[Effects of Tomato Planting Years on Soil Physical and Chemical Properties and Microbial Communities].

Long-term continuous cropping of facility soils could influence soil properties; however, the differences in soil properties among different continuous cropping years are still not well understood. The objective of this study was to explore the effects of continuous cropping years of tomato on the physical and chemical properties and biological characteristics of facility soil. Conventional analysis, high-throughput sequencing, and other methods were used to examine the soil physicochemical properties, soil microbial community diversity, and enzyme activities in facility soil after continuous tomato cropping for 1-3 years, 5-7 years, and more than 10 years. As the continuous tomato cropping years increased, soil bulk density and pH decreased; soil maximal water holding capacity increased; and organic matter, total nitrogen, and total phosphorus accumulated. As continuous cropping years increased, the total salt and EC value decreased with continuous cropping for 5-7 years and increased from 5-7 years to more than 10 years continuous cropping and showed a trend of secondary soil salinization. There was a significant increase in alkaline phosphatase for 1-3 years to 5-7 years continuous tomato cropping. There were significant differences in fungal community abundance among different cropping years. The Simpson index and Shannon index of fungi showed a trend of increasing first and then decreasing with the extension of continuous cropping years and reached the maximum value at 5 years of continuous cropping. The Chao1 index decreased continuously following the cropping years. As continuous cropping years increased, Streptomyces became the dominant bacteria, and Aspergillus and Pseudaleuria became the dominant fungi. The key factors affected by continuous cropping years were available potassium and available nitrogen based on the redundancy analysis. The results of this study lay the foundation for future research on the influence of continuous cropping years on the health of facility soil.

[Microbial Diversity and Population Structure of Different Salinized Soil Types in Hebei Province].

The objective of this study was to explore the microbial diversity and community composition under saline soil and to screen the salt-tolerant microbial flora from salinization habitats. The soil from three different habitats(primary salinization, secondary salinization, and healthy soil) in Hebei Province were sampled. The convention method and high-throughput sequencing technology were used to examine the physicochemical properties and microorganism diversity. The soil chemical properties of the three habitats were significantly different. Compared with those of field soil, the soil OM, AP, AK, TS, and EC values of greenhouse soil and TS and EC values of coastal saline soil were significantly higher. However, other chemical indexes of coastal saline soil were significantly lower. The diversity index and abundance of soil bacteria in greenhouse soil were the highest, followed by those in field soil and coastal saline soil as the lowest. The diversity index and abundance of fungi in two saline habitats were significantly lower than that in field soil. The community structure of saline soil was analyzed at the phylum and genus levels. Chloroflexi and its genera and Ascomycota and its genera, such as Trichocladium and Fusarium, were the dominant microbial groups in saline soil. EC and TS were the main factors affecting microbial diversity and community composition. EC and TS were positively correlated with unclassified_A4b, unclassified_Chloroflexi, unclassified_α-Proteobacteria, Trichocladium, unclassified_Chaetomiaceae, Crassicarpon, Cephaliophora, and Sodiomyces. The results of this study lay the foundation for future research on screening microbial resources needed for saline soil remediation.

[The structure and function analysis of bacterial community during aerobic composting of chicken manure].

In order to determine the changes of bacterial community structure and function in the early, middle and late stage of aerobic composting of chicken manure, high-throughput sequencing and bioinformatics methods were used to determine and analyze the 16S rRNA sequence of samples at different stages of composting. Wayne analysis showed that most of the bacterial OTUs in the three composting stages were the same, and only about 10% of the operational taxonomic units (OTUs) showed stage specificity. The diversity indexes including Ace, Chao1 and Simpson showed a trend of increasing at first, followed by decreasing. However, there was no significant difference among different composting stages (P < 0.05). The dominant bacteria groups in three composting stages were analyzed at the phylum and genus levels. The dominant bacteria phyla at three composting stages were the same, but the abundances were different. LEfSe (line discriminant analysis (LDA) effect size) method was used to analyze the bacterial biological markers with statistical differences among three stages of composting. From the phylum to genus level, there were 49 markers with significant differences among different groups. The markers included 12 species, 13 genera, 12 families, 8 orders, 1 boundary, and 1 phylum. The most biomarkers were detected at early stage while the least biomarkers were detected at late stage. The microbial diversity was analyzed at the functional pathway level. The function diversity was the highest in the early stage of composting. Following the composting, the microbial function was enriched relatively while the diversity decreased. This study provides theoretical support and technical guidance for the regulation of livestock manure aerobic composting process.

Effect of metformin on sepsis-associated acute lung injury and gut microbiota in aged rats with sepsis.

Background: Recent studies reported the association between the changes in gut microbiota and sepsis, but there is unclear for the gut microbes on aged sepsis is associated acute lung injury (SALI), and metformin treatment for the change in gut microbiota. This study aimed to investigate the effect of metformin on gut microbiota and SALI in aged rats with sepsis. It also explored the therapeutic mechanism and the effect of metformin on aged rats with SALI. Methods: Aged 20-21 months SD rats were categorized into three groups: sham-operated rats (AgS group), rats with cecal ligation and puncture (CLP)-induced sepsis (AgCLP group), and rats treated with metformin (100 mg/kg) orally 1 h after CLP treatment (AgMET group). We collected feces from rats and analyzed them by 16S rRNA sequencing. Further, the lung samples were collected for histological analysis and quantitative real-time PCR (qPCR) assay and so on. Results: This study showed that some pathological changes occurring in the lungs of aged rats, such as hemorrhage, edema, and inflammation, improved after metformin treatment; the number of hepatocyte death increased in the AgCLP group, and decreased in the AgMET group. Moreover, metformin relieved SALI inflammation and damage. Importantly, the gut microbiota composition among the three groups in aged SALI rats was different. In particular, the proportion of E. coli and K. pneumoniae was higher in AgCLP group rats than AgS group rats and AgMET group rats; while metformin could increase the proportion of Firmicutes, Lactobacillus, Ruminococcus_1 and Lactobacillus_johnsonii in aged SALI rats. Moreover, Prevotella_9, Klebsiella and Escherichia_Shigella were correlated positively with the inflammatory factor IL-1 in the lung tissues; Firmicutes was correlated negatively with the inflammatory factor IL-1 and IL-6 in the lung tissues. Conclusions: Our findings suggested that metformin could improve SALI and gut microbiota in aged rats, which could provide a potential therapeutic treatment for SALI in aged sepsis.