the surrounding soil. The weight of Ca-alginate in the soil decreased with time owing to chemical dissolution. However, the weight of Fe-alginate in the soil did not decrease, likely because it was protected by the microbial biofilm that formed on its surface. These results demonstrate that the use of Fe-alginate, in contrast to Ca-alginate, as a scaffold may allow for more efficient use of soil microbial functions in agriculture and bioremediation.

Using Klebsiella sp. and Pseudomonas sp. to Study the Mechanism of Improving Maize Seedling Growth Under Saline Stress

The increasing salinization of cultivated soil worldwide has led to a significant reduction in maize production. Using saline-alkaline-tolerant growth-promoting bacteria (PGPR) in the rhizosphere can significantly improve the saline tolerance of maize and ensure the stability of maize yields, which has become a global research hotspot. This study screened salt-tolerant microorganisms Klebsiella sp. (GF2) and Pseudomonas sp. (GF7) from saline soil to clarify the mechanism in improving the saline tolerance of maize. In this study, different application treatments (GF2, GF7, and GF2 + GF7) and no application (CK) were set up to explore the potential ecological relationships between the saline tolerance of maize seedlings, soil characteristics, and microorganisms. The results showed that co-occurrence network and Zi-Pi analysis identified Klebsiella and Pseudomonas as core microbial communities in the rhizosphere soil of maize seedlings grown in saline soil. The deterministic process of microbial assembly mainly controlled the bacterial community, whereas bacteria and fungi were governed by random processes. The application of saline-alkaline-resistant PGPR under saline stress significantly promoted maize seedling growth, increased the activity of soil growth-promoting enzymes, and enhanced total nitrogen, soil organic carbon, and microbial carbon and nitrogen contents. Additionally, it reduced soil salt and alkali ion concentrations [electrical conductivity (EC) and exchangeable Na+]. Among them, GF2 + GF7 treatment had the best effect, indicating that saline-alkaline-tolerant PGPR could directly or indirectly improve the saline tolerance of maize seedlings by improving the rhizosphere soil ecological environment. EC was the determining factor to promote maize seedling growth under saline-alkaline stress (5.56%; p < 0.01). The results provided an important theoretical reference that deciphers the role of soil factors and microecology in enhancing the saline tolerance of maize.

Harnessing microbes as sun cream against high light stress

Plants rely on solar energy for growth through photosynthesis, yet excessive light intensity can induce physiological damage. Despite the considerable harm, inadequate attention has been directed toward understanding how plant-associated microorganisms mitigate this stress, and the impact of high light intensity on plant microbial communities remains underexplored. Through this Viewpoint, we aim to highlight the potential of microbial communities to enhance plant resilience and understand how light stress can shape plant microbiome. A full understanding of these dynamics is essential to design strategies that take advantage of microbial assistance to plants under light stress and to effectively manage the impact of changing light conditions on plant-microbe interactions.

Biotechnological advances in plant growth-promoting rhizobacteria for sustainable agriculture

The rhizosphere, the soil zone surrounding plant roots, serves as a reservoir for numerous beneficial microorganisms that enhance plant productivity and crop yield, with substantial potential for application as biofertilizers. These microbes play critical roles in ecological processes such as nutrient recycling, organic matter decomposition, and mineralization. Plant growth-promoting rhizobacteria (PGPR) represent a promising tool for sustainable agriculture, enabling green management of crop health and growth, being eco-friendly alternatives to replace chemical fertilizers and pesticides. In this sense, biotechnological advancements respecting genomics and gene editing have been crucial to develop microbiome engineering which is pivotal in developing microbial consortia to improve crop production. Genome mining, which involves comprehensive analysis of the entire genome sequence data of PGPR, is crucial for identifying genes encoding valuable bacterial enzymes and metabolites. The CRISPR-Cas system, a cutting-edge genome-editing technology, has shown significant promise in beneficial microbial species. Advances in genetic engineering, particularly CRISPR-Cas, have markedly enhanced grain output, plant biomass, resistance to pests, and the sensory and nutritional quality of crops. There has been a great advance about the use of PGPR in important crops; however, there is a need to go further studying synthetic microbial communities, microbiome engineering, and gene editing approaches in field trials. This review focuses on future research directions involving several factors and topics around the use of PGPR putting special emphasis on biotechnological advances.

Elaborating the multifarious role of PGPB for sustainable food security under changing climate conditions

Changing climate creates a challenge to agricultural sustainability and food security by changing patterns of parameters like increased UV radiation, rising temperature, altered precipitation patterns, and higher occurrence of extreme weather incidents. Plants are vulnerable to different abiotic stresses such as waterlogging, salinity, heat, cold, and drought in their natural environments. The prevailing agricultural management practices play a major role in the alteration of the Earth's climate by causing biodiversity loss, soil degradation through chemical and physical degradation, and pollution of water bodies. The extreme usage of pesticides and fertilizers leads to climate change by releasing greenhouse gases (GHGs) and depositing toxic substances in the soil. At present, there is an urgent need to address these abiotic stresses to achieve sustainable growth in agricultural production and fulfill the rising global food demand. Several types of bacteria that are linked with plants can increase plant resistance to stress and lessen the negative effects of environmental challenges. This review aims to explore the environmentally friendly capabilities and prospects of multi-trait plant growth-promoting bacteria (PGPB) in the alleviation of detrimental impacts of harsh environmental conditions on plants.

Bacillus subtilis PE7-Mediated Alleviation of Phosphate Starvation and Growth Promotion of Netted Melon (Cucumis melo L. var. reticulatus Naud.)

Members of Bacillus species are able to enhance the level of available phosphorus (P) for plant absorption through mechanisms of P solubilization and mineralization. In our study, B. subtilis PE7 showed P-solubilizing activity in simple phosphate broth (SPB) medium, and acetic acid, iso-butyric acid, and iso-valeric acid were major organic acids responsible for the increase in soluble P and decrease in pH of SPB medium. In addition, strain PE7 released phytase on phytase-screening agar (PSA) medium, and analysis of semi-quantitative reverse transcription and polymerase chain reaction (sqRT-PCR) revealed that the phyC gene expression was the highest at 1 day after incubation. A low concentration of KH2PO4 in SPB medium induced more biofilm formation than a high concentration of KH2PO4. Strain PE7 showed swimming and swarming motilities in TY and TrA agar media. Under P starvation, inoculation with higher cell numbers of strain PE7 enhanced biomass and nutrient acquisition by melon plants, resulting in higher values of growth parameters and nutrient contents. Moreover, the persistence of bacterial cells on the root surface and in the rhizosphere of melon plants indicated colonization of the plants by strain PE7. Due to its capacity for P solubilization and mineralization, B. subtilis PE7 could be utilized as an alternative to synthetic fertilizer for P deficient-stress management in crop plantation.

Unearthing the soil-bacteria nexus to enhance potassium bioavailability for global sustainable agriculture: A mechanistic preview

Established as a plant macronutrient, potassium (K) substantially bestows plant growth and thus, global food production. It is absorbed by plants as potassium cation (K+) from soil solution, which is enriched through slow-release from soil minerals or addition of soluble fertilizers. Contribution of bioavailable K+ from soil is usually insignificant (< 2 %), although the earth's crust is rich in K-bearing minerals. However, K is fixed largely in interlayer spaces of K-bearing minerals, which can be released by K-solubilizing bacteria (KSB) such as Bacillus, Pseudomonas, Enterobacter, and Acidithiobacillus. The underlying mechanisms of K dissolution by KSB include acidolysis, ion exchange reactions, chelation, complexolysis, and release of various organic and inorganic acids such as citric, oxalic, acetic, gluconic, and tartaric acids. These acids cause disintegration of K-bearing minerals and bring K+ into soil solution that becomes available to the plants. Current literature review updates the scientific information about microbial species, factors, and mechanisms governing the bio-intrusion of K-bearing minerals. Moreover, it explores the potential of KSB not only for K-solubilization but also to enhance bioavailability of phosphorus, nitrogen, and micronutrients, as well as its other beneficial impact on plant growth. Thus, in the context of sustainable agricultural production and global food security, utilization of KSB may facilitate plant nutrient availability, conserve natural resources, and reduce environmental impacts caused by chemical fertilizers.

Unveiling the multifaceted potential of Pseudomonas khavaziana strain SR9: a promising biocontrol agent for wheat crown rot

Fusarium pseudograminearum, a soil-borne fungus, is the cause of the devastating wheat disease known as wheat crown rot (WCR). The persistence of this pathogen in the soil and crop residues contributes to the increased occurrence and severity of WCR. Therefore, developing effective strategies to prevent and manage WCR is of great importance. In this study, we isolated a bacterial strain, designated as SR9, from the stem of wheat, that exhibited potent antagonistic effects against F. pseudograminearum, as well as the biocontrol efficacy of SR9 on WCR was quantified at 83.99% ± 0.11%. We identified SR9 as Pseudomonas khavaziana and demonstrated its potential as a plant probiotic. SR9 displayed broad-spectrum antagonism against other fungal pathogens, including Neurospora dictyophora, Botrytis californica, and Botryosphaeria dothidea. Whole-genome sequencing analysis revealed that SR9 harbored genes encoding various cell wall-degrading enzymes, cellulases, and lipases, along with antifungal metabolites, which are responsible for its antagonistic activity. Gene knockout and quantitative PCR analyses reveal that phenazine is the essential factor for antagonism. SR9 possessed genes related to auxin synthesis, flagellar biosynthesis, biofilm adhesion, and the chemotaxis system, which play pivotal roles in plant colonization and growth promotion; we also evaluated the effects of SR9 on plant growth in wheat and Arabidopsis. Our findings strongly suggest that SR9 holds great promise as a biocontrol agent for WCR in sustainable agriculture.IMPORTANCEThe escalating prevalence of wheat crown rot, primarily attributed to Fusarium pseudograminearum, necessitates the development of cost-effective and eco-friendly biocontrol strategies. While plant endophytes are recognized for their biocontrol potential, reports on effective strains targeting wheat crown rot are sparse. This study introduces the Pseudomonas khavaziana SR9 strain as an efficacious antagonist to the wheat crown rot pathogen Fusarium pseudograminearum. Demonstrating a significant reduction in wheat crown rot incidence and notable plant growth promotion, SR9 emerges as a key contributor to plant health and agricultural sustainability. Our study outlines a biological approach to tackle wheat crown rot, establishing a groundwork for innovative sustainable agricultural practices.

Endophytic Bacterial Biofilm-Formers Associated with Antarctic Vascular Plants

Deschampsia antarctica and Colobantus quitensis are the only two vascular plants colonized on the Antarctic continent, which is usually exposed to extreme environments. Endophytic bacteria residing within plant tissues can exhibit diverse adaptations that contribute to their ecological success and potential benefits for their plant hosts. This study aimed to characterize 12 endophytic bacterial strains isolated from these plants, focusing on their ecological adaptations and functional roles like plant growth promotion, antifungal activities, tolerance to salt and low-carbon environments, wide temperature range, and biofilm formation. Using 16S rRNA sequencing, we identified several strains, including novel species like Hafnia and Agreia. Many strains exhibited nitrogen-fixing ability, phosphate solubilization, ammonia, and IAA production, potentially benefiting their hosts. Additionally, halotolerance and carbon oligotrophy were also shown by studied bacteria. While some Antarctic bacteria remain strictly psychrophilic, others demonstrate a remarkable ability to tolerate a wider range of temperatures, suggesting that they have acquired mechanisms to cope with fluctuations in environmental temperature and developed adaptations to survive in intermediate hosts like mammals and/or birds. Such adaptations and high plasticity of metabolism of Antarctic endophytic bacteria provide a foundation for research and development of new promising products or mechanisms for use in agriculture and technology.

Interspecies synergistic interactions mediated by cofactor exchange enhance stress tolerance by inducing biofilm formation

Metabolic exchange plays a crucial role in shaping microbial community interactions and functions, including the exchange of small molecules such as cofactors. Cofactors are fundamental to enzyme catalytic activities; however, the role of cofactors in microbial stress tolerance is unclear. Here, we constructed a synergistic consortium containing two strains that could efficiently mineralize di-(2-ethylhexyl) phthalate under hyperosmotic stress. Integration of transcriptomic analysis, metabolic profiling, and a genome-scale metabolic model (GEM) facilitated the discovery of the potential mechanism of microbial interactions. Multi-omics analysis revealed that the vitamin B12-dependent methionine-folate cycle could be a key pathway for enhancing the hyperosmotic stress tolerance of synergistic consortium. Further GEM simulations revealed interspecies exchange of S-adenosyl-L-methionine and riboflavin, cofactors needed for vitamin B12 biosynthesis, which was confirmed by in vitro experiments. Overall, we proposed a new mechanism of bacterial hyperosmotic stress tolerance: bacteria might promote the production of vitamin B12 to enhance biofilm formation, and the species collaborate with each other by exchanging cofactors to improve consortium hyperosmotic stress tolerance. These findings offer new insights into the role of cofactors in microbial interactions and stress tolerance and are potentially exploitable for environmental remediation.

IMPORTANCE

Metabolic interactions (also known as cross-feeding) are thought to be ubiquitous in microbial communities. Cross-feeding is the basis for many positive interactions (e.g., mutualism) and is a primary driver of microbial community assembly. In this study, a combination of multi-omics analysis and metabolic modeling simulation was used to reveal the metabolic interactions of a synthetic consortium under hyperosmotic stress. Interspecies cofactor exchange was found to promote biofilm formation under hyperosmotic stress. This provides a new perspective for understanding the role of metabolic interactions in microbial communities to enhance environmental adaptation, which is significant for improving the efficiency of production activities and environmental bioremediation.

Rooting for success: Evolutionary enhancement of Bacillus for superior plant colonization

Many strains from the Bacillus subtilis species complex exert strong plant growth-promoting activities. However, their efficacy in relevant conditions is variable, due in part to their inability to establish a strong interaction with roots in stressful environmental conditions. Adaptative laboratory evolution (ALE) is a powerful tool to generate novel strains with traits of interest. Many Bacillus evolved isolates, stemming from ALE performed with plants, possess a stronger root colonization capacity. An in-depth analysis of these isolates also allowed the identification of key features influencing the interaction with plant roots. However, many variables can influence the outcome of these assays, and thus, caution should be taken when designing ALE destined to generate better root colonizers.

Insight into endophytic microbial diversity in two halophytes and plant beneficial attributes of Bacillus swezeyi

This study utilized high-throughput sequencing to investigate endophytic bacteria diversity in halophytic plants Anabasis truncate (AT) and Anabasis eriopoda (AE) from the Aral Sea region. Following sequence processing, 356 Amplicon Sequence Variants (ASVs) were discovered. The abundance and variety of endophytic bacteria were higher in AT. Bacillota, Pseudomonadota, Actinomycetota, and Bacteroidota constituted the dominant in AE, whereas Pseudomonadota, Actinomycetota, Bacteroidota, and Chloroflexota constituted the dominant in AT. Biomarkers were identified through LEFSe analysis, showing host-specific patterns. PCoA indicated distinct bacterial community structures. Phylogenetic analysis revealed diverse endophytic bacteria, including potential novel taxa. PICRUSt2 predicted diverse functions for endophytic bacteria in halophytes, indicating recruitment of beneficial bacterial taxa to adapt to extreme hypersaline conditions, including plant growth-promoting, biocontrol, and halophilic/tolerant bacteria. Moreover, the evolutionary relationship, metabolic capabilities, and plant beneficial potentials of the Bacillus swezeyi strains, previously isolated from the above two halophytes, were analyzed using comparative genomic and physiological analysis. The B. swezeyi strains displayed versatile environmental adaptability, as shown by their ability to use a wide range of carbon sources and their salt tolerances. B. swezeyi possessed a wide range of enzymatic capabilities, including but not limited to proteases, cellulases, and chitinases. Comparative genomic analysis revealed that despite some variations, they shared genetic similarities and metabolic capabilities among the B. swezeyi strains. B. swezeyi strains also displayed outstanding plant-growth-promoting and antagonistic potentials, offering potential solutions to the global food crisis. This study enhances our understanding of microbial diversity in halophytes on saline-alkali land in the West Aral Sea, shedding light on the halophyte microbiome and its collaboration with hosts in highly hypersaline environments. This study also provides a scientific basis for developing high-quality microbial fertilizers and implementing sustainable agricultural practices.

Unearthing Earth's secrets: Exploring the environmental legacy of contaminants in soil, water, and sediments

The Earth's history is documented in human civilizations, soil layers, river movement, and quiet sediments throughout millennia. This investigation explores the significant legacy of environmental toxins in these key planet components. Understanding how ancient activity shaped the terrain is crucial as mankind faces environmental issues. This interdisciplinary study uses environmental science, archaeology, and geology to uncover Earth's mysteries. It illuminates the dynamic processes that have built our globe by studying pollutants and soil, water, and sediments. This research follows human actions, both intentional and unintentional, from ancient civilizations through contemporary industrialization and their far-reaching effects. Environmental destiny examines how contaminants affect ecosystems and human health. This study of past contamination helps solve modern problems including pollution cleanup, sustainable land management, and water conservation. This review studies reminds us that our previous activities still affect the ecosystem in a society facing rapid urbanisation and industrialization. It emphasises the importance of environmental stewardship and provides a framework for making educated choices to reduce toxins in soil, water, and sediments. Discovery of Earth's secrets is not only a historical curiosity; it's a necessary step towards a sustainable and peaceful cohabitation with our home planet.

Composite biomediated engineering approaches for improving problematic soils: Potentials and opportunities

Several conventional chemical stabilizers are used for soil stabilization, among which cement is widely adopted. However, the high energy consumption and environmental challenges associated with these stabilizers have necessitated the transition toward the adoption/deployment of eco-friendly approaches for soil stabilization. Biomediated techniques are sustainable soil improvement methods adopting less toxic microorganisms, enzymes, or polymers for cementing soil. However, these processes also have several drawbacks, such as slow hardening, environmental impact, high cost, and lack of compatibility with different types of soils. It is hypothesized that these limitations may be overcome by exploring the prospects and opportunities offered by hybrid technological approaches involving the integration of nontraditional stabilizers and microbial-induced biomineralization processes for improving problematic soils. This paper discusses selected previous studies integrating different technologies and their benefits and challenges. The emerging fungi-based bio-mediation techniques and the possibility of forming sustainable fungal-based biocomposites to improve problematic soils are also highlighted.

Adaptive mechanism of the marine bacterium Pseudomonas sihuiensis-BFB-6S towards pCO2 variation: Insights into synthesis of extracellular polymeric substances and physiochemical modulation

Marine bacteria can adapt to various extreme environments by the production of extracellular polymeric substances (EPS). Throughout this investigation, impact of variable pCO2 levels on the metabolic activity and physiochemical modulation in EPS matrix of marine bacterium Pseudomonas sihuiensis - BFB-6S was evaluated using a fluorescence microscope, excitation-emission matrix (EEM), 2D-Fourier transform infrared correlation spectroscopy (2D-ATR-FTIR-COS), FT-NMR and TGA-DSC. From the results at higher pCO2 levels, there was a substantial reduction in EPS production by 58-62.8 % (DW). In addition to the biochemical composition of EPS, reduction in carbohydrates (8.7-47.6 %), protein (7.1-91.5 %), and lipids (16.9-68.6 %) content were observed at higher pCO2 levels. Functional discrepancies of fluorophores (tyrosine and tryptophan-like) in EPS, speckled differently in response to variable pCO2. The 2D-ATR-FTIR-COS analysis revealed functional amides (CN, CC, CO bending, -NH bending in amines) of EPS were preferentially altered, which led to the domination of polysaccharides relevant functional groups at higher pCO2. 1H NMR analysis of EPS confirmed the absence of chemical signals from H-C-COOH of proteins, α, β anomeric protons, and acetyl group relevant region at higher pCO2 levels. These findings can contribute new insights into the influence of pCO2 on the adaptation of marine microbes in future ocean acidification scenarios.

Effects of varying nano-ZnO concentrations on the physiology, biochemistry, root exudate, and root microbial community of Agrostis stolonifera

This study investigates the adsorption and transport of nano-ZnO in Agrostis stolonifera, focusing on its effects on plant physiology, biochemistry, root exudate, and root microbial community.