Soil salinization poses a global threat to terrestrial ecosystems. Soil microorganisms, crucial for maintaining ecosystem services, are sensitive to changes in soil structure and properties, particularly salinity. In this study, contrasting dynamics within the rhizosphere and bulk soil were focused on exploring the effects of heightened salinity on soil microbial communities, evaluating the influences shaping their composition in saline environments. This study observed a general decrease in bacterial alpha diversity with increasing salinity, along with shifts in community structure in terms of taxa relative abundance. The size and stability of bacterial co-occurrence networks declined under salt stress, indicating functional and resilience losses. An increased proportion of heterogeneous selection in bacterial community assembly suggested salinity’s critical role in shaping bacterial communities. Stochasticity dominated fungal community assembly, suggesting their relatively lower sensitivity to soil salinity. However, bipartite network analysis revealed that fungi played a more significant role than bacteria in intensified microbial interactions in the rhizosphere under salinity stress compared to the bulk soil. Therefore, microbial cross-domain interactions might play a key role in bacterial resilience under salt stress in the rhizosphere.

Understanding the effects of pollution on ecological communities and the underlying mechanisms that drive them will helpful for selecting a method to mediate polluted ecosystems. Quantifying the relative importance of deterministic and stochastic processes is a very important issue in ecology. However, little is known about their effects on the succession of microbial communities in different pollution levels rural ponds. Also, the processes that govern bacterial communities in polluted ponds are poorly understood. In this study, the microbial communities in water and sediment from the ponds were investigated by using the 16S rRNA gene high-throughput sequencing technology. Meanwhile, we used null model analyses based on a taxonomic and phylogenetic metrics approach to test the microbial community assembly processes. Pollution levels were found to significantly alter the community composition and diversity of bacteria. In the sediment samples, the bacterial diversity indices decreased with increasing pollutant levels. Between-community analysis revealed that community assembly processes among water and sediment samples stochastic ratio both gradually decreased with the increased pollution levels, indicating a potential deterministic environmental filtering that is elicited by pollution. Our results identified assemblage drivers of bacterial community is important for improving the efficacies of ecological evaluation and remediation for contaminated freshwater systems.

The decline in agricultural productivity because of soil salinization has become a global problem in recent years. Biofertilizers show great potential for soil improvement as a sustainable strategy; however, their effectiveness in improving saline soils and enhancing plant growth under saline stress is poorly understood. We assessed the effectiveness of biofertilizers in improving saline soils and enhancing crop growth under saline stress and investigated the related potential mechanisms. Changes in soil physicochemical properties, plant physiological parameters, and soil microbial communities were analyzed using pot experiments. The results showed that biofertilizer application reduced total soluble salts in the soil by 30.8% and increased Brassica rapa L. biomass by 8.4 times. Biofertilizer application increased soil organic matter, total nitrogen, and available phosphorus by 56.1%, 57.0%, and 290%, respectively. Simultaneously, superoxide dismutase, catalase, chlorophyll a, chlorophyll b, total soluble sugar, and proline levels also increased by 89.5%, 140%, 110%, 190%, and 130%, respectively. Biofertilizers increased the abundance of Bacillus and Planococcus and decreased the abundance of Mortierella and Aspergillus, which could potentially be the underlying reason for the promotion of plant growth. Overall, the results of this study demonstrate the efficacy of biofertilizers in improving saline soils and that the application of biofertilizer could greatly promote agricultural production.

In this study, we conducted a genome-wide comparative analysis of a former Rhodobacter sphaeroides strain EBL0706, which is now recorded as Luteovulum sphaeroides EBL0706. The genome of EBL0706 was compared with that of Luteovulum azotoformans ATCC 17025, Luteovulum azotoformans KA25, and Luteovulum sphaeroides 2.4.1. The average nucleotide identity (ANI), tetra nucleotide signatures (Tetra), digital DNA–DNA hybridization (dDDH) values, comparative genome, and phylogenetic analysis proposed that EBL0706 is a strain of Luteovulum azotoformans. Functional annotations identified a total of 4034 protein-coding genes in the genome of EBL0706, including a complete photosynthetic gene cluster. This study provides genomic molecular verification for the strain EBL0706 to be reclassified to Luteovulum azotoformans.

Petroleum contamination poses a serious threat to human health and ecosystems worldwide, and microbially driven natural attenuation is an effective approach for accelerating hydrocarbon removal. Species of the genus Rhodococcus are recognized for their ability to degrade long chain petroleum hydrocarbons. However, their physiological traits and degradation mechanisms under alkaline conditions remain insufficiently understood. In this study, soil samples were collected from the Dagang oilfield in Tianjin, China, and Rhodococcus sp. A17 was isolated as an active indigenous strain for genomic and physiological characterization under high pH petroleum degradation conditions. The results showed that strain A17 grew optimally at 30 °C, pH 9.0, and 2% salinity. Petroleum hydrocarbon degradation reached 67.8% within 72 h, with a degradation half life of 34.2 h. Genome sequencing identified 18 oxygenase related genes involved in alkane degradation, including alkB, cytochrome P450 monooxygenases, and the long chain alkane monooxygenase ladA, together with four antibiotic resistance genes. Metabolite analysis suggested that alkane degradation might proceed via terminal and subterminal oxidation pathways. Overall, these findings indicate that Rhodococcus sp. A17 exhibits multiple adaptive traits that support its potential application in the bioremediation of petroleum contaminated alkaline environments.

Nitrous oxide (N₂O) emissions from agricultural soils are an important source of greenhouse gases and are strongly influenced by fertilization practices. In this study, a field experiment was conducted from 24 June to 12 October 2024, at a saline-alkali farmland site in Binzhou, Shandong Province, China, to evaluate the effect of Bacillus subtilis biofertilizer on N₂O emissions and to explore the underlying mechanisms. Compared with conventional chemical fertilization, the Bacillus subtilis biofertilizer treatment reduced the cumulative N₂O emission flux by 39%. At the N₂O emission peak, the emission flux under the biofertilizer treatment was 40.7%, 18.2% lower than that under the CF and CBF treatments, respectively. Functional gene analysis further showed that at the N₂O emission peak, the biofertilizer treatment reduced the copy number of Bacterial-amoA by 94% and 83% relative to CF and CBF, respectively, while the hao gene abundance in the CF treatment was 7.67, 24 times higher than that in the BF and CBF treatments, indicating that the reduction in N₂O emissions was closely associated with suppression of the nitrification process. In addition, the biofertilizer treatment showed the highest plant nitrogen uptake. All fertilization treatments significantly increased crop yield compared with the control, whereas there was no significant difference in yield among BF, CF, and CBF treatments (p > 0.05). These findings indicate that B. subtilis biofertilizer can mitigate N₂O emissions from saline-alkali farmland without reducing crop yield and may represent a promising strategy for sustainable agricultural management.