Deforestation and slash combustion have substantial adverse impacts on the atmosphere, soil and microbe. Despite this awareness, numerous individuals persist in opting for high-intensity Eucalyptus planting through slash-burning in pursuit of immediate profits while disregarding the environmental significance and destroying the soil. Slash-unburnt agriculture can effectively safeguard the ecological environment, and compared with slash-burning, there remains a limited understanding of its regulatory mechanisms on soil fertility and microbial community. Also, large uncertainty persists regarding the utilization of harvest residues. Thoroughly investigating these questions from various perspectives encompassing physical soil characteristics, nutrient availability, bacterial community structures, and stability is crucial. To explore the ecological advantages of slash-unburnt techniques on microorganisms and their associated ecosystems, we used two slash-unburnt (Unburnt) planting techniques: Spread (naturally and evenly covering the forest floor after logging) and Stack (residues are piled along contour lines) as well as the traditional slash Burnt method (Burnt) in a Eucalyptus plantation. A comparative analysis was conducted between the two methods. We observed that over a span of 4 years, despite the initial lower application of fertilizer in the Unburnt treatments compared with the Burnt treatment during the first 2 years, the Unburnt treatment gradually caught up or even surpassed and attained similar nutrient levels as the Burnt treatment. Alphaproteobacteria was the main phyla that indicated the difference in soil bacterial communities between Burnt and Unburnt treatments. The microbial networks also highlighted the significance of the Unburnt method, as it contributed to the preservation of crucial network nodes and the stability of soil bacterial communities. Therefore, rational utilization of harvest residue may effectively avoid the vast damage caused by slash-burning to Eucalyptus trees and the soil environment but may also increase the potential for restoring soil fertility, improving fertilizer utilization efficiency, and maintaining microbial community stability over time.

Root nitrogen (N) reallocation involves remobilization of root N-storage pools to support shoot growth. Representing a critical yet underexplored facet of plant function, we developed innovative frameworks to elucidate its connections with key ecosystem components. First, root N reallocation increases with plant species richness and N-acquisition strategies, driven by competitive stimulation of plant N demand and synergies in N uptake. Second, competitive root traits and mycorrhizal symbioses, which enhance N foraging and uptake, exhibit trade-offs with root N reallocation. Furthermore, root N reallocation is attenuated by N-supply attributes such as increasing litter quality, soil fungi-to-bacteria ratios, and microbial recruitment in the hyphosphere/rhizosphere. These frameworks provide new insights and research avenues for understanding the ecological roles of root N reallocation.

Climate warming is a pressing global issue with substantial impacts on soil health and function. However, the influence of environmental context on the responses of soil microorganisms to warming remains largely elusive, particularly in alpine ecosystems. This study examined the responses of the soil microbiome to in situ experimental warming across three elevations (3850 m, 4100 m, and 4250 m) in the meadow of Gongga Mountain, eastern Tibetan Plateau. Our findings demonstrate that soil microbial diversity is highly resilient to warming, with significant impacts observed only at specific elevations. Furthermore, the influence of warming on the composition of the soil microbial community is also elevation-dependent, underscoring the importance of local environmental context in shaping microbial evolution in alpine soils under climate warming. Notably, we identified soil moisture at 3850 m and carbon-to-nitrogen ratio at 4250 m as indirect predictors regulating the responses of microbial diversity to warming at specific elevations. These findings underscore the paramount importance of considering pre-existing environmental conditions in predicting the response of alpine soil microbiomes to climate warming. Our study provides novel insights into the intricate interactions between climate warming, soil microbiome, and environmental context in alpine ecosystems, illuminating the complex mechanisms governing soil microbial ecology in these fragile and sensitive environments.

Plant secondary succession has been explored extensively in restoring degraded grasslands in semiarid or dry environments. However, the dynamics of soil microbial communities and their interactions with plant succession following restoration efforts remain understudied, particularly in alpine ecosystems. This study investigates the interplay between soil properties, plant communities, and microbial populations across a chronosequence of grassland restoration on the Qinghai-Tibet Plateau in China. We examined five succession stages representing artificial grasslands of varying recovery durations from 0 to 19. We characterized soil microbial compositions using high-throughput sequencing, enzymatic activity assessments, and biomass analyses. Our findings reveal distinct plant and microbial secondary succession patterns, marked by increased soil organic carbon, total phosphorus, and NH4+-N contents. Soil microbial biomass, enzymatic activities, and microbial community diversity increased as recovery time progressed, attributed to increased plant aboveground biomass, cover, and diversity. The observed patterns in biomass and diversity dynamics of plant, bacterial, and fungal communities suggest parallel plant and fungal succession occurrences. Indicators of bacterial and fungal communities, including biomass, enzymatic activities, and community composition, exhibited sensitivity to variations in plant biomass and diversity. Fungal succession, in particular, exhibited susceptibility to changes in the soil C: N ratio. Our results underscore the significant roles of plant biomass, cover, and diversity in shaping microbial community composition attributed to vegetation-induced alterations in soil nutrients and soil microclimates. This study contributes valuable insights into the intricate relationships driving secondary succession in alpine grassland restoration.

Drought and nitrogen deposition are two major climate challenges, which can change the soil microbial community composition and ecological strategy and affect soil heterotrophic respiration (Rh). However, the combined effects of microbial community composition, microbial life strategies, and extracellular enzymes on the dynamics of Rh under drought and nitrogen deposition conditions remain unclear. Here, we experimented with an alpine swamp meadow to simulate drought (50% reduction in precipitation) and multilevel addition of nitrogen to determine the interactive effects of microbial community composition, microbial life strategy, and extracellular enzymes on Rh. The results showed that drought significantly reduced the seasonal mean Rh by 40.07%, and increased the Rh to soil respiration ratio by 22.04%. Drought significantly altered microbial community composition. The ratio of K- to r-selected bacteria (BK:r) and fungi (FK:r) increased by 20 and 91.43%, respectively. Drought increased hydrolase activities but decreased oxidase activities. However, adding N had no significant effect on microbial community composition, BK:r, FK:r, extracellular enzymes, or Rh. A structural equation model showed that the effects of drought and adding nitrogen via microbial community composition, microbial life strategy, and extracellular enzymes explained 84% of the variation in Rh. Oxidase activities decreased with BK:r, but increased with FK:r. Our findings show that drought decreased Rh primarily by inhibiting oxidase activities, which is induced by bacterial shifts from the r-strategy to the K-strategy. Our results highlight that the indirect regulation of drought on the carbon cycle through the dynamic of bacterial and fungal life history strategy should be considered for a better understanding of how terrestrial ecosystems respond to future climate change.

Low temperatures limit the denitrification wastewater in activated sludge systems, but this can be mitigated by addition of redox mediators (RMs). Here, the effects of chlorophyll (Chl), 1,2-naphthoquinone-4-sulfonic acid (NQS), humic acid (HA), and riboflavin (RF), each tested at three concentrations, were compared for denitrification performance at low temperature, by monitoring the produced extracellular polymeric substances (EPS), and characterizing microbial communities and their metabolic potential. Chl increased the denitrification rate most, namely 4.12-fold compared to the control, followed by NQS (2.62-fold increase) and HA (1.35-fold increase), but RF had an inhibitory effect. Chl promoted the secretion of tryptophan-like and tyrosine-like proteins in the EPS and aided the conversion of protein from tightly bound EPS into loosely bound EPS, which improved the material transfer efficiency. NQS, HA, and RF also altered the EPS components. The four RMs affected the microbial community structure, whereby both conditionally abundant taxa (CAT) and conditionally rare or abundant taxa (CRAT) were key taxa. Among them, CRAT members interacted most with the other taxa. Chl promoted Flavobacterium enrichment in low-temperature activated sludge systems. In addition, Chl promoted the abundance of nitrate reduction genes narGHI and napAB and of nitrite reduction genes nirKS, norBC, and nosZ. Moreover, Chl increased abundance of genes involved in acetate metabolism and in the TCA cycle, thereby improving carbon source utilization. This study increases our understanding of the enhancement of low-temperature activated sludge by RMs, and demonstrates positive effects, in particular by Chl.

Inoculation with plant growth-promoting rhizobacteria (PGPR) strains has promoted plant growth and decreased nitrous oxide (N₂O) emissions from agricultural soils simultaneously. However, limited PGPR strains can mitigate N₂O emissions from agricultural soils, and the microbial ecological mechanisms underlying N₂O mitigation after inoculation are poorly understood. In greenhouse pot experiments, the effects of inoculation with Stutzerimonas stutzeri NRCB010 and NRCB025 on tomato growth and N₂O emissions were investigated in two vegetable agricultural soils with contrasting textures. Inoculation with NRCB010 and NRCB025 significantly promoted tomato growth in both soils. Moreover, inoculation with NRCB010 decreased the N₂O emissions from the fine- and coarse-textured soils by 38.7% and 52.2%, respectively, and inoculation with NRCB025 decreased the N₂O emissions from the coarse-textured soil by 76.6%. Inoculation with NRCB010 and NRCB025 decreased N₂O emissions mainly by altering soil microbial community composition and the abundance of nitrogen-cycle functional genes. The N₂O-mitigating effect might be partially explained by a decrease in the (amoA + amoB)/(nosZI + nosZII) and (nirS + nirK)/(nosZI + nosZII) ratios, respectively. Soil pH and organic matter were key variables that explain the variation in abundance of N-cycle functional genes and subsequent N₂O emission. Moreover, the N₂O-mitigating effect varied depending on soil textures and individual strain after inoculation. This study provides insights into developing biofertilizers with plant growth-promoting and N₂O-mitigating effects.
OBJECTIVE: Plant growth-promoting rhizobacteria (PGPR) have been applied to mitigate nitrous oxide (N₂O) emissions from agricultural soils, but the microbial ecological mechanisms underlying N₂O mitigation are poorly understood. That is why only limited PGPR strains can mitigate N₂O emissions from agricultural soils. Therefore, it is of substantial significance to reveal soil ecological mechanisms of PGPR strains to achieve efficient and reliable N₂O-mitigating effect after inoculation. Inoculation with Stutzerimonas stutzeri strains decreased N₂O emissions from two soils with contrasting textures probably by altering soil microbial community composition and gene abundance involved in nitrification and denitrification. Our findings provide detailed insight into soil ecological mechanisms of PGPR strains to mitigate N₂O emissions from vegetable agricultural soils.

BACKGROUND: Endometriosis (EM) is a multifactorial disease that affects 10 - 15% of women of reproductive age. Additionally, 30-50% of women with EM suffer from infertility. The mechanism of infertility caused by EM has not yet been consistently explained. In recent years, studies have shown a link between infertility associated with EM and changes in the reproductive tract microbiota.
METHODS: In this study, we involved 26 EM patients (8 cases of stage I-II and 18 cases of stage III-IV) and 31 control subjects who were tubal obstruction-related infertility (TORI). The samples from peritoneal fluid (PF) and uterine fluid (UF) were collected and sequenced by 16 S rRNA amplicon.
RESULTS: In the comparison of microbial diversity, we found no significant differences in the microbial diversity of PF and UF between patients with stage I-II EM and those with TORI. However, there was a significant difference in microbial diversity among patients with stage III-IV EM compared to the previous two groups. Lactobacillus decreased in PF of EM compared to the control group, while it increased in UF. In PF, the abundance of Pseudomonas, Enterococcus, Dubosiella and Klebsiella was significantly higher in patients with stage III-IV compared to TORI patients. And in UF, the main differences existed between stage I-II EM compared to the other two groups. The abundance of pontibacter, aquabacterium, Rikenellaceae and so on at the genus level was significantly enriched in the EM patients with stage I-II. In the analysis based on KEGG database, EM may affect the receptivity related pathways of the endometrium by influencing changes in the uterine microbiota.
CONCLUSIONS: Our results indicated that as EM progresses, the microorganisms in UF and PF keep changing. These changes in the microbiota, as well as the resulting alternations in gene functional classification, may play an important role in the infertility associated with EM.

Clubroot disease, caused by Plasmodiophora brassicae, is a serious soil-borne disease in Brassica crops worldwide. It seriously occurs in conducive soils of southern China, while never happens in some areas of northern China with suppressive soils. To understanding the differences, we measured the soil suppressiveness, chemical properties, and microbial communities in suppressive and conducive soils by bioassay and sequencing of 16S and 18S rRNA amplicons. The biological basis of clubroot suppressiveness was supported by the ability to remove it by pasteurization. The pH value and calcium content in the suppressive soils were higher than those in the conducive soils. Suppressive soils were associated with higher fungal diversity and bacterial abundance. The fungal phyla Chytridiomycota, Olpidiomycota, and Mucoromycota and the bacterial phyla Acidobacteriota and Gemmatimonadota were enriched in suppressive soils. More abundant beneficial microbes, including Chaetomium and Lysobacter, were found in the suppressive soils than in the conducive soils. Molecular ecological network analysis revealed that the fungal network of suppressive soils was more complex than that of conducive soils. Our results indicate that plant health is closely related to soil physicochemical and biological properties. This study is of great significance for developing strategies for clubtroot disease prevention and control.

Changes in soil microbial activity and ecological function can be used to assess the level of soil fertility and the stability of ecosystems. To assess the fertility and safety of organic fertilizer of kitchen waste (OFK), soils containing 0% (CK), 1%, 3%, and 5% OFK were cultured, and the physical, chemical, and microbial properties of the soils were measured dynamically with routine agrochemical analysis measures and amplicon sequencing. The results showed that compared with those in CK, the contents of organic matter, available phosphorus, available potassium, NH4+-N, and NO3--N in soils with OFK increased by 23.80%-35.13%, 13.29%-29.72%, 16.91%-39.37%, 164.7%-340.2%, and 28.56%-32.71%, respectively. The activities of hydrolases related to the cycle of carbon, nitrogen, and phosphorus (α-glucosidase, leucine aminopeptidase, acid phosphatase, etc.) were also significantly higher than those of the CK treatment. OFK stimulated the growth of soil microorganisms and increased the carbon content of the microbial biomass. The amplicon sequencing analysis found that the microbial community structures of different treatments were significantly different at both the class and genus levels. In addition, it was found that the abundance of beneficial microbes in the soils with OFK increased, whereas pathogenic microbes decreased. RDA results confirmed that soil properties (including soil pH, organic matter, available nutrients, and microbial biomass) had a significant impact on microbial community structure. The results of investing bacterial community based on PICRUSt and FAPROTAX revealed that the function of the soil bacterial community was similar in the four treatments, but OFK supply significantly improved the microbial carbon utilization and metabolic ability. Moreover, by using the FUNGuild software, we found that the application of OFK increased the proportion of saprotroph-symbiotroph and symbiotroph and stimulated the growth of ectomycorrhizal fungi-undefined saprophytic fungi but inhibited plant and animal pathogenic fungi in soil. These results implied that OFK could promote the establishment of symbiotic relationships and inhibit the growth of pathogenic fungi. In summary, OFK could improve soil fertility and hydrolase activity, stimulate the growth of beneficial microorganisms, and defend against pathogens, indicating a promising use as safe and efficient organic fertilizer.