Tetracycline (TC) is effectively used antibiotic in animal husbandry and healthcare, has damaged soil ecosystems due to its misuse and residues in the soil environment. Therefore, the main objective of this study was to abate TC in hyphosphere soil by inoculating soil with arbuscular mycorrhizal fungi (AMF) and to explore its potential mechanisms. The results showed that under TC stress, inoculation with AMF reduced the contents of soil organic carbon and total nitrogen, and increased the activities of beta-glucosidase and urease in hyphosphere soil. The relative abundance of bacterial genera such as Pseudomaricurvus in the hyphosphere soil increased significantly after AMF inoculation. In addition, four bacterial genera, Cellulosimicrobium, Roseibium, Citromicrobium, and Hephaestia, were uniquely present in AMF-inoculated soil, and the functional genes Unigene456231 and Unigene565663 were significantly enriched in the hyphosphere soil. This suggests that the reshaping of the bacterial community and the enrichment of functional genes in the hyphosphere soil led to changes in the bacterial community's functions, which promoted the gradual abatement of residual TC in the soil. It should be noted that this study was solely based on a single pot experiment, and its conclusions may have certain limitations in broader ecological application scenarios. Subsequent studies will further investigate the remediation effects under different environmental factors and field trials. This study provides new insights into the use of AMF as a biological agent for the remediation of TC-contaminated soils, offering new perspectives for promoting sustainable agricultural development.

Phytoremediation assisted by endophytic bacteria is a promising strategy to enhance the remediation efficiency of heavy metals in contaminated soil. In this study, the capacity and role of the endophytic Bacillus sp. D2, previously isolated from Commelina communis growing near a copper (Cu) mine, in assisting the phytoremediation were evaluated. Results showed that inoculation of Bacillus sp. D2 significantly enhanced the biomass production of C. communis by 131.06% under high level of Cu stress. Additionally, the oxidative damages caused by Cu toxicity in C. communis tissues were alleviated as evidenced by significant reductions in malondialdehyde (MDA), superoxide anion (O2 center dot-) and proline content following Bacillus sp. D2 inoculation. Meanwhile, the activities of antioxidant enzymes in plant leaves presented upward trends after Bacillus sp. D2 inoculation. Notably, Bacillus sp. D2 inoculation significantly decreased Cu uptake and translocation by C. communis, while enhancing the Cu stabilization in contaminated soils. Furthermore, soil enzyme activities (acid phosphatase, catalase, and urease), as well as the richness of soil bacterial communities in Cu-contaminated soil increased following Bacillus sp. D2 inoculation. Importantly, the inoculation specifically augmented the relative abundance of key bacterial taxa (including Pseudomonas and Sphingomonadaceae) in the rhizosphere soil, which was positively correlated with soil nutrients cycling and plant growth. Our findings suggest that the endophytic strain Bacillus sp. D2 can strengthen the phytostabilization efficiency of Cu by C. communis through its beneficial effects on plant physio-biochemistry, soil quality and bacterial microecology, which provides a basis for the relative application to Cu-contaminated soils.

The microbiota, a component of the plant holobiont, plays an active role in the response to biotic and abiotic stresses. Nowadays, with recurrent drought and global warming, a growing challenge in viticulture is being addressed by different practices, including the use of adapted rootstocks. However, the relationships between these practices, abiotic stress and the composition and functions of the rhizosphere microbiota remain to be deciphered. This study aimed to unravel the impact of five rootstocks, water management and the combination of both on the rhizosphere bacterial microbiota in grapevines using shotgun metagenomics approach. The results showed that drought impacted the diversity, composition and functionality of the rhizosphere bacterial community. The genera Mycolicibacterium, Mycobacterium and Rhodococcus, and the bacterial functions, including DNA damage repair, fatty acid synthesis, sugar and amino acid transport, oxidative stress reduction, toxin synthesis and detoxification of exogenous compounds were significantly enriched under drought conditions. Rootstocks also significantly affected the rhizosphere bacterial richness but its influence on diversity and functionality compared to water management was weaker. Some taxa and function could be linked to water managements applied. The interaction between rootstocks and water management further influenced the rhizosphere composition, especially under drought conditions, where distinct clustering was observed for specific rootstocks. The results highlight the importance of conducting multifactorial studies to better understand their impact on shaping functional rhizosphere bacterial communities. This study paves the way for future research on beneficial bacterial inoculation and genetic engineering of rootstock to cope with drought stress.

Soil salinization is a severe environmental issue limiting the growth and yield of crops worldwide. Subsurface drip irrigation with micro-nano bubble hydrogen water (SDH) is an innovative way to realize the role of hydrogen gas (H2) in improving plant resistance to salt stress in practical agricultural productions. Nonetheless, limited information is available on how SDH affects the plant salt tolerance performance. Especially, the underlying physiological respond, hormone-regulated and soil microbial-mediated mechanisms have not been reported so far. In this study, the effects of SDH on lettuce (Lactuca sativa L.) growth, photosynthesis, root development, antioxidant system, phytohormone, and soil microbial community were investigated under normal and salt stress conditions. The results showed that, with salt stress, SDH significantly enhanced the lettuce fresh weight, photosynthesis activity, and root growth. The leaf antioxidant enzyme activities increased and reactive oxygen species (ROS) content decreased to reduce the oxidative damage. The decreased malondialdehyde (MDA) content indicated a low membrane lipid peroxidation responsible for cellular damage. SDH also helped to maintain osmotic homeostasis, which was reflected by the increased soluble protein (SP) content. Reduced Na+/ K+ ratio and ROS did not trigger excessive production of stress response hormones abscisic acid (ABA) and jasmonic acid (JA), which alleviated the mediated growth inhibition effects. SDH enriched the abundance of the plant growth-promoting rhizobacteria (PGPR) in the soil, such as Arthrobacter and Pseudomonas. That might be the reason for explaining the increase in hormone indoleacetic acid (IAA) in lettuce and 1-aminocyclopropane-1carboxylate (ACC) deaminase activity in the soil, which was beneficial for inhibiting ethylene production and promoting plant growth. Under the normal condition, variations of physiological and growth indicators as affected by SDH were similar to those under the salt stress condition, except for root development. High concentration of dissolved hydrogen gas in water might expel the oxygen. The induced soil anoxic environment limited oxygen diffusion, in turn inhibited root respiration and growth. The effect of hydrogen concentration on the plant tolerance against salt stress under different salt content could be further studied.

Illegal solid waste dumping is a significant factor contributing to environmental damage. In this study, 16S rRNA gene sequencing technology was used for the identification and assessment of environmental damage in an illegal dumping area in China, with the aim of confirming environmental damage through analyzing changes in the soil bacterial communities across slag, sewage sludge, and non-contaminated areas. The results indicate that the diversity of soil bacteria decreases with an increase in the degree of pollution. The illegal dumping of slag resulted in an increase in the relative abundance of Firmicutes and a decrease in the relative abundance of Acidobacteriota. Additionally, illegal dumping of sewage sludge resulted in an increase in the relative abundance of Proteobacteria and a decrease in the relative abundance of Acidobacteriota. The contents of Ni and Be in slag and Cu, Pb, and Cd in sewage sludge were key factors affecting bacterial community composition. The results reveal the effects of heavy metal pollution on the soil bacterial community structure and its environmental driving factors, thus expanding understanding in the context of management of the environmental damage caused by illegal dumping, as well as providing a perspective on the changes in the soil bacterial community, allowing for environmental damage confirmation.

Timber wood is a building material with many positive properties. However, its susceptibility to microbial degradation is a major challenge for outdoor usage. Although many wood-degrading fungal species are known, knowledge on their prevalence and diversity causing damage to exterior structural timber is still limited. Here, we sampled 46 decaying pieces of wood from outdoor constructions in the area of Hamburg, Germany; extracted their DNA; and investigated their microbial community composition by PCR amplicon sequencing of the fungal ITS2 region and partial bacterial 16S rRNA genes. In order to establish a link between the microbial community structure and environmental factors, we analysed the influence of wood species, its C and N contents, the effect of wood-soil contact, and the importance of its immediate environment (city, forest, meadow, park, respectively). We found that fungal and bacterial community composition colonising exterior timber was similar to fungi commonly found in forest deadwood. Of all basidiomycetous sequences retrieved, some, indicative for Perenniporia meridionalis, Dacrymyces capitatus, and Dacrymyces stillatus, were more frequently associated with severe wood damage. Whilst the most important environmental factor shaping fungal and bacterial community composition was the wood species, the immediate environment was important for fungal species whilst, for the occurrence of bacterial taxa, soil contact had a high impact. No influence was tangible for variation of the C or N content. In conclusion, our study demonstrates that wood colonising fungal and bacterial communities are equally responsive in their composition to wood species, but respond differently to environmental factors.

The utilization of plant growth-promoting rhizobacteria (PGPR) holds great promise for the restoration of damaged terrestrial plant ecosystems. However, there is a significant knowledge gap regarding the application of PGPR in rehabilitating aquatic ecosystems. In this study, we conducted a mesocosm experiment to investigate the effects of Raoultella ornithinolytica F65, Pantoea cypripedii G84, Klebsiella variicola G85, Novosphingobium profundi G86, and Klebsiella pneumoniae I109 on eelgrass ( Zostera marina L.), which is a crucial marine angiosperm. The application of these strains resulted in a significant increase in the new leaf area of eelgrass, with improvements of 55.4%, 14.4%, 39.1%, 20.6%, and 55.7% observed, respectively. Moreover, PGPR inoculation enhanced shoot biomass, rhizome elongation, leaf carbon and nitrogen content, as well as photosynthetic pigments. Furthermore, it stimulated enzymatic activities within the rhizosphere soil and positively influenced its physicochemical properties. The Illumina Miseq sequencing results revealed a positive shift in the bacterial community, leading to an enrichment of functional groups associated with nitrogen fixation and degradation of aromatic compounds. These findings underscore the significant potential of PGPR as a transformative tool for enhancing seagrass growth and survival, offering innovative strategies for the restoration of degraded seagrass meadows. This research not only advances our understanding of microbial-plant interactions in aquatic ecosystems but contributes to the broader goals of ecosystem revitalization and biodiversity conservation.

Heavy metal pollution can have adverse impacts on microorganisms, plants and even human health. To date, the impact of heavy metals on bacteria in farmland has yielded poor attention, and there is a paucity of knowledge on the impact of land type on bacteria in mining area with heavy metal pollution. Around a metal-contaminated mining area, two soil depths in three types of farmlands were selected to explore the composition and function of bacteria and their correlations with the types and contents of heavy metals. The compositions and functions of bacterial communities at the three different agricultural sites were disparate to a certain extent. Some metabolic functions of bacterial community in the paddy field were up-regulated compared with those at other site. These results observed around mining area were different from those previously reported in conventional farmlands. In addition, bacterial community composition in the top soils was relatively complex, while in the deep soils it became more unitary and extracellular functional genes got enriched. Meanwhile, heavy metal pollution may stimulate the enrichment of certain bacteria to protect plants from damage. This finding may aid in understanding the indirect effect of metal contamination on plants and thus putting forward feasible strategies for the remediation of metal-contaminated sites. Main findings of the work: This was the first study to comprehensively explore the influence of heavy metal pollution on the soil bacterial communities and metabolic potentials in different agricultural land types and soil depths around a mining area.

At present, the soil of Chinese greenhouses is experiencing severe nitrogen input in the form of fertilizer, which will cause damage to the soil environment and restrict crop growth in the long run. The response of potential functions of microorganisms as drivers of nutrient cycling and material transformation to nitrogen enrichment has rarely been reported in northern vegetable planting systems. Therefore, we set up four cucumber pot experiments with different nitrogen addition rates (0, 258, 516, and 1032 kg N ha-1 yr-1) in the greenhouse. Bacterial and fungal communities were detected by 16S and ITS rRNA gene sequencing, and bacterial and fungal functional groups were predicted using the FAPROTAX and FUNGuild databases. The findings showed that nitrogen addition induced soil acidification (a decrease of 0.25-1.63 units) significantly reduced microbial diversity and changed the community composition of bacteria and fungi. The relative abundance of bacterial functional groups associated with the nitrogen cycle increased significantly when medium and high levels of nitrogen were added. Conversely, the bacterial functional groups involved in the carbon cycle exhibited the opposite pattern. In this study, NO3- and soil pH were the main factors affecting the soil microbial community and its functional groups. Our results highlight that hydrocarbon degradation and saprophytic fungi may play key roles in yield formation during cucumber cultivation in northern solar greenhouses. In general, adopting a fertilization strategy that ensures low-medium nitrogen availability can contribute to the sustainable progress of facility agriculture.

Aims This study aimed to assess the effects of phenolic acid-degrading bacteria strains on phenolic acid content, plant growth, and soil bacterial community in phenolic acid-treated soils.Methods and results The strain of interest coded as B55 was isolated from cucumber root litter, and its degradation rates of ferulic acid and p-coumaric acid were 81.92% and 72.41% in Luria-Bertani solution, respectively, and B55 was identified as Bacillus subtilis. B55 had plant growth-promoting attributes, including solubilization of inorganic phosphate and production of siderophore and indole acetic acid. Both ferulic acid and p-coumaric acid significantly restrained an increase in cucumber seedling dry biomass, while the B55 inoculation not only completely counteracted the damage of phenolic acids to cucumber seedlings and decreased the content of ferulic acid and p-coumaric acid in soil, but also promoted cucumber seedlings growth. Amplicon sequencing found that B55 inoculation changed the cucumber rhizosphere bacterial community structure and promoted the enrichment of certain bacteria, such as Pseudomonas, Arthrobacter, Bacillus, Flavobacterium, Streptomyces, and Comamonas.Conclusions B55 not only promoted cucumber seedling growth, and decreased the content of ferulic acid and p-coumaric acid in soil, but it also increased the relative abundance of beneficial microorganisms in the cucumber rhizosphere.