[Objective] To explore the mechanism by which biochar alters the soil bacterial community structure and thereby affects the availability of soil phosphorus. [Methods] This study employed metagenomic techniques to investigate the soil bacterial communities and microbial functional genes involved in the phosphorus cycle after the application of biochar at different doses (CK: 0 kg/hm², T1: 300 kg/hm², T2: 600 kg/hm², and T3: 900 kg/hm²). [Results] The application of biochar significantly increased inorganic phosphorus, microbial biomass phosphorus, and alkaline phosphatase activity, which showed the increases of 21.75%, 699.39%, and 34.00%, respectively, under T2 treatment. Furthermore, the application of biochar changed the diversity and richness of soil microorganisms, especially bacteria, mainly enriching Actinobacteriota, Acidobacteria, Chloroflexota, Thermoproteota, Gemmatimonadota, Nocardioides, and Sphingobium. Soil pH, water content, organic matter, inorganic phosphorus, microbial biomass phosphorus, and available phosphorus were important factors influencing soil microbial communities. In addition, biochar significantly increased the abundance of the organic phosphorus mineralization-associated gene phoD, T2 increased by 9.28% compared with CK, and the abundance of phoD was significantly affected by total phosphorus, available phosphorus, and microbial biomass phosphorus content in the soil. [Conclusion] The application of biochar can enhance phosphorus availability by regulating soil bacterial community structure. The findings provide a theoretical basis for the application of biochar in improving phosphorus availability in farmland soil.

[Objective] Black soil acidification may exacerbate the soil degradation processes and reduce microbial functions, thus threatening the crucial role of the northeast region in guaranteeing the food security of China. Unraveling the impacts of soil acidification on the soil microbial community and its underlying mechanisms can help clarify the relationship between soil organic carbon (SOC) stabilization and soil acidification. [Methods] Soil samples with different acidification degrees were collected from the corn belts of black soil regions. The changes of living microbial groups in the soil samples with different pH were investigated by the phospholipid fatty acid (PLFA) analysis. Additionally, the relationship between changes in the soil physicochemical properties and microbial community composition was analyzed. [Results] A threshold effect of black soil acidification on SOC was identified in the corn belts. Moderate acidification did not cause significant changes in SOC. However, when pH dropped below a certain threshold (6.75), further acidification resulted in a significant loss of SOC. The cation buffering effect in soil changed significantly with different acidification degrees. Calcium ion was primarily responsible for buffering black soil acidification, while when the pH fell below 6.00, both calcium and magnesium ions buffered the acidification. Soil acidification imposed noticeable stress on soil microorganism growth. Different microbial groups exhibited an S-shaped response pattern, with PLFA content initially decreasing, remaining stable within the range of pH 5.25-6.25, and subsequently declining as acidification progressed. However, different microbial groups exhibited varying sensitivities to soil acidification. Gram-negative bacteria were the most sensitive, followed by Gram-positive bacteria and arbuscular mycorrhizal fungi. Fungi, particularly arbuscular mycorrhizal fungi, may play a crucial role in stabilizing SOC during soil acidification. [Conclusion] Soil acidification significantly alters the structure of the living microbial community, primarily through changes in cation exchange capacity and substrate availability, which further affect SOC accumulation. These findings provide scientific support for developing management strategies to alleviate black soil degradation and acidification.

[Objective] The conversion of upland to paddy fields and increased fertilizer application have significantly altered soil properties. However, the dynamic evolutionary characteristics and response mechanisms of microbial communities during habitat evolution different years after conversion remain unclear. [Methods] Soil samples were collected from the paddy fields converted from upland fields for different years (0, 3, 8, 15, 20, and 30). Soil physicochemical analysis, real-time quantitative PCR, and high-throughput sequencing were employed to investigate the dynamic changes in soil chemical and biological properties, microbial community composition and asynchrony characteristics, and the interrelationships among these indicators during the habitat evolution following conversion. [Results] As the years after conversion increased, soil organic carbon, total nitrogen, total phosphorus, ammonium nitrogen, and microbial biomass carbon content gradually increased (by 3 to 4 folds), while pH (decreased by up to 0.80) and nitrate content gradually decreased. However, soil potassium content, microbial abundance, and microbial diversity showed no consistent trends. Microbial community analysis revealed that as the years after conversion increased, stress-tolerant genera (Balneola, Flavobacterium, Myxococcus, and Nitrospira) presented enhanced asynchrony and divergence. This optimized interspecies interactions and functional division, thereby improving ecosystem stability. Conversely, increased convergence in genera such as Liberibacter and Variovorax weakened soil functions such as plant growth promotion and pathogen suppression. Correlation analysis indicated that soil pH, organic carbon, and total nitrogen acted as key environmental drivers. Through synergistic and antagonistic interactions, they governed microbial community succession and exerted decisive influences on changes in community asynchrony. [Conclusion] As the years after upland-to-paddy conversion increased, the microbial community asynchrony became enhanced, which improved system stability and reduced carbon losses while compromising soil capacities of plant growth promotion and disease suppression. In the future, strategies such as water management, organic amendment regulation, precision fertilization, and application of synthetic microbial consortia could be employed to directionally enhance microbial divergence and improve ecosystem functional stability.

Saline-alkali land is a common type of degraded soil with wide distribution across the globe. Among all types of saline-alkali land, soda saline-alkali land, characterized by the coexistence of high salinity and alkalinity, is particularly difficult to be managed and represent a major obstacle to the effective utilization of soil resources. Arbuscular mycorrhizal fungi (AMF) enhance plant growth and survival by improving nutrient uptake and increasing stress resistance, offering promising potential for the reclamation and utilization of saline-alkali land. [Objective] To explore how the structures and diversity of the AMF community vary along a soda saline-alkaline stress gradient in response to stress and other environmental factors. [Methods] We collected soil samples subjected to varying levels of soda saline-alkaline stress from Changling County and Da’an City in Jilin Province. The sampling sites included Suaeda glauca-covered wildland (pH 10.0-10.5), unvegetated bare land (pH 9.5-10.0), and maize (Zea mays L.) farmlands under varying levels of stress (pH 8.5-10.0). The structures and diversity of AMF communities in these soil samples were analyzed by Illumina-based 18S rRNA gene sequencing. [Results] AMF communities were predominantly composed of Entrophospora, Funneliformis, Rhizoglomus, and Dominikia. The relative abundance of AMF was significantly positively correlated with soil total carbon, total nitrogen, total phosphorus, and available nitrogen, and it was significantly negatively correlated with soil pH, electrical conductivity, and salt content. The AMF community structure was significantly associated with soil total carbon and pH. The Shannon diversity (alpha diversity) of AMF showed significantly positive correlations with total phosphorus and salt content, while the AMF community structure dispersion (beta diversity) was significantly negatively correlated with electrical conductivity. Moreover, the alpha diversity and beta diversity of AMF had a significantly negative correlation. [Conclusion] Saline-alkaline stress exerted homogeneous selection on the AMF community, leading to reduced community size, decreased beta diversity, increased alpha diversity, and altered community composition.

Nitrogen fertilizer is an important chemical fertilizer for agricultural planting and an important fertility factor for increasing crop yields. Lack or excess of nitrogen fertilizer in soil will lead to soil acidification, soil consolidation, low crop yields and so on. Nitrogen-fixing bacteria can reduce nitrogen in the air to ammonia that is beneficial to crops through the action of nitrogenase. This process helps improve soil quality and subsequently promote crop growth. [Objective] To obtain nitrogen-fixing bacteria from the black soil of northeast China and explore the effects of nitrogen-fixing bacteria on soil quality and maize growth, thus providing excellent strain sources for the development of microbial agents suitable for the environment of black soil in northeast China. [Methods] We employed microbial isolation, culture, and functional characterization to measure the nitrogen fixation, phosphorus solubilization, and indole-3-acetic acid (IAA) secretion of the screened nitrogen-fixing bacteria. Pot experiments and soil physical and chemical tests were carried out to evaluate the effects of nitrogen-fixing bacteria on soil quality and maize growth. [Results] Three strains of nitrogen-fixing bacteria were obtained from the black soil of northeast China. Among them, Paenibacillus sp. AHC-20 had higher nitrogen-fixing ability, while Raoultella sp. Z93 and Paraburkholderia sp. W22 were multifunctional strains capable of fixing nitrogen, solubilizing phosphorus, and producing IAA at the same time. The three nitrogen-fixing strains were then applied to the black soil planted with maize. The plant height, biomass, and chlorophyll content of maize significantly increased in the chemical fertilizer reduction+AHC-20 group compared with those in the control group with application of only chemical fertilizer. In addition, the content of inorganic carbon, organic carbon, organic matter, ammonium nitrogen, and nitrate nitrogen in black soil also increased significantly, which indicated that the efficient nitrogen-fixing bacterial strain AHC-20 promoted maize growth upon chemical fertilizer reduction and improved the fertility of black soil. [Conclusion] Nitrogen-fixing bacteria in black soil can effectively promote the growth of maize and improve the quality of black soil to achieve fertilizer reduction without compromising crop yields, showing the potential for the development of nitrogen-fixing microbial agents.

[Objective] Black soil regions are globally critical for grain production, with their soil health directly impacting world food security and ecological stability. These regions hold significant strategic importance for sustainable agriculture and human health. In recent years, rapid advancements in microbiome research methodologies have highlighted the pivotal role of soil microorganisms in the sustainable utilization and health management of black soil. [Methods] To systematically summarize the research status and trends in black soil microorganisms, we employed “bibliometrix” R package and VOSviewer to conduct bibliometric analysis. We quantitatively analyzed the literature from the Web of Science core collection (2014-2024) and manually screened the abstracts. [Results] The results revealed a surge in the research on black soil microorganisms after 2021, with China, Russia, and the United States being the most prolific contributors. Leading institutions included the Chinese Academy of Sciences, University of Chinese Academy of Sciences, Northeast Agricultural University, Heilongjiang Academy of Agricultural Sciences, and Chinese Academy of Agricultural Sciences. Key findings were predominantly published in Applied Soil Ecology, Soil Biology & Biochemistry, and Eurasian Soil Science. Current research focuses on microbial networks, biochar applications, and rhizosphere microecology, emphasizing the roles of microorganisms in soil fertility regulation, environmental remediation, soil improvement, climate change responses, and farming system optimization. Studies also explore interactions between microorganisms and environmental factors such as soil aggregates, physicochemical properties, and enzyme activities, with a growing shift toward mechanism insights. [Conclusion] Over the past decade, research on black soil microbiota has rapidly advanced, with current focus on the role of microorganisms in soil fertility enhancement and sustainable utilization. Future studies should integrate cutting-edge technologies such as microbiomics, metagenomics, metatranscriptomics, and metabolomics to comprehensively analyze microbial community distribution, functionality, and regulatory mechanisms. Ultimately, this will provide a robust theoretical and technical foundation for the sustainable use and health enhancement of black soil resources.

Streptomyces can produce various active secondary metabolites, which can be widely used in medical, industrial, agricultural, and other fields. The secondary metabolite synthesis in Streptomyces is regulated by pathway-specific, pleiotropic, and global regulatory genes. The two-component system, as the main signal transduction system in prokaryotes, participates in various physiological and biochemical reactions of Streptomyces and can globally regulate secondary metabolites. The deletion or overexpression of specific two-component system genes can significantly affect the biosynthesis of secondary metabolites. Identifying the functions of two-component systems and elucidating their regulatory mechanisms can contribute to enhancing the production efficiency of secondary metabolites by genetic engineering. This paper reviews the research trends of two-component systems in various Streptomyces species such as Streptomyces albidoflavus in recent years and particularly summarizes and elaborates on the regulatory mechanisms of their secondary metabolite synthesis.

As a major risk factor for cardiovascular disease worldwide, hypertension poses threats that cannot be ignored. In recent years, the role of gut microbiota in the pathogenesis of hypertension has gradually become a research hotspot. This review systematically explores the relationship between gut microbiota and hypertension and elaborates on the mechanisms of gut microbiota regulation of blood pressure by mediating inflammatory responses, influencing the microbiota-gut-brain axis, and producing specific metabolites. Furthermore, this article discusses the potential application value of gut microbiota-based intervention strategies in the prevention and treatment of hypertension and reveals the potential targets and evidence of gut microbiota in the treatment of hypertension and its complications, paving a new way for the exploration of therapeutic methods.

One Health integrates the health of the environment, animals, and humans, involving food safety, environmental hygiene, and animal and human health. Currently, antibiotic resistance is exacerbating worldwide, seriously hindering the achievement of One Health. Phages, as viruses with a century-long application history and the ability to specifically kill bacteria, bring new hope for addressing antibiotic-resistant bacterial infections. This article reviews the development history, diversity, and applications of phages in food safety and the environment, animals, and humans, with the aim of providing references for the application of phages in the era of One Health.

[Objective] To investigate the mechanism of the induced cross resistance of drug-resistant mutants of Escherichia coli to tigecycline in vitro. [Methods] We used doxycycline hydrochloride and the mutation preventive concentration (MPC) method to induce the drug resistance mutation of Escherichia coli ATCC 25922, and the drug resistance spectra of the mutants were determined. Genome-wide next-generation sequencing was utilized to analyze the mutations of key differentially expressed resistance genes of ATCC 25922 and the mutant with the highest resistance index. RT-PCR was used to determine the transcription levels of the key differentially expressed resistance genes of the mutant with the highest resistance index according to the whole genome sequencing results. The expression of key differentially expressed resistance genes in the mutant with the highest resistance index was knocked down by siRNA. [Results] Three drug-resistant E. coli mutants Y_3.2-2, Y₆₄, and Y_128-2 with different degrees of resistance to tigecycline were obtained after stepwise induction of drug resistance mutation, with the resistance following the order of Y_3.2-2<Y₆₄<Y_128-2. All the mutants showed multi-drug resistance. Fourteen resistance genes were detected with varying degrees of base mutations and amino acid mutations. In the mutant Y_128-2 with the highest resistance index, the expression of acrA, acrE, acrF, acrS, plsC, rpsJ, acrB, and macA was up-regulated, while that of tolC, marA, sdiA, and macB was down-regulated. The resistance genes rpsJ and plsC in Y_128-2 were successfully interfered with at tigecycline concentrations of 1×MIC and 1/2×MIC, and the strain regained sensitivity to tigecycline. [Conclusion] Y_128-2 develops resistance to tigecycline by the overexpression of the ribosome binding site gene rpsJ and the bacterial cell membrane permeability-related resistance gene plsC.