A novel Bacillus licheniformis strain (DM-1) was isolated from a mature reservoir in Dagang oilfield of China. DM-1 showed unique properties to utilize petroleum hydrocarbons and agroindustrial by-product (molasses) for exopolysaccharide (EPS) production under oil recovery conditions. The DM-1 EPS was proven to be a proteoglycan with a molecular weight of 568 kDa. The EPS showed shear thinning properties and had high viscosities at dilute concentrations (<1%, w/v), high salinities, and elevated temperatures. Strain DM-1 could degrade long-chain n-alkanes up to C36. Viscosity reduction test have shown that the viscosity of the crude oil was reduced by 40% compared with that before DM-1 treatment. Sand pack flooding test results under simulated reservoir conditions have shown that the enhanced oil recovery efficiency was 19.2% after 7 days of in-situ bioaugmentation with B. licheniformis DM-1. The obtained results indicate that strain DM-1 is a promising candidate for in situ microbial enhanced oil recovery (MEOR).

The Yellow River Delta region is densely covered with saline-alkali land. Wild soybean (Glycine soja Siebold & Zucc.), as a typical plant in this area, exhibits notable salt tolerance. Consequently, understanding the composition and function of its rhizosphere microbiota is therefore crucial for deciphering the mechanisms underlying its environmental adaptation. This study focused on wild soybeans from the Yellow River Delta region as the research subject. Salt stress treatments of varying concentrations were established, and Illumina-based high-throughput 16 S rRNA gene sequencing was employed to investigate the effects of salt stress on the composition and diversity of bacterial communities in both the rhizosphere and surrounding aquatic environments of wild soybeans. The findings revealed that salt stress significantly decreased the diversity of bacterial communities in both the rhizosphere and aquatic environments and altered their bacterial community structures. At the phylum level, Proteobacteria predominated across all samples, with a notable upward trend in relative abundance as salinity increased. In the rhizosphere of wild soybeans, Cyanobacteria accumulated progressively with increasing salinity. At the genus level, the relative abundances of Pseudomonas and Acinetobacter significantly increased (p < 0.05) in response to elevated salinity levels. The roots of wild soybeans harbor Pseudomonas, Shewanella, and Rhizobium, which contribute to enhancing salt stress resistance. Research has found that under salt stress conditions, the dominant bacterial communities in the rhizosphere and surrounding environments of wild soybeans may shift toward more salt-tolerant species. These bacteria likely play a critical role in facilitating the adaptation of wild soybeans to saline environments. This study not only deepens our understanding of microbial-mediated salt tolerance mechanisms but also provides valuable technical insights for utilizing saline-alkali lands and breeding stress-tolerant crops.

As a typical invasive species, Spartina alterniflora is widely recognized as one of the primary threats to biodiversity in various habitats, including wetlands. Although the invasion by S. alterniflora has been managed in multiple ways, it may reappear after treatment. How S. alterniflora affects the soil microbial community in coastal wetlands during its regeneration process has not yet been clarified. Here, rhizosphere soil samples (RSPs) and bulk soil samples (SSPs) were collected in the S. alterniflora community and a high-throughput sequencing method was conducted to analyze the composition and diversity of soil microorganisms. Meanwhile, we also obtain the soil physicochemical properties. In the present study, there was no significant difference in the alpha diversity of both bacterial and fungal communities in the SSP and RSP groups. The PCoA (principal coordinate analysis) also showed that the microbial community structure did not differ significantly between the SSP and RSP groups. The results showed that except for pH, the total sulfur (TS) content, total nitrogen (TN) content, and electrical conductivity (EC) did not differ significantly (p > 0.05) between the SSP and RSP groups. The composition of the bacterial and fungal community in the rhizosphere of S. alterniflora was similar to that found in the surrounding soils. The top two dominant bacterial phyla were Proteobacteria and Desulfobacterota in the present study. Venn diagram results also support this view; most OTUs belong to the common OTUs of the two groups, and the proportion of unique OTUs is relatively small. The LEfSe (LDA effect size) analysis showed that Campylobacterota (at the phylum level) and Sulfurimonas (at the genus level) significantly increased in the RSP group, implying that the increased Sulfurimonas might play an essential role in the invasion by S. alterniflora during the under-water period. Overall, these results suggest that the bacterial and fungal communities were not significantly affected by the S. alterniflora invasion due to the short invasion time.

Parthenium hysterophorus L., as an invasive plant, has negatively impacted the ecosystem functioning and stability of the terrestrial ecosystem in China. However, little information was available for its effects on microorganisms in the Yellow River Delta (YRD), the biggest newly-formed wetland in China. In the present study, high-throughput sequencing technology was used to obtain the bacterial community in soils and roots of different plant species, including P. hysterophorus and some native ones in the YRD. Our results showed that the Proteobacteria, Acidobacteriota, Gemmatimonadota, and Actinobacteriota were dominant in the rhizosphere soils of P. hysterophorus (84.2%) and Setaria viridis (86.47%), and the bulk soils (80.7%). The Proteobacteria and Actinobacteriota were dominant within the root of P. hysterophorus. A total of 2468 bacterial OTUs were obtained from different groups among which 140 were observed in all the groups; 1019 OTUs were shared by P. hysterophorus non-rhizosphere soil bacteria (YNR) P. hysterophorus rhizosphere soil bacteria (YRR) groups. The indexes of the ACE (823.1), Chao1 (823.19), Simpson (0.9971), and Shannon (9.068) were the highest in the YRR groups, showing the greatest bacterial community diversity. Random forest analysis showed that the Methylomirabilota and Dadabacteria (at the phylum level) and the Sphingomonas, and Woeseia (at the genus level) were identified as the main predictors among different groups. The LEfSe results also showed the essential role of the Acidobacteriota in the YRR group. The SourceTracker analysis of the bacterial community of the YRR group was mainly from GBS groups (average 53.14%) and a small part was from YNR groups (average 6.56%), indicating that the P. hysterophorus invasion had a more significant effect on native plants’ rhizosphere microorganisms than soil microorganisms. Our observations could provide valuable information for understanding the bacterial diversity and structure of the soil to the invasion of P. hysterophorus.

Neanthes japonica has high commercial value. The gut microbes in N. japonica can maintain the normal biological functions of the host. However, information on the gut bacterial community of N. japonica and its relationship with the surrounding environment is unclear. In this study, we used high-throughput sequencing technology to investigate the bacterial communities in the gut of N. japonica and soil. The results showed that the bacterial community diversity and structure differed obviously between the gut and soil samples. Bacterial richness and diversity in the gut samples decreased considerably compared to soil samples. In addition, dominant bacterial taxa varied significantly between the gut and soil samples. The dominant phyla in the gut and soil samples were Proteobacteria, Bacteroidota and Planctomycetota. The dominant genus in the gut was Burkholderia-Caballeronia-Paraburkholderia, while the dominant genera in the soil were Woeseia and Subgroup_23. In conclusion, the similarity between the bacterial communities in soil and the gut of N. japonica was small, indicating that soil had little effect on the establishment of the gut bacterial community. This study provides a better understanding of the gut bacterial community in N. japonica and the influence of the external environment on the colonization of the gut bacterial community.

Seagrass is a significant primary producer of coastal ecosystems; however, the continued degradation of seagrass beds is a serious problem that has attracted widespread attention from researchers. Rhizosphere microorganisms affect seagrass and participate in many life activities of seagrass. This study explored the relationship between the composition of microbes in the rhizosphere and the surrounding environment of Ruppia sinensis by using High-throughput sequencing methods. The dominant bacterial groups in the rhizosphere surface sediments of R. sinensis and the surrounding environment are Proteobacteria, Bacteroidota, and Firmicutes. Moreover, the dominant fungal groups are Ascomycota, Basidiomycota, and Chytridiomycota. Significant differences (p < 0.05) were identified in microbial communities among different groups (rhizosphere, bulk sediment, and surrounding seawater). Seventy-four ASVs (For bacteria) and 48 ASVs (For fungal) were shared among seagrass rhizosphere, surrounding sediment, and seawater. The rhizosphere was enriched in sulfate-reducing bacteria and nitrogen-fixing bacteria. In general, we obtained the rhizosphere microbial community of R. sinensis, which provided extensive evidence of the relative contribution of the seagrass rhizosphere and the surrounding environment.