Soil amendments reduce PFAS bioaccumulation in Eisenia fetida following exposure to AFFF-impacted soil.

The efficacy of RemBind® 300 to immobilize per- and polyfluoroalkyl substances (PFAS) in aqueous film forming foam (AFFF)-impacted soil (∑28 PFAS 1,280-8,130 ng g-1; n = 8) was assessed using leachability (ASLP) and bioaccumulation (Eisenia fetida) endpoints as the measure of efficacy. In unamended soil, ∑28 PFAS leachability ranged from 26.0-235 µg l-1, however, following the addition of 5% w/w RemBind® 300, ∑28 PFAS leachability was reduced by > 99%. Following exposure of E. fetida to unamended soil, ∑28 PFAS bioaccumulation ranged from 18,660-241,910 ng g-1 DW with PFOS accumulating to the greatest extent (15,150-212,120 ng g-1 DW). Biota soil accumulation factors (BSAF) were significantly (p < 0.05) higher for perfluoroalkyl sulfonic acids (PFSA; 13.2-50.9) compared to perfluoroalkyl carboxylic acids (PFCA;1.2-12.7) while for individual PFSA, mean BSAF increased for C4 to C6 compounds (PFBS: 42.6; PFPeS: 52.7; PFHxS: 62.4). In contrast, when E. fetida were exposed to soil amended with 5% w/w RemBind® 300, significantly lower PFAS bioaccumulation occurred (∑28 PFAS: 339-3,397 ng g-1 DW) with PFOS accumulation 23-246 fold lower compared to unamended soil. These results highlight the potential of soil amendments for reducing PFAS mobility and bioavailability, offering an immobilization-based risk management approach for AFFF-impacted soil.

Silver sulfide nanoparticles eliminate the stimulative effects of earthworms on nutrient uptake by soybeans in high organic matter soils.

A significant knowledge gap exists regarding the impact of soil organic matter on the bioavailability of Ag2S-NPs (environmentally relevant forms of Ag-NPs) in soil-earthworm-plant systems. This study used two soils with varying organic matter content, both with and without earthworms, to investigate the bioavailability of Ag2S-NPs. The findings revealed an 80 % increase in Ag bioaccessibility to soybeans in soils with high organic matter content compared to soils with low organic matter. Additionally, the presence of earthworms significantly increased Cl concentrations from 24.3-62.2 mg L-1 to 80.1-147.2 mg L-1, triggering the elevated bioavailability of Ag. Interestingly, Ag2S-NPs eliminated the stimulative effects of earthworms on plant nutrient uptake. In the presence of earthworms, the high organic matter soil amended with Ag2S-NPs exhibited lower concentrations of essential elements (Ca, Cu, Fe, K, and P) in plant tissues compared to soils without earthworms. Our study presents evidence of the transformation of Ag2S-NPs into Ag-NPs across various soil solutions, resulting in the formation of Ag nanoparticle complexes. Particularly noteworthy is the significant reduction in particle sizes in soils incubated with earthworms and high organic matter content, from 85.0 nm to 40.2 nm. Notably, in the rhizosphere soil, a decrease in the relative abundance of nutrient cycling-related phyla was observed, with reductions of 18.5 % for Proteobacteria and 30.0 % for Actinobacteriota. These findings offer valuable insights into the biological and biochemical consequences of Ag2S-NP exposure on earthworm-mediated plant nutrient acquisition.

Impact of future scenarios of climate change on lignin dynamics in soil: A case study in a Mediterranean savannah.

Lignin is an abundant and recalcitrant biopolymer of major relevance as soil organic matter (SOM) component playing a significant role in its stabilization. In this work, a factorial field experiment was established, where three climatic treatments (W, warming; D, drought; W + D, warming + drought), mimicking future climate change scenarios were installed over five years in a Mediterranean savannah "dehesa", accounting for its landscape diversity (under the tree canopy and in open grassland). A combination of analytical pyrolysis (Py-GC/MS) and the study of biogeochemical proxies based on lignin monomers is used for the direct detection of lignin-derived phenols and to infer possible shifts in lignin dynamics in soil. A total of 27 main lignin-derived methoxyphenols were identified, exhibiting different patterns and proportions, mainly driven by the effect of habitat, hence biomass inputs to SOM. An accelerated decomposition of lignin moieties -(exhibited by higher LG/LS and Al/K + Ac ratios)- is particularly exacerbated by the effect of all climatic treatments. There is also an overall effect on increasing lignin oxidation of side chain in syringyl units, especially under the tree canopy due to the alteration in biomass degradation and potential stimulation of enzyme activities. Conversely, in open grassland these effects are slower since the microbial community is expected to be already adapted to harsher conditions. Our findings suggests that climate change-related temperature and soil moisture deviations impact soil lignin decomposition in dehesas threatening this productive Mediterranean agroecosystem and affecting the mechanism of soil carbon storage.

Host-virus coevolution drives soil microbial function succession along a millennium land reclamation chronosequence.

INTRODUCTION: Gene exchange between viruses and hosts plays an important role in driving virus-host coevolution, enabling adaptation of both viruses and hosts to environmental changes. However, the mechanisms and functional significance of virus-host gene exchanges over long-term scales remain largely unexplored. OBJECTIVE: The present study aimed to gain insights into the role of viruses in virus-host interactions and coevolution by monitoring virome dynamics along a millennium-long land reclamation chronosequence. METHODS: We collected 24 soil samples from 8 stages of a millennium-long land reclamation chronosequence, including non-reclamation, and reclamation periods of 10, 50, 100, 300, 500, 700, and 1000 years. We characterized their metagenomes, and identified DNA viruses within these metagenomes. RESULTS: Our findings reveal a significant shift in viral community composition after 50 years of land reclamation, but soil viral diversity reached a stable phase approximately 300 years after the initial reclamation. Analysis of the virus-host network showed a scale-free degree distribution and a reduction in complexity over time, with generalist viruses emerging as key facilitators of horizontal gene transfer. CONCLUSION: These findings highlight the integral role of viruses, especially generalist types, in mediating gene exchanges between viruses and hosts, thereby influencing the coevolutionary dynamics in soil ecosystems over significant timescales. This study offers novel insights into long-term virus-host interactions, showing how the virome responds to environmental changes, driving shifts in various microbial functions in reclaimed land.

Building blocks towards sustainable biofertilizers: Variation in arbuscular mycorrhizal spore germination when immobilized with diazotrophic bacteria in biodegradable hydrogel beads.

AIM: We investigated whether there was interspecies and intraspecies variation in spore germination of twelve strains of arbuscular mycorrhizal fungi when co-entrapped with the diazotrophic plant growth promoting bacteria, Azospirillum brasilense Sp7 in alginate hydrogel beads. METHODS AND RESULTS: Twelve Rhizophagus irregularis, Rhizophagus intraradices, and Funneliformis mosseae strains were separately combined with a live culture of Azospirillum brasilense Sp7. Each fungal-bacterial consortia was supplemented with sodium alginate to a 2% concentration (v/v) and cross-linked in calcium chloride (2% w/v) to form biodegradable hydrogel beads. 100 beads from each combination (total of 1,200) were fixed in solidified modified Strullu and Romand media. Beads were observed for successful spore germination and bacterial growth over 14 days. In all cases, successful growth of A. brasilense was observed. For arbuscular mycorrhizal fungi, interspecies variation in spore germination was observed, with R. intraradices having the highest germination rate (64.3%), followed by R. irregularis (45.5%) and F. mosseae (40.3%). However, a difference in intraspecies germination was only observed among strains of R. irregularis and F. mosseae. Despite having varying levels of germination, even the strains with the lowest potential were still able to establish with the plant host Brachypodium distachyon in a model system. CONCLUSIONS: Arbuscular mycorrhizal spore germination varied across strains when co-entrapped with a diazotrophic plant-growth promoting bacteria. This demonstrates that hydrogel beads containing a mixed consortium hold potential as a sustainable biofertilizer and that compatibility tests remain an important building block when aiming to create a hydrogel biofertilizer that encases a diversity of bacteria and fungi. Moving forward, further studies should be conducted to test the efficacy of these hydrogel biofertilizers on different crops across varying climatic conditions in order to optimize their potential.

Chitinophaga pollutisoli sp. nov., isolated from contaminated sediment.

A Gram-stain-negative, yellow-pigmented, and facultatively aerobic bacterium, designated strain GPA1T, was isolated from plastic waste landfill soil in the Republic of Korea. The cells were non-motile short rods exhibiting oxidase-negative and catalase-positive activities. Growth was observed at 15-40 °C (optimum, 30 °C), at pH 6.0-9.0 (optimum, pH 7.0-8.0) and in the presence of 0-2.5 % (w/v) NaCl (optimum, 0 %). Menaquinone-7 was the sole respiratory quinone, and iso-C15 : 0, C16 : 1 ω5c, and iso-C17 : 0 3-OH were the major cellular fatty acids (>10 % of the total fatty acids). Phosphatidylethanolamine was identified as a major polar lipid. Phylogenetic analyses based on 16S rRNA gene sequences and 120 concatenated marker protein sequences revealed that strain GPA1T formed a distinct lineage within the genus Chitinophaga. The genome of strain GPA1T was 6078 kb in size with 53.8 mol% G+C content. Strain GPA1T exhibited the highest similarity to Chitinophaga rhizosphaerae T16R-86T, with a 98.6 % 16S rRNA gene sequence similarity, but their average nucleotide identity and digital DNA-DNA hybridization values were 82.5 and 25.9 %, respectively. Based on its phenotypic, chemotaxonomic, and phylogenetic characteristics, strain GPA1T represents a novel species of the genus Chitinophaga, for which the name Chitinophaga pollutisoli sp. nov. is proposed. The type strain is GPA1T (=KACC 23415T=JCM 36644T).

A critical systematic review on spectral-based soil nutrient prediction using machine learning.

The United Nations (UN) emphasizes the pivotal role of sustainable agriculture in addressing persistent starvation and working towards zero hunger by 2030 through global development. Intensive agricultural practices have adversely impacted soil quality, necessitating soil nutrient analysis for enhancing farm productivity and environmental sustainability. Researchers increasingly turn to Artificial Intelligence (AI) techniques to improve crop yield estimation and optimize soil nutrition management. This study reviews 155 papers published from 2014 to 2024, assessing the use of machine learning (ML) and deep learning (DL) in predicting soil nutrients. It highlights the potential of hyperspectral and multispectral sensors, which enable precise nutrient identification through spectral analysis across multiple bands. The study underscores the importance of feature selection techniques to improve model performance by eliminating redundant spectral bands with weak correlations to targeted nutrients. Additionally, the use of spectral indices, derived from mathematical ratios of spectral bands based on absorption spectra, is examined for its effectiveness in accurately predicting soil nutrient levels. By evaluating various performance measures and datasets related to soil nutrient prediction, this paper offers comprehensive insights into the applicability of AI techniques in optimizing soil nutrition management. The insights gained from this review can inform future research and policy decisions to achieve global development goals and promote environmental sustainability.

Assessment of the migration characteristics and source-oriented health risks of heavy metals in the soil and groundwater of a legacy contaminated by the chlor-alkali industry in central China.

The chlor-alkali industry (CAI) is crucial for global chemical production; however, its operation has led to widespread heavy metal (HM) contamination at numerous sites, which has not been thoroughly investigated. This study analysed 122 soil and groundwater samples from a typical CAI site in Kaifeng, China. Our aim was to assess the ecological and health risks, identify the sources, and examine the migration characteristics of HMs at this site using Monte Carlo simulation, absolute principal component score-multiple linear regression (APCS-MLR), and the potential environmental risk index (Ei). Our findings revealed that the exceedance rates for Cd, Pb, Hg, and Ni were 71.96%, 45.79%, 49.59%, and 65.42%, respectively. Mercury (Hg) displayed the greatest coefficient of variation across all the soil layers, indicating a significant anthropogenic influence. Cd and Hg were identified as having high and extremely high potential environmental risk levels, respectively. The spatial distributions of the improved Nemerow index (INI), total ecological risk (Ri), and HM content varied considerably, with the most contaminated areas typically associated with the storage of raw and auxiliary materials. Surface aggregation and significant vertical transport were noted for HMs; As and Ni showed substantial accumulation in subsoil layers, severely contaminating the groundwater. Self-organizing maps categorized the samples into two different groups, showing strong positive correlations between Cd, Pb, and Hg. The APCS-MLR model suggested that industrial emissions were the main contributors, accounting for 60.3% of the total HM input. Elevated hazard quotient values for Hg posed significant noncarcinogenic risks, whereas acceptable levels of carcinogenic risk were observed for both adults (96.60%) and children (97.83%). This study significantly enhances historical CAI pollution data and offers valuable insights into ongoing environmental and health challenges.

Accumulation of heavy metals from single and combined olive mill wastewater and pomace in soil and bioaccumulation in tissues of two earthworm species: Endogeic (Aporrectodea trapezoides) and Epigeic (Eisenia fetida).

Soil and earthworms are threatened by anthropogenic contamination resulting from olive mill waste dumping on the soil due to their pollutant properties. While several studies have explored the effects of olive mill waste on soil properties and the accumulation of heavy metals in soil, there is currently a gap in the literature regarding the potential bioaccumulation of heavy metals from olive mill waste in earthworms. In this study, soil with earthworms from two ecological categories (endogeic: Aporrectodea trapezoides and epigeic: Eisenia fetida) was treated with increasing doses of olive mill wastewater (OMWW) and olive mill pomace (OMP), applied individually or combined, in an indoor experiment in plastic containers, under laboratory conditions. The results revealed the presence of significant concentrations of heavy metals in the two types of wastes ranging as follows: Fe˃ Zn˃ Cu˃ Cd˃ Cr for OMWW, and Fe˃ Zn˃ Cu˃ Cr for OMP (with Cd below the detection limit). The study demonstrated distinct effects of OMWW and OMP, both individually and in combination, on soil heavy metal content, ranging as follows: soil OMWW > soil Combination > soil OMP for Cd; soil Combination > soil OMWW > soil OMP for Cr and Fe; and soil Combination > soil OMP > soil OMWW for Cu and Zn. Additionally, our investigation showed that both earthworm species exhibited significant uptake of these metals into their tissues, particularly the endogeic species. Interestingly, the most significant difference between species was in the accumulation of Cu, with the epigeic species accumulating significantly lower amounts.

Particle morphology and soil properties affect the retention of copper oxide nanoparticles in agricultural soils.

The interaction between nanoscale copper oxides (nano-CuOs) and soil matrix significantly affects their fate and transport in soils. This study investigates the retention of nano-CuOs and Cu2+ ions in ten typical agricultural soils by employing the Freundlich adsorption model. Retention of nano-CuOs and Cu2+ in soils was well fitted by the Freundlich model. The retention parameters (KD, KF, and N) followed an order of CuO NTs > CuO NPs > Cu2+, highlighting significant impact of nano-CuOs morphology. The KF and N values of CuO NPs/Cu2+ were positively correlated with soil pH and electrical conductivity (EC), but exhibited a weaker correlation for CuO NTs. Soil pH and/or EC could be used to predict KF and N values of CuO NPs or CuO NTs, with additional clay content should be included for Cu2+.The different relationship between retention parameters and soil properties may suggest that CuO NTs retention mainly caused by agglomeration, whereas adsorption and agglomeration were of equal importance to CuO NPs. The amendment of Ca2+ at low and medium concentration promoted retention of nano-CuOs in alkaline soils, but reduced at high concentration. These findings provided critical insights into the fate of nano-CuOs in soil environments, with significant implications for environmental risk assessment and soil remediation strategies.

Gene-centered metagenome analysis of Vulcano Island soil (Aeolian archipelago, Italy) reveals diverse microbial key players in methane, hydrogen and sulfur cycles.

The Aeolian archipelago is known worldwide for its volcanic activity and hydrothermal emissions, of mainly carbon dioxide and hydrogen sulfide. Hydrogen, methane, and carbon monoxide are minor components of these emissions which together can feed large quantities of bacteria and archaea that do contribute to the removal of these notorious greenhouse gases. Here we analyzed the metagenome of samples taken from the Levante bay on Vulcano Island, Italy. Using a gene-centric approach, the hydrothermal vent community appeared to be dominated by Proteobacteria, and Sulfurimonas was the most abundant genus. Metabolic reconstructions highlight a prominent role of formaldehyde oxidation and the reverse TCA cycle in carbon fixation. [NiFe]-hydrogenases seemed to constitute the preferred strategy to oxidize H2, indicating that besides H2S, H2 could be an essential electron donor in this system. Moreover, the sulfur cycle analysis showed a high abundance and diversity of sulfate reduction genes underpinning the H2S production. This study covers the diversity and metabolic potential of the microbial soil community in Levante bay and adds to our understanding of the biogeochemistry of volcanic ecosystems.

Shotgun metagenomic insights into secondary metabolite biosynthetic gene clusters reveal taxonomic and functional profiles of microbiomes in natural farmland soil.

Antibiotic resistance is a worldwide problem that imposes a devastating effect on developing countries and requires immediate interventions. Initially, most of the antibiotic drugs were identified by culturing soil microbes. However, this method is prone to discovering the same antibiotics repeatedly. The present study employed a shotgun metagenomics approach to investigate the taxonomic diversity, functional potential, and biosynthetic capacity of microbiomes from two natural agricultural farmlands located in Bekeka and Welmera Choke Kebelle in Ethiopia for the first time. Analysis of the small subunit rRNA revealed bacterial domain accounting for 83.33% and 87.24% in the two selected natural farmlands. Additionally, the analysis showed the dominance of Proteobacteria representing 27.27% and 28.79% followed by Actinobacteria making up 12.73% and 13.64% of the phyla composition. Furthermore, the analysis revealed the presence of unassigned bacteria in the studied samples. The metagenome functional analysis showed 176,961 and 104, 636 number of protein-coding sequences (pCDS) from the two samples found a match with 172,655 and 102, 275 numbers of InterPro entries, respectively. The Genome ontology annotation suggests the presence of 5517 and 3293 pCDS assigned to the "biosynthesis process". Numerous Kyoto Encyclopedia of Genes and Genomes modules (KEGG modules) involved in the biosynthesis of terpenoids and polyketides were identified. Furthermore, both known and novel Biosynthetic gene clusters, responsible for the production of secondary metabolites, such as polyketide synthases, non-ribosomal peptide synthetase, ribosomally synthesized and post-translationally modified peptides (Ripp), and Terpene, were discovered. Generally, from the results it can be concluded that the microbiomes in the selected sampling sites have a hidden functional potential for the biosynthesis of secondary metabolites. Overall, this study can serve as a strong preliminary step in the long journey of bringing new antibiotics to the market.

Myco-fabricated silver nanoparticle by novel soil fungi from Saudi Arabian desert and antimicrobial mechanism.

Biological agents are getting a noticeable concern as efficient eco-friendly method for nanoparticle fabrication, from which fungi considered promising agents in this field. In the current study, two fungal species (Embellisia spp. and Gymnoascus spp.) were isolated from the desert soil in Saudi Arabia and identified using 18S rRNA gene sequencing then used as bio-mediator for the fabrication of silver nanoparticles (AgNPs). Myco-synthesized AgNPs were characterized using UV-visible spectrometry, transmission electron microscopy, Fourier transform infrared spectroscopy and dynamic light scattering techniques. Their antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Klebsiella pneumoniae were investigated. In atrial to detect their possible antibacterial mechanism, Sodium dodecyl sulfate (SDS-PAGE) and TEM analysis were performed for Klebsiella pneumoniae treated by the myco-synthesized AgNPs. Detected properties of the fabricated materials indicated the ability of both tested fungal strains in successful fabrication of AgNPs having same range of mean size diameters and varied PDI. The efficiency of Embellisia spp. in providing AgNPs with higher antibacterial activity compared to Gymnoascus spp. was reported however, both indicated antibacterial efficacy. Variations in the protein profile of K. pneumoniae after treatments and ultrastructural changes were observed. Current outcomes suggested applying of fungi as direct, simple and sustainable approach in providing efficient AgNPs.

Estimating Hardening Soil-Brick model parameters for sands based on CPTU tests and laboratory experimental evidence.

The Hardening Soil-Brick model for soils is designed to carry out complex numerical analyses of soil-structure interaction problems taking into account strong stiffness variation in the range of small strains. However, to calibrate its parameters advanced triaxial and oedometric tests are required. In case of uncemented sands laboratory testing is usually difficult. Therefore, to facilitate calibration procedures, a CPTU based method, enhanced by an experimental evidence derived from advanced triaxial drained and oedometric tests, has been proposed and verified. It is shown in the paper that using exclusively the CPTU test results one can calibrate most important model parameters for sands with accuracy that is sufficient for solving real life problems. The major goal of this paper is to identify correlations between all reference stiffness moduli, then verify them, and finally link with the CPTU based identification procedures. It is shown in the paper that such correlations exist and they exhibit very high coefficients of determination. Moreover, as the seismic version of the CPTU test is not often available in the practice, an enhanced procedure for identification of very small strain shear stiffness modulus has been proposed and then verified, using set of the SCPTU tests conducted in Gdansk sands (Poland).

Inhibition of microbially mediated total organic carbon decomposition in different types of cadmium contaminated soils with wheat straw addition.

Wheat straw returning is a common agronomic measure in the farmland. Understanding organic carbon transformation is of great significance for carbon budget under the premise of widespread distribution of cadmium (Cd) contaminated soils. An incubation experiment was conducted to assess the influence of Cd contamination on the decomposition and accumulation of total organic carbon (TOC) as well as the composition and abundance of bacterial communities in eight soil types with wheat straw addition. The results showed that inhibition of Cd contamination on microbially mediated organic carbon decomposition was affected by soil types. The lower cumulative C mineralization and higher TOC content could be observed in the acidic soils relative to that in the alkaline soils. The content of Cd in soil exhibits different effects on the inhibition in decomposition of TOC. The high dosage level of Cd had stronger inhibitory impact due to its high toxicity. The decomposition of TOC was restricted by a reduction in soil bacterial abundance and weakening of bacterial activities. Redundancy analysis (RDA) indicated that Proteobacteria and Gemmatimonadetes were abundant in alkaline Cd-contaminated soils with wheat straw addition, while Bacteroidetes dominated cumulative C mineralization in acidic Cd-contamination soils. Moreover, the abundance of predicted functional bacteria indicated that high-dose Cd-contamination and acid environment all inhibited the decomposition of TOC. The present study suggested that pH played an important role on carbon dynamics in the Cd-contaminated soils with wheat straw addition.

Spatial-temporal variation and source analysis of heavy metals in different land use types in Beilun District (2015 and 2022).

The soil environment plays an important role in urban ecosystems. To study the heavy metal contamination of soil in Beilun District, Ningbo, we collected soil samples from 60 points in urban and peri-urban areas of Beilun District and analyzed the spatiotemporal variation and sources of heavy metal pollution in various land-use types. The results shown that the heavy metal contents in 2015 and 2022 were higher than the background soil values of Ningbo city, and there was an accumulation of heavy metals over these 7 years. The contents of heavy metals in green belts and woodland in 2022 were higher than those in 2015, while there was no significant change in agricultural land. The heavy metal contents in both years were mainly in the order green belts > agricultural land > woodland. The spatiotemporal distribution of heavy metal content showed that heavy metal pollution in Beilun District was concentrated in five industrial areas, and there was a trend toward the disappearance of highly polluted points. But the single-factor pollution index, pollution load index (PLI), and geoaccumulation index (Igeo) indicated that there was no significant heavy metal pollution in Beilun District, and individual elements at specific points showed slight pollution. The source analysis results showed that the main source of Hg is chemical, As is mainly derived from agricultural, Cr, Ni and Cu are mainly derived from natural, the main sources of Zn and Cd are electroplating and machinery activities, and the main source of Pb is traffic. These results specify a reference for future investigation on urban soil heavy metals, and the source apportionment results provide a scientific foundation for subsequent soil heavy metal pollution treatment.

Salt-tolerant plant growth-promoting bacteria as a versatile tool for combating salt stress in crop plants.

Soil salinization poses a great threat to global agricultural ecosystems, and finding ways to improve the soils affected by salt and maintain soil health and sustainable productivity has become a major challenge. Various physical, chemical and biological approaches are being evaluated to address this escalating environmental issue. Among them, fully utilizing salt-tolerant plant growth-promoting bacteria (PGPB) has been labeled as a potential strategy to alleviate salt stress, since they can not only adapt well to saline soil environments but also enhance soil fertility and plant development under saline conditions. In the last few years, an increasing number of salt-tolerant PGPB have been excavated from specific ecological niches, and various mechanisms mediated by such bacterial strains, including but not limited to siderophore production, nitrogen fixation, enhanced nutrient availability, and phytohormone modulation, have been intensively studied to develop microbial inoculants in agriculture. This review outlines the positive impacts and growth-promoting mechanisms of a variety of salt-tolerant PGPB and opens up new avenues to commercialize cultivable microbes and reduce the detrimental impacts of salt stress on plant growth. Furthermore, considering the practical limitations of salt-tolerant PGPB in the implementation and potential integration of advanced biological techniques in salt-tolerant PGPB to enhance their effectiveness in promoting sustainable agriculture under salt stress are also accentuated.

Saccharopolyspora mangrovi sp. nov., a novel mangrove soil actinobacterium with distinct metabolic potential revealed by comparative genomic analysis.

A novel mangrove soil-derived actinomycete, strain S2-29T, was found to be most closely related to Saccharopolyspora karakumensis 5K548T based on 16 S rRNA sequence (99.24% similarity) and genomic phylogenetic analyses. However, significant divergence in digital DNA-DNA hybridization, average nucleotide identity, and unique biosynthetic gene cluster possession distinguished S2-29T as a distinct Saccharopolyspora species. Pan genome evaluation revealed exceptional genomic flexibility in genus Saccharopolyspora, with > 95% accessory genome content. Strain S2-29T harbored 718 unique genes, largely implicated in energetic metabolisms, indicating different metabolic capacities from its close relatives. Several uncharacterized biosynthetic gene clusters in strain S2-29T highlighted the strain's untapped capacity to produce novel functional compounds with potential biotechnological applications. Designation as novel species Saccharopolyspora mangrovi sp. nov. (type strain S2-29T = JCM 34,548T = CGMCC 4.7716T) was warranted, expanding the known Saccharopolyspora diversity and ecology. The discovery of this mangrove-adapted strain advances understanding of the genus while highlighting an untapped source of chemical diversity.

A review of factors affecting the soil microbial community structure in wetlands.

Microbial community in wetland soils is crucial for maintaining the stability of the wetland ecosystem. Nevertheless, the soil microbial community is sensitive to the environmental stress in wetlands. This leads to the possibility that the microbial community structure may be influenced by environmental factors. To gain an in-depth understanding in the response of microbial community structure in wetland soils under different environmental factors, this review comprehensively explores the factors of natural conditions (e.g., different types of wetland, soil physical and chemical properties, climate conditions), biological factors (e.g., plants, soil animals), and human activities (e.g., land use, soil pollution, grazing). Those factors can affect microbial community structure and activities in wetland soils through different ways such as (i) affecting the wetland soil environment in which soil microorganisms survived in, (ii) influencing the available nutrients (e.g., carbon, nitrogen) required for microbial activity, and (iii) the direct effects on soil microorganisms (toxicity or promotion of resistant species). This review can provide references for the conservation of microbial diversity in wetland soils, the maintenance of wetland ecosystem balance, and the wetland ecological restoration.

Urease-producing bacteria combined with pig manure biochar immobilize Cd and inhibit the absorption of Cd in lettuce (Lactuca sativa L.).

The synergistic remediation of heavy metal-contaminated soil by functional strains and biochar has been widely studied. However, the mechanisms by which urease-producing bacteria combine with pig manure biochar (PMB) to immobilize Cd and inhibit Cd absorption in vegetables are still unclear. In our study, the effects and mechanisms of PMB combined with the urease-producing bacterium TJ6 (TJ6 + PMB) on Cd adsorption were explored. The effects of TJ6 + PMB on the Cd content and pH of the leachate were also studied through a 56-day soil leaching experiment. Moreover, the effects of the complexes on Cd absorption and microbial mechanisms in lettuce were explored through pot experiments. The results showed that PMB provided strain TJ6 with a greater ability to adsorb Cd, inducing the generation of CdS and CdCO3, and thereby reducing the Cd content (71.1%) and increasing the pH and urease activity in the culture medium. TJ6 + PMB improved lettuce dry weight and reduced Cd absorption. These positive effects were likely due to (1) TJ6 + PMB increased the organic matter and NH4+ contents, (2) TJ6 + PMB transformed available Cd into residual Cd and decreased the Cd content in the leachate, and (3) TJ6 + PMB altered the structure of the rhizosphere bacterial and fungal communities in lettuce, increasing the relative abundances of Stachybotrys, Agrocybe, Gaiellales, and Gemmatimonas. These genera can promote plant growth, decompose organic matter, and release phosphorus. Interestingly, the fungal communities were more sensitive to the addition of TJ6 and PMB, which play important roles in the decomposition of organic matter and immobilization of Cd. In conclusion, this study revealed the mechanism by which urease-producing bacteria combined with pig manure biochar immobilize Cd and provided a theoretical basis for safe pig manure return to Cd-polluted farmland. This study also provides technical approaches and bacterial resources for the remediation of heavy metal-contaminated soil.